As reported (Arable, 29 August) farmer groups from four Norfolk river catchments were last year challenged to reduce pollution from soil erosion and water run-off, while still producing top yielding crops.

The variations in their plot yields at Easton College showed that the differences in soil structure achieved by their chosen establishment methods had a big impact on both grain output and soil erosion and water run-off.

“The farmers did choose different varieties, so there was some muddying of the water,” admits challenge co-ordinator Simon Draper. “But even so the yield differences couldn’t be fully attributed to that. Indeed two plots had the same variety, Robigus, but there was more than 1.3t/ha difference in their yields.”

The highest performing plot was also one of the cheapest to cultivate, receiving only a subsoiling and then being Vaderstad drilled with no further cultivation.

However, the drill did compress the subsoil leaving a firm seed-bed, which while preventing soil erosion caused plenty of run-off, notes Mr Draper.

The best plot for preventing run-off and soil erosion was the one ploughed, furrow pressed and then tine drilled. This left a rough surface and stopped virtually all soil leaving the plot, explains Mr Draper.

“The crop there did produce good root growth in comparison to the other plots, but that wasn’t translated into yield because of the lack of uniformity and spacing of the individual plants.”

The plot with the highest spend – on subsoiling, furrow pressing and Vaderstad sowing – produced the second highest yield and second least run-off and erosion.

“But the extra cost of operations was equivalent to 0.4t/ha making it equal to the plough and combination drill option.

“Discing caused serious compaction,” he says. “While it’s a cheap way to establish crops it did result in the maximum amount of run-off and low yield.”

The college’s CSF trials are being repeated this season growing winter barley.

“The cultivation practices are the same, except that on half the plots 10t/ha of farmyard manure has been applied, the object being to see if the cultivation methods can cope with it being incorporated.”

Easton College CSF Cultivations Challenge plot yields

• Subsoil/plough/furrow press/Vaderstad drill – 11.33t/ha
• Disc/disc/Vaderstad drill – 10.66t/ha
• Plough/power-harrow combination drill – 10.83
• Subsoil/Vaderstad drill – 12.00
• Plough/furrow press/Carrier tine drill – 9.33
• Average yields taken from middle three combine swaths.