Making best use of nutrients

Rebecca Audsley, Principal Consultant, SAC Consulting.

Organic fertilisers such as slurry, manure, sewage sludge and anaerobic digestate (AD) can all offer benefits to the farm business, soil health and crop yields. But how do we get the best value from organic fertilisers whilst also minimising emissions? Here are three areas to consider:

  • Planning – Knowing soil nutrient status, nutrient value of organic manure as spread, and crop nutrient requirement are all ways to balance and optimise nutrient application. A nutrient budget will help to target what gets applied where and at what rate, optimising nutrient use from both home-produced and bought in fertilisers. Support from Scottish Government under the Preparing for Sustainable Farming (PSF) initiative means farmers in Scotland can claim funding towards soil sampling and analysis, assisting the nutrient budgeting approach.
  • Storage – More farmers are considering slurry store or lagoon covers when upgrading storage, reducing emissions and keeping more nutrient value within the slurry. Others are looking at ways to make better use of existing capacity to meet the 22-week storage requirement. Rainfall, collection from dirty yards and silage pits all need to be factored in when calculating storage needs, but are you also collecting ‘clean’ runoff that doesn’t need to go to your store? Taking a closer look at what goes into your collection system may show areas for reduction and ultimately free up storage space for slurry, pending investment in that new covered store.
  • Application – How and when we apply slurry counts. With high trajectory splash plates no longer an option for slurry application, the move to precision application techniques, such as trailing shoe or injection can reduce odour and minimise crop contamination. Various studies show a decrease in ammonia losses ranging from 33% to 63% when using precision application techniques in comparison to high trajectory splash plate application.

Free nutrient management planning tools are available at PLANET; guidance on the rules around slurry application and carrying out a dirty water audit are from Farming & Water Scotland; there is also a range of information on Scotland’s Farm Advisory Service (FAS), alongside access to the free FAS advice line.

Farming for a Better Climate is funded by the Scottish Government.

This article was first published in the May – June 2023 edition of the Farming Scotland magazine

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