Precision Agriculture collected over ten thousand deep Nitrogen (N) samples in Autumn 2022. Principal Scientist, Kirsten Barlow recently studied the information collated last season with the aim of understanding any regional trends within the data and insights to consider next year.
With soils sampled in different depth increments, the soil mineral N (nitrate and ammonium) to a depth of 60cm was calculated as kg N/ha. Generally, the mineral N levels were low across the board, reflecting 2021 crop yields and in some areas significant summer rainfall. While generally, low mineral N was highly variable within all regions and within many farms, highlighting the need to test different soils and stages of crop rotations on your farm rather than relying on district trends.
In summary, the mineral N levels across different regions (Figure 1 below) some of the key results were that:
- Vic Central, Vic North Central, and Vic Northeast were the only regions where the average mineral N was greater than 100 kg N/ha
- Vic North Central had the highest average but also the greatest range, from negligible mineral N up to almost 350 kg/ha, highlighting the risks of relying on district trends.