2009 Annual Report
1a.Objectives (from AD-416)
Enhance carbon sequestration for improved soil quality and erosion control; Quantify the form and release of major nutrients as affected by soil redox potential; and Determine the impacts of conservation tillage on fate of pesticide in soil.
1b.Approach (from AD-416)
Quantify dissolved organic carbon in runoff samples from subwatersheds in the St. Joseph River; Identify enzymes as soil quality indicators; Monitor effects of changing soil redox potential on nutrient form and release; and Quantify the fate of atrazine, metolachlor and glyphosate under varying temperature and crop residue; Quantify the competition between glyphosate and phosphorus and glyphosate and potassium for possible nutrient decline due to glyphosate usage.
Monitoring of dissolved carbon losses from runoff and subsurface tile drainage at fifteen sites within the Cedar Creek watershed was continued in FY09. This work is in tandem with the NSERL’s CEAP water quality project. Data from the first five years are being analyzed for publication.
Five additional ARS Experimental Watersheds were sampled for soil sequestration and soil quality (Upper Big Walnut Creek (OH), Mark Twain Reservoir (MO), Topashaw Canal (MS), Goodwin Creek (MS) and Jobos Bay (PR)). Original plans were for 12 watersheds, but to date fourteen have been sampled with two more planned in FY10. Analysis has been going slower than anticipated, however analysis has been completed for the first five watersheds (South Fork (IA), Walnut Creek (IA), Leon River (TX), Little River (GA) and Ft. Cobb (OK)). The first set of manuscripts are being prepared.
The Soil Management Assessment Framework (SMAF) has been updated to include three new indicators: ß-glucosidase activity, Extractable K, and Water-filled pore space. The paper on the development of the ß-glucosidase indicator is in press. ß-glucosidase is involved in the decomposition of plant residues and roots.
Monitoring of trace gas emissions and carbon sequestration continues at two experimental sites: ACRE, west of West Lafayette, a Mollisol soil and TPAC, south of Lafayette, an Alfisol soil. Both sites include corn-soybean rotations (five treatments) and ACRE includes grass management plots. A paper from the first four years of data from the ACRE site should be submitted by the end of FY09.
Monitoring of changes to soil quality characteristics, carbon sequestration and productivity are continuing in the field experiment designed to determine impacts of corn residue removal on the soil.
A series of incubation experiments are underway to study to explore the impact of glyphosate application rates on the form and release of soil P and K as well as impact on microbial activity.
Soil quality assessment of the South Fork of the Iowa River Watershed. Soil quality assessment is a critical component in understanding the long-term effects of soil and crop management practices within agricultural watersheds. In the South Fork of the Iowa River Watershed, an aerial survey was conducted during the summer of 2006, and fields that were planted to corn and appeared to have sections with underdeveloped canopy within the corn crop were marked. Fifty-one marked fields were assessed in autumn of 2006. Soil bulk density, aggregate stability, texture, pH, extractable P, K, Ca and Mg, KCl extractable NO3 and NH4, DTPA extractable Cu, Fe, Mn and Zn, electrical conductivity (EC), total soil organic carbon (SOC), total N (TN), microbial biomass C (MCB), potentially mineralizable C (Cmin)and N (Nmin), and ß-glucosidase (BG) activity were measured. The Soil Management Assessment Framework (SMAF) was used as the assessment tool. There was no single cause for underdeveloped canopy across all fields. Overall, the SOC, MCB, Cmin, Nmin, and BG activity were lower in the areas with poor canopy development. SMAF indicator scores for carbon, which compensate for differing soil types, were significantly lower for the poor canopy areas. Although there was little difference in the mean SMAF Soil Quality Index (SQI) values, which included eleven indicator scores, of the normal canopy areas vs. the poor development areas, the individual indicator scores could pinpoint specific problems in individual fields. Some of the specific problems included lower soil organic matter and other indications of poor nutrient cycling, low extractable P, high bulk density, and low water-filled pore space at time of sampling, all of which would impact crop development. Using SMAF to determine specific soil problems will help land managers develop management schemes ameliorate the poor performing areas of the fields.
Crow, S.E., Filley, T.R., McCormick, M., Szlavecz, K., Stott, D.E., Gamblin, D., Conyers, G. 2009. Invasive Earthworms and Forest Successional Stage Interact to Impact Plant Litter Inputs and Particulate Organic Matter Chemistry. Biogeochemistry. 92:61-82.