As farmers across the country consider whether to till grass and plant a tillage crop in the coming weeks there is a lot to be considered.

Costs should be top of the list. The first thing farmers need to do to calculate these costs is look at their soil test results and field history to calculate fertiliser spend.

If you are planting into below optimum ground, don’t expect to have a crop of spring barley yielding 3t/ac in August or September.

Soil pH should be at 6.5 for spring cereals or maize, while beet, beans, peas and oilseed rape will grow best at a pH of 7.

Spring barley

Spring barley will most likely be a popular option for farmers.

Phosphorus (P) and potassium (K) levels would ideally be at index 3, but maintenance levels can be applied. The application rate for P at index 3 is 25kg P/ha and at index 3 for K it is 95kg/ha.

It is important to remember that grassland will provide a lot of nitrogen to crops, so while nitrogen spend will be down, crops are at risk of lodging. A lot of silage ground is low in K, which can help to strengthen straw, so be cautious when planting into this ground.

Looking at nitrogen rates, fields will fit into two categories when planting after grass. Tillage farmers follow the nitrogen index system, which varies with different previous crops. Index 4 for nitrogen is a crop sown after very good long leys (five years or more) or permanent pasture which was grazed only.

Be cautious with high rates as the crop may lodge

Spring barley planted into index 4 soils for nitrogen can receive 40kg N/ha, spring wheat can receive 60kg N/ha and spring oats can receive 30kg N/ha.

Index 3 takes in any first or second tillage crop following long leys or permanent pasture. If the original long ley or permanent pasture was cut, only index 2 is used.

Spring barley crops in index 3 can receive 75kg N/ha, spring wheat can receive 95kg N/ha and spring oats can receive 60kg N/ha.

However, be cautious with high rates as the crop may lodge.

Grassland also carries an increased risk of leather jackets. Rolling is the only real way to tackle this, as chemicals have been taken off the market.