ARS | Publication request: Fluid fertilizer's role in sustaining soils used for bio-energy feedstock production

Submitted to: Fluid Fertilizer Foundation Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: April 16, 2012
Publication Date: May 1, 2012
Citation: Kovar, J.L., Karlen, D.L. 2012. Fluid fertilizer's role in sustaining soils used for bio-energy feedstock production. In: Leikam, D.F., editor. Proceedings of the Fluid Fertilizer Foundation Symposium, February 19-21, 2012, Scottsdale, AZ. 29:1-9. Available: http://www.fluidfertilizer.com/fertilizer_forum_proceedings2012.html.

Interpretive Summary: Growing crops as a bio-energy feedstock has attracted the attention of many producers – especially in the Corn Belt states. Both corn grain and stover are being evaluated as potential feedstocks. Unfortunately, our understanding of the short- and long-term effects of removing both corn grain and stover on soil nutrient cycling, physical properties, and biological activity is limited. In a field study with a variety of management systems, including both standard fertilizer management and a high-population treatment with increased nutrient additions, we found adequate levels of all nutrients in the growing crop, suggesting that fertilizer applications were sufficient for the two management scenarios. Differences in plant populations and tillage intensity, application of biochar, and use of cover crops did not affect corn grain or stover yields in 2011. In a separate laboratory study, 20-day-old plants grown in soil with 100 lb. P2O5/A produced more dry matter than those grown in soil without P fertilizer, but our results suggested that the ability of the plants to utilize the fertilizer P was improved by biochar application. As more data are generated with this experiment, we will have a clearer picture of the value of the biochar and any biochar-P fertilizer interactions that may affect the growth and nutrition of young corn plants. The results of this research will benefit commercial growers, as well as the fertilizer and ethanol industries by providing nutrient management guidelines that maximize crop utilization and biomass yields.

Technical Abstract: The use of corn (Zea mays L.) as a bio-energy feedstock has attracted the attention of many producers. Recently, the focus has shifted from grain-based to cellulose-based ethanol production. In addition to biological conversion of corn stover to ethanol, thermal conversion (pyrolysis) of stover is being explored. Regardless of post-harvest processing, the short- and long-term effects of both increasing grain yields and removing stover on soil nutrient cycling, physical properties, and biological activity must be understood to ensure that soil productivity and ecosystem services are maintained. Our objectives for 2011 were to evaluate: (i) the use of surface or subsurface bands of N-P-K-S fluid fertilizers to optimize positional and temporal availability of nutrients; and (ii) the effect of biochar application on P availability and cycling in Clarion-Nicollet-Webster soils. Corn was grown in a field trial under a variety of management systems including 30-inch row spacing with standard fertility management and a twin-row, high-population treatment with increased nutrient additions applied in split-applications. Analysis of whole plants at V6 and ear leaves at mid-silk showed adequate levels of all macronutrients, which suggests that nutrient management was balanced for the two planting scenarios and the amount of stover removed from the field with the 2010 harvest. Management scenario, tillage, and previous stover removal did not affect corn grain yields, which varied from 172 to 182 bu/ac in 2011. In addition, biochar application and cover crop growth had no effect on grain and stover yields. As expected, the amount of dry stover collected was higher for the 90% removal (low cut) treatments of all management scenarios. In 2011, the intensively managed (twin row) plots did not produce more grain or dry stover than the conventional plots. 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. P2O5/A 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/A 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 the fertilizer value of the biochar, any biochar-fertilizer interactions, and whether legacy or fresh biochar affect the nutrition of juvenile corn in different ways.