Soil testing to 60cm to measure Nitrogen and Sulphur, was undertaken in April 2017 across more than 150 client paddocks in the Cootamundra, Temora and Grenfell districts.
This information has allowed for more informed decisions to be made about Urea applications in 2017, plus Sulphur requirements in the future. Some key observations follow:
- Nitrogen losses from soils flooded during 2016 may not be as significant as anticipated. Many low lying paddocks which yielded poorly due to inundation, have returned total Nitrogen levels in excess of 100 kg N/ha.
- The highest soil Nitrogen levels were measured in paddocks with a recent history of legume pasture or pulse crops. Paddocks cropped for more than 5 years tended to have lower levels of soil Nitrogen, many with less than 70 kg N/ha. Of the paddocks tested, those which had field peas or vetch brown manured in 2016, all returned greater than 200 kg N/ha.
- Crops on soils with adequate drainage yielded very well in 2016. These crops exported large quantities of Nitrogen in grain, so consequently soil Nitrogen reserves are lower. Paddocks which suffered inundation during September and yielded poorly, generally have high levels of residual Nitrogen. This is especially true where Urea was spread prior to inundation.
- Sulphur levels in both 0-30cm and 30-60cm are well in excess of the requirements for wheat and canola, despite 0-10cm surface soil tests regularly indicating Sulphur levels are below critical values. These results indicate that Gypsum requirements, purely for Sulphur, should be reassessed.
- Deep soil testing for Nitrogen and Sulphur has been shown once again, to be a very good investment. Input allocation decisions are made with greater certainty and in some cases, significant fertiliser savings have been achieved.