Improve soil nutrients balance to increase yields

The yield and nutritional quality of forages will be improved if soils have the right balance of nutrients, but many fields are under-performing because farms have no testing programme in place.

A project run by EBLEX, in association with the Environment Agency and the Food and Wildlife Advisory Group (FWAG), revealed that of the 3,291 fields tested, only 2% were on target for pH, at index 2 for phosphate and at index 2- for potash.

Just 9% of the fields sampled were at the target indexes for both P and K, reveals Liz Genever, EBLEX sheep and beef scientist.

In this situation species including yorkshire fog and creeping bents will dominate, instead of better-quality grasses such as perennial ryegrass, she adds.

“There can be a difference of 10 D-value points between high-quality species and the less-productive species, which equates to a difference of 200g daily liveweight gain in lambs and 400g a day in cattle.

“By having the right soil nutrients farmers can improve the yield of higher-quality feed, thereby reducing the amount of bought-in feed and ensuring that more fertility and growth targets are met off grass alone. Without attention to the soil, grass and silage yields will be compromised,” she says.

Not only does testing identify nutrient imbalances, it can also save farmers money. Of the fields sampled in the soil-testing project, 44% of dairy farms had high levels of P and 37% high levels of K. “Applying additional P and K in these situations wastes time and money and risks water pollution,” warns Dr Genever.

She recommends sampling fields every five years, in the same season and at least two months after the last application of manure, fertiliser or lime.

One of the farmers involved in the soil-testing project, Chris Hodgkins, discovered that all of his fields that were sampled had high levels of P and K. Over a number of years the fields had been fertilised with mushroom compost, which has a considerably higher phosphate content than cattle manure. Most of the samples showed a phosphate index of between 4.5 and 5.2 and potash at up to index 4.

Mr Hodgkins, who runs 3,000 New Zealand Romneys and 50 suckler cows, says he will now apply fewer nutrients to the land, thereby saving money.

“For us, the results of soil testing has been a great indication that we can save some money by not applying nutrients that are not required,” says Mr Hodgkins of Locks Farm, near Pulborough. “Up until now we were unaware of the nutrient status of our soils and were very surprised by the findings.”

He now intends to test all his fields in rotation. “This is something we had overlooked because we were busy doing other things and had got into a situation where we were applying the compost year after year without necessarily analysing the situation.”

The soil-testing project not only sought to raise awareness of the implications for production, but also the environment.

Although farmers whose land had high indices are being given advice on how to reduce them, the guidance given to farmers with low indices is as important from an environmental perspective, according to FWAG’s technical director Jim Egan.

“It is important that applying higher inputs is done in a structured way, to not only maximise production, but to avoid jeopardising the environment,” he says.

Mr Egan urges every farmer to sample soils. “It is a means to responsible environmental farming that can save money.”

Tips for soil sampling

• Twist a soil corer down to 7.5cm and collect 25 samples in a ‘W’ pattern, avoiding gateways and feeding areas.

• Include fields that underperform and those that are going to be reseeded. Also include fields that receive high volumes of muck or slurry or where perennial ryegrass content is noticeably declining.

• Seal soil in plastic bag and label.

• Send to soil laboratory. This is often done through a local co-op, a fertiliser merchant or an independent company.

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