Soil Health and Organic Matter


In addition to the economic value of reduced tillage there are also benefits to the soil. Two measurements are the Soil Conditioning Index (SCI) and the Soil Tillage Intensity Rating (STIR). The SCI is used to estimate the effect the tillage sequence has on organic matter. If the value is negative, soil organic matter levels are predicted to decline under that production system. If the value is positive, soil organic matter levels are predicted to increase under that system. The STIR is used to evaluate the effect of tillage on soil health in each of the different systems. A STIR with a low value has a minimal adverse effect on soil health. Over time a system with a low STIR value will have a minimal adverse effect on soil structure and overall soil health. The low STIR will improve organic matter, fertility, productivity and water-holding capacity and soil structure. The table below lists the different SCI and STIR values for the different tillage systems.

Table 5. SCI and STIR Values for the Different Tillage Systems
Tillage Systems SCI STIR
Strip Till 0.63 52
Conventional Tillage with Moldboard Plow -0.26 161
Conventional Tillage with Chisel Plow -0.11 125