Long-term impact of tillage and crop rotation on soil health at four temperate agroecosystems

• We present relationships among soil attributes based on 4 long-term experiments.
• A new soil health score (OSHA) is developed using principal component analysis.
• The OSHA score is greater with long-term no-till compared to conventional till.
• Crop rotations with winter wheat or alfalfa produce the highest OSHA scores.

Long-term agricultural production with different tillage systems and crop rotations affect soil health, and thereby influence agricultural sustainability. However, quantifying and integrating the numerous soil health attributes is complex. One method of measuring overall soil health is the Cornell Soil Health Assessment (CSHA) used in New York; however, its applicability for other regions should be evaluated. Soil samples were collected from the 0–15 cm depth in 2009 and 2010 at four temperate, rainfed long-term experimental sites in Ontario (Ridgetown, Delhi, Elora, and Ottawa) and we evaluated the impact of tillage systems and crop rotations on 15 soil attributes. Based on a principal component analysis (PCA), the first two components accounted for 62% of the cumulative variability. The PCA eigenvectors were used to weight individual CSHA scores and develop the new Ontario Soil Health Assessment (OSHA) overall score. The OSHA scoring system was 2–10 times more sensitive than the CSHA in showing numerical differences for soil health among different tillage systems and crop rotations, which may help growers to more clearly see differences in soil health under different management practices. No-till (NT) compared to conventional tillage (CT) had significantly greater OSHA scores at Ridgetown, Delhi, and Elora, but there was no difference at Ottawa. At Ridgetown and Elora, crop rotations which included winter wheat or alfalfa tended to have higher OSHA scores, while lowest scores were with monoculture corn (monoC) or soybean–corn (S–C or S–S–C–C). This study provides the first soil health assessment for Ontario and a framework for improving overall soil health testing elsewhere.