Perennial warm‐season grasses for producing biofuel and enhancing soil properties: an alternative to corn residue removal

Humberto Blanco‐Canqui,Kent M Eskridge,Virginia L Jin,Robert B Mitchell,Marty R Schmer

doi:10.1111/gcbb.12436

Humberto Blanco‐Canqui, Kent M Eskridge + Show 3 more

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https://doi.org/10.1111/gcbb.12436

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Abstract

AbstractRemoval of corn (Zea mays L.) residues at high rates for biofuel and other off‐farm uses may negatively impact soil and the environment in the long term. Biomass removal from perennial warm‐season grasses (WSGs) grown in marginally productive lands could be an alternative to corn residue removal as biofuel feedstocks while controlling water and wind erosion, sequestering carbon (C), cycling water and nutrients, and enhancing other soil ecosystem services. We compared wind and water erosion potential, soil compaction, soil hydraulic properties, soil organic C (SOC), and soil fertility between biomass removal from WSGs and corn residue removal from rainfed no‐till continuous corn on a marginally productive site on a silty clay loam in eastern Nebraska after 2 and 3 years of management. The field‐scale treatments were as follows: (i) switchgrass (Panicum virgatum L.), (ii) big bluestem (Andropogon gerardii Vitman), and (iii) low‐diversity grass mixture [big bluestem, indiangrass (Sorghastrum nutans (L.) Nash), and sideoats grama (Bouteloua curtipendula (Michx.) Torr.)], and (iv) 50% corn residue removal with three replications. Across years, corn residue removal increased wind‐erodible fraction from 41% to 86% and reduced wet aggregate stability from 1.70 to 1.15 mm compared with WSGs in the upper 7.5 cm soil depth. Corn residue removal also reduced water retention by 15% between −33 and −300 kPa potentials and plant‐available water by 25% in the upper 7.5 cm soil depth. However, corn residue removal did not affect final water infiltration, SOC concentration, soil fertility, and other properties. Overall, corn residue removal increases erosion potential and reduces water retention shortly after removal, suggesting that biomass removal from perennial WSGs is a desirable alternative to corn residue removal for biofuel production and maintenance of soil ecosystem services.

Highlights

Developing sustainable dedicated bioenergy cropping systems such as growing perennial WSGs is a priority to promote energy independence, enhance rural development, and improve soil ecosystem services such as erosion control, C sequestration, and water and nutrient cycling, among others
Wind erosion potential Results of dry soil aggregate size distribution strongly suggest that removal of corn residue at
The 700% decrease in mean dry aggregate size due to corn residue removal across both years indicates that corn residue removal can have large negative effects

Summary

Introduction

Developing sustainable dedicated bioenergy cropping systems such as growing perennial WSGs is a priority to promote energy independence, enhance rural development, and improve soil ecosystem services such as erosion control, C sequestration, and water and nutrient cycling, among others. Growing dedicated bioenergy crops including switchgrass, big bluestem, and other WSGs can be an alternative to corn residue removal (Varvel et al, 2008). If succesfully established and properly managed with fertilization and organic amendments, WSGs grown in marginally-productive lands can provide cellulosic biomass for bioenergy (Varvel et al, 2008; Follett et al, 2012; Evers et al, 2013; Stewart et al, 2015). Managing dedicated energy crops could be part of redesigned agricultural landscapes where WSGs are grown on marginally-productive lands while annual row crops are grown on prime lands to produce biomass feedstocks sustainably and enhance vegetation diversity and heterogeneity (Hartman et al, 2011; Gopalakrishnan et al, 2011; Mitchell et al, 2016)

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