Quantifying soil quality in a horticultural-cover cropping system

Understanding and interpretation of soil quality is crucial to strategize land management practices for sustaining agricultural productivity while mitigating environmental degradation. A medium-term cover crop (CC) trial, established in 2007 and repeated in 2008, at Ridgetown, Ontario was used to evaluate the comprehensive assessment of soil health (CASH), to develop a weighted soil quality index (WSQI), and to compare scores of CASH, Haney soil health test (HSHT), and WSQI in surface soil (15 cm) in 2015 and 2016 (herein referred to as site-years). Out of 25 potential soil quality indicators, 19 soil indicators were responsive to CC treatments and represented a total dataset. Using principal component analysis (PCA) of the total dataset, a minimum dataset (five indicators; pH, organic matter (OM), Solvita labile amino N (SLAN), Solvita CO2-burst, and water extractable organic C (WEOC)) was identified to calculate a WSQI. The WSQI and CASH scores were equivalent in detecting CC treatment differences in site-year 2015, but CASH detected greater magnitude (12.1%) of treatment differences than WSQI (5.7%) in site-year 2016. Cereal rye and a mixture of oilseed radish and rye (OSR + Rye) led to greater soil quality values than other tested CCs. Our results indicate the potential of CCs in significantly improving soil quality in the medium-term (6 years). This study is the first independent evaluation of CASH in a horticultural system in a humid, temperate climate, and first study to compare WSQI with commercial soil quality tests. Even though CASH and WSQI differentiated between CC treatments for soil quality evaluation in both site-years, we recommend WSQI as a valuable and practical tool (lesser number of indicators; five vs. 15), for quantifying soil quality in similar production regions and climatic conditions.