Limestone, the foremost of fertilisers

Better soils
with Brett Petersen
Kiwi Fertiliser & Golden Bay Dolomite

 I can recall many occasions after a farmer or contractor had applied lime, dolomite, gypsum, or even burnt lime, “that is was good stuff, because the pH went up”. That is flawed thinking. How about applying lime to supply calcium, dolomite to supply calcium and magnesium, gypsum to supply calcium and sulphur, and so on? Applying substances that change the soil acidity should never be the aim of any valid soil fertility program. Whatever you apply should be to provide the nutrients that the soil requires. That way, the soil pH will be properly constructed and not a misleading figure.

At Kiwi Fertiliser, we follow the Albrecht system of soil fertility. It is backed up by manuals that provide the information to create superior soil fertility that produces high quality pastures, crops, and animals that require little or no therapeutic intervention, as the stock self-medicate on a minerally-correct balanced diet. This cannot be achieved if either Ca, Mg, K, or Na, are too far out of kilter with each other. The main aim on all soils is to balance the cations to their correct proportions in the soil and with each other. Adding one changes the others and that needs to be factored into the calculations.

Calcium is a nutrient in its own right. It is necessary for the good health of soil, plants, and animals. If it is in excess, something else will be in deficit. Some plants readily absorb calcium better than other plants. Those plants are healthier for animals and humans to eat than are the latter. As true protein levels in plants rise, so do Ca levels and as Ca levels increase, so too do vitamins.

However, excessive Ca will cause Mg, P, and minor element deficiencies. This translates to some plants with lower digestive calcium. E.g., too much oxalic acid, that can also lead to imbalances of enzyme and hormone systems. This poorer plant health, in turn can be a magnet for fungal, bacterial and insect attack. Excessive Mg will lead to P, K, and N deficiency. Coupled with low Ca, high Mg may also lead to decaying organic residues producing alcohol. This happens mostly when crop residues are buried too deep. Alcohol is damaging to most microbiology. High Mg low Ca may also lead to anaerobic soils and the consequences of a soil that will not absorb rainfall well, exacerbating the chances of drought. In turn, this creates opportunities for weeds.

Calcium in the proper range will improve soil structure and phosphate and other nutrients availability. According to Mulder’s Chart, soil P availability can double between pH6.0 and pH6.5. Better structure leads to an increase in soil microbes, including nitrogen fixers. Root systems improve along with stronger stems and larger leaves. That all adds up to increased photosynthesis and plant health. Photosynthesis is the most important process on the planet. Of course, carbon will also be sequestered in the soil at high rates. On average, dairy farms in NZ are losing carbon to the atmosphere. But all this is easily reversed when soil fertility is viewed as an investment instead of an annual crop-growing expense, where the common approach is to merely replace what is being removed, irrespective of what those levels are. We can all do much better when it comes to soil fertility.


There are no comments on this blog.

Leave a Comment

You must be logged in to make a comment. Login Now
Opinion Poll

We're not running a poll right now. Check back soon!