Managing maize ground to protect soil

Thursday 17.09.2020 , News

There’s no doubt maize is a staple for many farms – a reliable, high-energy and high-yielding forage that is relatively easy to grow. But one of the big challenges around forage maize remains the potential for soil erosion over the winter.

Not only does this risk damage to the environment, particularly from nutrient leaching, but soil is a precious resource. And having top-soil and nutrients washing away from your fields is not good for the long-term productivity of your farm.

With the maize harvest underway across the UK, we explore what you can do to minimise soil erosion on your maize land this winter.

Harvesting approach

At this stage, the maize harvest date is largely out of your control. While in some areas of the UK this year’s weather has helped maize mature earlier than normal, this is not the case everywhere. However, even that is no guarantee that the harvest can be completed in dry conditions.

But there are some practical measures you can take to reduce soil damage and erosion, even if you end up harvesting in wet conditions.

Safety measures

“Within safety parameters, try lowering tyre pressures on harvesting machinery and on tractors and trailers used for carting,” suggests Ben Wixey of Germinal GB.

“This reduces ground pressure and improves grip, potentially reducing ground damage, particularly around gateways. By avoiding the creation of deep ruts, water is less likely to be channelled towards gateways, reducing the risk of run-off.”

Driving the harvester

Ben also recommends that, where possible, the harvester should be encouraged to drive across slopes rather than up and down them for the same reason. This is because any ruts will then follow the contours of the land rather than funnel water downhill, reducing the risk of erosion.

Break up any soil pan

Once harvest is completed, Ben advises the stubble is cultivated to break up any soil pan and remove wheeling from machinery.

“Disrupting the surface with a cultivator improves drainage over the winter and reduces the risk of soil erosion,” he explained. But it’s a bare minimum and only a last resort only if harvest is late, reckons Ben.

“Ideally, a cover crop should be established, which not only stabilises the soil but also adds organic matter and may even provide some forage for the spring.”

Crop choice

In terms of crop choice, it depends on how you organise your crop rotation, what the land is being used for next, and what your herbicide strategy has been on the maize crop.

If maize is harvested early enough, which is possible this year, particularly in the South, then perennial grasses and hybrids can still be established, as soils will still be warm enough to allow decent germination and establishment.

Thinking ahead

While time is not on your side if you have don’t already have plans in place for cover cropping this winter, it is also important to think ahead for future years, Ben says.

“Establishing winter cover crops certainly helps, but under-sowing maize avoids the vagaries of autumn weather conditions and provides instant soil protection once maize is harvested,” he explained.

“Cover crops are generally sown once maize is established to avoid competition in the early stages of maize establishment. This is typically at the six-to-eight-leaf stage or when the maize is around 12 inches/30 cm in height.

“While the grass can be drilled or broadcast, either directly or harrowed, drilling has been found to be far more successful. Inter-row drills allow cover crops, such as grass, to be sown effectively, giving accurate seed to soil contact for germination.”

While under-sowing undoubtedly adds cost to the maize crop, it does mean an established grass crop is present immediately after harvest. This not only improves soil retention but also offers the potential for winter and early spring grazing, helping offset the additional costs.

“Using grass as a cover crop after maize makes good sense from an agronomic point of view but can also help meet the requirements of various environmental schemes,” Ben concludes.

“As such, the financial benefits can be more obvious than initially anticipated. But regardless of any potential payments, keeping soil and nutrients in your fields where they belong makes good sense.”