Location: Agroecosystems Management Research2013 Annual Report
1a. Objectives (from AD-416):
Research objectives of this project are to: 1) evaluate the use of surface or subsurface bands of N-P-K-S fluid fertilizers to optimize nutrient-use efficiency of P, K, and S, and to enhance corn grain and biomass productivity; and 2) determine the effect of biochar application on P availability and cycling in Clarion-Nicollet-Webster soils.
1b. Approach (from AD-416):
The overall goal of this project is to evaluate the use of N-P-K-S fluid fertilizers to enhance corn grain and stover productivity. This project will be part of a long-term corn grain and stover removal study that focuses on standard and intensive fertility management, tillage, biochar additions to test the “charcoal vision” for sustaining soil quality while producing bio-energy products, and use of annual or perennial cover crops to build soil carbon and help off-set potential negative impacts of stover removal. This project will include three separate studies, and will involve both laboratory and field research. Objective 1 will be addressed via field studies, and Objective 2 will be addressed with both field and controlled-climate chamber studies. The field studies will be conducted at the Iowa State University Agricultural Engineering and Agronomy Research Center (AEARC) where a long-term bio-energy feedstock production experiment was initiated during the fall of 2007.
3. Progress Report:
To evaluate the use of surface or subsurface bands of nitrogen-phosphorus-potassium-sulfur (N-P-K-S) fluid fertilizers to optimize positional and temporal availability of K and S, and to enhance corn grain and biomass (stover) productivity, we conducted field trials on a Clarion-Nicollet-Webster soil association in central Iowa. Using a variety of management systems, including both standard fertilizer management and a high-population treatment with increased nutrient additions, we found that N and K fertilizer applications were less than needed to carry the corn crop through the growing season. The hot, dry growing conditions may have limited N and K availability and uptake. Management scenario, tillage, and previous stover removal affected corn grain yield, although yields were likely influenced by the availability of water. Grain yields tended to be lower when corn stover was not removed than when ~50% or ~90% was removed. These results suggest that good nutrient management for systems producing both grain and residue feedstock is essential, and that it will differ from grain-only systems. Crop rotation had the most striking effect on corn grain yields. Corn grown in rotation with soybean (Glycine max L. Merr.) yielded 174 bushels per acre, compared with a mean grain yield of 143 bushels per for continuous corn. As during the three previous growing seasons, the intensively managed (twin row) treatments did not produce more grain or dry stover than the conventional treatments. In a separate controlled-climate chamber study, biochar and P fertilizer amendments affected soil P supply and corn seedling growth during five consecutive production and harvest cycles. Plants grown in soil with only 100 lb. Phophorus Pentoxide (P2O5) per acre had the highest shoot and root dry matter values, while those grown in soil amended with biochar in 2007 (legacy) without P fertilizer had the lowest values. Addition of 100 lb. P2O5 per acre numerically increased shoot and root dry matter values regardless of legacy or fresh biochar amendment. Although cumulative shoot dry matter production tended to be higher for treatments without biochar, the overall agronomic efficiency of the P fertilizer was improved by biochar application. Further statistical analysis of plant growth and nutrient uptake data should provide a clearer picture of any biochar-fertilizer interactions. The effect of biochar application on soil supply of nutrients is complex. Current research suggests that marginal soils will benefit most.