Growers continuing to take a ‘holiday’ from applying potash could be risking serious yield and quality effects, according to the Potash Development Association.
Results from the latest British Survey of Fertiliser Practice showed that 65% of arable crops did not receive a dressing of potash in the 2004/05 season, continuing the trend which began during the late 1990’s.
But this shortfall is not being made up by organic fertiliser, as less than 20% of the arable area (10-12% of winter wheat or oilseed rape) received manure, the survey also found.
While potassium is essential for all crops, sugar beet requires large amounts and soils should be maintained above the critical level for plants- K Index 2 for beet – as below this level, yield will be lost, the PDA warned.
The PDA has revised its ‘Potash for sugar beet’ leaflet to make growers more aware of the need to maintain soil potash levels and provide advice on application timing and sources of potassium – see www.pda.org.uk to download a free copy.
Some key points include:
• Maintain soil K index of at least 2
• Ensure K is where roots need it – sugar beet only occasionally responds to freshly applied potash
• Potassium in ploughed-in tops is returned to the soil K reserve
• K removed in harvested beet needs to be replaced on all soils below K index 3
• Applying sodium may be of benefit on soils with a K index of 0 or 1