Soil mineral nitrogen (SMN) results have come back from various farms and suggest similar levels to last year, generally between 50 and 70kg N/ha, with slightly higher levels after oilseed rape and beans. Crops are also quite variable, with some oilseed rape at green area index (GAI) 2 and over, resulting in around 100kg N/ha already in the plant.
Taking the SMN, crop growth and likely mineralisation, rates have been adjusted to ensure we are applying optimum nitrogen. As and when conditions allow, nitrogen is being applied to the more backward oilseed rape, barley and late drilled and second wheats. The nitrogen on some of the more forward OSR will be held back a little yet.
Despite the mild conditions Kerb (propyzamide) and Astrokerb (propyzamide + aminopyralid) applications appear to have worked well, especially where is was combined with a clethodim earlier in the autumn. In some cases there are a few cleavers and thistles still to tidy up and with applications only allowed after the 1March, it will be a race to apply Galera (clopyralid + picloram) before green buds. Flea beetle larvae are also causing some problems, with significant numbers in petioles. In most cases crops are large enough and thick enough to withstand some damage.
Cereal crops have continued to develop through the winter, as has the blackgrass, despite our best efforts chemically. Where drilling was delayed the surviving blackgrass is still only at 2-3 leaves, however, in earlier drilled fields some blackgrass is well tillered. With grain prices where they are, careful consideration should be given the viability of a crop with significant levels of blackgrass. There is still the full spring fungicide and plant growth regulator programme and also fertiliser to apply, and with current prices it may be the year to sacrifice some of the worst areas to ensure better and cleaner crops when hopefully prices improve.
As and when conditions dry up, spring land is being worked and once a warmer settled spell of weather appears drilling will begin, but this shouldn’t be rushed. Soil is still wet inside and the seed needs a good seed-bed to ensure it goes in and grows straight away. A spell of cold weather leaving the seed sat in the cold wet soil will reduce the vigour and competitiveness.
Where we are planting spring crops due to blackgrass, use the time to get a further flush of blackgrass prior to drilling and ensure the crop is planted into a good seed-bed. Also ensure seed rates are kept up to aid competition against spring weeds. Recent work from the PGRO Optibean project highlights that the highest yields come from spring beans planted up to 60 plants/sq m.