Deep soil Nitrogen testing carried out during 2012 showed that the majority of cropping paddocks had very low levels of Nitrogen. This was largely the result of extended cropping history and significant summer rainfall which may have lead to Nitrogen loss from leaching or denitrification.
The majority of wheat harvested in 2012 was low in protein, which reinforced the soil test data. In many cases these paddocks will still have a low Nitrogen status in 2013. An exception could be where late applications of Nitrogen were applied last year, which were not followed by significant rainfall. This Nitrogen may not have been utilised and is likely to be still located in the soil surface and available in 2013.
Given the potential variability in soil Nitrogen levels, the strategic use of deep soil Nitrogen testing will again be important in 2013. In order to gain the maximum value from deep soil Nitrogen testing, the samples need to be taken early to ensure enough time to plan applications of topdressed urea.
Collecting deep soil Nitrogen samples soon after sowing means tests results will be received early. This allows adequate time for application rates to be calculated, urea to be delivered and spreading to be organised. This will result in more effective Nitrogen decision making and better crop management.