Methods and tools to routinely obtain comprehensive insight into the soil health of grassland

Monitoring and steering soil health of grasslands enables dairy farmers to increase farm performance and to contribute actively to the UN Sustainable Development Goals, the European Green Deal and the EU Directive on Soil Monitoring and Resilience. Soil health encompasses physical, chemical, and biological soil characteristics. Commonly, many different tests are needed for a comprehensive soil health assessment, which is laborious, expensive, and many tests have a negative environmental impact. In many countries, a soil test report therefore includes only few soil characteristics. Broad-spectrum soil tests offer the potential to assess many soil characteristics quickly, but often face challenges with calibration and validation. Here, we describe the results of a 20-year research programme aimed at overcoming the aforementioned challenges. Two broad-spectrum techniques were selected, i.e., Near Infrared Spectroscopy (NIRS) and 0.01 M CaCl 2 extractions and combined with advanced analytical techniques for assessing plant-available nutrients and physical, chemical, and biological soil characteristics. The results indicate that the accuracy of NIRS determinations is high compared to the wet chemistry reference method for most soil characteristics including biological characteristics (R2≥0.90). The CaCl 2 extraction is used for fifteen essential and beneficial nutrients and for nine (heavy) metals. The broad-spectrum soil test results are incorporated in several tools (Soil Carbon Check, Soil Life Monitor, and Soil Health Indicator) to provide guidance to farmers to help them attain healthier soils and productive grasslands.