Scope there for P&K ‘holidays’ under SFP

BE SURE to measure soil nutrient levels before adjusting phosphate and potash application policies in the light of the single farm payment.

That is the advice to combinable crop and sugar beet producers from Brian Chambers, Notts-based ADAS principal research scientist.

“If you plan to continue growing crops under the SFP system, standard good practice is still very much appropriate.”

That involves knowing the soil P and K status and acting accordingly, says Prof Chambers.

“Where P and K indices are three or above, base fertiliser holidays” are wholly appropriate and should be taken advantage of in the short term. But it will be important to monitor the soils” P and K status while withholding these nutrients.”

At P and K index two, applications are for maintaining soil reserves, he notes. “So missing a season”s dressing should be OK, but it wouldn”t be advisable in the long term. It”s always a good idea to find out if fields are at the upper or lower end of index two.”

In fields with indices of only zero to one, crop responses to P and K treatments are likely, so annual additions will still be required, he warns.

“Don”t forget the P and K in farmyard manures, slurries, and biosolids (sewage sludge). Where they are available they offer substantial savings for the next and following crops.

“Given present margins, growers can”t afford not to realise the value of these manure nutrients.”

Based on the P and K off-take of an 8t/ha wheat crop, with its straw ploughed back in, typical manure applications will supply enough P to match the removal by one to four wheats, and enough K for two to seven, though K off-take will roughly double where the straw is carted off, says Prof Chambers.