A RESEARCH ON THE TECHNOLOGY OF SLURRY APPLICATION TO ARABLE LAND AND GRASSLAND

We examined the application of slurry by means of a vacuum tanker and of a pump tanker, the spreading systems for liquid manure, the techniques for its direct incorporation into the soil, taking into account, resp. the approximation of the wanted rate, the evenness of its distribution and the influence on ammonia emission. The following results were obtained. Application rates with conventional spreading by means of a vacuum tanker are adjusted by the travel speed, the time required for emptying the tank being known. With a pump tanker there is a good linear relationship between the revolution speed of the positive displacement pump and its output, almost independently from the dry matter content of the slurry. Possible dosages thus are a function of the number of gears and the presence of a supplementary gearbox between pump and pto of the tractor. A continously adjustable application rate of liquid manure is possible with a hydrostatic regulation of the displacement pump. Dosage by electronic way or using a multichamber reciprocating pump are recently developed techniques. Using conventional spreading implements (ordinary and inversed splash plate), a good distribution over the entire spreading width, i.e. with a sufficiently low variation coefficient (VC below 20 %) can only be reached under certain conditions (low wind velocity, overlapping). The use of a spraying beam with several discharging points connected to a multichamber rotary piston pump or with a large number of twong hoses (up to 40) where equal partitioning is realised by a hydraulically driven distribution unit, results in a good spraying pattern. Ploughing in slurry a few hours after spreading it, is necessary to reduce strongly the ammonia emission. Shallow injection and sod fertilization are fairly new techniques which make it possible to apply a limited rate of liquid manure (25 tonnes per hectare) on grassland. Important advantages with these techniques are the drastic reduction (with resp. 90 %, 85 %) in ammonia volatilization that can be attained and the fact that the sward is not contaminated with slurry. A (spring tine) cultivator with an injection tube behind each tine and connected by flexible tubes to a distribution unit is employed for liquid manure injection on arable land, which also almost completely eliminates ammonia emission.