Why forage breaks cut fertiliser costs
By Simon Wragg
WINTER cereal fertiliser bills can be cut by 25% if best use is made of forage break-crops, claims one college farm manager.
Where winter wheat follows a break-crop of Italian ryegrass and red clover, an early spring applications of N can be done away with, saving £31/ha (£12.60/acre), says Ian Sanday, farm manager at Rodbaston College, Stafford.
But for the wheat to benefit, the bi-cropped forage break – grown for the farms dairy herd -must be planted by August, he says. That allows clover sufficient time to establish before winter so the most is made of its nitrogen-fixing potential in the spring.
After the final forage cut, the ground is ploughed ready for drilling feed wheat in October. Buster is Mr Sandays preferred variety.
"According to the revised RB209 fertiliser recommendations booklet from MAFF [now DEFRA], we would be looking at applying 160kg N/ha to the wheat across the growing season, split one-third and two-thirds between mid-February and mid-April.
"But even on the light, sandy soils on this farm the ryegrass/ clover mix leaves sufficient residual nitrogen to get wheat off to a good start. Field tests regularly show indexes of 2 or 3, allowing us to bring total applied N requirement down to just 70kg/ha of nitrogen."
Early spring N is overlooked. "We do not find the wheat suffers from being too winter proud after the ryegrass/clover and there is not the tell-tale yellowing of foliage early in the growing season," says Mr Sanday.
The balance of N is made up of applications of slurry in spring and an April dressing of bagged fertiliser. "The saving of 90kg/ha of nitrogen plant food is equivalent to 260kg of bagged product. If we assume a typical cost of £120/t for commercial fertiliser the saving stacks up to £31.20/ha."
The forage break offers other benefits, too. "It leaves the ground free of disease, helping trim spray costs in the cereal crop. And on these sandy soils, which are prone to drying out during grain fill, there is enough anecdotal evidence to suggest the previous crops fibrous root mass helps retain moisture. Yields have been up by 1t/ha in some years."
Despite switching from feed wheat to triticale in a bid to cut cost/t for cereals destined for animal rations, the forage break still offers substantial savings in fertiliser costs. "It is a win-win situation for mixed farms. The ryegrass/clover forage cuts bought-in protein costs and then variable costs for cereals are also trimmed." *
• Drill mixed forage break early.
• 90kg/ha of residual N left.
• Cereal fertiliser bill down £31/ha.
• Other benefits might lift yield.