Abstract
AbstractPositive relationships between plant species diversity, soil microbial function and nutrient cycling have been well documented in natural systems, and these relationships have the potential to improve the production and sustainability of agroecosystems. Our objectives were to study the long-term effects of planted species composition and nitrogen (N) fertilization on soil microbial biomass C, extracellular enzyme activity, changes in total soil C, soil fertility and aboveground biomass yield in mixtures of native prairie species managed with and without N fertilizer for bioenergy production at four sites in Minnesota (MN), USA. Species were sown into mixture treatments and composition was not maintained (i.e., no weeding) throughout the duration of the study. Species mixture treatments at establishment included a switchgrass (Panicum virgatum L.) monoculture (SG), a four-species grass mixture (GM), an eight-species legume/grass mixture (LG) and a 24-species high diversity forb/legume/grass mixture (HD). Species diversity and aboveground productivity were similar for most mixture treatments at final sampling after 11 or 12 years of succession. Despite this homogenization of productivity and diversity throughout the study, the effects of planted species diversity and a decade of succession resulted in some differences in soil variables across species mixture treatments. On a peat soil in Roseau, MN, soil enzyme activities including β-glucosidase (BG), cellobiohydrolase (CBH) and phosphatase (PHOS) were highest in HD compared to GM treatments. On a sandy soil at Becker, MN, total soil C increased in all treatment combinations at the 0–15 and 15–30 cm depth intervals, with SG showing greater increases than HD at the 15–30 cm depth. Final soil pH also varied by species mixture at the Becker and Roseau sites, but differences in treatment comparisons varied by location. Nitrogen fertilization did not affect any response variable alone, but interacted with species mixture treatment to influence PHOS and total soil C at Becker. The inconsistent effects of species mixture and N fertilization on soil biological and chemical properties observed across sites highlight the importance of local soil and climate conditions on bioenergy and ecosystem service provisioning of perennial bioenergy cropping systems.
Highlights
Perennial cropping systems are increasingly studied for their capacity to balance provisioning services—such as biofuel, forage and food products—with regulating and supporting services —such as carbon sequestration and enhanced nutrient cycling (Werling et al, 2014; Crews and Rumsey, 2017)
Our objective was to determine the effects of plant species diversity and composition and N fertilization on soil microbial biomass C (MBC), enzyme activities (EEA), soil C change, and aboveground biomass productivity 11–12 years after the establishment of native prairie plant mixtures managed for bioenergy feedstock production
Species mixture treatments were applied as sub plots and included switchgrass monoculture (SG), four-species grass mixture (GM), an eight-species legume/grass mixture (LG) and a 24-species legume/grass/forb mixture (HD)
Summary
Perennial cropping systems are increasingly studied for their capacity to balance provisioning services—such as biofuel, forage and food products—with regulating and supporting services —such as carbon sequestration and enhanced nutrient cycling (Werling et al, 2014; Crews and Rumsey, 2017). Perennial crops provide year-round soil cover and can have greater net primary productivity than annuals (Jarchow and Liebman, 2013) as they capture more photosynthetic radiation over the course of a year (Crews and DeHaan, 2015). This greater net primary productivity of perennial systems is used to support belowground structures, which can result in enhanced carbon sequestration (Lal, 2004; Crews and Rumsey, 2017), microbial community diversity (Culman et al, 2010) and nutrient cycling (Crews, 2005). Even in small, targeted areas, native perennial cropping systems can provide multiple economic and ecosystem benefits when strategically integrated into croplands dominated by summer annual crops (Schulte et al, 2017)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
