2012 Annual Report
1a.Objectives (from AD-416):
Determine the amount of corn stover residue needed to maintain soil C content (soil quality) and crop productivity.
1b.Approach (from AD-416):
The investigation was initiated in 2001 at the University of Nebraska Agricultural Research and Development Center, near Mead, NE, as a randomized complete block experiment (six blocks) with a split plot treatment arrangement. Tillage treatments (fall disk or no tillage) are assigned to whole plots. Residue removal levels (0, 50, or 100%) are assigned to subplots. Subplots are 15.2 m by 9.1 m (12 rows). Residue removal treatments are applied after grain harvest by collecting stover with a flail-type forage chopper. No stover is removed from the 0% treatment, all stover is removed from alternate pairs of rows in the 50% treatment (switching the rows from which stover is removed in alternate years), and stover is removed from all rows in the 100% treatment. Plots assigned to the disk tillage treatment are tilled after stover removal treatments are applied. In Spring, disk treatments is tilled again and the entire experiment is planted to corn in late April. The crop is managed with practices (fertilizer, pesticides, irrigation, etc.) customary for the region. Corn in the disk treatment is cultivated at about V6.
At the beginning of the experiment, soil samples were collected. Analyses were conducted for soil chemical, physical, and biological parameters as outlined in the Statement of Work. Annually corn grain and biomass yield and nitrogen content are determined. In addition, mass of stover retain on the land and surface cover is measured. Soil chemical, physical, and biological parameters will be determined at intervals during the course of the experiment and at the termination of the study as outlined in the Statement of Work.
The effects of residue removal on the soil resource continue to be evaluated in two studies, one irrigated and one rainfed. Grain and biomass yields in 2011 were excellent in the irrigated study. Residue removal had no effect although yields tended to increase as residue was removed in the notill system. Grain yield in the rainfed study increased slightly with residue removal, but grain and stover yields were much lower than those from the irrigated study. Greenhouse gas samples are being collected from select treatments in both studies. Residue removal treatments were again applied in these studies. Soil samples were collected from the rainfed study in the fall after harvest in 2011 to do an assessment of residue removal treatments effects on soil carbon levels and those samples are currently being analyzed in the lab. Several papers are also being prepared for the national Sungrant meeting in October of 2012. Results continue to be summarized and input into the Oak Ridge National Laboratory database as required by the plan of work. Appropriate crop and soil data collected to date is being prepared for input into the GRACEnet/REAP database template that has been developed by the database team.