ARS | Publication request: MICROBIOLOGICAL ASSESSMENT OF SOIL QUALITY IN CONSERVATION RESERVE PROGRAM AND WHEAT-FALLOW SOIL

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 1996
Publication Date: N/A

Interpretive Summary: Soil quality has been defined as the ability of the soil to produce high quality, safe food while protecting human and animal health and maintaining environmental quality. Soil quality can serve as a key component of sustainable agriculture by providing a conceptual framework and methodologies for evaluating different farming systems. The Conservation Reserve Program (CRP), initiated by the Food Security Act of 1985, returne highly erodible land (HEL) to grass and forest vegetation. The primary objective of this program was to decrease erosion and increase soil quality. Since cultivation drastically depletes native grassland soil organic carbon, it could be hypothesized that grasslands have higher soil quality than cultivated land, as estimated from certain chemical, physical, and biological parameters. Our study showed that eventhough their has not been enough time to see quantative increases in soil C, the microbiological lassessments indicate an increase in soil quality of CRP land.

Technical Abstract: Microbial aspects of soil quality are an important consideration when evaluating the soil benefits of the Conservation Reserve Program (CRP). The objectives of this study were to determine the effects of CRP by comparing various microbial parameters of CRP and wheat-fallow (W-F) soil. Biological and chemical properties and C and N mineralization processes were measured on 20 CRP/W-F paired sites in Eastern Washington, on Ritzville silt loam (coarse-silty, mixed, mesic Calciorthidic Haploxerolls). Some/most potential enzyme activities and soil nitrogen were higher in the CRP soil compared to the W-F soil. Although there were no differences in soil organic carbon (SOC) or microbial biomass carbon (MBC), the ratio of MBC to SOC increased after 4 to 7 years in CRP. The C and N mineralization processes did demonstrate differences in soil quality between the CRP and W-F soils. Whereas there were few significant differences, trends indicated the quality of soil was improving in the CRP land previously in W-F rotation.