Biomass Production and Carbon/Nitrogen Ratio Influence Ecosystem Services from Cover Crop Mixtures

Abstract

Increasing plant diversity in agroecosystems with cover crops has been a successful strategy to augment ecosystem services from agriculture, and increasing diversity of cover crops may provide even greater benefi ts. Productivity and ecosystem services from multi-species cover crop mixtures were measured in a 2-yr fi eld study of 18 cover crop treatments preceding conventionally tilled corn in central Pennsylvania. Increasing the number of species in a stand increased cover crop biomass (R 2 = 0.15). However, mixing cover crop species that were complementary in phenology or N acquisition strategy did not result in mixtures that produced more biomass than high yielding monocultures. Increasing cover crop biomass was positively correlated with several ecosystem services, namely weed suppression, prevention of nitrate leaching, and aboveground biomass N, but negatively impacted inorganic N availability and corn yield in the subsequent cropping season. Th e cover crop C/N ratio was another determinant of ecosystem services positively related to nitrate leaching prevention, but negatively related to inorganic N availability and corn yield. Th is study supports the long-held assumption that increasing biomass can enhance certain ecosystem services from cover crops; however, because the mixtures tested did not produce more biomass than high yielding monocultures, opportunities to increase biomassdriven services with mixtures may be limited. Th e correlation between biomass C/N ratio and ecosystem services in this study also indicates that functional traits, as opposed to biomass alone, will be important for predicting ecosystem services from cover crop mixtures.

Management of service crops for the provision of ecosystem services in vineyards: A review

“…In Mediterranean climate, similar results were found in experiments that compared soil tillage and service crop treatments, with evidences of changes in weed community structure and dynamics (Monteiro and Lopes, 2007), and lower infestation by weeds under sown service crops (Gago et al, 2007). In other cropping systems, weed suppression was positively correlated to service crop biomass (service crop dominance on weeds) and C/N ratio (N retention, decomposition rate) (Finney et al, 2016;Vrignon-Brenas et al, 2016).…”

“…Competition for nitrogen may occur, as available N can be depleted by service crops during grapevine dormancy, and stuck in an organic form (alive or dead plants) before being released by mineralization (ThorupKristensen et al, 2003). It is known that the amount of nitrogen made available for the next or associated crop will depend on the C/N ratio of the service crop (Finney et al, 2016) and the biomass produced (Vrignon-Brenas et al, 2016). Indeed, service crop mixtures including leguminous and non-leguminous species can combine NO3-leaching reduction and green manure services, thus improving N use in cropping systems (Tribouillois et al, 2016).…”

Living cover crops have immediate impacts on soil microbial community structure and function

“…The winter-killed cover crops, namely soybean, sunn hemp, and forage radish, were associated with higher proportions of actinomycetes and Gram-positive bacteria (figure 2b). Again differences in biomass production by winter-killed versus winter-hardy cover crop species (Finney et al 2016) may have led to this result in spring. In other words, cover crops that provided C inputs to the microbial community in both fall and spring led to higher proportions of AM fungi, protozoa, Gram-negative bacteria, and non-AM fungi in the soil microbial community by spring.…”

“…We also measured cover crop and arable weed biomass in fall prior to the first killing frost and spring immediately prior to termination by clipping within quadrats. Aboveground biomass data have previously been reported in Finney et al (2016).Soil Sampling. Bulk soil samples were collected in fall at the time of peak cover crop growth and spring approximately one week prior to cover crop termination.…”

Supporting Agricultural Ecosystem Services through the Integration of Perennial Polycultures into Crop Rotations

“…Typically, crop mixtures produce more biomass as species richness increases [80], but the biomass is lower than high-yielding monocultures [81]. In general, for forage and biofuel production, both the yield quantity and quality are important; as such, they are both considered for the analysis.…”