blog

Build a healthy food pyramid

Wed, 08 Sep 2010 10:05:00 +1200

The food chain is often described as a pyramid – or, more precisely, a “biotic pyramid”.
Soil forms the base of the pyramid, plants are on the lower level, then plant-eating animals (herbivores), with animal-eating animals (carnivores) on the top level. If humans are included, they are placed at the very top.
The pyramid design shows very clearly that there are many species and individuals at the lower levels, and fewer at the higher levels of the food chain. The reason is that from one level to the next (when one organism eats or is fed by another), there is a certain amount of energy loss or wastage (food is stored energy). When we move from the plant realm to the animal realm, we are moving to the top of biotic pyramid.
So, what affects animal (and human) health and nutrition? Are animals really that much different from plants? If you raise animals, or your family just wants to be healthy, you need to know something about animal and human nutrition.

Sickness

We need to remember that sickness is not normal, either in humans or animals. Robust health is the normal condition or human and animal bodies. Certainly, some people are ill so much of the time they’ve probably forgotten what it feels like to be well. And farmers generally expect to have a certain number of sick and young animals that die.
Nor does it pay to be sick, whether you’re human or animal. Doctors and veterinarians, drugs and medicines do not come cheap. Just think how much money and time could be saved if you or your animals were never sick.
Unfortunately, medical and veterinary training institutes do not spend a lot of time teaching prospective doctors and vets how to keep their patients healthy by preventing disease. Rather it’s ambulance-at-the-bottom-of-the-cliff logic – diagnose a disease, give it a complicated name, and prescribe a drug or poison to fight it, often by attacking the symptoms rather than the cause.
We often hear the phrase, “you are what you eat”, and we know that animals get their food, which later becomes their body substances, from eating plants, or animals that eat plants. And, where do plants grow? In the soil, of course.
William Albrecht summed up the role and importance of the soil: “We know that the soil grows grass; that the grass feeds our livestock; and that these animals, in turn as meats, are our choice protein foods. We can, therefore, connect our soil with our health via nutrition. Since only the soil fertility, or that part of the soil made up of the elements essential for life, enters into the nutrition by which we are fed, we may well speak of animal health as premised on soil fertility.”
Remember that plants take simple chemical substances (carbon dioxide, water and minerals) and combine them into more complex substances (carbohydrates, fats and proteins), trapping and storing the sun’s energy in the form of chemical energy.

‘Building blocks’ combined

Animals, however, do the reverse. Their body and cell functions break down the complex food molecules, releasing some of the stored energy; but then, as plants do, animals combine the simpler “building blocks” obtained from food substances into more complex substances that make up the cells and issues of an animals’ body.
Remember, too, that plants can also break down complex food molecules into building blocks and energy. Many of the basic molecules (animo acids, ATP and vitamins) involved in animals are the same or very similar to those found in plants. But many are different, because plants do not have muscles, nerves, bloods etc.
Just as the wrong nutrients from the soil can disturb plant metabolism and cause ill health, so animals can become sick from not getting the right nutrients in the food they eat, and the consequent lack of vitamins and minerals.
Other factors can contribute to animal health problems, but essentially sickness comes down to the body succumbing to one or more stresses – such as poor ventilation, contaminated water, bad weather, infectious diseases, parasites, improper handling and injury, noise and other frightening conditions, lack of exercise, poor nutrition.
Most of these stresses can be reduced by good farming practices and animal management, with the payoff coming in higher production and healthy offspring.
It all starts in the soil. The healthier the soil, the better the food for animals; and well nourished animals are better equipped to resist or tolerate stresses such as diseases, parasites and bad weather.

Plumbing & food-factory secrets

Wed, 08 Sep 2010 09:51:54 +1200

Most of us are astounded to discover just how extensive and complex the plumbing system in plants is. Not only do plants take up water and nutrients through their roots, but also through their above-ground upholstery – their leaves.

Plants can take minerals from the air in the form of dust particles and floating ions. Indeed, some scientists believe the air contains all the nutrients plants need. A year’s rain delivers ample supplies of nitrogen, phosphorus and calcium, and these can be absorbed directly through the waxy cuticle that covers the outer cells of plants, or through the tiny openings (known as stomata or stomates) on the leaf surfaces.

Most plants have many tiny hairs on their leaves; the outer, waxy covering on these leaves provides an electrical charge which acts as an electret (a material with a permanent electrical charge). Similar wax-covered hairs on insects attract molecules out of the air, and there is evidence these plant hairs act as antennae to attract molecules from the air.

This ability of plants to absorb nutrients through their leaves is the basis of foliar feeding of some nutrients. It is often used to supply trace elements or to evoke a quicker response than is possible by relying on absorption through the plant roots.

Water and nutrient molecules are transported around the plant through two tubular vascular tissue systems (like pipes) - the xylem tissue takes them mainly upward, while the phloem carries food and minerals from one place to another.

When water and nutrients get into the xylem, they are carried upward through hollow, tubular vessels by a pulling force from above. Those parts of the plant, such as leaves and actively growing areas, that need water create a water deficit and pull the water up through the xylem.

Everywhere one or more leaves attach to the stem (what we call a node), there’s a complex “traffic interchange” where xylem and phloem tubes divide into branches that go out into the leaves. As the growing season progresses, mineral deposits can clog up the plumbing at the nodes of a plant in poor health – just as our house plumbing can get blocked.

Out into the leaf, the veins of the plumbing get smaller and smaller until the xylem vessel ends at the “food factory”. It’s surrounded by rows of tall, crystal-like columns, mostly transparent and studded with many emerald green, oval objects (chloroplasts).

It’s within these chloroplast-containing cells that the food is made which, ultimately, feeds nearly all life on earth. It’s where photosynthesis occurs – the chemical combining of two common materials (water and carbon dioxide) into a life-sustaining molecule (sugar). In other words, the plant is also a “chemical factory”.

Photosynthesis combines the raw materials of water and carbon dioxide by converting light energy from the sun into chemical energy to form the “manufactured product”. It’s a step-by-step process in and near the green chloroplasts inside the cells – just like the assembly line in any factory. The chloroplasts are green because they contain the pigment, cholorophyll, which “traps”, or absorbs, the light energy from sun.

The sugar molecule (food) is a form of stored chemical energy. Incidentally, we run our motor vehicles on stored photosynthetic energy that was trapped thousands of years ago and changed into oil.

Chemical energy in cells is stored temporarily, and carried from place to place in the cell by special energy carrier molecules. There are various types of carriers, but all contain one or more atoms of phosphorus – which, of course, is one of the macronutrients of plant nutrition. This ability to carry energy inside its cells is one of the main reasons plants and animals need phosphorus – and why P has been termed the “energy currency” of plants.

Nearly all “assembly-line” chemical changes in cells require enzymes – biological catalysts, or “spark plugs”, that speed up chemical reactions. Without them, chemical reactions would not occur fast enough to sustain life.

Enzymes are made up of a large protein molecule, and usually another necessary part, known as a cofactor, coenzyme or metal activator. This latter part can be a metal ion (iron, copper, zinc, magnesium, potassium or calcium) or an organic molecule (a vitamin or modified vitamin).

Each cell contains thousands of enzymes, each of which is very specific and can affect only one chemical change – only one step of the assembly line. Enzymes are believed to fit like a key into a lock on the surface of a substance, holding the reacting chemicals together long enough for reaction to take place.

And enzymes are the workers we’ve all dreamed about. They are not “used up”, but are released to perform the process over and over again – at a rate of anything from 10 to 10 million times a second!

Welcome to Plant City

Wed, 08 Sep 2010 09:34:39 +1200

Plants are a lot like people really. They just love stretching out and soaking up sun and moisture.
True, plants are different organisms from us and the animals we’re familiar with. Plants do not have eyes or ears, bones, nerves or muscles. They can’t walk or run around from place to place.
But, just like us and animals, plants are sensitive to light and vibrations. They have a supporting skeleton, they display electrical activities, and they do a considerable amount of moving. They are living, breathing organisms.
In fact, a living plant is very much like a busy city – only much more complex. Plants are built up of thousands of units, known as cells, just as cities are largely made up of buildings. Just as city buildings have different functions, so do plant cells – some are factories, so are for storage, some form a transportation system like the plumbing of a city. The people and workers in cities correspond to the active ions and molecules, enzymes and energy carriers that help “run” a living plant.
And surrounding these “plant cities” is the soil. And, just like the environs and hinterland of cities, so the rhizosphere – the zone close to plants’ roots – soil has a massive influence on plant life.
The soil around plants is perpetual motion – atoms, ions, molecules of all matter constant vibrate and float around. Fuzzy-looking spheres and lumps of various sizes float and zoom by – they’re ions and molecules of water, hydrogen, carbonate, calcium, potassium, ammonium, nitrate and so on.
Monsters, such as bacteria and protozoans (one-celled animals) also snuffle and gurgle about; there may be snakelike nematodes or threadworms.
Primarily, plants absorb water and nutrients from the soil. If they do not get enough of either, they will not grow.

