Alternative production systems' effects on the K-factor of the Revised Universal Soil Loss Equation

Abstract

The soil erodibility factor (K) of the Revised Universal Soil Loss Equation is currently considered a constant for all soils in the same type, regardless of production practice. To examine the effect of alternative production systems on the K-factor we compared pairs of alternatively and conventionally farmed fields on a Judson silt loam (Fine-silty, mixed, mesic Cumulic Hapludolls), a Yutan silty clay loam (Fine-silty, mixed, mesic Mollic Hapludalf), and a Wann fine sandy loam (Coarse-loamy, mixed, mesic Fluvaquentic Haplustolls). Soil cores were taken from the surface 10 cm and analyzed for organic matter, permeability, structure, and texture. These data were used to estimate K-factors from a nomograph. All soils in the study had a fine granular structure. Organic matter content and permeability were significantly higher for the alternatively managed field at every location, except for no difference in permeability on the Judson soil. However, the K-factor was significantly lower for the alternative system on the Judson soil. Of all the parameters, texture has the greatest influence in determining K-factors within the nomograph, with soils higher in silt being more erodible than soils higher in sand or clay. Thus, the influences of alternative production systems affected the Judson soil to a greater degree than other textures because of its higher inherent susceptibility to erosion. This study shows that alternative production systems affect the K-factor of some soil types and can reduce soil erodibility, and therefore should be considered when developing conservation plans.

Conservation tillage and organic farming reduce soil erosion

“…Most of those studies are based on models such as the Universal Soil Loss Equation (USLE, empirical) or the Water Erosion Prediction Project (WEPP, process-based) (Lockeretz et al 1981;Reganold 1988;Auerswald et al 2003;Pacini et al 2003;Arnhold et al 2014). Some studies indirectly assessed soil erosion by evaluating topsoil thickness (Reganold et al 1987), soil erodibility (Fleming et al 1997;Siegrist et al 1998;Kuhn et al 2012), aggregate stability (Mulla et al 1992;Pulleman et al 2003), or nutrients in runoff of farm drainage systems (Eltun et al 2002) and one study directly assessed soil erosion in organically versus conventionally managed plots (Weilgart Patten 1982) using the Alutin rill method. Even if it can be stated that erosion models have originally been calibrated with field data, there is a general lack of experimental in situ measurements to compare organic farming systems (Gomiero 2013).…”

The performance of organic and conventional cropping systems in an extreme climate year

“…The mitigation of runoff, erosion and crop losses as a result of rainfall excess, a serious agricultural constraint (Jaenicke, 1998;USDA, 1994), is also improved in organically managed systems. Organic management of soils leads to improved soil stability and resistance to water erosion compared to conventionally managed soils, due to higher soil C content and improved soil aggregation (Clark et al, 1998;Drinkwater et al, 1995;Liebig and Doran, 1999;Reganold, 1995;Reganold et al, 1993), permeability (Fleming et al, 1997;Gerhardt, 1997;Petersen et al, 1999;Reganold et al, 2001) and lower bulk density (Gerhardt, 1997;Liebig and Doran, 1999;Reganold et al, 1993), as well as higher resistance to wind erosion (Jaenicke, 1998). Comparisons of erosion rates in organic versus conventional systems, show significantly lower erosion in organically managed systems.…”

“…Lockeretz et al (1981) reported one-third less erosion from Midwest organic farms than from comparable conventionally managed farms. Fleming et al (1997) showed that the K-factor (soil erodibility) of the revised universal soil loss equation was reduced in organically managed systems.…”