Response of soil organic matter to cover cropping in water-limited environments

Thapa, Vesh R.; Ghimire, Rajan; VanLeeuwen, Dawn; Acosta-Martínez, Verónica; Shukla, Manoj K.

doi:10.1016/j.geoderma.2021.115497

Cited by 35 publications

(23 citation statements)

References 53 publications

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“…At the time of CC termination in our study, the higher TMB under oats, compared to canola, was likely attributed to the greater addition of biomass C. Immediately after CC termination, decomposing CC residues serve as a readily available C source, fueling microbial growth (Lehman et al, 2012). In a concurrent study conducted at the same site, oats as CC exhibited significantly greater average aboveground biomass production, greater C:N ratios, and more soil organic carbon and total N accumulation than canola (Thapa et al, 2022). Additionally, grass CCs, such as oats, often generate dense root systems and more root biomass, providing a C-rich substrate that stimulates microbial activity (Amsili & Kaye, 2021), which can result in a surge in microbial biomass and shifts in community structure.…”

Section: Discussionmentioning

confidence: 57%

“…Ghimire et al, 2017), promoting soil microbial growth and activity (Bartelt-Ryser et al, 2005). The lower C:N ratio of pea and canola compared to oats may have favored fast decomposition, providing a C source for diverse microbial groups within a month of CC termination (Thapa et al, 2022). Based on the results obtained by Thapa et al (2022) on soil properties such as potentially mineralizable C and N, C:N ratio, etc., in previous research involving the same treatments, CCs such as pea, canola, and brassicas, either alone or in combination, that is, pea + canola and SSM, resulted in greater particulate carbon and maintained belowground food chains for various microbial groups (Table 1; phase II).…”

Section: Discussionmentioning

confidence: 99%

“…The lower C:N ratio of pea and canola compared to oats may have favored fast decomposition, providing a C source for diverse microbial groups within a month of CC termination (Thapa et al, 2022). Based on the results obtained by Thapa et al (2022) on soil properties such as potentially mineralizable C and N, C:N ratio, etc., in previous research involving the same treatments, CCs such as pea, canola, and brassicas, either alone or in combination, that is, pea + canola and SSM, resulted in greater particulate carbon and maintained belowground food chains for various microbial groups (Table 1; phase II). A mixture of high biomass and high C:N ratio CC species, like oats, with low C:N ratio compared to species, such as peas, have slowly and gradually facilitated nutrient mineralization, making it accessible to microorganisms, specifically Gram+ bacteria, over time.…”

Section: Discussionmentioning

confidence: 99%

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Microbial community response to cover cropping varied with time after termination

Ogunleye,

Thapa,

Aryal

et al. 2023

Agricultural & Env Letters

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This study evaluates cover crop (CC) effects on microbial community structure in a winter wheat–sorghum–fallow rotation with pea, oat, and canola; mixtures of pea and oat; pea and canola; pea, oat, and canola; and six species mixture (SSM) of pea, oat, canola, hairy vetch, forage radish, and barley as CCs, and fallow as treatments. Soil microbial community structure was analyzed at CC termination (phase I), 36 days (phase II), and a year (phase III) after termination using an ester‐linked fatty acid methyl ester analysis. Total microbial biomass (TMB) under oats was significantly greater than under canola (by 47%) in phase I (p ≤ 0.05). The TMB was >48% under pea, pea + canola, and SSM, and arbuscular mycorrhizal fungi was 70%–93% more under pea, canola, and their mixtures than fallow in phase II. While microbial abundance varied with CCs at and after 36 days post‐termination, these effects did not persist for a year. Long fallow period after cropping or cover cropping appears detrimental to microbial community proliferation.

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Section: Discussionmentioning

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Microbial community response to cover cropping varied with time after termination

Ogunleye,

Thapa,

Aryal

et al. 2023

Agricultural & Env Letters

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“…• Hairy vetch, forage turnip, and winter pea had the greatest overall positive effect on soil health indicators. (Acharya et al, 2022;Thapa et al, 2022Thapa et al, , 2024, the arid growing region of California's San Joaquin Valley (Mitchell et al, 2017), and the high-desert region of Central Oregon where this study takes place. For instance, current and future irrigation water availability is severely constrained for growers serviced by the North Unit Irrigation District in Central Oregon, and without enough water for cash crops it is unlikely that growers will divert water to CCs.…”