Water

The absorption of water into plants is controlled by osmosis – which relies on the relative percentages of water on the outside of cells compared with that within. Water moves from where it is more concentrated to where it is less concentrated. So, if there is more water in the rhizosphere than inside a root, water automatically and easily seeps through. Sets of tiny hairs on the tip of plant roots add surface area to improve absorption.
The only complicating factor is that some water molecules are held so tightly on the surface of soil particles they can never be absorbed by roots.
If plants do not get enough water, they die. Drought – not enough water in the soil – is one cause. But plants can also die because too many salts have been dissolved in water, lowering relative percentage of water outside the root cells. This leads to reverse osmosis, where plants lose rather than absorb water, and either die or suffer root damage. The problem occurs from farmers applying too much salt fertiliser or manure to the soil.
In addition, the more humus – which works like a sponge – in soil, the more water it can absorb and hold, and the better the plant growth and crop.
Once water reaches the central core of a plant root, which is where the “plumbing” is, it enters the water-carrying tissue and is delivered via the root and stem system to wherever it’s needed.

Nutrients

Plants need a variety of chemical nutrients. Essential plant nutrients come as macronutrients (such as nitrogen, calcium, phosphorus, potassium, magnesium and sulphur) that are needed in larger quantities, and as micronutrients, or trace elements, such as iron, copper, zinc, cobalt, boron, manganese and molybdenum ) that are needed in very small amounts.
Plants can take in nutrients in various forms – as simple ions (potassium, calcium, zinc), as molecular ions (nitrate, ammonium, sulphate), as chelates (iron, zinc, copper, manganese, cobalt), as organic molecules ( amino acids, ).
Just like people, the more active a plant is, the hungrier it gets – and the more nutrients it needs, the more hydrogen ions its roots produce, and the more nutrients it can absorb. This is a precise, self-regulating system that supplies just the right amount of nutrients at the right time.
However, the system can be fouled up. Too heavy an application of highly soluble salt fertiliser will “flood” the soil water with so many ions the plant will be forced to take in more than it needs. This can upset its metabolism and can be toxic to animals.
But there is a second line of defence. Plant roots have a layer of cells, called the endodermis, just outside their “plumbing region”, which acts like a filter regulating the passage of water and nutrients from outside to inside. The endodermis can help protect the plant against toxic elements or help it concentrate needed nutrients and reject abundant unnecessary ones.

Soil – the core of our survival

Wed, 08 Sep 2010 08:44:31 +1200

Soil is the absolute basis of agriculture – and, therefore, of human existence. We survive by eating plants grown in the soil, or by eating animals that eat plants grown in the soil.

Quite clearly, soil is our most important national resource. Wise use and management of the relatively thin upper layer, the topsoil, is crucial for us to maintain good health and a high standard of living.

But, because of misuse, a frightening large amount of topsoil is lost to erosion – well over 30 tonnes per hectare in some of the worst-affected areas. It can take several hundred years for a couple of centimetres of soil to form, so it’s obvious we cannot keep losing our topsoil at this rate for much longer.

To make things worse, some of our once-fertile soil, along with our groundwater and wells, is being polluted by toxic substances.

We are literally in danger of destroying the land that feeds us.

Let’s look a little at the detail of soil. For a start, it’s not just dirt. It’s a very complex substance, a mixture of several components, formed by the weathering of rocks on the earth’s crust. Typical soil is made up of:

About 45% minerals. Some, such as sand, clay and iron oxides, are insoluble and are not used by plants; others, such as calcium, potassium and magnesium, are soluble and valuable plant nutrients. Particles of minerals range in size from coarse gravel and sand to fine silt and small clay particles (colloidal).
About 25% water. It’s needed as part of the plant cells, and to dissolve and carry nutrients. But too much water in the soil can exclude the necessary air.
About 25% air. It provides oxygen to the roots and micro-organisms, and nitrogen to nitrogen-fixing bacteria. A good supply of air is vital for fertile soil.
About 1-5% organic matter. This includes living soil organisms and dead organic matter that decomposes to form humus. Good soil has 2-5% organic matter, and up to 10% is beneficial.

Colloidal particles (less than 0.002mm in size) occur in clay and humus, and are important to soil because of their great ability to hold some plant nutrients. And humus colloids can hold three times the nutrients clay can.

A good soil should have a loose, almost spongy, texture created by tiny sand, silt and clay particles clustering into small “crumbs”. The soil structure, or tilth, affects the ease of water penetration and aeration, root growth, activity of soil organisms, and availability of nutrients.

Good tilth is usually found only in the upper layers of soil; the lower, harder layer is often referred to as “hardpan” or “claypan”. Soil with a good tilth is easy to plough, soaks up water like a sponge, and resists erosion.

Freezing and thawing, wetting and drying, penetration by plant roots, animal burrows, and colloids all contribute to a good soil. But the most important factor of all is a “glue” secreted by roots and soil micro-organisms – which is one of the many reasons soil organisms are so important.

Too much tillage can destroy good tilth in poor soils. So can removal of the vegetation cover, and excessively acidic or alkaline conditions.

pH is a soil condition you hear about a lot from “experts” – excessively so, in fact. It’s a measure of the acidity or alkalinity of any substance using a scale of numbers from 0 (most acid) to 14 (most alkaline) with 7 neutral. Most soil pH varies from 4 to 10, but most crops do best in slightly acid soils (6-6.8). Soil pH affects the availability of nutrients, which may be connected with nutrient deficiencies and toxicities; it also determines the types of soil organisms and their ability to flourish – most bacteria, for example, cannot live in very acid conditions, whereas many fungi can.

The traditional belief is that acidity is bad and should be countered by the application of lime. But some acidity is necessary for plants to absorb certain nutrients from soil colloids.

Experts usually base their liming recommendations on one pH test, but testing several times a year reveals pH can change significantly during a growing season. What’s more, fertilisers and soil conditioners have short-term and long-term effects on pH.

So, as long as the pH does not reach extremes either way, testing and “correction” are less important than many people think. The use of lime to “sweeten” soil is a case of doing the right thing for the wrong reason. In fact, crops benefit more from the calcium they get from the lime than they do from pH control.

A balancing act – naturally

Wed, 08 Sep 2010 08:29:17 +1200

Before we tackle a problem, it’s often best to step back and look at the bigger picture. If we can understand the whole issue – its symptoms, causes and possible solutions – we’re usually better placed than if we concentrate solely on the problem.

Agriculture works with things of nature…… with natural systems, with living biological species of plants and animals, with the natural environment. Nature, of course, is incredibly complex – even a tiny cell is more complex than any man-made machine.

The study of the way in which natural organisms (plants and animals) and their environment inter-relate is known as ecology. Like the gears and levers of a machine, each “part” of nature has its own tasks and functions. Together, the “parts” form a larger entity – ecosystem, to use the terminology of ecology. An ecosystem works under certain natural laws, and a further problem or penalty follows if you break any of these. The better we understand ecosystems and how they operate, the more chance we can cope with problems – or, even better, avoid them.

In terms of agriculture, the most important natural system is the general food chain. The basic food cycle is very simple, and most of us are subconsciously aware of it.

Lets start with the organisms we are most familiar with – our domesticated animals, and ourselves. We consume mostly plant and animal material. Domestic animals eat plants, almost entirely. Plants, however, make their own food through the photosynthesis process. They do this within their leaves, using carbon dioxide, water, mineral nutrients and light energy.

However, the food chain could not operate if that’s all there was to it.

Animals produce what we commonly call waste, mostly manure and urine. Most crop plants also produce unused roots, stalks and leaves, manure and plant residues we call organic mater. This is returned to the soil where it decomposes into humus, forming natural food for plants, and providing them with nutrients they need to survive.

This cycle runs on energy just as a man-made machine does. Energy stored by the plant moves through each step of the system. It works under definite rules, and a flaw in any part of the system creates a problem at the next step. In other words, the “balance of nature” can be upset – and we can do this easily.

