Start Date: 2010
Principal Investigator: Deborah Allan
Organization: University of Minnesota, Department of Soil, Water, and Climate
The development of bioenergy products is essential to reduce U.S. dependence on foreign oil. The use of cellulosic biomass for fuel production is one alternative, with corn stover being a potential feedstock for bioenergy- and bio-based products. In the first year of a two-year study, the question was asked, How much residue can safely be removed while maintaining cropping systems’ sustainability? Production of biofuels can alter nutrient removal by the amount of residue removed and changes in crop species and plant parts harvested. The objective of the second year was to evaluate the availability and removal of secondary nutrients (calcium [Ca], magnesium [Mg] and sulfur [S]) and micronutrients in soil and plants at three Minnesota locations with varying corn residue removal rates in a continuous-corn cropping system. Year one of the study included ongoing experiments that only determine nutrient balances for total nitrogen (N) and extractable phosphorus (P) and potassium (K). In addition, two soil quality indicators that are sensitive to management changes were measured: aggregate stability and particulate organic matter.
Evaluate the plant removal rate of secondary nutrients Ca, Mg, and S and micronutrients B, Zn, Cu, and Mn
Evaluate the availability of secondary nutrients Ca, Mg, and S, and micronutrients B, Zn, Cu, and Mn
Estimate the effect of residue removal on soil quality indicators such as potentially mineralizable nitrogen and carbon (PMN and PMC) and particulate organic matter carbon and nitrogen (POM-C and POM-N)
The amount of secondary and micronutrient plant removal was similar between tillage systems, except at Rosemount, where more Ca, Mg, S and boron (B) was removed under CT than ST systems, because of the higher yields and therefore greater biomass removal under CT systems.
The amount of secondary nutrient and micronutrient removal was significantly greater in the 100% than 50% residue removal rate. Despite the higher rate of nutrient removal under 100% treatments, there were almost no changes observed in soil availability of secondary and micronutrients by two to three years after establishment of the treatments.
During this same time period, soil quality indicators reflected differences between tillage treatments due to stratification under strip-till systems compared with conventional-till systems, but no differences were detected due to residue removal rates, except in Northfield, where POM-C tended to be 10 greater in the 0 to 50% than in the 100% residue removal rate.
Longer time periods are required to detect effects of residue removal on soil properties, including availability of secondary and micronutrients and amounts of active carbon (C) and N in these soils.