Performance of Slurry Injectors compared with Band Spreading on Three Swedish Soils with Ley

The main objective of the present study was to evaluate different injection methods for slurry to ley on three different soils. A further objective was to study the effect of soil moisture on the working depth of an injector and on the slurry infiltration rate. In full-scale experiments, the placement of slurry, ammonia emissions and yield were measured after injection with three techniques: pressurised injection, shallow injection with V-shaped discs, and shallow injection with two angled discs. In an adjacent experiment the effect of soil moisture was studied. The performance varied between the injectors and only the injector with angled discs was able to place the slurry in ley below the soil surface on all soils studied. The ammonia release was on average halved after injection with angled discs compared with band spreading, giving a mean ammonia loss of 39% of the total ammoniacal nitrogen (TAN) applied. Despite the reduction in ammonia losses with the angled disc injector, this did not result in higher dry matter yield or higher nitrogen efficiency of the second cut compared with band spreading. The working depth of a slurry injector increased significantly with increasing soil water content.