For now we will focus on one trace element that is essential in the metabolic process. We will look at others in latter editorials.

Take the example of a zinc deficiency in soil. If a plant doesn’t get enough zinc, problems occur. Zinc is needed in plant enzymes that are vital in the metabolic functions of cellular respiration. So a zinc-deficient plant will have poor cell functions, preventing it from becoming normal and healthy.

A zinc-deficient diet can lead to many problems in humans and animals – slower healing of wounds and skin irritations, major deficiency problems in the intestine, loss of hair, skin troubles.

Even if soil has a good level of zinc, only a minor amount may be available to plants. For instance, zinc is less available to plants in high-pH soils than in those with low pH. So, sickness in animals may be caused by zinc-deficient soil, or the low zinc content in the soil in which the plants grew?

Or maybe not – because these are just the symptoms. The real cause may be that something is wrong with the soil, that it has been affected by human interaction- such as using toxic chemicals in agriculture and modifying the pH level, or not returning enough manure and plant residues to the soil.

The good news is that whatever has happened can be fixed, and zinc availability can be restored to adequate levels. This creates an environment that develops healthy plants, which, in turn, helps keep animals and humans healthy too.

The science of ecology is based on the view that everything is connected to everything else – a view reflected in the way natural systems are organized, functions and and continually interacts.

Bottom line based in the soil

Wed, 08 Sep 2010 08:26:38 +1200

Animals need food for two reasons – to produce energy; and to build new cells and grow, reproduce, repair injury, and produce milk or eggs.

Animals normally use carbohydrates and fats as “fuels”, although proteins can also be used for this purpose in times of starvation or excess. As far as growth is concerned, the essentials are proteins and minerals (calcium and phosphorus for bones and teeth, iron in the blood, sulphur in some amino acids).

But the cellular metabolic activities of both energy production (catabolism) and growth (anabolism) also require thousands of different enzymes, each of which consists of a protein and a cofactor (a mineral element or a vitamin). So, there is a need for vitamins and minerals such as copper, zinc, iron, calcium, potassium and magnesium.

Some minerals also perform other vital functions. Phosphorus is part of the energy-carrier molecule; sodium and potassium regulate internal water balance; chlorine and potassium regulate pH; iodine is part of the thyroid hormone.

And then there’s water – an essential nutrient substance as it is a necessary component of all living cells. Indeed, cells are mostly water – 70% in the case of an average animal cell.

The essentials

Some nutrient substances are essential in an animal’s diet; others can be manufactured within the animal’s body or cells. On the “essential” list are: calcium, phosphorus, sodium, potassium, chlorine, magnesium, iron, manganese, copper, zinc, fluorine, sulphur, iodine, cobalt.

Around 10 of the amino acids, and vitamins are also essential. However, in ruminants and most plant-feeding animals, some amino acids and vitamins are provided by the bacteria living in the digestive tract. Most animals apart from humans, monkeys and guinea pigs can manufacture their own vitamin C.

But there’s more to feeding animals than just the presence of the essential nutrients. They must be present in the proper amounts and proportions to ensure optimum good health. For example, a lactating cow needs a large daily supply of calcium, but just a touch of cobalt. Some elements, such as fluorine, are toxic in too-large amounts. Some interactions can damage animal health.

As is so often the case, good animal health depends not just on heaps of any old food, but on high-quality food in the right proportions.

The most precise way to determine the energy value of food is to count calories (kilojoules in the metric lingo) just as humans do. A calorie, or kilojoule, is a measure of heat energy (the amount of heat required to raise the temperature on one gram of water by 1Cº).

Another measure of food value is the biological value. It is not a direct measure of total food value, but of protein quality. It compares the relative proportions of essential amino acids in the food with the animal’s needs. A protein lacking any essential amino acid is a poor-quality protein.

All of this reinforces the message that the quality, not just the bulk, of food is extremely important in promoting animal health. And the amount of those amino acids is one of most important aspects of food quality.

The amino-acid production of plants grown in mineral-deficient soil has been shown to be unbalanced. And animals are known to grow better when fed food where all nutritional substances are in balance.

The bottom line

The bottom line of feeding agricultural animals is their efficiency in converting food into meat, milk, eggs or wool. This goes beyond just the digestibility and assimilation of food into body cells. Farmers are paid according to production, and quality is generally as important as quantity in determining prices.

Food efficiency also varies from species to species. Dairy cows are around 25% efficient in using food calories and 34% efficient in converting proteins into milk; a hen is 10% efficient for calories and 16% for proteins in egg production; a beef steer is 3% efficient for calories and 9% for proteins in producing meat.

There are other variables, too – the breed or variety of animal, the presence or absence of the various stresses, genetic variation of individual animals, and the quality of food the animal eats.

A small increase in food quality can lead to a much greater increase in food efficiency and production, and in farming efficiency. In some cases, less of the correct food can produce more output.

Sounds like farming paradise. So what’s the catch? It all goes back to the soil and the proper fertility for the plants that grow in it, and the flow-through effect to providing animals with the correct balance and quantity of feed.

But, as with most things, it all starts with the basics – in this case, the soil.

The pH connection

Wed, 08 Sep 2010 08:24:43 +1200

pH is a soil condition you hear about a lot from "experts" – excessively so, in fact. Nevertheless, pH is important, and we should not ignore what it is telling us.

pH measures soil acidity and alkalinity. And, as soils become more acid, grasses and clover do not grow as well. Which reflects why pH levels provoke so much interest in New Zealand’s grass-based agricultural system?

The acidity or alkalinity of any substance is defined by pH using a scale of numbers from 0 (most acid) to 14 (most alkaline) with 7 neutral. Most soil pH varies from 4 to 10, but most crops do best in slightly acid soils (6-6.8).

Soil pH affects the availability of nutrients, which may be connected with nutrient deficiencies and toxicities; it also determines the types of soil organisms and their ability to flourish – most bacteria, for example, cannot live in very acid conditions, whereas many fungi can.

The traditional belief is that acidity is bad and should be countered by the application of lime. But it is important to remember that some acidity is necessary for plants to absorb certain nutrients from soil colloids.

We should also remember that, when pH levels are above 6, the nitrogen-fixing bacteria azotobacter can flourish; well aerated soil allows aerobic bacteria to grow, along with fungi and actinomycetes. But if heavy rain accumulates in a low area, air is excluded and harmful anaerobic, denitrifying bacteria are allowed to release nitrogen, while fungi actinomycetes and aerobic bacteria remain become temporarily dormant.

It’s also worth noting that experts usually base their liming recommendations on one pH test. But testing several times a year reveals that pH can change significantly during a growing season. What’s more, fertilisers and soil conditioners have short-term and long-term effects on pH.

So, as long as the pH does not reach extremes either way, testing and "correction" are less important than many people think. The use of lime to "sweeten" soil is a case of doing the right thing for the wrong reason. In fact, crops benefit more from the calcium they get from the lime than they do from pH control.

Once soil pH drops under 5.8, the availability of organic nitrogen to grasses and molybdenum to clovers is reduced. As pH drops below 5.5, the amount of toxic aluminium and manganese in the soil increases, and roots do not grow into the soil. The result is that plants suffer more when rainfall is low.

While nitrogen fertilisers (except calcium ammonium nitrate and any nitrate fertiliser) do increase soil acidity, their effect is much less than photosynthesis and nitrogen.

The Ministry of Agriculture & Forestry quotes these rules of thumb to determine the relationship between nitrogen fertiliser and ph levels: ammonium sulphate requires 5kg lime/kg N to neutralise acidity – 112kg/ha lime per 100kg/ha ammonium sulphate applied; diammonium phosphate (DAP) requires 3.5kg lime/kg N (64kg/ha lime per 100kg/ha DAP applied); urea requires 1.8kg lime/kg N (82kg/ha lime per 100kg/ha urea applied.

