Ecosystem services in grassland associated with biotic and abiotic soil parameters

Process parameters underlying the ecosystem service soil structure maintenance such as bulk density and the percentage of sub-angular blocky elements were mainly influenced by SOM and its qualities. The correlations between penetration resistance at 0-10 cm and the percentage of soil crumbs with earthworms suggested a relationship to earthworm activity. Parameters underlying the service of water regulation showed no clear relationship to biotic soil parameters. Water infiltration rate in the field was explained by the penetration resistance at 10-20 cm. Process parameters underlying the service of nutrients' supply such as the potentially mineralizable C and N were mainly determined by soil total N. The potential C and N mineralization were more related to biotic soil parameters, whereby each parameter was the other's antithesis. The grassland production without N fertilization viz. the nitrogen supply capacity of the soil measured as N yield, was mainly explained by soil organic matter (SOM) and soil moisture, and to a lesser extent by soil total N. One gram of SOM per kg of dry soil corresponded to 3.21 kg N yield ha−1, on top of a constant of 15.4 kg N ha−1. The currently applied calculations in the Dutch grassland fertilization recommendation, underestimated in 85% of the production grasslands, the measured nitrogen supply capacity of the soil by on average 42 kg N ha−1 (31%). This legitimizes additional research to improve the currently applied recommendations for sandy soils. The response of N yield to N fertilization ranged from 35 to 102%. This wide range emphasizes the importance of a better recommendation base to target N fertilizer. The response of N yield to N fertilization was predicted by the total number of enchytraeids, the underlying mechanism of which needs further investigation on different soil types. This knowledge can be important for the optimal use of fertilizer and its consequences for environmental quality.