Soil carbon – you can build it or burn it – but it’s the very thing we rely on for our survival. Without it there is no plant growth as we know it, and as its being diminished less nutrient and moisture is available for plant uptake.

Any reduction in soil carbon levels, due to it being a highly effective filter, results in a decrease in water quality.

A check of soil tests taken during the last 20 years, along with the fertiliser that’s been recommended, will show whether more nutrient is being recommended now just to maintain soil nutrient levels.

Is summer pasture production becoming a greater concern? It’s a given that at some time during summer there will be a hot dry period. It’s the way it’s been forever and due to the westerly flow patterns the east coast is likely to suffer more than the west.

Increasingly difficult

The issue is whether or not it’s becoming increasingly difficult to meet stock feed requirements from pasture grown during that period.

There’s any amount of data from Ministry for the Environment, and councils throughout the country, to show water quality is deteriorating and that it’s closely aligned to the recent intensification of dairy farming.

But here’s the thing – it is under-grazed pasture that soil organic matter and humus can be most rapidly built. It’s not intensive farming as such that’s the problem – it’s just the way it’s being carried out.

Accepting that as a fact it means intensive pastoral farming is potentially the saviour of water quality and the environment at large. As pasture growth increases so too can the amount eaten, resulting in extra dung deposited. And along with dead leaf and old roots soil organic matter rapidly develops, and everyone wins.

Without nitrogen

But it’s got to be carried out without regular applications of fertiliser nitrogen. Farm consultants agree on this point because they inform me the amount being applied has declined from about 200kg/ha to 160kg/ha, but argue that without some nitrogen, pasture production immediately declines.

Remove an essential component of any diet without replacing it and there will be a decline in performance. However, fertiliser nitrogen can be replaced and when this takes place there’s no reduction in annual pasture production; just a change in when it occurs.

Naturally, early season pasture production is slower with less nitrogen applied. However, from early-November onwards there is a steady gain due to vigorous clover growth. It’s more nutritious and digestible than grass resulting in less animal weight loss and higher levels of production, often without the requirement for supplementary feed.

Clover provides

Clover is the primary provider of nitrogen, so more is fixed naturally free-of-charge. However, because clovers thrive where there are higher levels of readily available calcium for best results soil conditions require modifying.

This means an initial application of lime and the rule of thumb is 1.0 tonne/ha/year and its best applied in late-spring. Autumn is little late to get full benefit, however there is a step that can be taken now in preparation for next season.

An autumn application of Golden Bay dolomite provides essential calcium and helps with an upward shift in soil pH, which both aid clover growth.

Dolomite application

Dolomite is also an outstanding soil conditioner in its own right, which means rain infiltrates the soil more readily speeding the growth of autumn and early winter pasture. Damage caused by treading during excessively wet periods during winter is lessened.

Dolomite, being primarily a magnesium fertiliser, is spread at the rate required to minimise calcium and magnesium-related metabolic disorders in spring.

Experience during close to 30 years shows a rate of 25kg/ha of magnesium is sufficient to markedly reduce not only the number but also the severity of spring metabolic disorders in calving cows, regardless of soil test numbers.  

With dolomite containing 115kg of magnesium per tonne, an application rate of 200kg/ha-225kg/ha is an ideal addition to the autumn nutrient programme, providing the base from which to reduce nitrogen fertiliser inputs and initiate a carbon positive farming future.  

For more information call Peter on 0800 436 566 (0800 4Dolomite).