MAF says that evidence from recent trials demonstrates that when soil temperates fall below 6ºC when nitrogen uptake is low, the risk of loss from leaching rises. MAF suggests farmers follow these strategies:

Match nitrogen applications to plant growth to increase N uptake by plants – nitrogen uptake increases during periods of active plant growth.
Avoid applying nitrogen during dry (drought) periods – dry periods reduce both plant growth and plants’ ability to take up nitrogen.
Avoid applying nitrogen after a dry (drought) period until sufficient regrowth has occurred after rain – this prevents the applied nitrogen from being lost before the plants are able to take up nutrients.
Ensure that applied nitrogen is in proportion to other nutrients, according to plant requirements. The application of nitrogen will increase plant growth and the uptake of other nutrients; but, if too much nitrogen is applied relative to other nutrient requirements, plant growth will be restricted and the efficiency of nitrogen use reduced.
Consider using nitrification inhibitors, especially on camp areas. In areas where animal urine is deposited, nitrification inhibitors reduce nitrate leaching and increase the amount of nitrogen available for plant uptake. The overall effect is to reduce nitrogen loss and increase dry-matter production.
Ensure that soil fertility and pH levels are at economic optimum for the individual farm before embarking on high nitrogen use. Increased use of nitrogen increases the uptake and export of other nutrients, and may result in pH changes. Use soil tests and nutrient budgets to establish optimum soil fertility and pH levels.
Ensure that your farm system and infrastructure allow the full use of extra pasture growth.

The decomposers

Wed, 08 Sep 2010 08:23:14 +1200

Remember the old line about what happens to composers when they die. They decompose. Well, forget all that when it comes to dead organic matter and the soil. Because quite the opposite occurs.

Dead organic matter – in the form of the dead bodies of plants and animals, plus the waste excretions of animals – is broken down and returned to the soil so that the nutrients it contains can be reused by plants.

Today’s environmentalists call it recycling. But Nature has been on to this secret since the world began. It is the final – or should that be the first – link in the food cycle.

There’s a whole host of special organisms out there ready, willing and able to break down -or digest – organic matter. They’re the decomposers, and they use this organic matter for food to build their own bodies or cells; when they eventually die or are eaten by other soil organisms, the nutrients can be used by plants.

The most important of these decomposers is the micro-organisms: bacteria, actinomycetes, fungi. Earthworms also perform valuable service if they’re around by consuming and chewing fresh organic matter into finer particles that can later be more readily attacked by the micro-organisms. Worms haul a lot of surface organic matter down to the deeper layers of the soil. They also aerate and turn over the soil through their burrowing activities, and they enrich the soil through their waste and dead bodies.

But back to the main working decomposers. Single-celled bacteria help decompose organic matter to form humus, convert inorganic chemicals into useful plant nutrients, and break down (detoxify) man-made toxic chemicals. Thread-like actinomycetes help in producing humus, while the similarly thread-like fungi produce humus, with one fungus type (the mycorrhizae) symbiotic in the plant roots where it helps with nutrient absorption and root growth.

Most dead organic matter used in agriculture is of plant origin, either crop residue (dead stalks, leaves, roots, cobs etc) or animal manures containing a large percentage of partly digested plant matter).

So, the hungry army of decomposers starts with a food source that contains a large amount of the components of plant-cell walls – cellulose, hemicellulose, lignin. These materials are very resistant to decay, especially lignin which can take years to break down. The rest of the plant material is made up of whatever cell contents used to be in the plant, and includes sugars, starches, fats and proteins, all of which are easily digested.

These initial components of organic matter have much more carbon than nitrogen. Animal manures not only contain a considerable amount of undigested food containing these components, but also millions of bacteria (living and dead) from the animal’s digestive tract, important mineral elements (calcium, boron, manganese, copper and zinc), and vitamins.

What exactly happens when dead organic matter decomposes depends on the circumstances.

If material is left exposed to air on the surface where temperatures do not favour microbial growth and where there is too little moisture, a slow process of decomposition occurs. It is known as oxidation/mineralisation. The elements of carbon, oxygen, hydrogen and nitrogen, which make up carbohydrates, fats and proteins, are released into the air as gases: carbon dioxide, water vapour, nitrogen, nitrogen oxides. The inorganic mineral elements (sulphur, potassium, phosphorus etc) are returned to the soil.

This process of oxidation/mineralisation is very wasteful, as a lot potentially useful energy and nutrients are lost into the air. Only the minerals are saved for later use. However, there are advantages of leaving organic matter on the surface as a mulch: protection from erosion; better water absorption and retention; moderating soil temperature; weed control.

Nutrients can be used much better if organic matter decomposes in the soil, not on it, as the moisture and temperature conditions are more favourable for the growth of micro-organisms.

Decomposition can happen anaerobically or aerobically.

Anaerobic decomposition occurs wherever organic matter does not contain much or any oxygen – such as inside a pile of manure or deep in the soil. Typically, the organic matter goes through two stages – ammonification when some bacteria release considerable nitrogen in the form of ammonia; fermentation when bacteria and fungi release gases, many of which have strong smells and some of which are toxic to plants and animals. It’s what you notice when your nose gets too close to manure, rotted grain or silage.

There is little cellulose or lignin breakdown in anaerobic decomposition (these are the conditions under which peat forms), and it is a slow process (up to 10 weeks) that releases little heat. Aerobic decomposition has the advantages of providing more nutrients to plants without producing toxic by-products.

Aerobic decomposition happens quickly and releases a considerable amount of heat. Several types of micro-organisms take turns in breaking down the various elements of the organic matter.

Aerobic decomposition creates humus – a complex, colloidal material containing proteins, lignin, fats, carbohydrates and organic acids, plus other broken-down products, metabolic products, and the remains of the micro-organisms that did the decomposition job.

Humus is very valuable to the soil because it is a storehouse of plant nutrients, it helps make nutrients available to plants, and it improves soil tilth.

In reality, of course, most organic matter decomposes under both anaerobic and aerobic conditions. On the outside of a mass of organic matter, there will be plenty of oxygen and aerobic organisms flourish. Inside the organic matter or in poorly aerated soil, the conditions are anaerobic. In addition, many bacteria can function as either aerobes or anaerobes.

Detox – by decomposers

Wed, 08 Sep 2010 08:21:17 +1200

Nearly all of us are familiar with composting. For many of us, it’s going on in our backyard everyday. Like rust, it never sleeps.

But composting – the practice of letting organic matter rot before you apply it to the soil – is more than merely a backyard hobby. It’s a direct application of microbial decomposition to agriculture, and is particularly favoured by followers of organic farming methods and, of course, by many gardeners.

It’s quite simple really. You just let organic matter rot before you put it on the soil. The product of this rotting (decomposition) is compost – and it is essentially humus, which, of course, is so crucial to soil health.

It is, therefore, very beneficial to the soil, particularly well-drained, sandy soils because it reduces drainage (leaching) more than fresh, uncomposted organic matter will.

Compost also has "instant" properties. It comes already prepared ("instant" humus), and its beneficial properties are available to the soil immediately – no waiting weeks or months for organic matter to decompose in the soil. Compost is an instant elixir – it can transform unhealthy, poorly aerated, toxic soil that lacks beneficial organisms into healthy and aerobic soil.

In contrast, adding fresh organic matter to unhealthy soil will do no good, and often causes harm by promoting anaerobic decomposition. What’s more, if fresh organic matter is added to soil, the rapid microbial decomposition "ties up" most of the nutrients before the crop plants can use them. In other words, the micro-organisms compete with the plants for nutrients which do not become available to plants until the micro-organisms die.

Compost, however, does not cause this problem, and can be applied at any time. If it is applied at high temperatures, it kills weed seeds and disease-causing organisms.

On the minus side, some nutrients and carbon dioxide that could be used by crop plants are lost during the composting process. If the soil is healthy, and fresh organic matter is applied in the right way at the right time, the results can match or better those of compost.

Animal manures

Used properly, animal manures can be a very big asset to soil and crops. But if they are not used properly, manure nutrients can be lost, and soil and crops can be harmed. In general, manure that has rotted aerobically will help soil and crops by adding organic matter and nutrients.

Ploughing under a growing crop is generally very beneficial to the soil and future crops. Young growth is usually decomposed very quickly, adding nutrients. Older plants have more resistance to decay and, therefore, contribute more to the soil’s humus content. Ploughing in non-legumes creates rapid decomposition, which temporarily ties up nitrogen needed by crops; legumes, however, can increase the soil’s nitrogen content straight away. Hence the practice of planting a mixture – a legume, with a grain or a grass.

Green manures generally release their nutrients quickly, benefit only one year’s crop, and contribute little humus to the soil. Animal manures decompose more slowly, provide nutrients for more than one year, and add more humus. Mixing the two picks up the advantages of both.

The detox

Soil decomposers also provide another valuable service: the breakdown (detoxification) of many of the toxic chemicals we spread so liberally around the environment.

