Don’t gamble with what your slurry and farmyard manure will contribute to maize land this winter and be extra vigilant if applying it on light soils or sloping land, warns Wilson Hendry of forage specialists Grainseed Ltd.

“The next few weeks should be used to assess exactly what farmyard manure and slurry you have but you need to be realistic about what these will really provide once applied,” he says.

“The actual nutrients gained will depend on when you’re spreading it, how quickly it’s going to be incorporated and what’s actually in the slurry store.”

Drymatter content of slurry is also critical, he says.

“If you’ve got an acre’s worth of roof leading into the store, your slurry will be about 2% drymatter. If you’re able to exclude rainwater, you could get up to 10% drymatter - most peoples will be around 6% drymatter.

“But don’t guess. Get it tested and make nutrition plans based on facts rather than assumptions.”

If maize land has any degree of slope or is on lighter soils, rainfall run-off could also be a problem complicated by the recent wet conditions.

Heavy harvest equipment, in particular, can cause surface compaction that makes the problem worse, Wilson Hendry warns.

“As rainwater runs down the hard soil, it builds up enough energy to start picking up soil particles which then wash down the slope.

“This lost soil is a problem in itself, but it also creates diffuse water pollution in watercourses and nutrients from previous crops can cause problems too.”

Using a chisel plough to loosen the compacted surface layer to a depth of 4” or so is often all that is needed to allow the water to soak in, he says.

In fact, work at the Institute for Grassland and Environmental (IGER) research in Devon has shown use of chisel ploughs in this way can reduce water run off from 433 to just 10 cubic metres/ha.

“The key is to harvest early and use the chisel plough when the soil is dry enough to allow effective shattering. The IGER work showed the technique can have limited benefits if the soil is too wet.”

If you’ve cultivated the top layer of soil a muck spreader or slurry tanker is not going to travel as well, he adds.

“An umbilical system will work fine but if you’re spreading solid muck or using a slurry tanker, the best way is to put a cultivation path across the side of the slope every 20m or so.

“This allows the spreader to travel easily on the uncultivated areas and the water to soak in when it reaches the cultivated sections.”