Slurry use technologies range from hand-application with the help of a bucket to mechanized distribution, supported by GPS (global positioning system) and a computer on board of the liquid manure spreader. The choice of technology essentially depends on the amount of slurry and the area to be fertilized as well as on the financial means and the opportunity cost of labor.
On small farms in developing countries, simple but effective tools are used. They include buckets, scoops, containers with straps, wooden wheelbarrows with lids, barrels on wheels and others. The most economic way to apply slurry is by means of gravity, either by a network of small slurry furrows or by mixing slurry in the irrigation system. Both options require a gradient of at least 1% (for irrigation water) and 2% (for slurry distribution), sloping from the biogas plant’s overflow point to the fields.
Making best and least labor-intensive use of the slurry is an important planning parameter. Especially where gravity distribution is feasible, the positioning of the biogas plant and the expansion chamber and the level of the expansion chamber overflow are of high importance. In rather flat areas, it should be considered to raise both the stable and the biogas-plant in order to allow a slurry distribution by gravity.
Application with liquid manure rainer
Figure 47. Adding biofertilizer to irrigation system.
Photo: Vedenev А.G., PF «Fluid»
The vessel of the rainer is filled form the storage and is then transported to field for application. The slurry is squirted through a nozzle against a reflection plate which, by it’s special
form, diverts and broadens the squirt. An improvement of the simple reflection-plate distribution
is a swiveling plate which leads to a more even distribution.
Direct application through sliding hoses
The slurry is pumped into a distribution system which feeds a number of hoses which move closely to the ground. The slurry is applied directly on the soil surface, therefore reducing nutrient losses. Distances between the hoses can be adjusted to suit different plant cultures.
Hoses with drill coulters
The soil is opened with two disks (drill coulters) in a v-shape. The slurry is applied with sliding hoses into the v-furrows, which are closed behind the hose. It is the most advanced method in terms of avoiding nutrient losses [8].