Many herbicides and pesticides are highly toxic, often to "good" animals and even to crops. They may also pollute and accumulate in soil, surface-water and groundwater. Fortunately, many herbicides are less dangerous, and most do eventually break down, some faster than others.

Some become held (absorbed) by particles of clay and organic matter, where their toxicity is greatly reduced. Some are broken down by sunlight or chemical reactions with soil.

But a major method of breakdown is by the metabolic activities of living soil organisms. Soil bacteria are especially talented at degrading many pesticides simply by using them as food. High levels of herbicides or pesticides will kill most or all soil life in a local area, but new organisms usually colonize the poisoned area from surrounding soil. Some toxic chemicals are readily broken down, but others are very resistant to microbial attack.

High humus levels in soil are the most important factor in facilitating pesticide degradation. Unfortunately, many modern farming practices generally reduce or destroy humus, along with the beneficial organisms that produce it. Too often, more and more pesticides and herbicides are poured on to kill the weeds and pests that result from destroying humus and soil organisms.

It’s one of those vicious circles. And it doesn’t really make much sense – does it?

You reap what you grow

Wed, 08 Sep 2010 08:19:13 +1200

Flower buds and flowers are prerequisites to the production of seeds or fruit by plants.

Tiny flower buds are actually formed long before they become obvious. In corn, for example, the cob and tassel buds form when the plant is only about knee high. In apple trees, the buds that will produce next year are formed this year.

The quantity and quality of fruit and seeds depends partly on the number and health of the flower buds – along with other factors such as weather, light, nutrients and pollination. Farmers clearly have no control over some of these, but they can certainly influence plant nutrition and health. Once again, this reinforces the importance of fertile soil.

After flowers have been pollinated, seed and fruit development begins – and the nutrition and health of plants are critical during this time. Water, sugars, amino acids, organic acids, inorganic nutrients, and hormones from roots, stems and leaves are redistributed to the developing seeds and fruit.

Plants’ needs for some soil nutrients peak at this time – similar to the demands of human pregnancy. If plants are to cope properly with this demand for nutrients, their "plumbing" (xylem and phloem) must be in good condition, and all their metabolic and photosynthetic activities must be in top nick.

Remember the xylem and phloem. They’re the two tubular vascular tissue systems (like pipes) that transport water and nutrient molecules around the plant. The xylem tissue takes them mainly upward, while the phloem carries food and minerals from one place to another.

Both the xylem and phloem systems can be plugged if plants are not healthy. A lot of poor health in plants can be traced to soil problems – not enough nutrients; nutrients not available or not in the correct form; the wrong balance of nutrients (when nutrients interact, too much of one and not enough of another can have drastic adverse effects).

These problems can very often be traced to insufficient humus and soil organisms in the soil.

Now, imagine you’re inside a phloem cell and gliding down a leaf, back into the plant’s stem and out into, say, a developing corn cob. It’s a beehive of activity.

In the earlier stages of seed and fruit development, a lot of new cells are produced by cell division; later, the existing cells simply enlarge as the seed and fruit swells. Now, large quantities of food and other chemical substances from the leaves are moving into the seed or fruit for storage. Later, in grain crops, much of the moisture in the kernels is, or should be, removed, producing a "dry" grain that can be stored without turning mouldy.

In both seeds and fruit, there are also chemical transformations in the type of stored food, from sugars to starches, organic acids, proteins, and fats or oils.

These are all metabolic activities, and they all require cell energy (supplied by phosphate-containing energy carriers), enzymes and, often, hormones.

If the reproduction process is to occur normally and result in top-quality seeds and fruit, plants must be healthy, and well fed with water and nutrients.

If there are trace-element deficiencies, for example, there may be a shortage of the enzymes that regulate vital metabolic steps. This will lead to low test-weight, low yields or low-quality (low biological value) animal feed.

Or, if the all-important plumbing is blocked, the food the seeds and fruit need may not get through. Or water may not be removed, and the grain will not be "dried down" naturally – which will leads to additional grain-drying expense for farmers.

As with so many living organisms, most of these problems can be prevented quite easily. Prevention in this case comes down to maintaining a healthy soil with good tilth, adequate humus and soil organisms, and proper fertilisation.

Don’t kill your volunteer army

Wed, 08 Sep 2010 08:15:47 +1200

Most people misunderstand or know little about the movement of water in soils.

The average person will assume that water simply moves downwards. But, in fact, if water is applied to soil at a single point, it defies the law of gravity and moves sideways just as fast as it goes down. The result – it soaks into the soil in a spherical pattern.

Of course, rain normally falls all over the soil surface rather than on a single point, so a horizontal "front" of water will generally soak in.

However, differences in soil texture – a subsoil hardpan or even just a change from fine to coarse, for instance – produce a barrier effect to water penetration. When water encounters this change, its rate of penetration slows considerably, and, in reverse, later rise of water to supply roots will also be slowed.

The role of porous matter, such as plant residue, in absorbing water can also be important under some conditions. Organic matter (a mixture of dead, decomposed humus and the living soil organisms) that has been thoroughly incorporated into the upper layers of the soil or is partly exposed to the surface acts as a wick to increase water penetration. A compact sloughed-under mass or organics matter will also act as a barrier.

Indeed, organic matter is of crucial importance in soil – it has been described as the "constitution" of soil.

The "humus" component of organic matter is a structureless material formed through the decomposition of mostly plant residues and manures. It’s a complex chemical mixture that includes proteins, lignin (originally part of plant-cell walls), fats, carbohydrates and organic acids.

Its colloidal nature gives it great ability to hold nutrients, which leads to a number of beneficial qualities:

It stores essential plant nutrients – 95% of the nitrogen, 60% of the phosphorus, and 98% of the sulphur available to plants.
It helps make some nutrients more soluble and available to plants. It stores nutrients and releases them when plants need them most. Acids in humus also dissolve soil minerals slowly and release nutrients.
It contains substances that stimulate plant growth and improve both crop quality and resistance to pests and diseases.
Its spongy nature allows it to absorb and hold large quantities of water.
It contributes to good soil structure (tilth) by helping make the soil crumbly and porous. It also reduces wind and water erosion, and makes soil easier to work.
It acts as a protective buffer to plants against high salt levels, toxic chemicals and drastic changes in pH.
It’s a source of food for beneficial soil organisms, especially during fresh organic matter’s pre-humus form.
Now to the living part of the soil.

Fertile soil teems with a variety of plant and animal life, most of it microscopic and therefore little known and little appreciate by most people. But these life-forms – which include bacteria, actinomycetes, fungi, algae, protozoa, nematodes, worms and insects – are a valuable "work force" that performs a multitude of chemical transformations as well as many other services.

Bacteria, actinomycetes and fungi are the most important:

Bacteria are single-celled organisms that can live in conditions with or without oxygen, but usually not in very acid soils. Soil bacteria help decompose organic matter to form humus, convert inorganic chemicals into useful plant nutrients, break down manmade toxic chemicals (herbicides and pesticides), and trap nitrogen from the air for later use by plants.
Actinomycetes are thread-like organisms, somewhere between bacteria and fungi, that require aerobic, neutral or slightly alkaline soils. They help produce humus.
Fungi, or moulds, are thread-like, mainly aerobic, and able to tolerate fairly acid conditions. Many of them help produce humus, and one particular group is especially because it lives inside plant roots helping absorb nutrients (especially phosphorus and nitrogen), secrete growth-promoting hormones and protect roots from disease.
Soil organisms "tie up" nutrients from minerals and organic matter temporarily in their bodies and counteract the loss of soils nutrients through leaching into groundwater. When the organisms die, the nutrients become available to plants, which are fed slowly over the growing season.
Soil organisms, along with humus, produce the "glue" – a sticky carbohydrate – that holds soil particles together and forms a loose, crumbly, porous soil.

Humus and soil life work together as a team to perform these valuable services – and, best of all, they work for nothing if given the chance. So why would anyone want to dump toxic materials on the land that will kill or inhibit this volunteer army?

Biochemical photos

Wed, 08 Sep 2010 08:14:09 +1200

Mankind has long understood the words of Ash Wednesday: “Remember that you are dust and that you will return to dust.”

Our ancestors were well aware that this “dust” of the soil is what determines vigour and health. Well before metabolism and enzymatic functions were known about, our forebears looked at what they saw around them, and declared that “the animal is a product of the soil”.Scientific discovery now allows us to put this belief in more modern terms which are, however, no more than a copy of the olden words – “The living organism (animal or human) is the biochemical photograph of the environment in which it lives, particularly of the soil which manufactured the nutrients for it.”

