To me it is quite clear your soil management shall have three major aims:

  1. to grow crops for profit
  2. to maintain or improve soil fertility
  3. to avoid contaminating the environment and water supplies with nutrients or other chemicals from your farm

To achieve all of the above you would need to apply the right awareness towards nature;

Change a few of your farm management practices as example  like reducing leaching of nutrients and reducing top soil erosion, simply by fencing in all waterways on your farm.

Mangere River at Knights Road

Total phosphorus (µg/L)  average 181  :   range 58 – 296

Awanui River at Waihue Channel

Total phosphorus (µg/L)      average 109    :  range 68 – 434

Manganui River

Total phosphorus (µg/L) average 70      :    range 45 – 131

Mangahahuru Stream at Apotu Road

Total phosphorus (µg/L)   average 123    :   range 54 – 279

Waiotu River at SH1

Total phosphorus µg/L)  average 63       :    range 30 – 112

Guideline trigger values New Zealand Lowland Rivers for total phosphorus are 33 µg/l.


The phosphate cycle is an important cycle within the environment, it is essential to the growth and development of plants.  Phosphate is usually the limiting factor in photosynthesis for plants, zooplankton, and bacteria.  High phosphate levels in waterways contribute to the destruction of a once ecologically stable area in a similar way as nitrogen.  The fact that phosphate is generally the limiting factor in plant development,  
indicates that when there are high levels of phosphates in the water then there is cause for concern of algal blooms, which can kill off a body of water.

The recommended maximum phosphate-phosphorus level for rivers in Europe is 20 µg/L.  High levels of phosphate can come from industrial waste, and lawn and farm fertilizer run off, waste water treatment plants, septic tanks etc.

Nitrate and Ammonium

The bases of growth and development of species is based on several different natural cycles, one of these is the nitrogen cycle. This cycle is very complex and has a careful balance; to upset this balance can lead to terrible consequences.

Nitrogen makes up about 78% of the air we breathe daily.  Even though nitrogen surrounds everything on the earth, excesses of nitrates in water bodies can cause environmental problems.  Nitrogen generally enters water in the form of nitrites, which are converted to nitrates by bacteria and algae through a process that depletes the amount of available oxygen in the water for fish and other aquatic organisms.  Increased amounts of nitrates in the water allows for uncontrollable growth of algae, called algal blooms.  An algal bloom is a condition where excessive nutrient levels cause rapid growth of algae.  An algal bloom can cause change in the color of the water and will reduce the amount of dissolved oxygen available for aquatic life.  High levels of nitrite, if not quickly converted to nitrates can lead to a serious condition in fish called, “brown blood disease”.  High levels of nitrites can cause harm to humans, by causing hemoglobin, the oxygen carrier in blood, to produce met hemoglobin, which destroys the ability of red blood cells to carry oxygen.


In most aerobic soils under optimal soil conditions, ammonium is rapidly converted to nitrate by soil bacteria through a process known as nitrification.

  • Nitrification involves two steps:
    • First, ammonium is converted to nitrite
    • Then, nitrite is converted to nitrate.

As you can see from the outline of steps above, the intermediate product of nitrification is nitrite. If conditions are unfavourable to undergo the second step of nitrification, nitrite can leach into the ground water and pose as a health risk.

The process of nitrification produces hydrogen ions. When large quantities of ammonium-containing fertilizers are applied to soil over time, this process can acidify the soil. See figure below for a simplified presentation of the nitrification process.

Rule of thumb

  • When the C:N ratio of decomposing organic residues is between 20:1 and 30:1, mineralization and immobilization occur at fairly equal rates.
  • Net mineralization occurs at C:N ratios less than 20:1.
  • Net immobilization occurs at C:N ratios greater than above 30:1.
  • Most well decomposed organic matter in soils have a C:N ration near 10:1

The problem with Urea fertiliser are not only that they acidify the soil, but also lock up some of the carbon in the soil and therefore compete against the microorganisms in the soil which are responsible for a nitrification to nitrates

Also Urea fertilizers experience greater losses due to volatilization than ammonium fertilizers.

So in my few if you need to add nitrogen to your soil, do not use Urea but an ammonium fertiliser which is less damaging the soil microorganisms

Just as a remark in Europe Urea is band in most countries and if you like to apply it you mast gain a special permit.

And since we are already on some artificial fertilisers which should not be used in a healthy soil there are two more candidates which I would never use;

Muriate of Potash; not only does it induce Magnesium deficiencies, but more it acts like cement in concrete it chemically compacts the soil.


For both products we have today alternatives


One example

In New Zealand we haven’t got a limiting level for Phosphate discharge from Farms or waste water treatment stations, either a limiting use of Phosphate Fertilisers.

