The Admont Grassland Experiment: 70 years of fertilizer application and its effects on soil and vegetation properties in an alluvial meadow managed under a three-cut regime

Fertilizer application is a widely used management technique for increasing forage production from agricultural grassland. Fertilization is also a key driver of changes in soil nutrient status and plant species composition of grassland as shown in many short-term studies. Results from long-term experiments can further improve understanding of plant-soil relationships and help with management recommendations for agricultural and environmental outcomes. We collected data from a long-term experiment on alluvial meadow (Admont Grassland Experiment, Austria; established 1946) with 24 fertilization treatments managed under a three-cut regime. Soil sampling in autumn 2015 and vegetation sampling in spring 2016 were conducted in seven selected treatments. Combinations of N (nitrogen 80 kg ha(-1)), P (phosphorus 35 kg ha(-1)) and K (potassium 100 kg ha(-1)) were applied annually and compared with a non-fertilized control. Treatments were: Control, N, P, K, NP, NK, PK and NPK fertilization. Long-term different fertilization affected soil pH and nutrient concentrations in the soil and plant species composition, but no significant effects on species richness were found. Short species (<0.5 m height) prevailed in all treatments regardless of nutrient application, probably as a result of the three-cut defoliation. The dry matter biomass (DMB) yield in the Control was limited by N and P and synergisticly co-limited by N, P and K, and DMB yields of more than 5 t ha(-1) per year were achieved under nutrient combinations containing P (NP, PK, NPK) without loss of species richness. Results from the Admont Grassland Experiment show that the tested nutrient combinations significantly increased DMB yield and changed the species composition, but without significant effects on species richness. Long-term biomass yields of more than 5 t ha(-1) DMB per year can he achieved with any nutrient combination containing P without lass species richness in an alluvial meadow managed under a three-cut regime.

Automated summary

Fertilizer application is an effective technique for increasing forage production in agricultural grasslands. Long-term experiments show that different fertilization methods can impact soil pH, nutrient concentrations, and plant species composition, but not species richness. The Admont Grassland Experiment results demonstrate that nutrient combinations containing phosphorus significantly increase dry matter biomass yield and alter species composition without affecting species richness.