Improved Efficiency of Water Use
Research shows that organic systems use water more efficiently due to better soil structure and higher levels of humus and other organic matter compounds (Lotter et al., 2003; Pimentel, 2005). Lotter and colleagues collected data over 10 years during the Rodale Farm Systems Trial (FST). Their research showed that the organic manure system and organic legume system (LEG) treatments improve the soils’ water-holding capacity, infiltration rate, and water capture efficiency.
The LEG maize soils averaged 13% higher water content than conventional system (CNV) soils at the same crop stage, and 7% higher than CNV soils in soybean plots (Lotter et al., 2003). The more porous structure of organically treated soil allows rainwater to quickly penetrate the soil, resulting in less water loss from run-off and higher levels of water capture.
This was particularly evident during the two days of torrential downpours from Hurricane Floyd in September 1999, when the organic systems captured around double the water than the conventional systems captured (Lotter et al., 2003).
Long-term scientific trials conducted by the Research Institute of Organic Agriculture (FiBL) in Switzerland, a European mountain country, comparing organic, biodynamic, and conventional systems (DOK Trials) had similar results showing that organic systems were more resistant to erosion and better at capturing water. (Mader et al 2009)
This is consistent with many other comparison studies that show that organic systems have less soil loss due to better soil structure and higher levels of organic matter. (Reganold et al. 1987, Reganold et al. 2001, Pimentel 2005) “We compare the long-term effects (since 1948) of organic and conventional farming on selected properties of the same soil. The organically farmed soil had significantly higher organic matter content, thicker topsoil depth, higher polysaccharide content, lower modulus of rupture, and less soil erosion than the conventionally farmed soil.
The higher levels of organic matter allow the soil in the organic field to resist erosion in heavy rain events and capture more water. (Source: FiBL DOK Trials)