The collapsed dairy milk price and the downturn in sheepmeat export prices has caused a sudden flurry of promotion for good management of permanent pasture.
The advice has emanated from all levels and related organisations, many of which had formerly been passive about the national shift to reliance on chemical nitrogen and supplement-reliant farming regimes, despite the dangers of reduced true profitability.
Our voice (The Dolomite Company NZ) has been one of a small number which have consistently supported permanent pasture as the only management alternative that allows farmers to earn more than they are required to spend each season. And our point of difference has always been concern about the costs and impacts of fertiliser nitrogen.
Most fertiliser nitrogen is applied in the form of urea, an estimated $300,000,000 a year industry, with the argument for its existence being that, without it being regularly applied, pasture and total farm production would significantly decline.
Of course nitrogen is an essential element for plant growth. And until the development of the Kapuni based ammonia urea plant in the late 1980s, the nitrogen in our pastures came largely from the activity of bacteria on the nodules of clover roots. At that time clover/ryegrass pasture was the basis of our primary industries. There is far less clover seen in current pastures.
Records show that production from high quality pasture at that time was often measured at 18,000kgDM/ha annually, whereas now the expectation seems to be around 14,000kgDM/ha. The explanation given for this change is that measurement systems are different these days, and research figures from that time are no longer relevant. However, higher yields are still being achieved by farmers who are no longer applying copious nitrogen during the growing season.
As well as high yields and production, these farmers have substantially reduced costs. Purchasing 100kgN/ha as urea for a 110ha property would cost $12,100 with transport and spreading costs still to be added. In addition, they are reporting increased pasture production year on year, the most important (and appealing) upside of a well managed clover-based system. This is due to an increase in humus and soil carbon formed from dung, dead grasses and old plant roots when nature operates naturally.
With steadily increasing humus, greater amounts of moisture and nutrient are stored, with an improved spread of growth throughout the year. Pastures grow longer into a dry spell, recover more quickly when rain arrives, and reduce the requirement for plant renewal.
It is true that, for a nitrogen dependent fertilizer system, there will be a decline in growth initially, until a more natural system is encouraged through a shorter-than-might-be- expected risk-free transition process which favours establishment of strong vigorous clovers.
Where nitrogen has been regularly applied, plant available calcium levels are likely to be too low for optimum clover growth. Therefore autumn is not the best time for a correction with an application of lime, as excess calcium in pasture prior to calving reduces the availability of magnesium, and an increase in costly calcium/magnesium related metabolic disorders can occur.
Instead, an application of Golden Bay Dolomite now at between 200 – 250kg/ha, at approximately $50/ha, applying 23– 28kg Mg/ha, provides the initial transition step, as well as ensuring animals fully fed on pasture receive sufficient magnesium for robust good health at calving.
The dolomite will increase pasture palatability and allow better utilization (often commented on), and a consequent improvement in physical soil structures will allow excess water to drain, reducing damage from pugging over winter.
A lime application in November, further increasing soil pH, will stimulate beneficial earthworm activity, and provide the calcium necessary for strong clover growth. Thus reducing or removing the need for fertiliser nitrogen during the next growing season.