Research highlights key nutrients could alleviate in-season crop stress
January 25, 2013, (Source: Farmers Guardian ) — DO not underestimate the effects of potassium and magnesium at mitigating the effects of plant stress, growers are being advised.
According to recent research, both nutrients can help reduce damage from drought, strong radiation and severe cold conditions, as well as protect against lodging.
The advice, given in a paper to the International Fertiliser Society’s annual conference, is to maintain adequate levels to keep crop yields on track. According to the paper’s co-author, K+S UK & Eire technical manager Jerry McHoul, the demand for potassium and magnesium is particularly high during reproductive growth.
He says: “Trials by a number of European research teams confirm reduced stress – particularly due to drought – over this key period of growth when both nutrients are well balanced and in good supply.”
New research also highlights the role of potassium within the soil to help improve its physical structure and water holding capacity during times of drought.
And under extreme cold stress, plants with high levels of potassium in the cell sap have a lower freezing point.
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Looking back to last season, Mr McHoul suggests poor grainfill in the wet, dull conditions meant many cereal crops simply did not have the weight in the ears to lodge.
“In a more normal season, given the rainfall we had, we’d have expected to see more evidence of lodging.”
There were signs both potash and magnesium nutrition do not get sufficient attention, he says. “Potash use, in particular has declined year-on-year for the last 20 years in the UK.”
Of the two nutrients, magnesium is more mobile than potassium and in light soils under intensive crop production needs regular replenishment. While potassium is generally required at much higher levels than magnesium, it is much less mobile and more readily held in the soil. Both nutrients though need to be in balance as too high a level of potassium can restrict magnesium uptake.
“This is where agronomists and farmers have to ensure fertiliser contains a balance which works for each specific soil and crop situation,” says Mr McHoul.
“Foliar use of available magnesium in the form of magnesium sulphate will help alleviate in-season crop stress, but in the long-term, we need to build adequate supplies in the soil.”