Lower South Island farmers are being advised to consider applying a nitrification inhibitor this month in line with scientific recommendations.
Jeff Morton, a Technical Consultant based at Ballance Agri-Nutrients in Rolleston, says a large proportion of the nitrate leached from dairy urine patches occurs in the autumn because there is not as much taken up by plants and drainage starts to occur.
He says AgResearch work at Tussock Creek in Central Southland found that the best application dates for Ballance’s DCn, which contains the nitrification inhibitor dicyandiamide (DCD), to minimise nitrate leaching are mid-to-late March and again in mid-to-late April.
‘Farmers in South Otago and Westland can benefit by acting smartly on this issue, as their farms require the DCn ahead of the other regions,’ says Jeff. ‘The application dates ease back slightly the further north you travel, but now is certainly the time to make your plans.
‘Farmers have come under pressure to manage nitrogen inputs and nitrogen effectiveness, and DCn offers a simple way to reduce nitrate leaching by up to 35 percent. Nitrous oxide emissions are also reduced when DCn is used.’
He says two applications are required for maximum effectiveness because DCD is gradually broken down in the soil by bugs and also because fresh urine will be added when the cows re-graze the pasture in April/May.
‘DCn should be applied at 50 kg/ha by a certified spreader to ensure an even distribution or if spreading yourself at no more than 10m bout widths. It should be applied within one week after each grazing.’
The DCn product works by holding nitrogen in the ammonium form so that plants have time to utilise this nutrient to the maximum, explains Jeff. This results in less nitrate loss to the environment and potential pasture growth increases.
‘Reducing nitrogen losses on your farm has clear benefits for the environment and for your pocket,’ says Jeff.
‘When nitrogen is lost as nitrate it takes with it cations such as calcium, magnesium and potassium. Reducing nitrate leaching will reduce cation loss and lower the need for maintenance fertiliser inputs of those cations.’
3 March 2010
