Under-sowing maize has soil health benefits

Trials in Cumbria are showing how a low-cost way of under-sowing maize with Italian ryegrass could have significant benefits for soil health.

The trials, run by Hutchinsons, are taking place at the firm’s Smalmstown Farm demonstration site near Carlisle. The aim is to find a cost-effective way of preventing the potential issues that can arise when bare maize stubbles are left over winter.

“Under-sown grass can help condition the soil, prevent winter erosion and nutrient leaching, and potentially provide grazing,” said local agronomist, Jim Clark. “It can also help dry the soil and improve ground conditions for cultivations or manure/slurry applications ahead of following spring-sown crops.

“In some areas cover crops like brown mustard, fodder radish, stubble turnips or vetch, can do well in a similar role, but they really need to be sown early in the autumn. A lot of cover crop mixes just don’t perform well enough in this region, especially if they’re being sown late after maize.”

In contrast, he added, Italian ryegrass can be sown in the summer into a standing maize crop, so cover is already well established by the time the forager goes through.

In the Hutchinsons’ trial, hosted by Mr & Mrs R Fisher, a slug pelleter mounted on a self-propelled sprayer was used to broadcast three rates of Italian ryegrass seed, at 3kg, 6kg and 9kg/acre, into the five-foot high crop on July 5. Results so far look promising, according to Mr Clark.

“It rained two days later, so seed on the ground struck straight away and greened-up nicely with no detrimental effect to the crop,” he said. “It seems 6kg/acre is the minimum seed rate needed, while the 9kg rate looks as though you could graze heifers on it.

“Drilling Italian ryegrass as a cover crop after maize is popular in Holland where bare winter stubbles aren’t allowed. It is attracting more attention here, although drilling won’t work where plastic is on the ground until late in the season. There’s also the extra cost.

“Broadcasting seed however, is relatively cheap given a typical contractor charge of £1/acre for slug pelleting and seed cost of £20-25/acre at the 9kg rate. You could get away with 6kg/acre, which would cost nearer £15-17/acre.”

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