Having the correct pH, P and K levels in your soil is the base to optimising yield. If you don’t have recent soil analyses, get these done and target pH 6.0 - 6.5, P index 2 and K index 2+. Did you know having a soil pH of 5.5 rather than 6.5 can knock 40% off your grass yields?

Grass silage removes a lot of Potash from the soil system and slurry is a good source of both Potash (K) and Phosphate (P). Every 1,000 gals/acre (11 m³/ha) will supply about 25% of your AfterCut Potash requirement. Don’t apply more than 3,000 gals/acre (33m³/ha).

Compacted soils don’t have enough air and water in them to let the regrowing grass roots effectively get the nutrients needed for optimum growth. To avoid compacted soils, which can reduce your AfterCut yields by up to 25%, dig inspection pits and identify any issues and rectify them this autumn in readiness for next season.

For a 3-cut silage system, you should be using 75kg N/ha (60 units/acre) for 2nd cut. On a two cut system this can come down to 50kg N/ha (40 units/acre) and up to 90kg N/ha (72 units/acre) on a four cut system. Slurry alone won’t provide your grass with enough N to optimise your yields. To manage your system you need to know how much N, P, K and S you are putting on with slurries and bagged fertilisers. Every 1,000 gals/acre (11 m³/ha) slurry only contains enough available N to grow about 0.3t fresh weight grass per acre (0.75 t/ha).

If you use urea on AfterCuts, warm and dry conditions will mean that you lose up to 58% of the Nitrogen you apply to the atmosphere.
That’s bad for your:
• Grass growth (you could lose around 15% of growth potential)
• Your pocket (58% of your AfterCut fertiliser purchase could end up in the atmosphere)
• The environment (that lost N is likely to come down to earth again with particulates that harm peoples health).
AN works faster than urea and with fewer losses.

All soil types except heavy (clay loam) and peaty soils will respond to added Sulphur fertiliser and give you more dry matter yield, crude protein content and sugar levels. You need around 20 to 25kg SO₃/ha (16 to 20 units/acre) across your aftermaths to optimise grass yield and quality, and a standard slurry application will only provide about 2kg SO₃/ha - there’s not much Sulphur in cattle slurry and at least 85% of that is unavailable for plant use.

Your second cut is likely to need 60 to 90 kg Potash per ha (48 to 72 units/acre) if your soil K indexes are 2+ or 2- and 25 kg Phosphate per ha (20 units/acre) at P index 2. That may not all come from slurry. A granular compound will have P and K in every fertiliser granule, giving you better nutrient spread and uptake compared to a blended equivalent, and that could add 15% yield to your AfterCut grass.