Chapter 9. Development of a soil health index based on the ecological soil functions for organic carbon stabilization with application to alluvial soils of northeastern Italy

Abstract

There is a need to assess soil health quantitatively to assist with sustainable soil management in agroecosystems. The objective of this research was to develop a farmlevel soil health index (SHI) to help identify the most sustainable management practices including C sequestration and agroecosystem resilience to climate change. For all indexing phases we used the Soil Management Assessment Framework. The SHI was created using a minimum data set (MDS) of physical, chemical and biochemical soil indicators chosen via expert opinion (EO-MDS) (24 indicators) and via the results of PCA (PCA-MDS) (16 indicators). Each observed value was converted into a score (0 to 1) by using site-specific non-linear scoring algorithms. Indicator scores were incorporated into a composite SHI which quantified the ecological performance of 5 soil functions: habitat and biodiversity, water movement and availability, filtering and buffering, nutrient cycling, physical stability and support, and long-term C stabilization. For both MDS evaluations, we assessed agroecosystems managed organically (OS) or conventionally (CS). Results from our study showed that OS had significantly higher ( P<0.05) SHI scores compared to the CS. SHI, with EO-MDS, was more efficient ( P=0.028) than the PCA-MDS (P=0.039) when determining the effect of soil management practices on soil health. Non-linear transformation was a useful technique and represented soil ecological functionality effectively. Five out of six soil functions had significantly greater ( P<0.05) ecosystem performance in OS compared to CS, except for water movement and availability. The benefit for OS lead to a greater soil health status, allowing the system to be more resilient to climate change, to efficiently provide nutrients to plants, and to sustain an active soil food web for