Assessing Soil Health Indicators for Manure-Amended Soils

Efforts to quantify soil health have recently increased, yet there has been limited work to establish soil health indicators for manure-amended soils. Beginning with the soil health indicators in the Comprehensive Assessment of Soil Health, we used principal component analysis (PCA) to develop a simplified group of soil health indicators for irrigated (60, 120, 180 Mg ha-1 ) and dryland (30, 60, 90 Mg ha& ) soil in semi-arid southern Alberta subjected to beef cattle feedlot manure applications from 1973 to 1986, 1973 to 2002 and 1973 to 2016. We simplified the set of soil health indicators into 8 core measurements, shared by both the irrigated and dryland sites, but PCA revealed that the relationships among the soil health indicators varied based on water management. Overall, the simplified soil health indicator set included soil organic C, electrical conductivity, permanganate oxidizable-C (Active C), available water capacity, soil texture (clay, sand, silt), penetration resistance from 15 to 45 cm (subsurface hardness), root health and soil pH. We propose that these core measures are included in the development of soil health indicators for manure-amended soils across the Northern Great Plains, which are likely also applicable to other soils in this vast region and beyond. If consumers and export markets heighten their demand for environmental sustainability certification of animal products then the development of soil health scoring functions by using multiple sites with different manure histories is one approach to add value to Canadian products. This will involve coordinated efforts among researchers.