There’s a school of thought seemingly prevalent among the science and farming communities in NZ that, although changes are required to soil fertility systems in order to stem further environmental damage, they can be made by tweaking the existing urea fuelled conventional system.

Recent reports indicate that some of our pastoral soils have been losing carbon at the rate of one tonne per hectare per year for the last twenty to thirty years, and currently all irrigated land without exception is losing carbon.

Carbon is the foundation of future farming and growing, with the most productive soils being those with the greatest amount of carbon.

There may be debate about whether carbon is the same as humus and how stable that may be. However, it doesn’t alter the fact that, under present systems, we’re chewing through our productive base at an ever increasing rate.

Overseas trial work shows that the reason for the loss is almost certainly the use of fertiliser nitrogen, particularly urea, of which over 750,000 tonnes is applied each year to pastoral land in NZ.

Urea, according to the research, stimulates bacterial activity, which in turn utilises carbon for energy. If this use of carbon is greater than the amount sequestered, there is a net loss and, as a result, physical soil structures deteriorate, and nutrient and moisture storage as well as plant growth steadily decline.

Tweaking the existing systems won’t provide the necessary fundamental changes, and current discussion around mitigating the adverse environmental effects of conventional practices indicates that there’s no genuine alternative technology coming out of mainstream science and advice.

There are, however, other pathways that increasing numbers of farmers are exploring and, at the base of the most effective is Golden Bay Dolomite.  Dolomite is essentially a magnesium fertiliser and not appropriate for use where natural magnesium levels are high; soil testing will provide that information.

However, in most dairy farm situations magnesium is an ongoing requirement.  Dolomite is often dismissed as being too expensive, and there are cheaper magnesium products, but none that are as effective.

Dolomite is a naturally occurring rock containing both calcium and magnesium.  The normal annual application rate of 200 – 220kg/ha provides 23 – 25kg magnesium/ha, and may be applied at any time.

The main reason for considering its use is the positive effect it has on calcium/magnesium related metabolic disorders in spring, and these effects can often be almost immediate.

Fewer clinical cases are reported, with the tell-tale signs of wobbling and aggressive behaviour usually obvious well in advance, providing time for effective treatment to take place.  The response to the initial treatment is usually rapid and often no further action is required.

Dolomite is a powerful soil conditioner in its own right, alleviating at least some of the downward pressure caused by heavy feet.  This means excess water percolates away more readily, and plant roots are able to penetrate further, accessing both moisture and nutrient from a greater depth.

Magnesium is a carrier of phosphorus, and when phosphorus inputs are being reduced to limit fertiliser costs, it’s good to know that the cycling of phosphorus is being given some extra impetus.

With improved soil structures clovers are healthier and fix more nitrogen, with the potential damage by flea and weevil reduced.

The importance of clover is difficult to overstate.  Its ability to replace fertiliser nitrogen is critical to the future of farming, and its value as milking and fattening tucker is also often underestimated.

Clover contains three to four times the amount of calcium of grasses and is more digestible.  During the period from early November until late April, when soil temperatures decline, animals fed a diet rich in clover produce at significantly higher levels.

If dolomite is to be applied prior to November, nitrogen inputs can then be steadily reduced, encouraging clover growth when soil temperatures are too high for strong grass growth.

Spreading dolomite is a useful first step in the implementation of a more efficient and effective programme that allows farming to continue within the coming regulations.  For more information call Peter on 0800 436 566 (0800 4Dolomite)

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