Farmer Focus: Questioning closed season spreading rules
© Tim Scrivener The dry and mild winter conditions made a January turnout tempting, but we have held off to avoid dietary changes in the final weeks of breeding.
Production dropped more than hoped through January, to 1.9kg milk solids a cow a day.
A dip in milk ureas and a consequent silage analysis have shown the earlier first-cut grass is much lower in protein (14.5%) than the later first cut.
The slow spring of 2021 is the likely culprit.
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In the short term we’ve accepted the higher cake price and increased cake protein to 18% until turnout. Fresh grass samples look promising at 27% protein and more than 12.5 metabolisable energy (ME).
See also: How tests for additionally available N can cut fertiliser use
Whether conventional or organic, with input prices sky-high, maximising production of good-quality forage should be the focus more than ever. With soil temperature above 6C throughout most of the winter, the grass has continued to grow and we are in a strong position starting the spring.
In our area, with the mild and dry winter, the Environment Agency’s nitrate vulnerable zone closed season rules could be questioned.
Growing grass could have benefited from a low dose of organic nitrogen. Often November and December present better in-field conditions than February.
That said, the rules were made because winter spreading was abused by a few farmers with the aim of “getting rid of slurry” rather than using it to its full potential.
Soil temperature, moisture probes and grass growth monitoring can prove nutrients are being taken up by the plant and low rates can be adhered to through flowmeter GPS mapping. This allows farms to build good winter grass covers and better their position for cheap feed costs in the spring.
Recently there has been talk about cutting spring nitrogen due to inflated prices, but I would not cut back on spring nitrogen if I were a conventional dairy.
Applied on good soils at low application rates in early spring we expect 10kg DM/ha (4kg DM/acre) growth for every 1kg of N applied as slurry at 25cu m/ha (10cu m/acre).
This drops to 5kg DM/ha (2kg DM/acre) for every 1kg N when overapplied and lower when the grass is in its reproductive stage later in the season.