Around half of commercial oilseed rape crops are suffering from poor rooting which could be limiting yields, according to new research.
The two year Home Grown Cereals Authority-funded project found that around 50% of commercial crops suffered from “sub-optimal” rooting below 50cm depth, explained Jonathan Blake of ADAS Rosemaund.
“We have noticed over the years that oilseed rape yields were often adversely affected when June rainfall was low and that this was probably linked to the root system being unable to exploit soil moisture and nutrients well enough and so being unable to satisfy the crop’s demands at pod fill.”
The project tried to find solutions to this and looked at the effect of different management strategies on rooting. It found that ploughing and subsoiling had positive effects on root growth near the surface and at depth, he said.
“These effects at depth are the more significant. Effects on rooting near the surface are unlikely to increase water uptake and pod fill in June. Also there is generally more than enough rooting near the soil surface.
“However, if good rooting near the surface can significantly affect the ability of the roots to penetrate deeper in the soil, then this could increase availability of water and nutrients at the critical stage of pod fill.”
Applying autumn nitrogen and delaying spring N also improved the root system by forcing the crop to ‘hunt’ for nutrients, he added. “This will be a particularly important strategy to consider this year with the advanced crops we are seeing.”
The use of the triazole fungicide Caramba (metconazole) at 0.6litres/ha in the spring also had a positive effect on yields by reducing lodging and improving root growth at 0-20cm and 40-60cm depth, Mr Blake said.