Title: Native Grass Canopy Management and Species Mixture Effects on Soil C and N Authors
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 6, 2010
Publication Date: March 1, 2010
Citation: Riedell, W.E., S.L. Osborne, J.L. Pikul Jr., and T.E. Schumacher. 2010. Native Grass Canopy Management and Species Mixture Effects on Soil C and N. p. 169-173. In: A. Schlegel and H.D. Bond (eds.). Proceedings Great Plains Soil Fertility Conference. March 2-3, 2010. Denver CO. Interpretive Summary: Soil organic matter, roughly half of which is composed of carbon, is an important part of the soil that consists of plant and animal residues in various stages of decay. Soil organic matter helps to even improve soil physical properties, increase water holding capacity, and increase water infiltration which in turn prevents water from running off farm fields. Therefore, soil organic matter is an essential component of healthy soil. Managing soil organic matter is an important priority on all farms. One way to increase soil organic matter is to plant grasses in areas where soil erosion is an important problem. There are 2.9 million conservation reserve program (CRP) acres in South Dakota and Minnesota. This region is also slated to provide cellulosic feedstocks for biofuels. Thus, scientific inquiry on CRP/grass management and its effect on soil organic matter (i.e. soil carbon) as well as the transfer of this knowledge to producers in this region are important priorities. This study was conducted to determine whether levels of soil carbon and nitrogen could be manipulated through grass canopy management and different native grass mixtures. Our results show that spring burning as a grassland management treatment was detrimental to soil C concentration. Mow and remove management, which would be compatible with cellulosic biomass production, showed values of soil C concentration comparable with those seen under the no management treatments. Collection of additional time-course data is needed to determine if mow and remove would be sustainable in terms of long-term soil resource quality.
Technical Abstract: There are 2.9 million conservation reserve program (CRP) acres in South Dakota and Minnesota. This region is also slated to provide cellulosic feedstocks for biofuels. Thus, scientific inquiry on the effect of CRP/grass management on soil condition is an important priority. Experiment objectives were to determine whether soil C and N could be manipulated through grass canopy management and different grass mixtures. Effects of forced management (burning in early spring, mowing and residue removal at grass anthesis, or no management) and native grass mixtures (cool season species, warm season species, or combined cool and warm season species) on C and N levels in soil were investigated on a Barnes clay loam. Soil C (0-6 inches) increased linearly over the 9 years of the experiment. Soil C accumulation rate was significantly greater under no management (638 lbs C acre-1 year-1) than burn treatment (345 lbs C acre-1 year-1) while that under mow was intermediate (450 lbs C acre-1 year-1). In conclusion, soils under the burn treatment had the lowest rate of C accumulation. Mow and remove management, which would be compatible with cellulosic biomass production, showed soil C accumulation rates comparable with those seen under the no management treatments. Additional time-course data is being collected to determine if mow and remove would be sustainable in terms of long-term (> 9 years) soil resource quality.