Testing the benefits of spring potash for yield enhancement

The spring potash FIG is now in its second season, in 2017/18 four farmers undertook tramline trials testing a spring application of 0, 100 and 200 kg/ha of Muriate of Potash (MOP, 60% K2O) in winter wheat with five farmers taking part in 2018/19. 

The five farmers include David Brightman, Thomas Maynard (Warwickshire), Ian Holmes (Nottinghamshire), Andrew Wilson (Yorkshire) and Rick Davies (Buckinghamshire), with industry support from Ian Matts at the Potash Development Association. The trials are testing the potential benefit of adding potash alongside the main nitrogen (N) application to improve crop N uptake.

Christina Clarke, ADAS Crop Physiologist who is leading the trials explains why spring potash is worth considering for improving yield.  Potassium is a macronutrient and is taken up in large quantities due to its major role in water regulation and the transport of nutrients in the plant. Consequently, adequate potassium supplies can promote the yield and quality of a cereal crop through improved nutrient uptake and well filled grains. Potassium and nitrogen are strongly associated within plant processes as nitrogen stimulates cell growth which increases cell water intake. Potassium is then needed to maintain cell turgor by regulating cell water content. The formation of proteins from nitrate and their distribution around the plant is also dependant on adequate potassium levels, therefore affecting the crop N response.

In the first season, there was no significant effect of applying MOP at 100 or 200 kg/ha in four of the five trials. A significant treatment effect did occur in a single trial in Buckinghamshire where yield increases due to MOP were consistently 0.25 t/ha for each 100 kg/ha MOP applied. The 2017-18 growing season was characterised by abnormally warm and dry conditions from May to July. It is likely these drought conditions reduced crop responses to nutrient applications, exaggerating the effects of soil variation on yield and increased within field variability, potentially reducing precision of the tramline trials conducted.

This season we are also monitoring tissue nutrient levels at multiple growth stages in the hope this will give us more detailed information on the potential benefits of the MOP application.

Find out more

For more information on the spring potash trials, contact Christina Clarke