Biological nitrogen fixation of cool‐season legumes in agronomic systems of the Southern Great Plains

MacMillan, Jennifer; Adams, Curtis B.; Hinson, Philip O.; DeLaune, Paul B.; Rajan, Nithya; Trostle, Calvin

doi:10.1002/agg2.20244

Cited by 9 publications

(13 citation statements)

References 45 publications

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“… a An estimate of biological nitrogen fixation associated with this data is available from MacMillan et al. (2022). …”

Section: Resultsmentioning

confidence: 99%

“…Estimates of the percentage of N derived from the atmosphere (%Ndfa) and BNF from the hay crop, which was primarily a mix of Austrian winter pea and wheat, were reported by MacMillan et al. (2022) as 92.7% and 55 kg N ha −1 , respectively. In the same report, winter pea acting as cover crops in cotton ( Gossypium hirsutum L.) cropping systems in the region were found to have lower %Ndfa (57–73%), but somewhat elevated BNF (67–74 kg N ha −1 ) than the organic system.…”

Section: Discussionmentioning

confidence: 99%

“…Detailed information on the methods for estimating BNF and the results of the analysis were presented by MacMillan et al. (2022). To assess hay quality, protein concentration of the winter hay crop was estimated by multiplying the total N concentration of the individual plant species by 6.25 (AOAC, 2010).…”

Section: Methodsmentioning

confidence: 99%

“…The ground biomass samples were analyzed for total N and δ 15 N at the Texas A&M Stable Isotopes for Biosphere Science Laboratory, which was used to estimate BNF using the natural abundance method (Shearer & Kohl, 1986). Detailed information on the methods for estimating BNF and the results of the analysis were presented by MacMillan et al (2022). To assess hay quality, protein concentration of the winter hay crop was estimated by multiplying the total N concentration of the individual plant species by 6.25 (AOAC, 2010).…”

Section: Winter Hay Crop and Summer Cover Crop Measurementsmentioning

confidence: 99%

“…The results from the winter hay (cash) crop, which was planted in the second year of organic transition, demonstrated that the winter season was the prime opportunity for introducing legume-based N fixation to the system. Estimates of the percentage of N derived from the atmosphere (%Ndfa) and BNF from the hay crop, which was primarily a mix of Austrian winter pea and wheat, were reported by MacMillan et al (2022) as 92.7% and 55 kg N ha −1 , respectively. In the same report, winter pea acting as cover crops in cotton (Gossypium hirsutum L.) cropping systems in the region were found to have lower %Ndfa (57-73%), but somewhat elevated BNF (67-74 kg N ha −1 ) than the organic system.…”

Section: Other System Dynamics With a Focus On Nitrogen Managementmentioning

confidence: 99%

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Organic transition in dual‐purpose wheat systems: Agronomic performance and soil nitrogen dynamics

et al. 2022

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The Southern Great Plains (SGP) region of the United States is widely known for its dryland dual-purpose winter wheat (Triticum aestivum L.) cropping systemsintegrated systems that provide both livestock grazing and grain production. Few of these systems are organic, however, and no relevant research had been conducted on this topic. A large-scale (41 ha) systems research study was conducted for 3 yr (2018-2021) to compare a transitional organic dual-purpose wheat system with a conventional one, with system management components customized to the ecological region. Organic wheat yield was 20% lower than conventional in the first season of organic transition, but there was no yield difference by the third year.The yield improvement in the organic system may be attributed to N fixation by a legume-based cash crop the previous winter season, exogenous nutrients from application of composted manure, and appropriate wheat cultivar selection. Because of limited moisture, relying on annual establishment of summer cover crops to fix N and deliver other ecosystem services in the organic system was not feasible in most years. Grain protein concentration (GPC) of the transitional organic wheat ranged from 91 to 103 g kg −1 , below the 120 g kg −1 threshold for a food market organic price premium. More intensive N management, including in-season application of a more available form of N that is organic approved, could be an effective strategy to increase GPC. This proof-of-concept study shows that organic dual-purpose wheat systems can be a viable enterprise in the SGP, though additional research is needed to address challenges identified herein. INTRODUCTIONAmong all grain crops, more acreage of wheat (Triticum aestivum L.) has been produced organically in the United States since 1995 than all other countries (McBride et al.

