A nitrogen boost could be the most cost-effective way to get more milk in the vat this summer.
Field trials1 during a dry summer in 1997 revealed applying nitrogen as late as December or January boosted shoot numbers by 37 percent – more than double the response achieved through the use of irrigation. Josh Verhoek, Ballance Science Extension Officer, says, “Applying nitrogen to pasture during growth periods encourages tillering. You’ll also get larger leaves on each tiller. This will make your pasture more resilient to summer grazing, weed invasion and drought, and enable it to recover more quickly for the next season.”
Another trial2 showed an extra 800 kilograms of Dry Matter per hectare (kg DM/ha) and 66 kilograms of Milk Solids per hectare (kg MS/ha) could be produced from December to April by applying 100 kg of Nitrogen per Hectare (N/ha), split between December and January. Gains came from having more cows in milk over summer and being able to dry them off later, rather than an increase in daily milk production. “But regardless of the ‘how’, the end result was more milk,” says Josh. With economic value in mind, obviously gains are meaningless if the cost of achieving them is too high. The ‘More Summer Milk’ study3, carried out in the 1990s, compared cropping, silage and nitrogen use as ways of increasing summer food supply, looking at effects on milk solids production and financial returns. “Applying nitrogen resulted in the most consistent and profitable response,” says Josh. “Cropping removed grazing area at the time of highest feed demand and cultivation costs affected profitability. Silage also proved to be less cost-effective compared to nitrogen.”
To get the best returns from nitrogen there are a few things to consider:
Volatilisation can commonly steal around 20 percent of the nitrogen applied.
Losses can be as high as 50 percent. Low soil moisture, organic matter content, cation exchange capacity and crop/pasture cover can all increase the risk of loss. Loss potential also rises with the amount of nitrogen applied.
Using SustaiN or SustaiN K if your soil also needs a potassium boost, can help. The urea in these products is coated with Agrotain™ nitrogen stabliser, which significantly decreases volatilisation losses, giving you more flexibility with the timing of nitrogen application.
“You’ll still need to monitor cow condition closely and dry off if it drops too far but, for many, nitrogen-boosted pasture will be the best way to extend your season,” says Josh.
1DairyNZ Farm Fact 7-16 ‘Nitrogen use going into summer’, DairyNZ 2012
2Penno J.W., Bryant A.M., Carter W.A., Macdonald K.A. 1995. Effect of nitrogen fertiliser and summer rotation length on milk production in a dry Waikato summer. Proceedings of New Zealand Society of Animal Production Vol 55: 64-66
3McGrath, D.F.; Dawson, J.E.; Thomson, N.A.; Simons, H.P. 1998. More summer Milk – the Opportunities Identified. Proceedings of the Ruakura Farmers’ Conference 50: 85-94.
Article supplied by Ballance Agri-Nutrients