Article taken from Bioenergy Insight, July/August 2017
Maize is a very useful crop. It feeds livestock, and it is a key energy source for anaerobic digestion (AD). Securing a reliable feedstock supply is vital to the profitability of any AD plant. Most farmers will have had a straightforward harvest, but maize has the tendency to leave the ground totally bare. There is more than meets the eye when it comes to farming maize, because it is the soil that suffers.
The main issues revolve around nutrient levels and soil structure. Nobody wants soil running into watercourses or local lanes, or soil that is lacking in nutrients. Recent estimates by Cranfield Soil scientists show soil degradation costing the UK £900m (€1.1m) to £1.4m per year. In fact, soil regulations are changing to address this issue. With food security concerns in mind, there is mounting pressure to adopt sustainable farming practices. To this end, Countryside Stewardship schemes and regulations have altered so that three new Good Agricultural and Environmental Conditions (GAEC) have replaced Soil Protection Reviews (SPR’s). This is to ensure more proactive soil management, maintain minimum soil cover over winter, and reduce soil loss from erosion.
This poor environmental profile developing around maize calls for a solution. Undersowing maize with other grasses has been presented as a way to make maize farming more sustainable. The idea is that certain cover crops can be sown with maize to maintain soil structure and valuable nutrients. At Hilley Farm in Shropshire, UK, a trial has taken place to measure the outcome of undersowing. A number of organisations have come together for the occasion, namely Shropshire Wildlife Trust, Agrovista UK, Hilley Farm (Pentre), and E4environment, the Environment Agency, and Meres and Mosses Landscape Partnership.
Maximising soil to seed contact
Barry Jones, of Hilley Farm, was eager to find a solution to reduce the negative outcomes of maize farming. He says: “As a practise to improve soil in terms of fibre content and friability, maize undersowing is of great benefit.
“The important thing is to apply it post weed control and to do it in a way to maximise soil to seed contact. We used a seed drill and tine harrow combination in between the rows of maize. Once set up it worked a treat.”
The trial itself was designed by technical manager Antony Wade of Agrovista. As part of the Hilley Farm trial, a number of undersowing and cover-crop options were tested. Representatives from the supporting organisations gathered to see for themselves how undersowing could be a game changer.
In summary, the six under-sown treatments all germinated successfully and formed substantial swards helped by the showery weather post drilling. Hilley Farm decided they represented grazing quality potential. The three post-harvest applications were disappointing and it was felt a risky approach. Germination in the post-harvest treatments was poor and sward development inadequate.
Wade says: “The trial showed the fantastic potential of this low cost establishment technique in providing a green cover post-harvest of the maize crop that stabilises the soil mitigating against erosion whilst improving the structure of the soil so that it is more resilient to subsequent field work and benefits following crops.
“Perennial ryegrass gave the best ground cover and surface rooting with tall fescue offering deeper structural rooting. Undersowing is a win-win for maize growers, they keep their soil and nutrients in the field whilst getting additional grazing and improving their soil.”
Pete Lambert, river projects manager at Shropshire Wildlife Trust is hopeful for the future of maize undersowing. He concludes: “We hope the trial will spark local debate in Shropshire’s maize growing community and where there is recognised value in the treatments then we hope enhanced cultivations will keep soil where it needs to be, in the field, growing food.”
Trial Facts
- The trial took place on Hilley Farm, North Shropshire.
- Full field length strips were under-sown using six treatments.
- ChloroFiltre SCM (Hybrid ryegrass 50% + Hairy Vetch 50%)
- Aberniche (Hybrid festulolium ryegrass) Low seed rate
- Aberniche + Clover + Vetch
- Tall Fescue
- Perennial ryegrass
- Aberniche (Hybrid festulolium ryegrass) Normal seed rate
- No under-sowing with scuffling of the surface and without [rain pan quickly developing on bare compacted soil]
Post-harvest treatment - Cover crop
- Chlorofiltre SCM [Hybrid ryegrass 50% + Hairy vetch 50%] Seedrate: @ 25kg/ha
- Black oats cv.E04 seedrate: @30kg/ha
- Hybrid rye cv. SU Drive seedrate: 30kg/ha
- The seeding was done with an Einbock grass harrow with seed box about a month post-establishment.
- All treatments showed good establishment.
- The strong sward growth promised additional grazing for the hill sheep that come to the farm over winter in other areas it also used for early spring grazing for dairy cows.
- In addition good weather this year allowed for the planting of post-harvest cover crops allowing comparison between the two establishment timings.