2013 Annual Report
All crops are present each growing season to account for differences in environmental conditions. Annual soil samples are collected and analyzed for soil physical properties (bulk density, aggregate stability) and soil chemical properties (soil organic matter, total nitrogen, inorganic nitrogen, phosphorus (Olson) and potassium (Mehlich III, levels). During the course of the experiment, data collection includes environmental characteristics (rainfall, air temperature, etc. using standard techniques), crop emergence and growth (stand counts, phenological development stage, plant biomass production and nutrient concentration), and yield quality (combine harvest with determination of yield, yield components, seed moisture, nutrient concentrations, oil content).
1)low (corn harvested for grain; all residues remain on soil surface),.
2)medium (corn harvested for grain; residue raked, baled and removed), and.
3)high (above ground corn biomass and grain removed). Impacts on soil health were determined following six complete rotational cycles, measured through particulate organic matter, soil organic matter, and dry aggregate size distribution. When residue was removed from the soil surface, there was a consistent decrease in the amount of soil organic matter and particulate organic matter, indicating a possible decrease in soil health. The presence of cover crops increased the soil organic matter and particulate organic matter in the low and high residue removal treatments compared to the same residue removal without the presence of a cover crop. Potential further degradation of the soil structure was indicated by a shift in dry aggregate size distribution among the different residue removal treatments: the high residue removal treatment had nearly double the erodible fraction compared to the low removal treatment. Within this study, removal of corn residue had a negative impact on the soil physical and chemical properties measured, illustrating the importance of crop residue in maintaining our soil resource and the importance of guidelines being based upon regionally specific research studies associated with different growing conditions to ensure our soil resource.