By Chris Martin, Agrovista AgronomistAt a trial site at Blagdon Estate in Northumberland, we are measuring the cost savings associated with improved soil health resulting from growing cover crops. We are replicating the work at a site near Brechin. The purpose of these field-scale trials is to determine the contribution of different cover crop species and mixes to the improvement in soil organic matter, structure and nutrient availability. We already know that soils with organic matters up to 5% grow higher yielding crops, but there is a lack of information about how these biological improvements translate into financial gains.
The Blagdon trial has 12 cover crop strips ranging from a simple single species row of berseem clover costing £10/ha (£4/acre), through to more complex mixes of berseem and crimson clover, black oat and common vetch, which costs closer to £50/ha (£20/acre). The soil at the site is a heavy clay that is often too wet and cold to grow a good consistent second wheat; the organic matter ranges between 2.5-3.5%.
We need to maximise returns from first wheat on this land, so introducing cover crops into the rotation makes economic sense. We also need to capture nitrogen, release locked up phosphate and introduce life back into the soil profile in a region where open cast mining has been commonplace; all of which cover crops can deliver. The cover crop strips were drilled on the 9 May using a Lemkin Solitair drill and power harrow, everything was desiccated at the end of July before the crops went to seed. After sowing we had a very dry spell, which gave us just six to eight weeks of crop growth; yet there was a marked visual improvement to the soil’s friability compared with the uncultivated strips between the rows.
The improvements in the soil are being measured in two ways. We are using a Veris Sensor Cart to map the field for the soil’s electro conductivity, organic matter and pH – we did this in April before the crop was drilled and will repeat the mapping this autumn. We are also employing a pioneering microchip technology that can measure all aspects of tractor performance
We have partnered a former F1 engineer who has developed a chip that’s now fitted to a tractor; it measures things such as power requirement and fuel consumption as it drives the implement working the soil. We have already seen a 13 litre/ha difference in fuel consumption between the zones mapped with the highest and lowest levels of organic matter, so the trial is looking extremely promising. This autumn wheat is going to be drilled following the cover crops. It will be very interesting to see what impact the different mixes have had on both fertility and workability.