Section: Core Ideasmentioning

confidence: 99%

Winter cover cropping to improve soil health in semiarid, irrigated cropping systems of Central Oregon

Sullivan,

Kleber

2024

Agrosystems Geosci & Env

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A 1‐year experiment was conducted in Madras, OR, to examine the ability of winter cover crops (CCs) to improve physical, chemical, and biological soil properties over a bare fallow control. Competition for water is frequently seen as an obstacle to cover cropping in semiarid, irrigated systems. Benefits from CCs need to be demonstrated and quantified in regions such as Central Oregon's high desert for growers to make cost/benefit analysis decisions. To support such decisions, the effect of eight winter CC treatments (two brassicas, four legumes, two cereal mixtures) on five agronomic parameters and 39 soil health indicators (0–5 cm) were measured in the spring of 2019 after 8 months of CC growth. We identified four soil indicator response patterns in reference to the fallow: (i) steady improvement over fallow across all CCs (16 indicators, with hairy vetch and turnip being most efficient); (ii) marked improvement over fallow but somewhat constant response among CCs (organic C and N, surface hardness); (iii) negligible change from fallow; and (iv) varied response to CCs including both a deterioration and an improvement of soil health. Overall, 13 soil health indicators and five agronomic parameters responded significantly to CC treatment. CCs generated a stronger response of soil chemical and biological parameters than physical (average 82%, 79%, and 18% improvement over fallow, respectively). Hairy vetch had the greatest positive impact on soil biological and chemical properties but the lowest average impact on physical indicators. Winter CCs do offer soil health benefits in Central Oregon but should not be viewed as a short‐term fix to physical soil deficiencies. Our study provides strong evidence for the general ability of CCs to improve soil health in water‐limited systems. It also demonstrates the need for further studies focused on multiyear rotations, especially related to the improvement of soil physical properties such as soil moisture availability.

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“…However, the frequent tillage common in organic systems may limit the ability of soil to sequester the C from cover crop biomass in SOM (Larsen et al., 2014). Incorporated cover crop biomass serves as a large energy source for soil microbes as well as mineralizable N available for crop uptake (Kuo et al., 1997; Muchanga et al., 2019; Muhammad et al., 2021; Thapa et al., 2022). In addition to using residue C for their metabolism, soil microorganisms transform the C derived from cover crops and partially incorporate it into aggregate‐protected C, thereby increasing soil organic C (SOC) concentration (Maughan et al., 2009; Sainju et al., 2003; Schmer et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

Legume cover crop type and termination method effects on labile soil carbon and nitrogen and aggregation

et al. 2022

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Growers use cover crops to provide nutrients for crops and build soil organic matter (SOM). Termination methods may alter the effects of cover crops on soil labile C and N. We examined how two cover crops and three termination methods affected soil microbes, soil aggregates, and C and N pools in an organic grain system. We compared crimson clover (Trifolium incarnatum L.) (CC), hairy vetch (Vicia villosa Roth) (HV), and a control together with disking, mowing, or a roller-crimper for effects on hot-water-extractable carbohydrates, microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN), potentially mineralizable C and N, and aggregation (quantified by mean weight diameter [MWD]). Disking comprised flail mowing plots and then cultivating. Roller-crimping occurred via a roller with blades. Vetch soil contained 14% higher MBC than no cover crop pretermination, possibly because of enhanced rhizodeposition. Planting CC resulted in 44% higher MBC than no cover crop a week after termination, likely due to its higher biomass C/N ratio. Disking decreased MWD relative to flail mowing in no cover crop soils at 4 wk after termination across both years at 0-to-5-cm depth. In addition, MWD was lower under CC than under no cover crop for both the flail mowed and roller-crimped treatments at 4 wk after termination across both years from 0 to 5 cm. This is possibly due to enhanced desiccation of the soil in bare plots after termination. Our results indicate that quantity and quality of biomass of different legume species, rather than termination methods, dominated effects on labile C.

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Response of soil organic matter to cover cropping in water-limited environments

Cited by 35 publications

References 53 publications

Microbial community response to cover cropping varied with time after termination

Microbial community response to cover cropping varied with time after termination

Winter cover cropping to improve soil health in semiarid, irrigated cropping systems of Central Oregon

Legume cover crop type and termination method effects on labile soil carbon and nitrogen and aggregation

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