Influence of Annual Plant Diversity on Forage Productivity and Nutrition, Soil Chemistry, and Soil Microbial Communities

Abstract

Forage cover crops are gaining in popularity on the Canadian prairies, where multi-species crop mixtures are grown for soil and ecosystem enhancing benefits, but also harvested for forage. As the use of these forage mixtures increases, more knowledge is needed to understand the impact these mixtures have on forage production systems. The objective of this study was to determine the effects of increasing plant species diversity on forage productivity, soil chemistry, and soil microbial communities. Field trials were conducted in 2016 and 2017 at two separate locations in the Canadian Prairie region that included four treatments: (1) oat monoculture, (2) three spp. mixture (one grass, one legume, one brassica), (3) six spp. mixture (two grasses, two legumes, two brassicas), and (4) nine spp. mixture (three grasses, three legumes, three brassicas). Soil and plant samples were collected at the mid and late growing season to assess soil chemistry, plant biomass and composition, forage nutrition and quality, and soil bacterial and fungal communities. Overall, the oat monoculture had the highest biomass productivity, while the nine spp. mixture produced the lowest biomass among the treatments. All three mixtures had a better nutritional profile [i.e., greater concentrations of Ca, Cu, Fe, total Kjeldahl nitrogen (TKN), total phosphorus (TP) and total potassium (TK), and lower concentrations of acid detergent fiber (ADF) and neutral detergent fiber (NDF)] compared to the monoculture. Differences in forage nutrition were particularly heightened at the end of the growing season. Soil chemical properties did not differ greatly among the treatments with the exception of higher levels of soil nitrate availability in the mixtures compared to the monoculture. Early indicators of a shift in soil microbial diversity and fungal community composition, and an increased abundance of fungal pathotrophs in the mixtures compared to the oat monoculture, was observed at one of the field sites. This study indicates that increasing plant species diversity does not always lead to an increase in biomass production or significant changes or improvements in soil microbial communities. However, the inclusion of multiple plant species can improve the quality and nutritive value of forages over a monoculture forage crop.

Influence of beef genotypes on animal performance, carcass traits, meat quality, and sensory characteristics in grazing or feedlot-finished steers

“…Multi-species forage mixtures are becoming increasingly popular in forage production. Aside from meeting nutrient requirements of finishing cattle, high-energy mixed-species forage accumulates evenly, is highly palatable, and sustains vegetative biomass later in the growing season in comparison to perennial pastures ( Bonin and Tracy, 2012 ; Villalobos and Brummer, 2017 ; Bainard et al, 2020 ). Thus, these forages are able to support finishing growth, marbling and fat deposition, as well as carcass quality grade.…”

Pulse Frequency in Crop Rotations Alters Soil Microbial Community Networks and the Relative Abundance of Fungal Plant Pathogens

“…FUNGuild was used to parse the fungal community datasets by functional ecological guild ( Nguyen et al, 2016 ). See Bainard et al (2020) for a full description of the bioinformatics.…”

Choice of cover crop influences soil fungal and bacterial communities in Prince Edward Island, Canada

“…Peters et al (2003) have found that long-term crop rotations can increase the disease-suppressive ability of the soil and suggested changes in soil microbial communities as potential mechanisms. It has also been reported that the choice of cover crops influences the abundance of specific microbial communities (Martínez-García et al 2018;Bainard et al 2020). The recent development of high-throughput sequencing technologies allows for more detailed characterization of the soil microbial communities associated with specific crops (Bartram et al 2014;Bainard et al 2017Bainard et al , 2020Hannula et al 2020).…”

“…It has also been reported that the choice of cover crops influences the abundance of specific microbial communities (Martínez-García et al 2018;Bainard et al 2020). The recent development of high-throughput sequencing technologies allows for more detailed characterization of the soil microbial communities associated with specific crops (Bartram et al 2014;Bainard et al 2017Bainard et al , 2020Hannula et al 2020). Metagenomics, including amplicon and shotgun sequencing, of deoxyribonucleic acid (DNA) extracted from environmental samples has been used in microbiome research to study microbial communities and their interactions (Caporaso et al 2012;Schloss 2020).…”