Farm Ireland

Friday 23 February 2018

Cover crop specifications will create major problems for growers

Oil-seed Rape crop
Oil-seed Rape crop
Pat Minnock

Pat Minnock

The likely late harvest will again delay the establishment of cover crops. Up to September 15 farmers will sow 20,000ha of catch crops for GLAS purposes.

Unfortunately, the Department of Agriculture specifications are unyielding and dictate management which is not always in the best interest of growers particularly from a pest and disease point of view.

There is no doubt that some of the specifications foisted on growers will lead to major problems over the coming years.

As a group, the Irish Tillage Consultants Association (ITCA) have sought changes to these specifications.

For example, DEFRA (UK) funded research indicates, as a general rule, once a third to half ground cover is achieved there is a substantial reduction in Nitrates run off and erosion risks.

In our opinion DAFM recommended seeding rates are way too high. Seeding rates should be determined by the cover crop species/ variety, weather, soil and seed bed conditions and especially the seeding date.

The high inclusion rates demanded by the Dept of Agriculture for cover crops for GLAS, regardless of seeding dates, are not necessary and can be detrimental in the long run for both establishment and management of the crops themselves and the subsequent cropping programmes.

For example, the GLAS minimum rate of 8kg per hectare for a mix of leafy turnip and fodder rape is much higher than required especially when you consider recommended oilseed rape sowing rates of approximately 2kg in late August.

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This very high seeding rate is particularly worrying, when cover crops are sown early. Brassica mixes, particularly leafy turnip and rape, I understand, make up almost 90pc of the area sown to catch crops, partly due to their cost competitive advantage.

Cover crops are now the third largest tillage crop grown in Ireland. Brassica mixes should be avoided where the rotation includes oilseed rape as it increases the likelihood of club root, sclerotinia and nematodes and their over use can only lead to serious pest and disease issues and a reduction in suitable land available for oilseed rape production over the next number of years.

Pat Minnock is a Carlow based agricultural consultant and a member of the ACA and the ITCA.

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