While our increasingly globalised world blurs this “biochemical photograph” for humans (it’s now more an album of many pictures of very different environments), the grass continues to maintain a close connection between soil and animals for most of the year.And this relationship reveals the profound influence of the soil on the cell metabolism of animals (which, incidentally, is very similar to that of humans). Between the grass and the grazing animal, we get an excellent “biochemical photograph” of the soil, which demonstrates how the elements of the soil control the functioning of the cells of living organisms.

All of the mineral elements in soil impact on the quality of the plants and animals that depend on the soil for life and survival. The mineral matter of the soil is a profound force in modifying the organic matter and metabolism of cells, vegetables and animals.

The traditional NPK – nitrogen/phosphorus/potassium – mix has long been the staple of the fertiliser industry. These elements are important and necessary in the soil to increase the level of organic matter in grass. But so, too, are the minor and trace elements – so named because they appear in very small quantities (parts per million or less). They play crucial roles in the manufacture of living matter. Some of them are names we know; others are less familiar. We’re talking of minor nutrients such as calcium, chloride, iron, magnesium, sodium and sulphur, and trace elements such as boron, cobalt, copper, iodine, manganese, molybdenum, selenium and zinc.

These trace elements are needed to activate the enzymes which, in turn, are the catalysts in the synthesis of living matter. In other words, the trace element is the catalyst that unleashes the catalyst.There are numerous examples to illustrate the beneficial influence of the correct use of mineral fertilisers – and, in particular, the strategic use of trace elements – on plant quality. Mineral fertilisers not only have the capacity to increase the yield of crops, but clearly also to improve the quality.

But it is crucial that they are used correctly and in the correct proportions. If fertilisers are used incorrectly, the quality of the produce is likely to be lowered.

These elements provide essential nutrients in the soil. The mineral matter of the soil obviously has a profound effect on the organic matter and the metabolism of cells, plants and animals.They also help the constituents of the soil to do their job. Take the amino-acids, for example. They’re the bricks from which proteins are constructed. Calcium, phosphorus, boron and nitrogen enhance the level of tryptophan, one of the essential amino-acids; sulphur helps raise the levels of two other amino-acids, methionine and cysteine.

Then there is catalase, an enzyme that comes to the aid of and plays a decisive role in helping cells that are struggling for life. A complete dressing of fertiliser enriches the soil’s carotene content; so does iron. And thiamine, one of the most important vitamins, thrives through the addition of phosphorus and potassium.But, be cautioned. The application of nutrients is all about balance. Balance is achieved by thorough analysis to establish what is lacking in the soil in question. The nutrients, or fertiliser, should be formulated specifically to remedy these identified shortfalls. It should be formulated with precision to achieve balance and health in the soil, rather than merely piled on quantity in the hope something will stick in the right place.

The soil makes the being

Wed, 08 Sep 2010 08:06:19 +1200

It’s a small – and entirely logical – step from the realisation that “the soil makes the grass” to “the soil makes the animal”.

The better the quality and balance of the soil, the better the protein of the grass and crops, and the better the quality of the animal – always with the rider that the animals have the benefit of a balanced feeding regime.

Given this framework, you can expect animals to gain weight faster and for longer, to thrive and to be healthier, and to look better.

In other words, healthy soil will produce healthy plants and crops, which, in turn, will produce healthy animals. Simple. Isn’t it?

But the chain does not stop with animals. It extends to the people who eat the crops, animal products, and animals. In other words, healthy soil, healthy grass and crops, and healthy animals also produce healthy people.

The fundamental of this relationship between soil, grass and crop, and animal is the ability of the soil’s elements to modify the composition of the “crude” protein of the grass. This improvement of “crude” protein boosts the nutritional value of plants for animals.

The key, of course, is that the correct elements need to be present in the soil in the correct quantities and in the right balance with one another. This balance is often out of kilter in the soil, and mineral fertilisers are needed to restore equilibrium.

However, these mineral fertilisers must be chosen and used judiciously in the light of soil analysis and their known efficacy. It is not a case of one mix suits all soils. In fact, the wrong mix – or the wrong balance – can be a disaster.

While the effects of over-use or lack of the major elements are generally well understood, the effects of the exhaustion of trace elements through the prolonged use of nitrogenous fertilisers are less obvious. Generally, the lack of trace elements is not immediately apparent, and, usually, their absence does not lead to an immediate loss of income.

But the hidden effects are deadly serious because they endanger the health of animals and people.

The problems presented in the replacement of many elements we remove from the soil without replacing them are often very delicate. The imbalance and deficiencies created in the soil are much more complex than a relatively straightforward case of copper deficiency, for example.

Too often, we concentrate on the results of trace-element neglect rather than the causes. In terms of our soil-grass-animal/people relationship, it is not merely a matter of healing the animal or the person; rather we have to heal the soil as a preventative measure so that we do not have to heal the animal or the person.

The connection between an imbalance of, and/or the absence of some, mineral elements in the soil has been demonstrated to be a major factor in many of the diseases that afflict animals and humans. Upsetting the equilibrium of mineral elements in the soil has been shown to upset the equilibrium of mineral elements in the blood of both animals and humans.

These problems also extend to fertility. The fertility of soil is often reflected in the fertility levels of the animals and humans that live off the products of this soil, and the reproduction process is often where the first sign of problems from soil deficiencies appears.

Some scientists have promoted the concept of “agronomic original sin” through which problems arising from the absence of certain elements in the mother’s diet during pregnancy create problems or make offspring more susceptible to some diseases.

There’s a similar view on the ageing of cells – that the cells of an organ wear out or age prematurely because of deficiencies in their nourishment or because they have been abused. In a number of cases, premature ageing has been linked to the absence of specific mineral elements.

Similarly, the presence of specific mineral elements are crucial to animal and human development of resistance to diseases and disease-carrying organisms. This applies to both resistance to specific diseases and organisms, and to general defensive strength against illness.

Microbes out front in ‘key challenge’

Tue, 07 Sep 2010 14:18:23 +1200

When we at Fertilizer New Zealand, talk about the urgency of managing nitrogen-fertiliser use, we know we are in good company.

Nitrate losses to the environment were identified as “a key challenge for farming” in the 2004 findings presented by the Parliamentary commissioner for the environment, Morgan Williams, in his report, ‘Growing for Good: Intensive farming, sustainability and the New Zealand environment’. Williams drew on the words of Australian CSIRO researcher Barney Foran to an international grasslands conference in Palmerston North more than a decade previously:

“The biggest challenge at the moment is to produce a vision of why we produce products from grasslands. If we are worried by the energy consumption of our developed economies, then we must develop low-energy, integrated pasture systems that give high-quality products with no downstream pollution effects – a “cradle-to-grave” concept.

“Our experimental methods must now be redesigned to reflect product quality rather than product quantity. We must re-examine why production per hectare is seen as the holy grail. In many areas, land is overvalued in terms of its productive worth, rather than limiting in amount. We could do better by helping to crash land prices rather than developing technologies to run the land harder to make it pay.

“Grasslands give much more than production. Using our grasslands are people who are real, and have life goals. Many of our landscapes are beautiful and biodiverse, and our technologies must accommodate these other uses.”

Eleven years on, Williams reinforced Foran’s synopsis as being “even more pertinent”. “Unfortunately,” Williams adds, “New Zealand has made glacial progress in addressing (or even fully acknowledging the issues, opportunities and needs…in particular, the need for a new vision and to redesign farming systems seems to have gained little traction”.

“We cannot continue to respond so slowly and in such a piecemeal fashion.”

Williams says the redesign of farming “ranges along a spectrum from tools for remedy and mitigation of adverse environmental impacts, to the development of new farming systems which deliver environmental sustainability and economic wealth (i.e. sustainable agriculture), to approaches which promote sustainable agriculture and seek to integrate farming into the wider environment”.

“Hear, hear,” you will hear from us at Fertilizer NZ. Just like Barney Foran and Morgan Williams, our aim is to help farmers towards sustainability and wealth. We do it by providing them with products designed to keep the soil nutrients in balance, and, therefore, keep the soil healthy.

We know that healthy soil produces healthy crops and healthy pastures, which, in turn, produce healthy animals and healthy products, and, ultimately, healthy humans.

One of the secrets to Fertilizer NZ’s success is our access to special microbes that are renowned internationally for their ability to bring added value to soil.

