‘Maximise’ the value of slurry first and then balance with chemical fertiliser

CAFRE’s Richard Gibson explains how farmers can maximise the efficiency of chemical nitrogen this spring.

With significantly higher fertiliser prices this spring, farmers need to exercise caution when applying early chemical nitrogen (N).

Ensure conditions are correct to minimise losses and maximise the response to N applied.

Monitor soil conditions and long-range weather forecasts to plan applications. Soil temperature must be above 6°C.

Also, think about:

• Optimum sowing rate – split dressings may be a good option to limit the risk of losses this spring;
• Accuracy of the spreader – consider GPS application and sowing pattern. Also, monitor field boundary spreading;
• Maximising the value of slurry first and then balance with chemical fertiliser, where necessary.

Soil sampling

Fields that have not received fertiliser since mid-September and are free of applied slurry or farmyard manure from the end of October are in an ideal state for soil sampling. Carry out soil sampling before planned spring slurry application.

When you get your soil analysis results, enter them into the CAFRE Crop Nutrient Calculator to calculate specific field requirements whilst keeping within the Nutrients Action Programme Regulations.

The calculator takes account of the time and method of slurry application when calculating how much N to apply for first cut silage.

Use slurry on farm

As a general rule, grazing fields have phosphate and potash recycled by grazing cattle.

Therefore, it is likely that you will be applying slurry to land that is used for growing silage and targeting the fields that have been soil tested and require additional phosphate and potash.

This makes the best use of the soil and slurry nutrients and helps avoid nutrient shortfalls where the demand is greatest.

To maximise the potential of slurry:

• Have a plan in place, to include area and rate of application and analysis of nutrient content.
• Analyse the slurry to determine nutrient content. As slurry can be a variable resource, analysis will provide an accurate measure of nutrient value. This will also allow calculations to establish how much purchased fertiliser could potentially be replaced.

Average slurry analysis indicates that 1,000 gallons of dairy slurry is equivalent to 9 units per acre of N, 5 units per acre of phosphorus (P) and 32 units per acre of potash.

This is based on spring application using (Low Emission Slurry Spreading Equipment) LESS equipment.

• Use LESS to reduce the amount of N lost to the atmosphere. Optimum weather conditions, timings and rates are also essential.
• Spread slurry over a larger farm area at a low rate; maximum rate of 2,500 gallons per acre.