Fert facts part four

Better soils
with Brett Petersen
Kiwi Fertiliser & Golden Bay Dolomite

Over the past several months, Brett has shared his top facts about fertiliser to help optimise your soil. This is the last instalment.


31 Soluble phosphorus products kill vesicular-arbuscular mycorrhizal fungi (VAM). Mycorrhizal fungi can increase the roots effectiveness by 10-1000 times or more, and plants grown with VAM have superior nutrition. Lack of VAM leads to soil erosion and leaching. New Zealand's rates of soil erosion and leaching are very high.

32 Soil scientists claim 16 elements are required to support life. However, geneticists maintain that at least 64 nutrients are required for healthy life. If one or more minor element is missing, another can substitute, but it cannot carry out the same function as the missing nutrients, so disease will follow.

33 Potassium chloride kills microbes; just 2ppm (4kg/ha) of chloride is enough to cause harm and the net effect of this is rock-hard soil. Potassium chloride also encourages certain weed growth. Potassium chloride has a salt index of 116 – potassium sulphate has a salt index of 46. Insist on applying only potassium sulphate. Use of Potassium chloride increases the leaching/erosion of nitrogen and phosphorus. Plants grown with Potassium chloride taste awful to both humans and animals. The chloride partly overwhelms the plant, reducing potassium uptake, making potassium sulphate a far more economical and healthy option.


34 If nitrogen is high in the soil, potassium should also be at high levels. If both of these elements are at luxury levels, then all elements need to be lifted to luxury levels for maximum production. If tissue tests show high manganese and low zinc, that may indicate a potassium deficiency, regardless of the reported potassium level.

35 In general, the more NPK applied, the higher the yield, but the lower the mineral content, health, and quality of that product. A balance of all nutrients is required and must also include minerals that are required by animals, not just plants. When that balance is attained, yields and quality of produce are much higher than with NPK.

36 NPK grows crops, but does not build fertility or humus; carbon, calcium and microbes do. The higher the humus content the greater the ability of the soil to hold nutrients and moisture. NPK has grown pasture and is growing pasture, but the decline of organic matter and transfer of carbon to the atmosphere, is not sustainable or acceptable and must be addressed if farming is to be sustainable in the long term.


37 The label primary, secondary, major, trace, or minor signifies quantities of nutrients required, not their importance. All the minerals need to be included in a balanced crop fertiliser as they are all important. A shortage of trace minerals will cause crop problems the same way missing major minerals do.


38 Copper and sulphur improve flavour and nutrition, along with potassium sulphate. Adequate sulphur increases stem girth and leaf size. Stone fruit with uneven halves are lacking boron. Cracked stones and shrivelled kernels signify lack of manganese, manganese deficiency may lead to an excess of bull calves. Potassium, manganese and copper all contribute to timber and branch strength. Silicon strengthens plants’ ability to withstand pest and disease attack, and much more.

39 When base saturation comes into balance, foliar applications work more effectively and will have a positive effect on quality and yield.

40 Use pesticides, fungicides, herbicides, and nitrogen in minimum amounts and only when necessary. Always add a carbon (humic and fulvic acids) to those substances. Sprays are only a quick fix and are a sure sign that soil and plant health is not optimum.

Kiwi Fertiliser can show you how increase profitability while growing your soils. Human and humus are the same root word, “of and from the soil”.



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