Agroforestry Practices, Runoff, and Nutrient Loss

Abstract

A paired watershed study consisting of agroforestry (trees plus grass buffer strips), contour strips (grass buffer strips), and control treatments with a corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation was used to examine treatment effects on runoff, sediment, and nutrient losses. During the (1991-1997) calibration and subsequent three-year treatment periods, runoff was measured in 0.91- and 1.37-m H-flumes with bubbler flow meters. Composite samples were analyzed for sediment, total phosphorus (TP), total nitrogen (TN), nitrate, and ammonium. Calibration equations developed to predict runoff, sediment, and nutrients losses explained 66 to 97% of the variability between treatment watersheds. The contour strip and agroforestry treatments reduced runoff by 10 and 1% during the treatment period. In both treatments, most runoff reductions occurred in the second and third years after treatment establishment. The contour strip treatment reduced erosion by 19% in 1999, while erosion in the agroforestry treatment exceeded the predicted loss. Treatments reduced TP loss by 8 and 17% on contour strip and agroforestry watersheds. Treatments did not result in reductions in TN during the first two years of the treatment period. The contour strip and agroforestry treatments reduced TN loss by 21 and 20%, respectively, during a large precipitation event in the third year. During the third year of treatments, nitrate N loss was reduced 24 and 37% by contour strip and agroforestry treatments. Contour strip and agroforestry management practices effectively reduced nonpoint-source pollution in runoff from a corn-soybean rotation in the clay pan soils of northeastern Missouri.

Improved APEX Model Simulation of Buffer Water Quality Benefits at Field Scale

“…1), i.e., West (3.16 ha), Center (4.44 ha), and East (1.54 ha), located in Knox County, Missouri, at the University of Missouri Greenley Memorial Research Center (40° 1′ N, 92° 11′ W) (Udawatta et al, 2002. Slopes within the watersheds ranged from 0% to 6%.…”

“…The numbers of sediment and TP data available for each watershed varied and are provided in table 2. Other details not included in this summary of the research methods for the 16-year data collection period can be found in Udawatta et al (2002Udawatta et al ( , 2004Udawatta et al ( , 2011.…”

Agroforestry—The Next Step in Sustainable and Resilient Agriculture

“…Soil quality is improved by increased levels of organic matter, more diverse microbial populations, and improved nutrient cycling, which may increase crop productivity and the ability to cope with drought [65,86,87]. The water quality benefits occur as non-point source pollution from row crops is reduced by incorporating agroforestry vegetative buffer strips [88][89][90]. On a "paired" watershed study in Missouri, agroforestry and grass buffer strips reduced phosphorus and nitrogen loss from a corn-soybean rotation [88].…”

Evaluation of the ecological status of an impaired watershed by using a multi-index approach

“…The highest levels of organic matter were observed at the upstream stations, where riparian quality was also highest (higher percentage of forest, and higher QBR values) and leaf litter represents an important local source of organic matter (Udawatta et al 2002;Webster et al 1999). Levels of organic matter were lower at station 2 possibly related to the lower levels of forest land use compared to the upper stations.…”