The effects of organic fertilization systems on yield and yield variability of lucerne and market crops: Insights from a 10-year field experiment in Austria

The 10-year effects of organic fertilization have been shown to enhance crop yields and contribute to sustainable agricultural productivity, although the extent of these benefits can vary depending on specific conditions and management practices. To investigate the impact of different organic fertilization approaches, the present study examined the effects of livestock-keeping and stockless organic fertilization systems on the yield and yield variability of lucerne and market crops (such as grain maize, spring barley, field pea, winter rye, winter wheat after lucerne (WWL), and winter wheat after peas (WWP)) in Eastern Austria over a 10-year period. The study tested three organic fertilization systems with continuous application of organic fertilizers as follows: FS1: without livestock, only lucerne green manure (GM); FS2: without livestock, lucerne green manure and municipal compost (GM+MC); and FS3: with livestock, lucerne forage use and farmyard manure application (FU+FYM). The study found that the dry matter (DM) of lucerne and the grain yield of market crops distinctly varied from year to year, with higher productivity observed during years with more favorable weather conditions. Moreover, the 10-year application of organic fertilizers, especially GM+MC and FU+FYM, increased the grain yield of all studied market crops except maize and field peas in comparison with GM. The simplified soil surface nitrogen (N) balance estimation revealed large differences between the fertilization systems. The GM treatments showed a highly positive N balance (196–374 kg N ha −1 a −1 ) due to N retention in the aboveground biomass of lucerne and assumed minimal gaseous ammonia losses (GM and GM+MC) as well as high N input via compost fertilization (GM+MC). Regarding yield stability, the study found that organic fertilization systems only affected the variability of DM in WWL, with the highest variability observed in the FU+FYM system. In conclusion, the study suggests that GM+MC (FS2) and FU+FYM (FS3) have potential for improving crop productivity and nutrient values in organic farming, based on findings from a 10-year investigation. Moreover, during the study period, no adverse effects of a diversified farming system without livestock (FS2: GM+MC) were observed during the study period compared to a manure-based farming system with livestock (FS3: FU+FYM). • Long-term organic fertilization systems impact crop productivity and sustainability. • GM+MC and FU+FYM systems increased grain DM yield of crops compared to GM alone. • Soil surface N balance varied greatly between organic fertilization systems. • FU+FYM system significantly affected dry matter yield variability in WWL. • Diversified farming without livestock (GM+MC) showed no adverse effects vs. FU+FYM.