Long-term perennial management and cropping effects on soil microbial biomass for claypan watersheds

Authors: ALAGELE, SALAH - University Of Missouri; ANDERSON, STEVEN - University Of Missouri; UDAWATTA, RANJITH - University Of Missouri; Veum, Kristen; RANKOTH, LALITH - University Of Missouri

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2019
Publication Date: 4/4/2020
Publication URL: https://handle.nal.usda.gov/10113/7019801
Citation: Alagele, S.M., Anderson, S.H., Udawatta, R.P., Veum, K.S., Rankoth, L.M. 2020. Long-term perennial management and cropping effects on soil microbial biomass for claypan watersheds. Agronomy Journal. 112(2):815-827. https://doi.org/10.1002/agj2.20116.
DOI: https://doi.org/10.1002/agj2.20116

Interpretive Summary: Restoration of degraded lands by adoption of perennial management systems can rehabilitate soils and lead to improved environmental quality. Soil organic matter and the soil microbial community are known to play key roles in important soil functions such as nutrient cycling and crop growth. The objective of this study was to evaluate the soil microbial community under different types of perennial systems including grass buffers, biofuel crops, grass waterways, and tree-grass buffers compared with a typical corn-soybean rotation. This study found that the biomass of all microbial groups and soil organic matter content were enhanced under perennial systems relative to the row cropped system. This study also highlighted how microbial measurements varied across the landscape. Overall, this study provides producers and land managers with information on the potential benefits of a wide range of perennial systems for improved agricultural management.

Technical Abstract: Sustainable vegetation management plays a significant role in improving soil biodiversity in degraded agricultural landscapes by enhancing soil microbial biomass. Planting perennial vegetation such as trees, shrubs, and grasses is recommended to enhance the soil microbial community. This study investigated the effects of grass buffers (GB), biofuel crops (BC), grass waterways (GWW), and agroforestry buffers (AB), on total microbial biomass, microbial community structure, and soil organic carbon (SOC) compared with row crop (RC) on claypan soils. The influence of landscape position and soil sampling distance from the base of the tree in the AB treatment were also evaluated. The RC, AB, GB, and BC treatment watersheds were established in 1991, 1997, 1997, and 2012, respectively, and are located at the Greenley Memorial Research Center in Missouri, U.S.A. Soil samples were collected from the 0 - 10 cm depth along three transects within each watershed at the summit, backslope, and footslope landscape positions. Within the AB treatment, soils were collected from the 50 cm (AB50) and 150 cm (AB150) distance from the tree base. Total microbial biomass and microbial biomass of gram (+) bacteria, gram (-) bacteria, actinobacteria, rhizobia, fungi, arbuscular mycorrhizae, saprophytes, and protozoa were determined by phospholipid fatty acid (PLFA) analysis. Results showed that SOC and soil microbial biomass across all microbial groups were significantly greater (p<0.01) under perennial vegetation (GB, BC, GWW, and AB) compared with RC management. The footslope landscape position exhibited the highest total microbial biomass compared with the summit and backslope positions, and a sampling distance of 50-cm from the tree base demonstrated 16% greater total microbial biomass and 15% greater SOC compared with 150-cm. These study findings highlight the influence of landscape on soil biological properties and show that perennial vegetation has the potential to increase soil microbial biomass, improve microbial community composition, and enhance sustainability in degraded row crop systems.