Importance of soil fertility in reseeding

To get the maximum from a new reseed and to improve the productivity of a sward, soil fertility must be correct. Prior to reseeding it is crucial to carry out soil tests for Phosphorus (P), Potassium (K) and pH (lime requirement), testing to a minimum of 10cm soil depth. For accuracy, it is important that the newly cultivated soil is tested and not the soil of the pre-existing sward.

Target pH – 6.3 for mineral soils and 5.5 for peat soils.

P and K must be brought up to soil Index 3. N is essential for new reseeds and should be applied at 30 units/acre. When ploughing it is recommended to re-test new reseeds the following year to ensure optimum soil fertility for maximum grass performance.

Phosphorus and Potassium
Phosphorus (P) is essential for root development. It is immobile in the soil, and if the young seedling roots are to get adequate P, there must be an abundance of this element dispersed in the soil. Table 1 shows the P and K requirements when reseeding grassland at the different P and K index levels.

Table 1: P and K rates required for pasture establishment

Soil P Index Soil P Range
(Morgan’s mg/l)
P Application Rate
1 0.0-3.0 60
2 3.1-5.0 40
3 5.1-8.0 30
4 >8.0 0
Soil K Index Soil K Range
K Application Rate
1 0-50 110
2 51-100 75
3 101-150 50
4 >150 30

An additional 15 kg P/ha is permitted in addition to normal allowances for reseeded grassland on index 1, 2 and 3 soils. These advice rates must be checked against total annual P allowances for the farm under Nitrates rules.

Browse our website to read more about our grass seed mixtures or download our Agritech Grass Seed Brochure (2MB).

To buy our Tipperary Grass Seed range, contact your local distributor.

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