Combined sowing could be on rise
COMBINED seed and fertiliser sowing, widely used to get spring crops off to a good start in Scotland and the north of England, could be beneficial further afield.
"For seedling development, it is vital that crops get as much phosphate as possible immediately after planting to promote photosynthetic and respiratory processes," says Bill Petrie from Carrs Fertilisers of Carlisle.
"The best way to achieve this is to fertilise and drill simultaneously. Its not unusual for cereal crops to take up 50% of their total P need in their first 60 days.
"The availability of phosphorus is even more critical during short growing seasons, in low soil temperatures and for plants with restricted root systems."
Downsides of combine-drilling include reduced output, potential corrosion and the hassle of frequently filling two small hoppers or a second one on the front of the tractor.
As a result growers have been reluctant to consider the technique and there have been few recent developments.
However Jim Carver of Simba-Horsch believes the idea helps release manganese, and the firm is developing its first drill for handling granular fertiliser, the DS/D3.
"You need nitrogen in the ground to reduce the soils pH which in turn unlocks manganese. And in poor soils there is even more benefit from putting granular fertiliser in with the seed."
But seed scorching can occur if the ground is too acidic, and risk rises as increasing yields tempt growers to apply more N.
Norman Robb of HRN Tractors near Insch, Aberdeenshire, offers Accord DC tractor-mounted grain and fertiliser drills and front-tank DFC combination systems.
"We have many customers with spring malting barley. To get the quality they require in such a short season, the crop needs to germinate quickly and get established.
"The only way to do this successfully is to put fertiliser in the ground at the same time as the seed."
Other firms with combined drilling equipment include Amazone, Landmec and Weaving Machinery.
New to the technique for 2002 is Vaderstad with its RDA400M – a 4m pneumatic machine using the heat from its hydrostatically powered fan and auger to prevent fertiliser from becoming moist and blocking the coulter pipes. *
Vaderstads new combination unit is designed to keep fertiliser dry.
• Common northern practice.
• Can boost early crop growth.
• Slower sowing & scorch risk.
• Range of modern equipment.