Soil carbon that is; 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 over the last twenty 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 that 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.
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 that water quality is deteriorating, and that it’s closely aligned to the recent intensification of dairy farming.
But here’s the thing. As 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 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.
But it’s got to be carried out without regular applications of fertiliser nitrogen. Farm consultants agree on this point because they inform me that the amount being applied has declined from around 200kg/ha to 160kg/ha, but argue that without some 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 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 and an autumn application of Golden Bay dolomite provides essential calcium and helps with an upward shift in soil pH, both of which aid clover growth.
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 spring 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/magnesium related metabolic disorders in spring.
Experience over close to thirty years shows that 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 200 – 225kg/ha is an ideal addition to the nutrient programme providing the base from which to reduce nitrogen fertiliser inputs and initiate a carbon positive farming future.