Seed-and-feed drilling is making a comeback this autumn on a family farming business in Essex. Robert Harris finds out why.
Until the early 1980s, all crops at Clarks Farm, near Sudbury, were sown using a combine drill. But the greater work rate of grain-only drills and the advent of accurate pneumatic fertiliser spreaders spelled the end of the practice here and across most arable farms south of the Scottish border.
Now, after 30 years, a combine drill has returned to the farm, the base for Hogsbjerg Farms, which grows 356ha of winter wheat, spring barley, oilseed rape and beet on owned, tenanted and contract-farmed land on the Essex/Suffolk border.
Tony Hogsbjerg, who runs the business with wife Rosemary and son Aaron, bought a Horsch Sprinter 4 ST drill this summer, convinced that placing fertiliser where the seeds can access it quickly is key to strong early growth and a well-established crop.
"Wheat yields have barely increased since we stopped combine drilling. There are lots of other factors at play, but I believe combine drilling can help us to push yields up to the next level," he says.
The technique is being employed across all combinable crops on the mainly medium to heavy soils. Oilseed rape drilled with 150kg/ha of 20-17-9-13.5SO3 leapt out of the ground, says Aaron.
By mid-October, the evenly emerged, robust crop had achieved about 70% ground cover. A seed-only comparison sprayed with 30kgN + 20SO3, which, together with a maintenance dressing of Fibrophos every three years, had been standard farm practice, was much less even and smaller and had achieved roughly 40% ground cover.
"The aim is to apply enough nutrients for the first 40 days, placed where the small plant can easily access them," says Aaron. "Phosphorous is especially important in encouraging strong rooting, and it certainly has made a very visible difference."
The Horsch's Duett coulter points, set 25cm apart, create a 5cm-deep furrow into which the fertiliser is placed. A wedge-shaped plate then closes the slot before twin bands of seed are placed just above and to the side of the fertiliser. A following tine harrow and rear tyre packers complete the job.
Aaron expects a similar boost with wheat. Heavy land crops received 60kg/ha of triple super phosphate (TSP) and medium land wheat 105kg/ha of 0-26-26 NPK. Different rates are being trialled and will be taken to yield. Spring barley after beet will receive 150kg of 17-17-17 in the seed-bed.
There are other potential spin-offs, says Aaron. "We are putting fertiliser only where the crop needs it. We may be able to use less product, and the accurate placement will restrict the amount of nutrient available to weeds between the rows. We have some very resistant blackgrass on the farm, so any help we can get to control it will be very welcome."
Fertiliser consultant Bill Petrie of Liebig Technology, near Forfar, says the main benefit of combine drilling is that it puts key nutrients, particularly phosphorous, near the seed. "Seeds have very limited nutrient reserves and take time to develop sufficient root mass to search for nutrients. They need a 'colostrum' boost."
Early season P nutrition is critical, he adds. "Its main function is to promote cell division, so a deficiency in the first four or five weeks will have a major impact on rooting and ultimate yield potential. P is negatively charged and can be locked up by the positive charged elements, and it is not very mobile in the soil, moving less than 0.2mm/week."
Putting fertiliser where it is needed will outweigh the potentially slower work rate and additional cost of combine drills, he maintains. Even high P index soils benefit. "Work at HRI showed even at an index of 8 there was a still a financial benefit in applying a starter fertiliser."
Cereal growers can typically expect a yield lift of 15-20% from combine drilling, provided other potentially limiting factors such as pH, micronutrients and soil physical factors have been addressed, he maintains. SAC work at Auchterarder as far back as the 1980s with spring barley showed combine-drilled plots gave a 57% increase in yield over broadcast plots, Mr Petrie says.
Horsch demonstration (unreplicated) trials at Schwandorf in Germany in 2010-11 showed significant benefits in winter wheat from shallow placement of fertiliser. Soils had received 40kg/ha each of P2O5 and K2O; adding an additional 120kg of NPK (18-18-26) at 5cm deep produced a yield of 7.61t/ha compared with 6.29t/ha when the same fertiliser was placed throughout the working depth of the loosening tine (up to 25cm).
Oilseed rape growers also stand to benefit, he adds, given the small seed's very low nutrient reserves. Di-ammonium phosphate (DAP) (18-46-0) is a popular choice in that crop, but he prefers to include 50% nitrate N (ammonium nitrate or calcium ammonium nitrate) to ensure enough N remains available if it turns cold. "Apply crop removal of potassium and boron as per manufacturers' recommendations."
For winter cereals, he suggests applying enough TSP and additional K as needed at drilling to provide 80% and 20% of crop need and broadcasting the rest in the spring. "Crops go to sleep in the winter, so applying more P in good time will help them restart rooting when they wake up."
Peter Smart Contracting – Braevail Farm, Nairn, Highland
All of the winter and spring cereals drilled across the 2,200ha of land under Peter Smart Contracting’s care are combine drilled. The father and son business operates two Horsch Pronto DC drills from its base at Braevail Farm, Nairn, Highland – one 4m and one 6m model, both new this year.
“We are over-machined, but, given the tight drilling windows this far north, that ensures we can cover the ground when we get the chance,” says Peter Smart Jnr. The drills are matched to a 250hp John Deere 7930 and 200hp 7530, respectively, and 40ha a day is easily achieved with the bigger unit, including travelling time.
The tight drilling timeframes account for the popularity of combine drilling among his customers, he adds. “We have always applied fertiliser when we sow cereals. Placing it with the seed ensures much quicker uptake of nutrients – you can really see the difference.”
Spring barley is the main reason combine drilling has never gone out of fashion in much of Scotland. “We try to wait until soils have warmed but it is not always possible. Applying fertiliser with the seed gets the crop out of the ground quickly.
“The same is true of winter crops – we need to promote as much root growth as possible before winter sets in.”
All the seasonal P and K requirement is applied through the drill and autumn N is widely used to boost early growth – it also promotes P uptake. “We typically apply 300kg of 17-17-17 NPK or 200kg of 8-24-24 NPK+S depending on requirements. In the spring we usually put down 300kg of 17-17-17.”
Accuracy is maintained from start to finish, whatever the weather, says Mr Smart. Warm air from the fan-cooling arrangement blows fertiliser down the tubes, avoiding the problem of restricted or blocked coulters that dogged some older drill designs in wet weather.
“Ensuring we can get the fertiliser on when and where it is needed makes all the difference this far north,” says Mr Smart.