Article taken from Farm Contractor Magazine
At Reaseheath College, Nantwich, Agrovista and Pottinger have worked together on a project researching new methods of undersowing grass into maize. With two months to go until harvest, we went along to find out more. Matthew Tilt reports.
Maize continues to grow in popularity, as demand for its use in anaerobic digestion and as a high-energy feed increases. More people are looking to companion cropping to reduce soil erosion and compaction. Grass has proven to be popular; it provides a strong rooting system and healthy ground cover, which absorbs the weight of machinery during harvest and provides a viable grazing crop. Hoping to give some insight into the timing of sowing companion crops, Agrovista and Pottinger arranged a trial with Reaseheath College. The raison d'être for the project is the Pottinger Aerosem, launched in 2013; a pneumatic single seed drill with a modular design which enables two crops, or one cash crop with fertiliser, to be planted simultaneously.
For the trial, the Aerosem was used to sow maize at 75cm row spacings, with three rows of grass in-between each row, spaced at 15cm. In the centre of a 42-acre field, already set aside for Pioneer P7326 maize, twelve plots were planted - five planted simultaneously and seven at the conventional four to eight leaf stage. It was also hoped that it would address concerns about the effects of pre-emergence sprays on the companion, as while none were applied to the trials, their proximity to the main crop meant residuals would be present. Agrovista's John Ball gave some background to the research. ""Companion cropping is not a new idea. However, while a crop such as grass would normally be undersown or broadcast when the maize is between the four and eight leaf stages, advancements in drilling technology mean that there is the potential for two crops to be sown at once. This would not only reduce the amount of passes required, but also avoid damage to the maize; although, there are concerns about competition between the crops.""
As would be expected, the grass planted with the maize established itself far quicker than those drilled at a later stage, with the equal access to light and nutrients allowing the more vigourous varieties to shoot upwards and outcompete the weeds. Somewhat surprisingly, even the most aggressive grass types (Prorubka) appeared to have little affect on the maize itself - although, at the present stage we can only comment on the height of the maize, which stood at around 7ft across the whole field.
Grass drilled under the canopy of established maize took longer to take root and was less effective at suppressing weeds. However, this seemed to benefit mixed cropping such as AberNiche, clover and vetch, as the aggressiveness of the individual plant mattered less and each could grow at a steadier pace. Residuals appeared to cause minimum damage, even to more sensitive varieties. Mr Ball concluded that companion cropping should be done with an eye on the bigger picture. ""While we won't know the possible yield lags until October, the benefits of companion cropping are vast, and concurrent planting can eliminate many of the negatives. A slight reduction in yield can be far less harmful than extensive soil damage if harvest falls during a wet season.""