Anyone who harvested maize in the wet autumn of last year will have experienced some of the difficulties that can frequently arise with that crop and the resulting damage to soil structure. In many parts of the Island soil was washed off fields, highways received much runoff and ditches filled with silt. How much of your own valuable topsoil ended up in rivers and wetlands?
The growing maize is sometimes questioned, not least because of environmental issues, but also its use as a feedstock for anaerobic digesters. However, Island farmers are already taking steps to counter the negative aspects of maize growing. One farm covering fields around Blackwater and Rookley is a great example of how undersowing maize protects soil throughout the winter. But is there more than can be done whilst still achieving a reasonable crop?
The CSF starting point is first to consider whether it really is sensible to grow maize in any particular field. Any light land with a half decent slope is going to be vulnerable to erosion. Assume a worst case – a really wet autumn which isn’t that unusual the way our climate is heading. Will harvesting mean your soil is going to be compacted by machinery movements and where will the runoff end up? If it’s heading for a ditch, drain, river or field gateway and onto the highway that is asking for trouble.
Having identified fields where cropping will not present an unacceptable risk to soil or the environment the next thought might be in choosing the maize variety. Early maturing varieties might help avoid harvesting in a wet autumn.
Without going into detail on seedbed preparation what else should be considered? For those thinking of joining the Countryside Stewardship scheme there is a payment of £133/ha each year if you can harvest the crop before 1st October and establish a quick-growing cover crop by the 15th October. In the Netherlands drilling Italian ryegrass as a cover after harvesting is often practised.
Undersowing is an even better approach where the maize is sown along with a grass (and fertiliser applied) which is completed in a one-pass operation. It is also possible to drill grass into the crop at the four to six leaf stage. The grass could be a blend of fescues which will improve soil quality, reduce erosion and increase levels of organic matter. This has been tried with success across the water in Sussex. Nitrate leaching is reduced, harvesting is made much easier should rain arrive and, by completing the operation in one-pass, there is a saving on fuel, CO2 and labour. The choice of the undersown crop need not be limited to grasses. Clover and a variety of flowering plants with different properties may suit different objectives post-harvest cropping.
What else might be considered? Positioning a buffer against watercourses is always worthwhile just in case the weather is unkind. Stewardship offers several options:
- 12 -24m wide buffer strips @ £512/ha each year.
- 4-6m wide buffer strips against woodlands and hedges @ £170/ha/year.
- In-field grass strips @£557/ha/year – these could be located to make a break of slope where soil erosion is a risk.
Whichever approach you choose do get in touch with CSF who will be happy to advise on the approach to avoid environmental issues.