Too late for cover crops?

As spring crop harvesting edges into September, tillage farmers may begin to question the value of establishing cover crops at this late stage.

Teagasc research has shown that early sowing, preferably in mid to late August, is vital to achieve good autumn growth – bringing with it nitrogen capture, soil structural benefits and the possibility of incorporating good yields of organic material back into the soil profile before the establishment of the next crop.

However, as spring plantings were delayed on many tillage enterprises across the country this year, the resulting later harvest has limited the opportunities for achieving this, especially in the case of parcels sown under spring barley.

Joining Michael Hennessy on a recent episode of the Tillage Edge podcast and shedding some light on what’s the best approach to take when establishing cover crops later in the season was Dr Richie Hackett, Research Officer in the Teagasc, Crops Research Centre, Oak Park.

Dr Hackett confirmed the benefits of sticking to the cover crop establishment plan noting that although total biomass yields may decline as sowing moves into September, the establishment of a cover crop is still better from a nitrogen capture point of view than leaving soil bare and exposed to the elements over the winter months.

“If you’ve just bare soil, whatever is there is going to be lost and you’re getting no positive effect on the next crop,” Dr Hackett explained.

With a later cover crop planting programme now a reality for many, Dr Hackett explained: “It becomes more and more important to get in as quickly as you can after the harvest and not let it go into late September when you get around to sowing your crop.”

At this stage, attention also needs to be given to the species selected for sowing with Dr Hackett recommending the use of cheaper mixes to limit the farm’s financial exposure from the use of more expensive species if only poor yields are produced. Additionally, careful consideration needs to be given to the cover crop species and the subsequent crops planned as part of the farm’s rotation.

As lower catch crops yields are now likely, Dr Hackett recommended the use of a simple two way mix as opposed to mixes consisting of multiple species, preferably of faster growing species such as brassicas, provided they won’t cause rotational issues.  However brassicas should not be used where there is oilseed rape in the rotation to reduce the risk of clubroot occurrences. Similarly legume cover crops should ideally be avoided directly before legume crops such as beans or peas.

For more insights from Dr Richie Hackett on the multiple benefits from cover crops, listen into the Tillage Edge podcast below: