Interannual Effect of Digestate Fertilization on Yields and Quality of Winter Rye Forage

Abstract

In two-year pilot field experiments (harvest 2021-2022) we explored the interannual effect of digestate fertilization (30 t/ha prior to sowing) on yields and some qualitative parameters of winter rye (KWS Progas) forage silage. The yields of the aboveground biomass differed insignificantly on a year to year basis: 31.07 t/ha FM in 2021 and 25.17 t/ha FM in 2022 (4.9 t/ha DM in 2021 and 4.2 t/ ha DM in 2022) although the dry matter content differed significantly: 15.6% in 2021 and 16.6% in 2022. Interannual differences in the qualitative parameters were significant for these characteristics (% of DM) - Ntot.: 2.2% (2021) versus 1.9% (2022); crude protein: 13.8% (2021) versus 11.7% (2022); ash matter: 6.5% (2021) versus 7.6% (2022); NDF: 63.8% (2021) versus 57.8% (2022). Differences of ADF were insignificant 37.0% (2021) versus 35.2% (2022). The results show that the applied dose of digestate (150 kg N/ha plus other nutrients) is sufficient to achieve an adequate yield and quality of winter rye forage. The influence of the year was significant for dry matter content and most of the monitored qualitative parameters, especially from the point of view of the intensity and distribution of air temperatures and rainfall. In addition, the residual nutrients in the soil after the winter rye forage harvest (N, K) will be utilized by the subsequently grown maize in the dual rye-maize system. Based on results of two-year field experiments, digestate applied to winter rye forage prior to sowing at an amount of 30 t/ha proved to be sufficient in terms of biomass yield and its quality. In view of this finding digestate is a suitable and efficient organic fertilizer with readily available nitrogen and other macro- and microelements. The use of digestate is a cost-effective substitution for expensive mineral fertilizers, namely nitrogen, which is a very current topic now. Considering that winter rye forage is harvested in spring, usually in May, a very important factor for achieving high yields is the course of the weather i.e. the total amount and distribution of precipitation and temperature during vegetation especially. Residual nutrients in the soil after the winter rye forage harvest will be utilized by the subsequently grown maize in the dual rye-maize system which is an important economic-environmental benefit.

Keywords

• winter rye
• silage
• quality
• dry matter
• crude protein (cp)
• ash content
• acido-detergent fibre (adf)
• neutral-detergent fibre (ndf)