Farm Ireland

Sunday 17 December 2017

Trace element deficiency identified due to the extremely cold conditions

Jim O'Mahony

Soil temperatures are now 1-2C above normal for this time of the year, although the forecast for the week is not good. However, the lift in temperatures brought some welcome greening of winter cereal crops.

Good growth in April should help crops to progress during the growing season. Winter barley crops are behind normal in terms of development, generally at mid- to end-tillering stage (GS22-29) and advisers and farmers are seeing more trace element deficiencies than usual, probably due to the very cold weather over winter and early spring.

The three most important trace elements are copper, zinc and manganese, so it is worth checking those first and taking actions, ideally around mid-tillering stage.

Winter wheat crops have recovered somewhat in the last week but are still backward. Crops are varying from early growth stage 21 to late growth stage 29 but most crops are at GS24. With the rise in soil temperatures, winter wheat crops will respond to nitrogen now and the first split should be completed if it hasn't already.

This will be a big help to crops with low plant counts and low tiller numbers, and will improve the structure of the crop.

Crops with less than 150 plants or less than 800 tillers /sqm should get 50-75kg of nitrogen now with the main N split at GS30-31. Nitrogen is the most yield-responsive input in cereal production and it remains essential to apply optimum rates, taking into account crop yield potential.

Visitors to Oak Park over the years will have seen the control plots in various trials where no N is applied and the contrast in crops is clear.

To fullfil that crop potential, crops need sufficient P and K to meet crop requirements, based on a recent soil test analysis.

Also Read

The economic optimum N application rate is based on the relationship between the expected grain price and cost of fertiliser.

This is an important calculation and will vary from farm to farm based on your interpretation of market prospects for grain and what price you can source your N at. Based on a dry grain price of €135/t and CAN at €225/t, the economic optimum N for winter wheat is 235kg/ha.

For spring barley using the same price assumptions the economic optimum N application rate is 135 kg/ha. If your N is being sourced more com- petitively than this or if you are more optimistic about grain prices, then the optimum N rate will differ from these figures.

While the dry cold spell in early March held back crop growth, rapid progress has been made in getting crops into the ground.

Nearly all of the spring wheat and beans are now sown and generally in good condition. Well over half of the spring barley, which obviously is the big crop in terms of national cereal area, is now sown as well.

Most progress has been made in the south and southeast of the country, with some early crops in the south starting to emerge. Whether the remaining unsown area gets drilled or not is largely an economic decision for the individual land owner.

Projected cereal margins for this coming season are tight and the best growers are making decisions field by field, based on yield potential. Those operating on conacre are, in many cases, still in negotiations with landowners.

The Teagasc cereal crops margins show that total variable costs excluding VAT for spring feed barley is €754/ha, which means that the crop needs to deliver 7.2t/ha to cover costs based on a grain price of €105/t and excluding the Single Farm Payment.

Irish Independent