28 June 2002

NVZ extensions add to college worries

New bacteria treatments could promise an end to slurry

worries at Bishop Burton agricultural college, East Yorks

SERIOUS head scratching at Bishop Burton agricultural college, near Beverley, East Yorks, followed news that nitrate vulnerable zones are to be extended.

Farms director Colin Dennis had long worried about disposing of slurry and FYM from the colleges 364ha (900 acre) farm stocked with dairy cows and pigs. But Mr Dennis thinks he may have found an answer after testing two new live bacteria products, one of which has reduced stored pig slurry by about 25%.

Two Imtec-Bio products, both powders, have been tested on the colleges farm. Imtec for bedding can be sprinkled on the floor or mixed to a paste and put in the drains. The other product is added to slurry storage systems. Both contain bacteria which digests waste to release ammonia that turns into a harmless insoluble protein on contact with the moisture in FYM or slurry, claim the makers.

The main reason for the reduction in pig slurry is the improved flow of material through the drainage system, explains Mr Dennis. "The pig unit is straw-based but waste from the dunging passages ends up in the slurry system. Previously, the drains would often block and staff had to flush them with water which also added to storage problems."

The Imtec bacteria for bedding was first sprinkled on the floor at a rate of 50g/cu m whenever the animals were given fresh bedding. A weekly maintenance application of 20g/cu m was then used. That resulted in a drier bedding area and less mucking out.

The Imtec bacteria designed for slurry storage systems was applied at 200g/cu m of slurry. It was emulsified with water and pumped under the slurry crust every three weeks.

"We had always had difficulties dealing with slurry from the dairy unit, with a hard crust on the slurry and the solids settling out. Now, we have a more efficient mix of solids and liquids without expensive stirring devices."

Pig unit staff also liked the reduction in ammonia levels after using the Imtec treatment. "Levels of ammonia in the air are measured in parts per million (ppm) and 25ppm is considered to be unacceptable for staff and for pig health," says Mr Dennis. "We took measurements before and after applying the live bacteria and found that it reduced ammonia levels from 11-20 ppm to just 1-2 ppm."

Further claims by the manufacturers that the Imtec products can cut the need for bought-in fertiliser are also being tested.

"Slurry was applied to a crop of winter wheat in March," explains Mr Dennis. "We are conducting tests using a soil nitrogen tester which measures chlorophyll in the flag leaf. Knowing the nitrogen uptake, we can calculate the amount of top dressing required.

Imtec is said to increase the availability of nitrogen because it cuts ammonia volatilisation. Early results support the manufacturers claims.

But questions remain to be answered, stresses Mr Dennis. "We are looking how to reduce the amount of powder to cut costs. And a number of factors can influence the products efficiency, such as stocking rates and weather.

"But we will probably continue to use it commercially after the trial has ended because it has been so effective in the drains. The product also appears to help dry out the pig slurry, so we expect that our winter storage problems will become less critical. Hopefully, that will make it easier to comply with new regulations."