Increasing cost pressures and a desire to know exactly what animals are being fed means many farmers are considering growing alternative forages, but just what do they require in terms of nutrients?
In many cases a good application of farmyard manure or slurry can be enough to suffice, says Martin Titley of Advanta Seeds.
“But it is essential to have these analysed prior to application to ensure optimum growing conditions.
“However, those growing root crops where the bulb is the most important part of the crop, such as swedes and fodder beet, need some artificial fertiliser input,” he adds.
As a fast growing crop kale requires plenty of nourishment, but fertiliser requirements will depend on the previous crop.
When crops follow cereals up to 212kg/ha of nitrogen may be necessary, whereas when following grass this will fall to nearer 94kg/ha.
For soil indexes of two an application of 198kg/ha of potash and phosphate is advisable.
Requirements are generally low, with crops typically needing about 75kg/ha of nitrogen and 37kg/ha each of phosphate and potash.
When they follow cereals, fertiliser should be worked well into the seed-bed and a top dressing of 75kg/ha of nitrogen 3-4 weeks after sowing can boost crop growth.
Applying 50kg/ha of both phosphate and potash to a soil with an index of two will provide an ideal establishment for the crop.
When nitrogen is required at sowing a dressing of 50kg/ha should be sufficient.
A further application of 75kg/ha of nitrogen in spring is often beneficial.
As a catch crop forage rape will use residual nutrients in the soil from the previous crop.
However, further dressings of all the main nutrients will benefit the crop and ensure a sufficient yield.
Applying 35kg/ha of nitrogen, 14kg/ha of phosphate and 21k/ha of potash should be sufficient.
This is a demanding crop, needing high inputs of nitrogen, with trace elements equally important.
Nitrogen should be applied immediately after drilling at the rate of 49kg/ha, while phosphate and potash are best applied in autumn at 19kg/ha and 29kg/ha, respectively.