Sub-optimal soils in UK hindering yield

Half of grassland soils in the UK have sub-optimal pH levels, which not only reduces nutrient efficiency, but can lead to a 5-30% reduction in dry matter yield.

That’s according to George Fisher of the British Grassland Society, who said soil pH was fundamental for a profitable grass system.

Speaking at the British Grassland Conference in Malvern last week, Dr Fisher said scientific studies proved a soil pH of 6-6.5 would achieve the maximum yield for grass and white clover mixes. But he said many grassland farmers were still getting it wrong.

Another study found only 8% of 38,266 grass samples contained the correct index for phosphorus and potassium.

“Most of these gaps are to do with knowledge exchange and transfer. The science is there,” he added. But he said “a great deal” of work still needed to be done on soil science.

“We know the fundamentals, but what’s the interaction between soil structure and nutrients and what’s the effect of worm population?”

He said tests conducted on one of his clients’ farms found lime application failed to bolster pH on compacted soils.

Dr Fisher said in this sense “farmers were ahead of the researchers”. He added: “In the North West a lot of farmers that used to spike don’t think it’s doing a lot for them, so they’ve started to sward lift instead.

“There’s no research out there to show farmers when the best time is to do it [spike or lift] and, more importantly, what the effects are on grass growth and use.

“If you spike or lift at the wrong time you could cause more of a problem. All you do is push the sogginess down a few inches,” he warned.

Dr Fisher said applied research needed to be completed to show the benefits of such practices in terms of grass growth yields and how spring and autumn treatments differed.

“It’s about giving farmers the confidence to know they are getting it right,” he said.

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