Muck & Slurry


How to improve soil health with anaerobic digestate


• Excess nitrogen captured by cover crops • Risk of nitrate leaching largely reduced • More nutrients available for next crop


C


over crops can improve effectiveness of anaerobic digestate applications – and reduce nitrate leaching, sug- gests farmer-led research. Growing more cover crops


could help farmers capture more nitrogen from anaerobic digestate, according to the results of an Inno- vative Farmers field lab coordinat- ed by Agri-TechE. A further study has been launched to further in- vestigate their potential. The farmer-led trial benefits


from having the support of re- searchers at NIAB and Cranfield University. They have already spent three years investigating how to use digestate effectively within government regulations.


Analysis This included assessing whether cover crops could help improve soil health in combination with autumn applications of diges- tate – a by-product of anaerobic digestors. Farmers from six farms took soil samples after separating their land into four different treat- ment areas – digestate with cover crops, digestate only, cover crops only, and a control area of neither treatment.


Soil samples were analysed at different depths across the four ar-


eas to see different treatments af- fect nitrogen levels. Where nitro- gen sinks to lower soil levels, it potentially becomes unavailable to the next crop – and the risk of nitrate leaching into ground wa- ter increases.


Results found that often when cover crops were grown on soil af- ter the digestate was applied, the available nitrogen was significant- ly reduced in all levels of the soil – and more than halved in the low- er levels, indicating that the cover crops had absorbed the excess ni- trogen.


Soil health Researchers said this suggests cover crops can potentially im- prove soil health by increasing the effectiveness of digestate applica- tions, reducing the risk of leach- ing, as well as making more ni- trogen available for the farmer’s next crop.


More trials are needed to test this theory say the researchers – prompting Innovative Farmers and Agri-TechE to launch a fol- low-on study with sponsorship from the Agriculture and Horti- culture Development Board. Launched last autumn, this second phase is continuing to in- vestigate how best to stabilise ni- trogen so it is not released as a


The next stage of the study will see farmers undertake worm counts


greenhouse gas or leaches into wa- ter. But there is also interest from the farmers to explore how diges- tate affects soil bacteria. Researchers in the field lab are


also providing training to help farmers carry out Visual Evalu- ation of Soil Structure (VESS). This is to see whether any of the different treatments have an im- pact on soil compaction, which would suggest an improvement in soil health. Worm counts and green area index measurements are also be- ing done by triallists.


Exciting results Lydia Smith, head of NIAB Inno- vation Farm and the Eastern Ag- ri-Tech Innovation Hub, said: “The early results were very exciting – often the cover crops were doing exactly what we wanted in tak- ing up that excess nitrogen from the soil.


“Going forward we’re keen to


look more closely at the nitrogen availability and at worm counts, and to get the VESS training up to scratch so farmers can help in working out how and when is best to carry out these assessments.”


Vervaet launches Hydro Trike 5x5 with improved traction The new Trike incorporates fully electronic traction control


Dutch specialist equipment man- ufacturer Vervaet is currently testing a five-wheel-drive ver- sion of its popular Hydro Trike self-propelled spreader. This new option utilises an up- dated powertrain along with oth- er improvements. This new all- wheel-drive configuration will be particularly advantageous when working on hilly terrain. It will be available for 2021 from UK im- porter J Riley Beet Harvesters. From a distance, the new ma-


chine doesn’t appear much dif- ferent to any other Vervaet Hy- dro Trike, with the same striking lines and innovative features, but operators of current machines will notice several changes. The main new features are the option of driven mid-wheels and a completely renewed powertrain. This incorporates fully electronic traction control and an electron- ically-controlled flow divider be- tween the front wheel drive and rear axle.


JANUARY 2020 • MIDLAND FARMER 43


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