Agronomist urges early nitrogen programs

By Dairy News

DAIRY FARMERS are encouraged to start nitrogen programs early this season to maximise spring pasture and fodder growth.

Incitec Pivot Fertilisers technical agronomist Lee Menhenett said where there was adequate soil moisture, nitrogen could be used from late winter to stimulate growth.

“Opportunities to capitalise on spring fodder conservation are always relatively short-lived, even in good seasons, and replenishing on-farm fodder reserves is especially important for many dairy farmers this year,” Mr Menhenett said.

“Sometimes it’s a good idea to take advantage of soil moisture and good growing conditions when they are available, because we don’t know what will be around the corner.”

Mr Menhenett said responses to nitrogen in spring were typically 15 to 30 kg of dry matter/kg of nitrogen applied and the cost of growing this additional feed was easy to calculate.

“For example, by applying 40 kg/ha of nitrogen, an additional 600 kg of dry matter/ha can be grown in spring assuming a nitrogen response rate of 15 kg of dry matter per kg of nitrogen. If we value nitrogen at $1.30 kg, the additional dry matter would cost $52/ha or $87/tonne of dry matter standing,” he said.

Mr Menhenett suggested that dairy farmers fertilise the grazing area as well as the fodder conservation area.

“Growing more feed on the grazing area allows more space to be set aside for fodder conservation,” he said.

To get the best results from nitrogen, he said pastures and crops must have adequate soil moisture.

“Stored soil moisture needs to be in excess of 50 mm for significant dry matter responses to nitrogen and a minimum of 5 to 10 mm of rainfall or irrigation is also required after application.”

Mr Menhenett suggested using robust nitrogen rates of 40 to 60 kg/ha of nitrogen per application in improved grass-based pastures and 50 to 60 kg/ha of nitrogen in hay and silage paddocks.

On the second cut in hay and silage paddocks, when soil mineral nitrogen rates can be low, he said rates of up to 80 kg/ha of nitrogen could be considered.

“Good base soil fertility with phosphorus, potassium and sulphur is also required for good nitrogen responses. These can be topped up or maintained by using BoostaTM fertilisers or blends.”

Turning to timing, nitrogen fertilisers should be applied immediately post grazing because nitrogen responses decreased by one per cent for every day application is delayed.

“Allow at least four weeks between nitrogen application and mowing,” he said.

“It always helps to be proactive and prepared when it comes to hay and silage. Be ready to reduce the grazing area early and allocate more paddocks for conservation, have the stack site or shed prepared and be willing to cut earlier rather than later if rain is coming or the contractor is ahead of schedule.

“Don’t forget that quality is king — don’t be tempted to leave it too long chasing quantity.”