Injection methods to reduce ammonia emission from volatile liquid fertilisers applied to growing crops
2008
Nyord, T. | Sogaard, H.T. | Hansen, M.N. | Jensen, L.S.
Advanced techniques for separation of animal slurry are now available and used for optimising the use of nutrients present in manure, resulting in the production of two liquid fractions and a solid residue. One liquid fraction rich in nitrogen is used as a biofertiliser locally on the farm and the other liquid fraction with a low nutrient concentration is used for irrigation on the farm. In this study, ammonia volatilisation following landspreading of the liquid biofertiliser was investigated. Three application techniques were compared: a disc coulter injector, a spoke wheel injector and a newly developed high-pressure injector using a trailing shoe technique. Two field studies using the micrometeorological mass-balance technique and a laboratory study employing a dynamic chamber technique showed that when the liquid biofertiliser was surface applied, 20-35% of the applied total ammonical nitrogen (TAN) was lost as ammonia, whereas disc coulter injection into 5-7 cm depth reduced the loss to 2-3% of TAN. In the laboratory study, it was seen that the high-pressure injection reduced the ammonia volatilisation as much as disc coulter injection into 5-7 cm depth, but in the field experiment the high-pressure technique was not able to inject deeper than 0-2 cm, thereby it had no reducing effect on ammonia volatilisation compared to surface application. A yield experiment showed significantly higher yields from spoke wheel injection and high-pressure injection of biofertiliser compared to surface application, but significantly reduced yields compared to commercial mineral fertilisers.
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