Abstract
In the U.S. biofuel industry is using corn (Zea mays L.) residue mix (CRM) consisting of corncob and stover for cellulosic ethanol and biogas production. The field storage method left different depths of CRM on the field after its removal, where negative effects on plant growth were observed. The objective of this study is to evaluate the CRM effect on selected soil health indicators. The field study conducted with four different depths of CRM, two tillage systems (no-till (NT) and chisel plow (CP), and three nitrogen (N) rates (0, 180, and 270 kg⋅N⋅ha−1) in a randomized complete block design with split-split arrangements in three replications in a continuous corn system from 2010 to 2012 at the Agronomy Research Farm at Iowa State University. The findings of this study showed a negative effect on soil organic carbon (SOC) change across all treatments at 0 - 15 cm (−0.35 to −0.03 Mg⋅ha−1⋅yr−1), while at 15 - 30 cm there was an increase in SOC rate (0.13 to 0.40 Mg⋅ha−1⋅yr−1) after 2-yr. In addition, soil aggregate-associated C of macro-aggregates decreased by 8%, while micro-aggregates increased by 2%. Soil microbial biomass carbon (MBC) across tillage and N rates for 2.5 & 7.5 CRM treatments increased by 14% in June to July 2011, while in 2012 increased by 9%. However, at the 15 cm soil depth, soil bulk density (ρb), soil penetration resistance (SPR), and soil pH showed no significant differences among CRM treatments. The findings of this study showed that in-field CRM management can affect certain soil health parameters in the short term.
Highlights
In the past two decades the transformation of energy from fossil fuel base to bioenergy sources encouraged the establishment of a new industry; which is dependent on corn (Zea mays L.) grain as the main feedstock material for biofuel production in the Midwest, U.S [1]
Changes in soil organic carbon (SOC) were mostly negative across corncob residue mix (CRM) treatments, tillage systems, and soil depths (Figure 2(a) and Figure 2(b)), with the exception at 15 - 30 cm soil depth under CP
The 2.5 cm and 7.5 cm CRM treatments greatly influenced microbial biomass carbon (MBC) in this experiment over tillage systems and N rates, which was documented by another study [22] [23]
Summary
In the past two decades the transformation of energy from fossil fuel base to bioenergy sources encouraged the establishment of a new industry; which is dependent on corn (Zea mays L.) grain as the main feedstock material for biofuel production in the Midwest, U.S [1]. Methods of collection and storage of feedstock for cellulosic ethanol production in the Midwest, U.S, can present significant challenges to soil health and plant growth. In Iowa, where soils are inherently fine-textured with poorly drained conditions, storing and handling CRM can have significant effects on soil moisture, nitrogen (N) availability, and tillage timing. These conditions present challenges for soil and crop residue management, which are essential to provide optimal seed conditions for germination, seedling development, and plant growth [4] [5]
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