Arable crops

If you remove straw then you also remove the nutrients that are contained in it, which is fine, but you need to take into account that they won’t be available to the following crop. 

Removing both grain and straw with cereal crops removes 8.0-8.5kg/t of P2O5 and 10.5-12kg/t of K2O, therefore is it important to take this into account when calculating next season’s fertiliser plan.

Post-harvest soil sampling will, of course, give a good indication of the P&K levels. If the indices are below 1 then an autumn application of P&K is justified. However, if the indices are 1 or above then autumn P&K applications are not always necessary. At those kind of levels, there will be sufficient P&K in the soil to establish cereal crops and an application of foliar phosphate, such as YaraVita Crop Boost, could be applied with a herbicide spray if required.

The real demand for phosphate comes in the spring from March to May, when a typical crop of winter wheat will require 1-2kg per day for optimum growth. Any phosphate applied in the autumn is unlikely to still be present in the soil in a plant-available form and therefore won’t be able to supply this daily demand.

Therefore, when purchasing P and K products make sure you think about the timing of application to meet the demand from the plant, otherwise you will be feeding the soil and most of the phosphate applied will have been rendered unavailable for the following spring.

For more information on different options for P & K and other nutrient solutions please visit Agronomy Advice.