5 steps to improve soil fertility on your farm
Delegates arrived in Kilkenny this week for Teagasc’s Soil Fertility Conference, where the importance of optimal soil fertility levels were highlighted.
During the Soil Fertility Conference, Teagasc staff highlighted five steps for effective soil fertility management.
1. Soil testing
Soil testing and fertiliser planning are key requirements for any successful farm and should be conducted during autumn in advance of fertiliser purchase.
Soil fertility is hugely influenced by soil pH, along with phosphorus (P), potassium (K) and nitrogen (N) present in the soil.
When addressing soil fertility, a soil test or analysis is key to knowing what state your soils are in. If you fail to complete a soil analysis, you’re essentially working blind when it comes to the nutrients required on your farm.
2. Addressing pH
The starting point when building soil fertility is to apply lime according to the soil test recommendations to bring pH to the target required by the crop.
Soil pH has a major effect on soil nutrient availability and farmers should aim to maintain mineral soils at pH levels of 6.3; peaty soils should have a pH of 5.5-5.8.
Research from Moorepark and Johnstown Castle indicates that by increasing soil pH from 5.2 to 6.4 – and using only lime – an average grass production response of 1t/ha was achieved. This – Teagasc says – is worth €105/t.
However, results of soil tests undertaken by Teagasc show that approximately 47% of soil samples from grassland farms still have below target soil pH, indicating that lime applications are required.
3. Optimal P and K indices
After focusing on soil pH, the next step is to aim for a target index of 3 for both P and K.
It’s worth remembering that low soil fertility equates to reductions in grass growth potential in excess of 3t/ha/year of grass, which is worth at least €540/ha/year on a dairy farm and €315/ha/year on a drystock farm.
Raising these indexes to the optimal will have both benefits for grass growth and ultimately the farm’s bottom line.
4. Slurry and manures
After identifying fields that may not be optimal for P and K, the next step is to target these fields with organic manures first.
It’s advisable to soil test this autumn to decide where to apply slurry and to maximise yield potential. Ideally, slurry should be targeted at first-cut silage ground or low P and K index soils.
Many farmers get caught in the trap of applying slurry to the fields/paddocks closest to the yard, when it might be better served being spread on other areas of the farm.
5. Make sure the fertilisers used are properly balanced
After using organic manures, the next tool in the armoury is artificial fertiliser. Choose a fertiliser compound that has the correct balance of N, P, K and sulphur (S).