A new online calculator aims to help growers correct soil nutrient problems, as data reveals nearly one-third of British soils show serious deficiencies in phosphate and potash.

To help growers to correct these soil deficiencies more quickly, and so lessen the time over which a field is at significant risk of yield loss, a calculator has been developed by the Potash Development Association (PDA). The calculator provides an indication of the nutrients required for correction as well as the annual applications needed over a chosen number of years.

“The calculator starts the conversation about what to do about widespread and serious deficiencies,” says Chris Dawson of PDA.

“With the guide results you can see field-by-field the deficiency – correcting steps to take for better yields and quality,” he says.

Its smart farming at your fingertips, the PDA phosphate and potash deficiency correction and nutrient offtake calculator gives instant results.

Simply tap in the crop and expected yields for the harvest offtake, then soil type and current and desired phosphorous P and potassium K indices (or mg/litre) and over what period to make the improvements. Press “calculate” and the results quickly and clearly give the fertiliser recommendation in two parts – the nutrients that will be removed at harvest and the estimate of the nutrients needed to correct any underlying deficiency.

After the calculations come the costings for the correction. Mr Dawson cautions against expecting the crop to carry the cost. “Farmers should only set the cost of the P and K offtakes at harvest against the crop. Fertiliser to correct the deficiency should be charged to another account, as would be the case for liming and drainage.”

For many UK farms, correcting P and K deficiencies will take time as well as careful calculations. The calculator indicates what’s needed over what timeframe is chosen to achieve change.

“Soil analysis will show farmers what P and K their soils have,” advises Mr Dawson. “Correcting deficiencies may require some costly dressings, especially for farmers with heavier land. Applying an extra 30kg of P or K per hectare is simply too little to solve the underlying problem quickly enough; it could take 20 years.”

Yield and quality reductions are every year we leave P and K deficiencies uncorrected. We have to tackle serious problem of low index fields in the UK. The calculator is the tool to help in that job.

More on this topic

Chop or bail: exploring the cost benefit analysis

Go to the PDA online calculator site