These microbes – mycorrhizal fungi – have been shown to increase plants’ ability to absorb soil nutrients. There is a best balance of micro-organisms for each type of plant. If it’s right, the plant lives at its healthiest, and often yields to higher levels.

By judicious use of these fungi, phosphate in the soil can be used more efficiently, less nitrogen fertiliser needs to be used – and, all the time, production is maintained.

While several million microbes live in the soil, even more – up to 100 times more, in fact – live near and in the roots of plants. These microbes give phosphate to roots and, in return, receive carbon dioxide. In other words, they do naturally what nitrogen fertiliser is intended to do.

Mycorrhizal fungi are widespread in New Zealand’s native forests, native tussock, and agricultural and horticultural soils. They spread out into the soil, increasing the area of the host plant’s root system and stimulating soil phosphorus uptake. This improves clover growth at low to moderate soil-phosphorus levels and ryegrass growth at high soil-nitrogen levels.

Some strains of these fungi are more efficient than others, and some soils contain only inefficient species. The introduction of the more efficient fungi to these soils will increase plant growth through enhanced uptake of phosphorus.

It’s easy to overlook microbes. They’re infinitesimal beings so tiny you need a high-powered microscope just to sight them. They are so numerous that a teaspoon of soil contains more bacteria than there are people in the world.

And our entire existence depends on these unseen earthlings.

Obviously, at Fertilizer NZ, we are aware of the crucial significance of microbes. We are not alone. Many scientists and soil specialists around the world are aware of how much we depend on these mites, even though it is believed that barely 6% of soil microbes have been discovered out of potentially 1.5 million species of fungi, 1 million species of nematode worms, and similar multitudes of bacteria.

One is Landcare Research scientist Graham Sparling who sums up soil succinctly: soil is soil only if it has biological activity, otherwise it’s dead like moon dust – and we are lucky to have it in New Zealand. He is adamant humans have gone too far in their abuse of the soil that is their life-blood.

“We think soil comes for free,” he says. “It’s our repository for waste, it cleans up our excess liquids, contains out contaminants, and we use it for sports fields, golf courses and cricket pitches. We do all that, and think soil is miraculously going to take it all.”

No, he says, New Zealanders’ habits are coming home to roost as we tread down the same path as the European and Americans – unless we take action.

Which is where Fertilizer New Zealand comes in. Our philosophy of restoring and maintaining nutrient balance in soils, and fostering microbe populations, is designed to slow down the degradation Sparling speaks of and to reverse the trend.

Sparling, who has issued dire warnings on the state of New Zealand’s soils and natural environment, briefed Morgan Williams. Many of Sparling’s sentiments are echoed in Williams’ report which pinpoints the management of nitrogen fertiliser use as a key plank in the redesign of farming.

We believe Fertilizer New Zealand is capable of cleaning up New Zealand’s water – much of which is under threat from nitrate run-off and leaching.

Williams spells out specific tools and practices to achieve this management:

Matching total nitrogen applied to attainable yield goals to avoid excess applications.
Applying nitrogen only during suitable weather conditions - for example, late-autumn and winter fertiliser applications have the greatest risk of direct-leaching loss of nitrogen fertiliser.
Timing nitrogen applications to fit pasture and crop needs, such as high nitrogen-demand periods.
Monitoring soil nitrate so that fertiliser rates can be adjusted appropriately.
Using nitrogen-stabilisation techniques to slow the formation of nitrate.
Specific placement of nitrogen-containing fertilisers.
Applying fertilisers with irrigation water for controlled plant uptake.
Balancing fertility to maximise nitrogen-use efficiency.
Application of nitrification inhibitors.

Which is very much what Fertilizer New Zealand’s philosophy and practice is all about.

The Battle of the Lurgi

Tue, 07 Sep 2010 14:11:02 +1200

There’s no denying the considerable contribution vaccines and anti-biotics make to animal and human health. But wouldn’t it be even better if we did not need to use them so much, if we could avoid the conditions that force us to use them.

Think for a minute: How successful have vaccines been in preventing colds and flu’s in humans? How many times can we rely on anti-biotics to bring us right? How often have we heard the medics mourn that we need to modify a vaccine because Virus A, which had become Virus C, has now become Virus E? How often have we heard them lament that viruses have become immune to the present strain of anti-biotics?

Should we not be giving more attention to the causes of the disturbances to metabolic mechanisms that leave cells vulnerable to virus attack?

The thing about viruses is that that they do not have a life of their own: they live and reproduce only in a living organism. A healthy cell is a like an automatic door: it shuts out viruses. But if the human or animal metabolism is upset in some way, the disturbance can cause the transformation of the cell’s nucleo-protein into a virus molecule. In other words, the cell’s automatic door develops a fault and no longer shuts properly – and a virus can sneak in.

However, numerous scientific studies have demonstrated and revealed that an enzyme, catalase offers significant protection against viruses and bacteria, and, thus, against the diseases they carry.

The catalase enzyme originates in the soil, and, like so many things in nature, its presence in human and animal systems in sufficient quantities to effectively fight off bacteria, viruses and illnesses depends on the health of the environment in which those animals and humans live.

As we know full well, the health of what’s on top of the ground is almost entirely dependent on what’s below the ground. Remember the axioms: “the soil makes the grass” and “the soil makes the animal”. If the soil is in balance, it is healthy. And if the soil is healthy, there’s a far higher chance the grasses, animals and humans that live on it will be healthy as well. And, in this example, if the soil is healthy and balanced, it will generate an ample supply of catalase enzymes.

Researchers have long identified many illnesses as “diseases of poverty” because they attack animals and humans that live in unhealthy conditions and eat poorly.

Just as catalase is known to provide protection against the lurgies, so some foods are known to help combat certain illnesses in people and animals. Recognition of the role of nutrition in “protective medicine” has accelerated in recent years and is now widely adopted by the medical and veterinary worlds.

This comes as no surprise to those with an understanding of the benefits of maintaining balance in all aspects of the natural world – the very basis of nutrition lies in food, which, of course, is grown in the soil and nourished by the nutrients in the soil. The equation is simple: healthy, balanced soil = healthy, nutritious food.

Yet again for our human and animal species, it all comes back to that first weapon of defence against poor health – soil with a proper balance of nutrients.

An environment based on a healthy and well balanced soil reinforced by a strong presence of the catalase enzyme is less attractive and less hospitable to viruses, bacteria and other sundry bugs than an ailing, out-of-balance soil. And the grasses and crops produced on healthy soils are healthier and more nutritious than those that struggle to survive in sub-standard soils. The same principle applies to animals. The healthier and better balanced the soil, the healthier the animals.

Let’s strip the message down to its bare essential. Soil is the very basis of our life – in every sense of the word and from all points of view.

Always has been. Always will be.

Makes sense to look after it, doesn’t it?

A Brief Note on Carbon

Tue, 07 Sep 2010 14:04:28 +1200

Where soil Organic Matter is 10% in the top 7.5 cm, that soil is about 5.8% carbon. The bulk density of soil in the field is generally greater than one, if we use a bulk density of 1, this is 43,500 kg C in the top 7.5 cm, which is quite a large amount. There will be some C further down the profile so it is quite possible in summer moist districts that the C in the top 30cm of soil could easily be 100,000 kg/ha (100 t/ha).

Cultivation to grow one crop or to re-grass is likely to result in the loss of about 3% of the C during that growing season mineralised and released as atmospheric CO2. Repeat cultivation or cropping during successive years will result in a gradually reducing rate of C loss, but loss of C will continue and can be monitored with the soil OM test. Heavy or excessive applications of N fertiliser can eventually have a similar effect.

The good news is that management options can be taken aimed at accumulating soil C. Adoption of crop rotations where soil C (and N) is alternately accumulated under grass pasture and reduced with cropping was the basis of ‘old fashioned’ crop rotations practised before N fertiliser use increased dramatically. Irrigation of pastures has a beneficial effect, increasing plant growth (utilisation of atmospheric CO2) and decreasing the negative effect of summer dry conditions. Soil husbandry aimed at stimulating deep root development, application of lime to enhance soil structure and biological activity all have an effect on the soil C reserve.

If NZ is serious about managing C emissions and involving horticulture and agriculture, then monitoring of soil C is essential. There should be some incentive for land-based industries to be good guardians of the soil C ‘pool’. It could be worked into a carbon credit system. However this would be a ‘two edged sword’, if loss of C occurred, a debit would be incurred…

Food for thought

The potential is BIG

If Carbon leaves the soil it has to go somewhere.

