Crops may source much of their nitrogen (N) from in-crop mineralisation (ICM) of soil organic matter. Of total crop N at harvest, an estimated average 63% came from ICM in a recent Victorian study. Total crop N includes grain, straw and roots. Root N is about 10% of grain and […]
Question to @aucropnutrition via twitter
What effect do high crop residues have on spread urea? Does some of the applied nitrogen (N) get used to break down the stubble and therefore become unavailable to the plant?
When urea dissolves on the surface of the residues in humid air or dew it gets […]
A national effort has been going into understanding Nitrogen dynamics in Australian soils. The driver is to help growers and agronomists refine their Nitrogen fertiliser decisions. The completed review reduces uncertainty around some of the soil processes involved in supplying Nitrogen to crops, and future research needs. The review characterised:
It used to be that nitrate was often the only form of nitrogen (N) specified in soil test results. Now it’s common for soil test results to specify the quantity of ammonium-N as well.
Recently some unusually high ammonium levels – equal to or higher than nitrate levels – have […]
Stock grazing crops high in nitrate can develop toxicity disorders. Plant nitrate levels are directly affected by nitrogen (N) fertiliser rates. Targeting high grain yields with additions of nitrogen fertiliser can elevate nitrate levels in plants to dangerous levels for livestock.
What can be done to reduce risk to stock
Avoid grazing […]
Rain encourages soil microbes to mineralise soil organic nitrogen (N) into plant available mineral forms. Some mineral N can leach, moving down in the soil profile with subsequent rain.
Deep N soil testing can better estimate the amount of N available in the soil for the crop to make use […]
John Angus is a researcher with the CSIRO and a mixed enterprise farmer in southern NSW. At the 2016 GRDC research updates John reported on a three stage process to make strategic decisions about Nitrogen (N) nutrition through the season for dryland farmers.
Stage 1 – Prior to sowing
Prepare a Nitrogen […]
Optimal timing of Nitrogen fertiliser applications can maximise crop uptake and reduce losses to the atmosphere. Soil Nitrogen (N) dynamics in Victoria show some big differences between regions. High rates of N losses recorded from soils in the High Rainfall Zone (HRZ) emphasise how important timing of N applications can […]
Strategies to reduce Nitrogen (N) losses in Victorian High Rainfall Zone (HRZ) cropping systems are getting clearer.
Recent research in south western Victoria examined rates of N applied, placement of fertilisers and nitrification inhibitors. This work is part of the national agricultural nitrous oxide research program, supported by the GRDC.
Some fertilizer goes on at or just before sowing. As the season progresses we need to:
revisit paddock yield potential
decide if, when and how much to top up Nitrogen (N).
Splitting applications of N fertilizer through the season is a way of increasing nitrogen use efficiency, and better matching total N applied […]