Tuesday, August 20, 2019

Test soil and manure to boost grass yields say experts

March 31, 2017 by  
Filed under Crops

Grassland & Muck 2014 Picture Tim Scrivener 07850 303986

Farmers could significantly boost grass yields and quality by making better use of soil and manure analysis, visitors will be told at next month’s Grassland & Muck Event.

Around 40-45% of UK grassland is deficient in potash, and more than half has a pH below six, dramatically reducing the efficiency of nutrient uptake by plants, says Jon Telfer, development manager of analytical services at Yara.

“Supplies of soil sulphur are more or less exhausted,” Mr Telfer will tell visitors on 24-25 May at Stoneleigh Park, Warwickshire.

He added, “There are a huge number of soils that need attention, and some really straightforward gaps to be plugged.”

A comprehensive soil test typically costs around £30 and will be valid for about five years, so the return on investment can be considerable.


“If you’re applying fertiliser to a soil with a low pH, or the incorrect grade of fertiliser, it will look very expensive. This is about taking a measure to manage approach: A nutrient management plan will only be as good as the data you put into it.”

Visitors to this year’s event will be able to bring their soil problems along to discuss with ADAS experts in the Soil Management Clinic, where they can also examine soil structure and hear how to remedy common issues like compaction.

The second step to creating a nutrient management plan is to measure the nutrient content of organic manures. Yara analysis has shown that this can vary by a huge amount – the equivalent of up to £34/acre.

Nutrient-rich slurry might deliver 64kg/ha of nitrogen, 81kg/ha of phosphate and 129kg/ha of potash. Compare that to slurry with a low nutrient content of 21kg/ha of nitrogen, 26kg/ha of phosphate and 44kg/ha of potash.

“You can see that the extra fertiliser required to make up the difference is significant,” says Mr Telfer.

Average figures for the nutrient content of manures are published in the RB209 handbook – the new version of which will include digestate for the first time and is being released at the Grassland & Muck event. But there is a wide range within those averages.


“Without testing their manures farmers may well be over- or under-applying fertiliser, says Mr Telfer.

Taking a balanced approach to crop nutrition will not only boost grass yields, but also forage quality, he adds.

“The sulphur to nitrogen ratio is critical; it affects the level of protein, sugar and starch in the grass, as well as its digestibility. Micronutrients are also important: There is life beyond 20.10.10 and it doesn’t have to be difficult.”