Correctly applying nitrogen fertiliser in the right place, at the right rate and time, can maximise pasture growth while minimising environmental impacts. However, nitrogen responses can vary depending on soil conditions, nitrogen levels and temperature.
Nitrogen fertiliser guidelines
- Apply nitrogen strategically, rather than by a fixed recipe.
- Only apply nitrogen when pasture is actively growing and can utilise it.
- Ensure extra pasture grown is used either through grazing or as harvested forage.
Using the right rate
- The most efficient pasture growth responses occur when nitrogen fertiliser is applied at rates of between 20-50kg of nitrogen per hectare (N/ha) at any one time.
- Do not apply nitrogen fertiliser above 50kg N/ha in any single application or less than 21 days apart.
- Applying less than 20 kg N/ha in any single application will often produce unpredictable nitrogen responses.
Applying in the right place
- Apply nitrogen to pastures with a high density of desirable species and good ground cover.
- Apply nitrogen to pastures that have no limitations to other major soil nutrients.
- Do not apply nitrogen to pastures that are drought stressed or water-logged.
- Consider applying less nitrogen to the front half of a paddock than the back, as cows transfer nitrogen towards the gate.
- Avoid applying nitrogen to animal hot spots (e.g. gateways, water troughs, shelter belts, stock camps) which already high nitrogen levels and are prime nitrogen loss areas on dairy farms.
Applying at the right time
- Apply nitrogen as soon as possible after grazing.
- Avoid grazing until growth has reached at least the 2.5-leaf regrowth stage (or canopy closure) for temperate grasses (e.g., ryegrass) and 3-leaf stage for tropical grasses (e.g. kikuyu and paspalum).
- Temperate pasture grasses (e.g., ryegrass) generally respond to nitrogen fertiliser when soil temperatures (at 10 cm) are above 4°C, and subtropical pasture grasses (e.g. kikuyu) respond to nitrogen fertiliser when soil temperatures are above 10°C.
- Do not apply nitrogen unless there is adequate soil moisture in the root zone from either irrigation or rainfall, plus potential irrigation or rainfall to follow through the regrowth period.