Application of P and K now matter of urgency
Published 08/03/2011 | 05:00
Fine weather last week has farmers active in the fields again, with many anxious to get nitrogen applied. If your phosphorous and potassium fertility is low, this must be applied as a matter of urgency -- but make sure you stick to the Nitrates Directive recommendations.
This includes a maximum of 25kg/ha of phosphorous for soils with a phosphorous index of three. Account must also be taken of any organic fertiliser applied to these crops.
In broad terms, depending on location, applications of nitrogen to advanced crops of winter barley could still be delayed a little longer. This allows for the formation of more grain sites before the plant switches over to vegetative growth. Backward crops will immediately benefit from the application of 50-60kg/ha of nitrogen. Winter wheat should receive the first split of around 50kg/ha this week and late-sown and backward crops of wheat should have already received some nitrogen. Backward crops will also benefit from the application of 0.5l/ha of a liquid phosphate. Sulphur should also be applied early to all crops.
As most of the backward crops have yet to receive their herbicide, liquid phosphorous can be applied at the same time with 0.5l/ha of the growth regulator K2. Autumn herbicides can still be used until the end of tillering. An application of 0.25l/ha of a diflufenican product, plus 0.66l/ha of IPU to wheat or barley, is a broad spectrum option. If grass is a problem in winter barley, there is little that can be done at this stage.
However, I have had reasonable results with late applications of Bacara at 0.6l/ha. If you have grass problems in wheat you have the option of using Alister at 0.8l/ha, which has the advantage that there is no immediate urgency and the possibility of good wild oats control. Remember, if applying this product early, you run the risk of late-emerging wild oats, which may require further treatment. For even later weed control, especially if there are difficult weeds, Pacifica plus a suitable Sulphonyl Urea is an excellent, although expensive, option. Your best choice should be to go for reasonably priced, effective weed control immediately, with the option of a further 'clean up' later if required.
Over the past week, the damage to the winter oats crop during the winter has become more apparent. Most farmers have now made their decision to stick with the crop or re-sow. Many of the crops I have inspected were either completely wiped out or had a plant population stand of 50-130/m2. This is a long way short of the preferred target of more than 200 plants.
If you still have to decide whether to re-plant or not, it is important that you also consider the viability and distribution of the remaining plants. A well-established root system is essential.
Oats is the poorest cereal crop to tiller and will not have the same capacity to recover as wheat would. Nevertheless, at plant stands of 80/m2, plants there can still have reasonable expectations of 3t/ac, if properly managed. Rolling only in good conditions, the immediate application of fertiliser and the addition of liquid phosphorous and a small amount of Ceraide or Moddus will all help.