With heavy rain in many parts of the country over the weekend, conditions change quickly on farms.

While dry parched farms will be delighted to get as much rain as possible and hopeful of a bounce in growth, farms on heavier soils may already have received adequate rainfall and paddocks are already back at field capacity.

The main considerations for these farms are obviously very different.

ADVERTISEMENT

On dry farms with low levels of grass availability, the rain may have just come early enough to build grass during September.

With big feed bills already incurred this summer, the objective now has to be to slow down rotation length after the rain to 50 days for the next two weeks and allow as much grass as possible to build up ahead during September.

Where adequate rain has fallen, the target should be to increase average farm cover by 200kg each week and to get as close to 1,200kg DM/ha by the end of September.

Very dry farms will probably sit at low growth for another week or 10 days after the rain arrives, but some paddocks will pick up again quicker than others, so keep measuring and clean off any stagnant grass.

Big increase

Achieving a big increase in farm cover over four weeks may even mean partially housing cows by day or night for two weeks, as feeding outdoors may be difficult if we have more rainfall next week and conditions get dirty.

We may yet get extra compensatory regrowth for the next two months after such dry weather, so going slow now will allow grass supply to build while day length is still good.

The more grass on the farm over the next month, the greater the chances of increasing growth rates and extending the grazing season during the rest of the autumn.

Empty cows

If empty cows have been identified or there are animals within the herd which are persistent high SCC or lame cows, culling these now will help to build up grass.

Speaking at Dairy Day last autumn, New Zealand farmer Simon Lynskey was very clear that booking the scanner and the lorry to take cull cows were his first two steps when managing feed supplies coming out of drought conditions.

If you are concerned about winter feed levels, removing culls now is the first step to solve a feed shortage.

Nitrogen

A chemical nitrogen (N) application of 25kg N/ha this week on green area, ideally as protected urea with potassium (K), will boost grass supply.

There has been no N spread on many farms since early July, so now is the time to begin.

Previous studies indicate that each 1kg N applied in early September can yield up to 30kg dry matter (DM) in additional grass response.

Even with chemical N reaching €1.70/kg N, this is the cheapest feed source for the farm this autumn.

On heavier farms which are already growing well now (40kg to 50kg DM/day), it’s likely that heavy rainfall over the next few days may make grazing conditions more difficult.

There’s no substitute for using strip wires and 12-hour allocations to protect available grass supplies and achieve good utilisation of the available feed.

These farms should also aim to extend round length to 40 days and build farm cover to 1,100kg DM/ha over the next three weeks.

These farms have already spread fertiliser in the last month in most cases, so there is probably only one more application required over the next two weeks.