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“… a An estimate of biological nitrogen fixation associated with this data is available from MacMillan et al. (2022). …”

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Winter Hay Crop and Summer Cover Crop Measurementsmentioning

confidence: 99%

Section: Other System Dynamics With a Focus On Nitrogen Managementmentioning

confidence: 99%

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Organic transition in dual‐purpose wheat systems: Agronomic performance and soil nitrogen dynamics

et al. 2022

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Forage and cattle production during organic transition in dual‐purpose wheat systems

Hinson

Pinchak²,

Adams

et al. 2023

Agronomy Journal

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Dual‐purpose wheat (Triticum aestivum L. emend. Thell.) production systems (i.e., graze and grain) are prevalent in the U.S. Southern Great Plains region, though few of them are managed organically and organic research is very limited, particularly on forage and grazing aspects of the system. Therefore, the objective of this 3‐year systems study (2018–2021) conducted near Vernon, TX, was to compare forage production, forage nutritive value, and cattle gains in transitional organic and conventional dual‐purpose wheat systems. Forage data were collected each year during the early‐season dual‐purpose grazing period until maturity. Monthly standing crop biomass, rate of forage production, and forage nutritive value did not differ during the grazing period between systems in any year. Limited early‐season precipitation resulted in slow forage growth in all years and inadequate forage production to support grazing in 2 of 3 years. In the year when grazing occurred (2018–2019), cattle performance did not differ between systems. Following the dual‐purpose grazing period, the organic system trended toward lower forage production and crude protein concentration than the conventional system, suggesting that in a “graze‐out” scenario (i.e., season‐long grazing and no grain production), the organic system might not support as much cattle production. The late‐season divergence between systems could likely be minimized or eliminated by improving N availability in the organic system. Agronomic viability of the organic system, in terms of forage production, nutritive values, and cattle gains, was supported by its overall similarity to the conventional system.

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Species richness and functional diversity enhance winter annual forage productivity and nutritive value

Rusch,

Dubeux,

Queiroz

et al. 2023

Crop Science

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Winter annual forages can extend grazing into the cool‐season in the US southeast, however uncertainty regarding potential tradeoffs between winter annual mixtures versus monocultures exists. We examined increasingly species‐rich and functionally diverse winter annual forage mixtures at two Florida locations to evaluate impacts of including more plant species with distinct traits (e.g., different maturities and nitrogen [N] scavenging vs. N2‐fixing capabilities) on forage accumulation (FA), nutritive value, and evenness of forage distribution across the cool‐season compared with a rye (Secale cereale L.) monoculture. Furthermore, we quantified the N2‐fixing potential of winter annual legumes to measure their contribution to soil fertility and ecosystem N cycling. We found that greater species richness enhanced total cool‐season FA at both sites, ranging from 0.92 to 4.38 Mg DM ha−1 in Gainesville and 6.48 to 9.11 Mg DM ha−1 in Marianna. In Marianna, where legumes accounted for approximately 25% or more of the biomass accumulated by winter annual forage mixtures, legume inclusion enhanced forage shoot N concentration. Furthermore, >50% of the N in legume tissues derived from the atmosphere, supplying 0.18–2 kg N ha−1 in Gainesville and 30–52 kg N ha−1 in Marianna. Altogether, our data suggest that species richness enhanced winter annual forage production and legume inclusion improved forage nutritive value although these responses were site‐specific. Thus, our multi‐site study provides information that can guide decision‐making regarding appropriate winter annual forage selections to increase cool‐season forage production in the southeastern United States.

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Biological nitrogen fixation of cool‐season legumes in agronomic systems of the Southern Great Plains

Cited by 9 publications

References 45 publications

Organic transition in dual‐purpose wheat systems: Agronomic performance and soil nitrogen dynamics

Organic transition in dual‐purpose wheat systems: Agronomic performance and soil nitrogen dynamics

Forage and cattle production during organic transition in dual‐purpose wheat systems

Species richness and functional diversity enhance winter annual forage productivity and nutritive value

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