Soil test – the new must-have for 2021

By Jennifer Rhymes, Bangor University and Lizzie Sagoo, ADAS

Soil testing allows for more accurate, efficient, and cost-effective nutrient applications. Through the Soil Testing Pastures project funded by The Sustainable Agriculture Research & Innovation Club at Bangor University, Dafydd Williams from North Wales explored the potential gains from soil testing on one of his silage fields:

“My experience of soil testing for the first time has been an eye-opener. Correcting soil pH with lime is so important to improve your soil condition. I think it really is beneficial to soil test.”

Soil test results for Dafydd’s silage field indicated that whilst phosphorus indices met targets for optimal grass growth, soil pH and potash indices did not. This allowed Dafydd to take a more targeted approach to his nutrient application by applying calculated rates of lime, nitrogen and potash. He was also able to exclude a phosphorus application that year, meaning nutrients were not applied unnecessarily and saved some costs.

 “Through this trial we managed to get more silage with less fertiliser from one field on our farm. I will definitely carry on sampling and will soil test the rest of my fields from now on. Hopefully, our stock numbers will improve over the years too,” he said.

Dafydd’s targeted management improved his yield on the field by 600 Kg DM/ha in the first year. This highlights the potential for reducing the amount of purchased feed and increasing stock numbers to improve farm returns.

Soil testing in England is now compulsory under the Farming Rules for Water and likely to follow in Wales and Scotland soon. Follow this four-step checklist for testing your soils:

1. Test each field every 3–5 years.
2. Wait for six months after lime or fertiliser application (except nitrogen) or six weeks after a manure application before taking a soil sample.
3. Walk a ‘W’ pattern across the field, stopping at least 25 times to take a sample using a gouge corer or screw auger to a depth of 7.5 cm.
4. Put the samples from the same field into one bag and send to a laboratory facility for pH, extractable phosphorus (P), potassium (K) and magnesium (Mg) analysis.

Find a laboratory to send your sample to here. 

The results from soil sampling will help the farm make the best use of its fertiliser and manure nutrients. Use your soil results to:

• Identify any fields which are above or below the target pH of 6.2
• Identify any fields which are above or below nutrient indices (P = Index 2, K = Index 2-, Mg = Index 2)

Laboratory analysis reports provide lime and fertiliser/manure application rates. Alternatively, discuss with a FACTS qualified advisor who can provide nutrient management planning support.

AHDB Managing nutrients for better returns contains more information.