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 2010 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 indicated that management scenario, tillage, and the amount of stover removed from the field with the 2009 harvest did not affect uptake of most nutrients. Nitrogen concentrations in ear-leaf tissue, however, were below the critical value for all treatments. Management scenario and tillage and did not affect corn grain yields, but plots from which corn stover was not removed always yielded less than plots from which ~50% (harvested just below the ear shank) or ~90% (harvested at a stubble height of approximately 4 inches) of the stover was removed. We suspect that this is a short-term effect. The wet growing conditions in central Iowa during June and early July may have caused significant nitrate leaching and denitrification, thus limiting N availability and decreasing yields of all treatments. If wet weather patterns continue, mid-season N applications may become necessary. In a separate controlled-climate chamber study, 20-day-old plants grown in soil with only 100 lb. P 2 O 5 /A had the highest shoot and root dry matter values, while those grown in soil amended with biochar in 2007 without P fertilizer had the lowest values. Addition of 100 lb. P 2 O 5 /A numerically increased shoot and root dry matter values regardless of legacy or fresh biochar amendment. Continued generation of plant growth and nutrient uptake data should provide a clearer picture of the value of the biochar, any biochar-fertilizer interactions, and whether legacy or fresh biochar affects the nutrition of juvenile corn in different ways.

Publication Information
Author: 
John L. Kovar
Douglas L. Karlen
Publication Year: 
2011
DOE Information
Bioenergy Category: