Plan nutrient applications using a soil analysis report
By Aidan Kerr, Countryside Management Delivery Branch, DARD
Many farmers will now be planning their chemical and organic manure applications for the growing season. This planning should be based on the results of a soil analysis.
Remember that any chemical fertiliser containing phosphorus (P) must only be applied if there is a crop requirement, as shown by a soil analysis report and this report will help determine which type of fertiliser best meets the needs of the growing crop. .
The table below provides a guide to interpreting the P index stated in the soil analysis report. For more advice see pages 155-156 of the Code of Good Agriculture Practice (CoGAP). This is available online at www.ruralni.gov.uk/cogap
| P. Index | Advice | |
|---|---|---|
| 0 | Deficient | Low P levels likely to limit production. Increase P by applying slurry or manure and/or P fertiliser. |
| 1 | Optimum for extensive grassland | Extensive grazing:. If current level of production is satisfactory continue with your usual fertiliser and slurry policy. Intensive grazing, silage and arable crops: Low P levels are likely to limit production. Increase P application with slurry and/or fertiliser. |
| 2 | Optimum for intensive grassland, silage and arable crops | Extensive grazing: High P levels present. No yield response to added P. Use zero P fertiliser. Redistribute slurry to lower P fields on the farm. Intensive grazing, silage and arable crops: Optimum for intensive grazing and silage fields. If current production is satisfactory, continue with your usual slurry and fertiliser policy. |
| 3 | High | High P present. No yield response to added P. Use zero P fertiliser. Avoid slurry applications on grazing fields. Redistribute slurry to lower P fields on the farm, concentrating on February/March application for first cut silage and dilute slurry applied at low rate between cuts. This should take place no more than three days after cutting. |
| 4 | Excessive | Excessive levels of soil P. No yield response above to added P. Use zero P fertiliser. Avoid slurry applications on grazing fields. Redistribute slurry to suitable fields of lower P status on the farm, concentrating on February/March application for first cut silage and dilute slurry applied at a low rate between cuts. This should take place no more than three days after cutting. |
The Phosphorus Regulations have led many farmers to reduce the P content in their chemical fertiliser. The majority of silage swards are now low in potash leading to reduced yields and in addition sulphur levels are falling and increasingly this nutrient is also becoming deficient. It is useful to monitor soil P, K (potash) and pH (soil acidity) through soil analysis to make sure that the levels of these nutrients are maintained at optimum levels. An analysis for sulphur can be asked for on a soil analysis but there is additional charge.
Farmers can use the Crop Nutrient Recommendation Calculator, available online at www.ruralni.gov.uk which will help you manage your nutrients efficiently. It will:
- Nitrogen (N), Phosphate (P2O5), and potash(K2O) required by crops;
- Calculate the amount of nutrients supplied by organic manures;
- Select the correct chemical fertiliser and application rate to ensure nutrients are optimised;
- Retain information required for record keeping;
- Help reduce chemical fertiliser cost
If you have any queries on soil analysis contact your local DARD Countryside Management Delivery or CAFRE adviser. More information on soil analysis can be found in the CAFRE leaflet, 'Understanding your soil analysis laboratory report', available online at www.ruralni.gov.uk/cafre_soil_analysis.pdf