In addition we have the worst record of land erosion in the western world. Other countries are using the bad land management example of New Zealand as how not to do it !!!

Organic Matter

We are destroying our environment and losing every year more and more organic matter.

The organic matter in top soil is every year less caused through intensive Farming and general bad habits, using artificial Fertilizer, not fencing the waterways, not growing trees along the waterways etc…

Organic matter holds the nutrients and gives the pasture something to grow on. The soil microorganisms are responsible for the decomposing all the organic matter which enters the soil and recycling the contained in it for further plant production. The microorganisms and earthworms help to preserve and ultimately raise the organic matter.

So what can we do ?

First we need to understand the soil

Microorganism in soil

Soils contain an incredible number of organisms. The range of different species of animals and microorganisms in soils is similar to the biodiversity found in rainforests and tropical reefs. These soil organisms range in size from tiny virusesand bacteria up to earthworms as large as 2m in length (found in Australia)

Current estimates of the number of species of some groups include;

  • bacteria (30,000) 
  • fungi (1,500,000) 
  • algae (60,000) 
  • protozoa (100,000) nutrients
  • nematodes (500,000) 
  • earthworms (3,000)

These soil organisms are responsible for decomposing all the organic matter which enters the soil (ie leaves falling on the surface, roots dying underneath the surface) and recycling the contained in it for further plant production. Larger soil animals chew the organic material into smaller pieces and make burrows, which aerates the soil and provides channels for water movement. Tiny microorganisms are responsible for most of the decomposition of organic materials and also produce special glues which stick soil particles together, making the soil less prone to wind erosion. Somemicroorganisms can even produce plant growth hormones which speed up the growth of plants. Without these millions of creatures, the soil is dead and produces nothing.

If we nurse the above microorganism there is nearly no erosion

Soil analysis

Most of you had the soil of your farm analysed and got the report from the Laboratory?

Now how many of you can tell me according to the analysis results what element and which form and which concentration would need to be added to your paddocks to improve the fertility and increase the grass production?

How many of you would need to relay on the Sales Rep from a Fertiliser company to tell you what you should add?

How many of you can tell me what milliequivalents means?

This is a wake up call. You as a farmer should take the responsibility to understand your own soil report and act accordingly.

Either you get an independent consultant or you learn fast how to read the report.

In the future you will tell the laboratory which has analysed your soil sample to write the report in kg of each element / hectare

Here is an example of the way in which I report soil results to farmers.

A short explonation of Milliequivalent /100 g

The soil cations including Calcium , Magnesium, Potassium and Hydrogen can be expressed in terms of their relativity to displace other cations. The unit of measure is meq/100g.

From Moles to Milliequivalents

Many important substances in the body are measured in equivalents. The technical definition of an equivalent is the amount of substance it takes to combine with 1 mole of hydrogen ions

Many soil test reports include a section on per cent base saturation

What Is Base Saturation?

Base saturation refers to the proportion of the cations exchange sites in the soil that are occupied by the various cations (hydrogen, calcium, magnesium, potassium). The surfaces of soil minerals and organic matter have negative charges that attract and hold the positively charged cations. Cations with one positive charge (hydrogen, potassium, sodium) will occupy one negatively charged site. Cations with two positive charges (calcium, magnesium) will occupy two sites.

Base saturation does not have any relation to fertilizer recommendations for the negatively charged nutrient ions, such as phosphate, nitrate and sulphate.

To determine the base saturation, you must first know the cations exchange capacity (CEC), which is a measure of the amount of negative charge in the soil.

So a balanced soil has a base saturation of 70 to 80 % and between

  • 50 – 70 % Calcium of the base saturation
  • 2 -5 % Potassium
  • 0.5 – 5 % Sodium
  • 15 – 20 % Magnesium

Then the pH should be adequate, and there is an adequate supply of phosphate and sulphate as well as the trace elements

If we can keep the nutrients in the right balance in an organic soil the loss of elements through leaching would be minimal.

Once you have all the above information including your own or independent fertiliser recommendations you then go to the fertiliser company of your choice and tell them what fertiliser blend you need. In fact you will give them a recipe of all the products you like to have in the mix and in which quantities.

Please remember most of the products you apply are water soluble and the grass roots can only take up a very small amount at any given time; so to avoid leaching please add less, but more often.

Soil analysis of interest:

  • Soil type
  • Carbon : Nitrogen ratio
  • Soil fertility
  • Compaction {chemically and physically}
  • Acidity
  • pH
  • Soil density
  • Active organic matter
  • Elements
  • CEC
  • Base saturation