Effects of perennial aromatic grass species richness and microbial consortium on soil properties of marginal lands and on biomass production

Abstract

AbstractThis study investigates the effects of perennial grass species richness levels and consortium of three bacteria on properties of a slightly alkaline soil and on biomass production of grasses. Four species of perennial aromatic grasses namely: vetiver (Vetiveria zizanioides), lemongrass (Cymbopogon citratus), palmarosa (Cymbopogon martinii), and citronella (Cymbopogon winterianus) were planted in all possible combinations at one, two, three, and four species richness levels in a randomized block design with three replications and two treatments, these were PGPR+ (with plant growth promoting rhizobacteria) and without (PGPR−). Species and richness level specific changes in soil physicochemical properties: electrical conductivity (EC); bulk density (BD); total soil organic carbon (TOC); available nitrogen (Nav), microbial colony forming unit (CFU); microbial biomass carbon (MBC), and enzymatic alkaline phosphatase (ALKP) and dehydrogenase activity (DHA) were observed. The highest reduction in soil pH and EC and increase in soil TOC, CFU, Nav, MBC, and enzymes activities were found at two species richness levels of vetiver and lemongrass in both PGPR+ and PGPR− plots followed by monoculture of vetiver. The highest annual total dry biomass 22.8 and 27.5 Mg ha−1 was produced by monoculture of vetiver in PGPR− and PGPR+ plots, respectively, with similar values at two species richness levels of vetiver and lemongrass in PGPR− and PGPR+ plots. The highest plant carbon was found in vetiver monoculture and two species richness levels of vetiver and lemongrass. The soil carbon sequestration potential was highest at two species mixtures of vetiver–lemongrass and lemongrass–palmarosa as well.