Yes…into the air.

If Carbon builds up in the soil it comes from somewhere…

Yes…the air

Credits: John Turner

Magnesium Importance

Tue, 07 Sep 2010 09:36:41 +1200

MAGNESIUM is an extremely important element for all stock. It is defined as a macro element, which means it is required in large quantities. Magnesium is vital for a number of different functions in the body; including relaxation of muscles and nerves, utilisation of calcium and converting sugars to energy. Magnesium is not stored well as a reserve in the body, therefore stock need their daily requirement from feed intake.

Under low magnesium uptake, hypomagnesaemia (or grass staggers) occurs which is most common at peak lactation. A heavily lactating animal requires three times as much magnesium as dry stock. Often with dairy cows you will not see the clinical signs of magnesium deficiency (muscle twitching, convulsions and death) but will suffer a drop in milk production and the cows will exhibit agitated/nervous behaviour.

Most of the soils in New Zealand have adequate levels of magnesium. However due to high levels potassium and nitrogen in pasture and the lack of magnesium fertiliser inputs, magnesium deficiency in livestock is relatively common. With the increasing awareness throughout pastoral farmers of the importance of magnesium nutrition VitaLife Magnesium has been developed. VitaLife Magnesium can supply two thirds of a dairy farms magnesium requirement if applied at 400kg/ha. As part of a well-balanced fertiliser programme VitaLife Magnesium can help in achieving optimum production from animals in optimum health.

Hidden Tillers of the Soil

Thu, 05 Aug 2010 09:37:36 +1200

Soil is very much a living substance –it’s either breaking up or building up. Millions of micro-organisms and other life-forms that live in or on the soil are the main agents of this continuous change. Without these micro-organisms – many of which are microscopic and beyond the vision of the naked eye – dead organic matter would pile high on Earth’s surface, and the soil would suffocate.

Soil structure is subject to a raft of influences related to soil type and all aspects of its chemical, physical and biological make-up. But these tiny critters are most influential factor. Their work is crucial because soil structure is directly linked to soil erosion, water intake and crop growth. A compact soil has a low infiltration rate. Whereas a stable, granulated soil allows rapid water intake, drainage, aeration and beneficial microbial activity. Crops grown in such soil respond well to favourable moisture, fertility and cultural practices.

Micro-organisms eat organic matter such as grass clippings, fallen plant leaves, and algae. In doing so, they reduce dead organic matter on Earth’s surface and release nutrients from the decomposing organic matter for living plants to use.

Some of them burrow and channel through soil, improving soil structure and aggregation in the process; while others have the ability to break down resistant organic matter such as lignin, toxins, and pesticides.

During the decomposition of plant and animal remains, micro-organisms produce many organic compounds and release organic substances that influence the stability of soil units. However, the ability of micro-organisms to stabilise soil varies greatly.

Some of the compounds that are produced and released have a tremendous effect on stability; others have little or no effect. Some of the natural products produced by micro-organisms are more effective per unit of weight than synthetic stabilisers.

The soil fauna is an important factor too. For example, earthworm can secrete slimes that render the cast several times more stable than the original soil. Under some mulching regimes, huge quantities of worm casts can be produced and deposited on the soil surface.

Micro-organisms also have the ability to protect plants from antagonistic pathogens, and some can dissolve minerals, making nutrients available to plants.

Earthworms are like "Nature’s tillers". They incorporate dead organic matter into soil, ingest it, and excrete the nutrient rich casts in to the soil. They improve aeration, water infiltration, drainage, and enhance nutrient availability and cycling.

Fungi are able to break down resistant materials such as cellulose, gums, and lignin. They dominate in acidic, sandy soils and in fresh organic matter. Plants roots and the mycelia (vegetative parts) of some fungi tend to push primary particles closer together to form aggregates or structural units in the soil. In other words, they help hold the soil together.

Earthworms, crayfish, ants and many insects also form aggregates, and, in many cases, may stabilise them. Some bacteria produce gums that have similar effects. Burrowing animals separate the soil mass into units. Actinomycetes can decompose resistant substances in soil. One type helps plants get nutrients from the air by breaking triple-bonded nitrogen down into ammonium that plants can use. Antibiotics are made from soil actinomycetes.

Bacteria decompose a wider range of earth material than any other microbe group. Heterotrophs gain their energy and carbon from other organisms, while autotrophs synthesise their own energy from light or by chemical oxidation. Some bacteria can fix nitrogen in to forms plants can use. Beyond the work of the micro-organisms, nature provides a number of examples of ways in which particles, crumbs, granules, lumps, clods and various aggregates are formed from the soil mass into the many-sized units found in the soil.

Changes in the charge of soil particles can account for the bringing together of very small (less than two microns) primary particles. However, this process is of limited importance in aggregation under natural conditions in the soil. When wet soil dries, the particles tend to come together as the attractive charges are brought closer together when water films between the particles are reduced. Drying can also cause unequal stresses that may break the soil into particles. Other physical forces, such as freezing and thawing, can also cause fragmentation on the soil mass into smaller units. While tillage, of course, breaks up the soil mass into various components.

The Underground Currency

Mon, 02 Aug 2010 15:03:49 +1200

Think of the soil in commercial terms for a minute. It’s not as out there as you might think. Cation nutrients are the currency in which soil deals, and soil colloids are the traders. As a couple of American researchers put it, "the first order of business for soil colloid is to hold nutrients – nutrients that can be traded off as the roots of a plant demand them". Because soil colloids come from clay and organic matter, there are clay colloids and there are humus colloids. Both have been broken down as far as they will go.

Laboratories usually report cation exchange capacity – the energy of the clay and the humus – in terms of milliequivalents. Think of this in similar terms to an electrician measuring electricity in volts and amperes, or a physicist measuring magnetic energy in ergs and joules. It all comes back to principle of positives and negatives. Negative attracts positive. Cation nutrients (which are positive) are attracted to and held on the soil colloids (which are negative), and remain free to move in the soil solution or water. A milliequivalent represents the amount of colloidal energy needed to absorb and hold to the soil’s colloid. For instance, in the top 17-18 centimetres of a 0.4-hectare (one acre) block of soil, the colloid is holding on to 182kg of calcium, 109kg of magnesium, 355kg of potassium – or, simply, 9kg of exchangeable hydrogen.

That’s the big picture, but what does it all mean for individual farmers?

It all comes back to soil analysis, and the need for you to know where your soil is.

Because the clay and humus that make up soil colloids carry negative charges, you need to use the right type of fertiliser. You need to use a fertiliser with a positive charge. Fertilisers with a negative charge will not be attracted to and held by the colloid, and you’ll be wasting your time and money.

Calcium and magnesium from lime compounds have this positive charge. So does sodium and hydrogen (in gas form). Negatively charged elements (called anions), such as nitrogen, phosphorous and sulphur, do not hold to colloids.

In addition the more colloids in the soil, the more negatives there are to attract the positively charged elements (cations). But there is always a saturation point. The soil can hold only so much fertiliser – put on too much, and some will be lost.

Colloids are also very mobile. Because they are the merest pieces of clay and humus (imagine broken-down particle of dust or talcum powder) they are extraordinarily susceptible to erosion.

If you could collect the dust the wind has shuffled around, you would find it has the highest fertility of any part of the paddock. When water or wind is at work, it always moves the most fertile part of the soil first. As a result, soils can not only be torn down, but also built up. Which explains why soil quality and fertility can vary so much in even in a small area. Remember that you cannot see any of this with the naked eye. But, while these colloids are microscopic, they form the bottom line in this positive-negative transfer (trade). They govern most of the chemical reactivity that goes on in soil.

The first thing you need to do for your land is to get a detailed analysis to measure the amount of clay and humus in the soil. You need to know your soils’ cation exchange capacity – a measure of your soil’s capacity to exchange nutrients.

The result will tell you a lot about its capacity to hold nutrients such as calcium, magnesium and ammonia nitrogen. It has a strong bearing on the quantity of nutrients needed to improve their relative levels in the soil.

This knowledge will help pinpoint the amount of fertiliser needed to get the right nutrient balance. It will also tell you about your soils’ capacity to retain fertiliser.

In other words, this analysis arms you with the information to use the correct fertiliser for your soil – and to use in the most effective quantities. The bottom line for you is; whatever you spend you know it will be effective.