The use of nitrogen after a dry summer or autumn

Nitrogen is important to not only help increase pasture cover after summer or autumn dry but also to encourage ryegrasses to tiller. Nitrogen is a low risk option as it has been proven to increase dry matter yields although the responses are variable from 4:1 to 10:1.

Nitrogen is a cost effective method of increasing feed supply when used effectively in the autumn. At a 6:1 or 8:1 response the cost per kg DM is 28 to 20 cents respectively.

Nitrogen can be applied as soon as there is significant rain. It is more important to get nitrogen on than when it is applied.

Research has shown that the drymatter responses were similar regardless of whether the nitrogen was applied after the first rain or following subsequent rain.

Nitrogen should be applied at 30-40 kg N/ha. If the drought breaks in April a second round of nitrogen can be applied in May if soil temperatures remain above 7 degrees.

Nitrate poisoning is a risk in the autumn especially when grazing new grass and annuals, on cool, cloudy days and on fast rotations - conditions that are likely to occur after severe drought conditions. If concerned about grazing a pasture or crop the pasture/crop can be tested with test kits available from your vet.

The risk of nitrate poisoning can be reduced by:

Grazing pasture that is older than 21 days - long rotation
Ensuring that the cows are not hungry when put onto high risk pastures
Feeding forage supplement first and
Restricting the time on high risk pastures.

Stock also need to have access to fresh and clean water. Contrary to popular belief the nitrate content of pasture or crop is not reduced by using glyphosate, chopping or a frost.