September deadline for GLAS cover crops
Published 13/07/2016 | 02:30
Over 44,500ac of green cover crops are due to be planted for the GLAS scheme this autumn. Much of it will be planted by farmers who have never grown these types of crops before, and the basics of variety choice, crop establishment and management are all new to most, explained Goldcrop's grass and forage crop manager, Dave Barry.
He outlined the 12 different species that were eligible to farmers attending the crop walk on Podge and Ian Howard's farm in Bellewstown.
However, at a cost of over €100/ha, Mr Barry stressed that some of the options would be simply uneconomical for participants in the scheme.
"Cover crops such as clover can in theory fix about 15 units of nitrogen and they will help condition the soil structure, but it is difficult to measure any quantifiable benefit beyond the payment that they qualify for under GLAS. For this reason, we expect most farmers to go with the cheaper options," he said.
He added that farmers needed to plant a combination of at least two different species from the list, and that minimum seeding rates were also required.
"For this reason, planting something like berseem clover at 22kg/ha and vetch could cost €66/Ha, while black oats and phacelia could be even more.
"They all have different functions. The oilseed and tillage radishes have the deepest roots, while the clover and vetch will both fix nitrogen into the soil. Phacelia is also a good soil conditioner.
"Some farmers have been using mustard as a green cover for many years, and it has the advantage of being ok if you are sowing a little late.
"Most of the others need to be sown by September. But you also need to be careful that it doesn't get out of hand over the winter. Some of the crops will develop a 4ft high canopy so they need to be sprayed off in plenty of time before you go in to sow your next crop. They can also start flowering before the December 1 window for spraying off reopens. In that case, you need to top the crop to stop it spreading volunteers.
"The clovers and vetches can also be grazed, but only after December 1.
"You need to be careful that the cover crop is unrelated to the subsequent crop that you plant. So the oilseed radish and fodder rape would not be suitable if you are following with oilseed rape crops due to the risk of disease carry-over.
"We would expect leafy turnip and fodder rape, which will cost about €25/ha in seed, to be one of the most popular options because it establishes good ground cover, which is important to keep the weeds down. But it can be prone to bird damage.
"The best way to establish the cover is by a min-till system or disking, one-pass and rolling, but the likes of mustard can be broadcast and rolled into cultivated ground.
"Remember, the crops need to be sown by September 15 to qualify for the scheme."