Some say record high prices for nitrogen, phosphorus and potash will do more to help improve water quality than any Government policy ever could. I’m not sure that this is the case, as water quality is multi-factorial.

However, one thing is for sure – farmers will be watching where and when they spread fertilisers in 2022 and beyond.

How much nitrogen dairy farmers should spread in 2022 is a difficult question to answer.

It largely depends on the stocking rate, as this governs how much feed the farm needs to grow to support all the stock on the farm.

Nitrogen is a growth accelerator, so the more you apply, the faster the grass will grow.

The problem is that the law of diminishing returns kicks in, so response rates decrease for every additional kilo of nitrogen applied

The sweet spot on a well-run grassland farm with good underlining soil fertility is probably around 200kg N/ha to 225kg N/ha.

This presumes an annual grass growth requirement of 14t/ha or thereabouts. If less grass than this is required, then less nitrogen can be spread.

Equally, if the farm or individual paddocks on the farm have high clover contents, then much less nitrogen can be spread there too.

Going cold turkey on nitrogen just because it is very expensive risks a feed deficit emerging on the farm. Now, many farms have good banks of silage built up and some farmers will be happy to eat into this next winter and that’s fine.

The only thing to keep in mind is that fertiliser prices, while likely to fall from their current highs, may or may not be back to normal by next year, so the cost of replacing the silage in the yard will be expensive.

Capital fertiliser

Grassland farmers need to look at their farm and soils more like a tillage farmer does. The main crop, in the case of the dairy farm, is grass. How many nutrients does this crop require on an annual basis? This depends on the stocking rate.

Highly-stocked and productive dairy farms have high offtakes, as nutrients leave the farm every day in the form of milk.

Cattle rearing systems have lower offtakes, although heavy crops of silage do have big offtakes.

Farmers should look at each field on a case-by-case basis and fertilise it according to what will come off it.

This is called maintenance application, because you are neither increasing nor decreasing the soil fertility status, effectively just feeding the crop. Failure to feed the crop has consequences for yield and depletes soil fertility.

Fields with low soil fertility require capital fertiliser to bring them back to target level of soil index three. In my view, this is not the year to spend money on capital fertiliser, as it is just too expensive.

The exception to this is lime – where soil pH is low, it should be corrected as soon as possible.

However, if phosphorus or potash is low, then I think it is better to concentrate on feeding the crop (to prevent any further reductions) and purchase capital fertiliser when prices drop.