Yield linked to soil structure

Features Posted 30/01/20
“Soil is most important asset,” says Nick August who farms 400 hectares near Burford in Oxfordshire, writes Richard Shepherd-Barron.

To grow any arable farming business to realise its full potential and profit needs great concentration on the positives and minimising the negative aspects of the operations. It is clear that quality results need the right ideas and equipment and often quite small solutions provide the right answer. Everyone is aware nowadays that their knowledge of varying soil types and their structure has increased dramatically along with the need to improve the soil by modern farming practices.

One farmer who, in 2008, looked long and hard at his farm is Nick August, talking recently about his 400 hectare farm near Burford in Oxfordshire on the Cotswold brash soil which can sometimes be as thin as 20cm. He farms over 300 hectares of undulating and flat arable land which also includes silty clay loam, Kimmeridge clay and lower green sand; growing wheat, barley, oilseed rape and peas on a four-year rotation. In addition, he has around 80 hectares of flooding meadows which are grazed by sheep and cattle from other local farmers plus growing useful crops of hay.

As yield is directly linked to good or poor soil structure, cereal crops are affected greatly by inconsistency in structure, depth texture and organic matter within the soil profile. In addition, compaction restricts root growth and limits infiltration of water and air to the soil. It can also exacerbate soil run-off leading to erosion of topsoil and leakage of nutrients and pesticides into the surface water. So, twelve years ago, Nick decided that his current use of minimum tillage could be converted to no tillage and direct drilling. As he thought: “Why not?” and “Why are we tilling at all?”. He realised that controlled traffic farming (CTF) would be an additional help due to its efficiency and minimum soil impact. These changes to his operations have had a major effect on soil protection as well as maintaining profitability. At the same time, Nick changed his drilling method to working across the slopes in order to minimise the erosion risks and his soil has a reasonable clay content so opens up well for direct drilling. The major benefits have been in cost saving, being able to drill seed at exactly the right time, the improved soil structure and the speed of the soil recovery from any major weather problems with the ability to get back on the land quickly without significant damage.

The reduced tillage of the land with CTF and direct drilling is very important for maintaining soil quality and Nick uses GPS and real time kinematic (RTK) technology (accurate to within 2.5cm) for precision control of his equipment and for accurate yield mapping and field zoning. All his machinery – tractors, drills, sprayers, spreaders and grain trailers – follow permanent set tramlines of 2.25 metres with 22 metre headlands to facilitate turning and ensure accurate spraying with auto section control, thus traffic on the land is reduced. Tim Chamen of CTF Europe was very helpful to Nick in getting the system adapted to his farm and it was relatively easy to match the equipment to the requirements of the CTF system. Obviously, not all equipment could be incorporated into this system easily – notably the combine with its 3 metre track. This is where Tim Chamen’s advice was especially helpful and the combine is operated on an “out track” pattern where it straddles the 2.25 metre tramlines.

Subsequent soil testing has shown very clearly that compaction on the farm is very limited and that the soil structure has improved over the years with the soil becoming noticeably easier to work and with the coulter pressure having been reduced considerably over the time of no tillage. He uses Fendt and John Deere tractors of 200 and 150 horsepower, since investment in huge and expensive machines is not needed – the money is better spent on the control technology. Drilling is with an 8 metre Vaderstad SeedHawk; he uses an antiquated but reliable Kuhn spreader and a Chafer sprayer for crop protection.

As soil management that increases the humus content can support the formation of clay-humus-complexes and increase biotic engineering by providing a good environment for soil organisms, the diversity and richness of the soil is of course the key to sustainable healthy soil to meet today’s needs for high volume and quality crop yields. For additional help with the quality of his land, Nick uses cover crops to provide vital support in improving the biological function of his soil. He said: “It’s important for good autumn establishment of cover crops to help with blackgrass control prior to the spring established pea and barley crops, helping to improve soil fertility. Furthermore, cover cropping provides the necessary protection of the soil over winter, thus reducing the threat of erosion.” He has trialled a wide variety of cover crops over the years in a programme with Catchment Sensitive Farming in respect of soil biological quality, nutrient loss and run-off. The results showed that mustard and other broad-leaved cover crops have clear soil conditioning properties. He also uses stubble turnips and his experimentation has shown that he is looking at a wide range of benefits both for the land and subsequent crops - blackgrass control, winter forage, frost hardiness and the resultant soil condition. The annual break between winter sown crops to spring sown barley gives an ideal opportunity for the cover crop to make a serious impact on the land. Nick commented, “of the cover crops used, oil radish and spring barley have produced excellent results and haven’t been heavily impacted by pests, conforming to the CS and EFA rules, though it can be a reason for the RPA to delay BPS payment until after the January 15th retention date”.

Nick has no stock of his own but combining his arable systems with livestock provided by local graziers and stock-keepers gives great usage and nutrient benefits for his land. This land is grazed hard but the cover crops re-grow very quickly and the income from the grazing helps towards the cost of the cover crops. To work with the cover crops, Nick has been using a modified crop rotation of winter wheat/winter oilseed rape/winter wheat/winter cover crop/spring barley/spring peas. Nick said: “There’s no doubt that rotational spring cropping eased the burden of grass weed control and the cover crops most certainly help with soil conditioning, fertility and organic matter. A lack of mineralised nitrogen to help autumn vigour in winter crops can be a problem, being more profound in cold dreary seasons; however, crops seem to catch up in the spring.” Looking back at his previous history of more conventional farming practices, Nick commented that his pesticide requirements have remained about the same but that snails are being a bigger problem than slugs on his calcareous soil. No potash has been applied in twenty years and phosphate only in the form of DAP as a starter fertiliser for winter oilseed rape.

The AHDB defines precision farming as “the management of farming practices that uses computers, satellite positioning systems and remote sensing devices to provide information on which enhanced decisions can be made”. Nick August’s farm very much typifies this approach. He said: “Precision farming won’t make a good farmer out of a bad farmer but it does make the job easier, less tiring and more productive. In low visibility, for example, there’s no need for markers so guesswork is unnecessary. It’s all about managing your resources.”

To ‘spread the word’ about precision farming and his no-drill and CTF farming operations, Nick has spoken on many different platforms - Radio 4 “Farming Today” and “Costing the Earth”, European Intelligent Agriculture Congress in Brussels, Geospatial Technologies Conference for Precision Agriculture in Qingdao (China), Controlled Traffic Farming Conference in Prague and at the Royal Agriculture University in Cirencester. His main theme has always been: “Conservation agriculture has proven potential to improve crop yields, while improving the long term environmental and financial sustainability of farming”.

Speaking to the NFU in 2015, Nick said: “I use a well-rounded approach to soil management that is appropriate for my Oxfordshire farm. The successful results come from developing high quality soils with limited compaction and high organic matter levels. By using cover cropping and through direct drilling, I’ve reduced the risk of erosion and nutrient loss on this farm. The present state of the soils shows that by adopting management and engineering changes, farmers can develop biologically healthy and resilient soils on their farms. By utilising the biological benefits of a diverse crop rotation and cover crops together with new developments in engineering and technology. I’m now managing healthy and productive soils that are good for my business and for the environment.”

Today, Nick feels that: “Farmers have a responsibility to sequester carbon, improve their soils and mitigate climate change. A government policy should recognise and support initiative with these objectives without losing sight of food production in this country. We must not become more dependent on imported food because we have no control over quality or production processes and we must not become more reliant on increasingly fragile crop production areas of the globe”.

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