Less really can make more, according to recent trials with potatoes and onions which have shown clear benefits from using microgranular fertiliser at planting. This type of nutrition can be used either as a replacement for traditional fertilisers or in addition, depending on local conditions.

The trials were carried out by Vegetable Consultancy Services for Sipcam UK, which markets the microgranular fertiliser Umostart. Applications of just 30 kg/ha at planting lifted onion yields by 22% above untreated controls and salad potato yields by 7% compared to a conventional base application of 150 kg/ha of phosphate.

Already well established for use with other crops, Umostart granules are around 10 times smaller than those of conventional fertiliser, providing a very high interface with the seed. Applying the granules at planting also means they are close to the developing root system.

In its report on the potato trials, Vegetable Consultancy Services points out that, traditionally, high levels of phosphate fertiliser have been applied to potato crops despite low levels of off-take from the tubers of the crop.

Umostart has the potential to help overcome this problem, especially in the early growth stages. In the trials with Maris Peer, tuber numbers and average yield were found to be significantly greater for the treated plots. Treated plots of the onion variety Red Baron performed well in comparison with controls where no granular fertiliser was applied.

 James Ward of Sipcam said: “In some onion crops it has been possible to see the difference in the field where Umostart has been missed. In previous French and Dutch trials improvements were recorded in quality as well as in yield.

“Our UK farm experience also suggests it can improve uniformity and help reduce scab in potatoes. Applying smaller volumes of fertiliser exactly where it is needed has obvious environmental benefits and another practical advantage is that the relatively small amounts required are much easier to store, transport and apply, cutting the number of field operations.”