Key Points:
- Dairy shed effluent can supplement or replace conventional fertilisers on low fertility soils being used for maize production.
- Low and high rates of urea, low and high rates of effl uent were compared with a no fertiliser or effluent control. The focus was on nitrogen; phosphorus and potassium levels were not limiting in the soil. High rates of urea and effl uent were designed to meet the crop requirements leaving little residual N at the end of the season.
- Effluent application did not affect crop establishment and the fi nal grain yields were not affected by the nitrogen source; the high fertiliser and high effl uent treatments had similar yields (~14 t grain /ha, at 14%MC).
- Nutrient practice had no effect on the post-harvest soil minN levels which were similar to the pre-cultivation levels. Based on the trials to date, 30–40% of the total N in the effl uent will be released in the fi rst season, the remainder will be released in the following seasons. The rate of release is affected by the seasonal
- soil mineralisation processes including soil temperature and soil moisture.