SW—Soil and Water: Application of Slurry to Ley by Band Spreading and Injection Methods

In Sweden, 90% of the total amount of ammonia released to air originates from agriculture,e.g . manure handling. Incorporation of slurry into soil can reduce ammonia emissions after spreading. The objective of this study was to compare cattle slurry application to ley using (1) band spreading, (2) pressurized injection, and shallow injection with two different types of disc tines (3) and (4). Two years of field experiments were conducted to study slurry position after spreading, ammonia volatilization, grass yield, and silage quality. An economic analysis was also performed. Injection (2) and (3) were unable to satisfactorily incorporate the slurry, neither on a loam under dry soil conditions, nor on a clay soil. Year 1, high ammonia emissions were measured following application by all methods. Injector (3) with V-shaped disc tines gave a significantly (probability P<0·05) higher ammonia release compared to the other methods. Injector (3) also gave a significantly better silage quality than band spreading. Year 2, injector (4) with tines consisting of two-angled disc coulters resulted in the lowest ammonia losses. Certain differences in yield were observed in year 2. Computer simulations showed, that broadcast and band spreading were economically more profitable than shallow injection.