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5 Steps to soil fertility management

1) Soil Samples

Have soil samples taken for the whole farm. Unless you know what is already in the soil, it is impossible to know how much fertiliser it needs. Therefore, by taking soil analysis and putting the results into practice, the fertiliser programme can be tailored to the needs of the soil and the crop. Repeating soil analysis over time (3 to 5 years) is also critical to monitor the effectiveness of the farm fertiliser strategy. 

Soil Analysis Step 1

2) Lime

Lime should be applied to neutralise soil acidity and raise the soil pH to the target soil pH for the crop been grown. For mineral soils, a soil pH 6.3 is recommended for grassland. The soil pH should be higher (Barley / Beet) for tillage crops and aim to maintain at pH 6.5 to 6.8. Acid soils will result in reduced release of the major nutrients (especially P) from soil, and result in a poorer response to applied fertilisers. Apply lime as a priority in line with the lime advice as per the soil test report.

3) Target Index 3

Aim to have optimum soil P and K (Index 3) fertility levels in all fields. At optimum fertility levels, nutrients being removed in products (Meat / Milk / Grain) need to be replaced. Low fertility (Index 1 & 2) soils need to be fertilised correctly to achieve soil index 3. For soils in Index 3 the fertiliser program should be designed to replace the nutrients being removed, thus maintaining the soil fertility levels. Index 1 and 2 soils have a very low to low nutrient supply, and require additional nutrients to increase the fertility levels on an annual basis. Index 4 soils have a high nutrient supply. These soils present an opportunity to save money on fertiliser inputs by harvesting the P and K soil reserves for a number of years depending on the soil test reading. For example, high P index 4's (>10-15 ppm) omit for 2/3 years and retest. For high soil K levels (>150- 200ppm) omit for 2/3 on grazing ground and one year on silage ground. Then revert back to index 3 advice until next soil tests. 

 4) Slurry and Manures

While slurry can be more difficult to manage than chemical fertiliser, it can be a very cost effective resource to increase fertility levels. Use slurry / FYM on the farm as efficiently as possible, and top up with fertiliser as required. Aim to apply slurry and manures to fields that have high P and K requirements (e.g. grass/maize silage). Apply in spring time under cool and moist weather conditions to maximise N recovery.

5) Balanced Nutrient Supply

If one nutrient is deficient, no amount of another nutrient will overcome this. For example, if a field is deficient in K, then excess N application will not be fully utilised. Make sure the selected fertiliser compound is supplying nutrients in the correct balance for the crop, the soil, and to complement any other nutrients applied in organic manures. Other nutrients such as sulphur / magnesium can play a very important role to ensure a balanced fertiliser programme and should be applied where necessary. For other crops, such as cereals/vegeatables always check minor nutrients such as boron, copper, managanese and zinc.