Root traits of cover crops and carbon inputs in an organic grain rotation

Author(s):  
Joseph P. Amsili ◽  
Jason P. Kaye

Abstract Cover crops are widely used to increase the quantity of organic carbon (C) returned to the soil between cash crops. Roots play an important role in increasing soil organic carbon (SOC) levels, but the root traits that impact SOC likely vary widely among cover crop species and this variation has yet to be characterized. Recently, cover crop mixtures have expanded in popularity as a way to increase the diversity of cover crop benefits. We tested the quantity, quality and spatial distribution of roots in three monocultures and one mixture to increase our understanding of root trait variation among species, and how that variation impacts mixture design. Root cores were taken from in-row and between-row locations to a depth of 40 cm from cover crops planted after winter wheat during the 2016–2017 growing season. These samples were taken from a larger maize–soybean–winter wheat organic grain rotation experiment (2012–2018) located in central Pennsylvania, USA. Cover crop treatments included monocultures of triticale (X Triticosecale Wittmack cv. ‘Trical 815’), canola (Brassica napus L. cv. ‘Wichita’), crimson clover (Trifolium incarnatum L. cv. ‘Dixie’) and a five species mixture dominated by those three species. Additionally, cumulative carbon (C) inputs were assessed for the entire rotation to determine cover crop and cash crop root C contributions. Root biomass C vertical and horizontal distribution, root-to-shoot (R:S) ratio, and root carbon-to-nitrogen (C:N) ratio differed among cover crop treatments. Triticale produced more root biomass in the between-row space at all depth intervals compared to other cover crop treatments. The five species mixture had more total 0–5 cm and between-row 0–5 cm root biomass than crimson clover in spring 2017. Cover crop and cash crop roots increased cumulative C estimates by between 37% (crimson clover) and 46% (triticale) compared to shoot C alone. Cover crop root trait information can inform the belowground benefits from combining different species into cover crop mixtures. Crimson clover produced less root biomass, surface root biomass and between-row root biomass than other cover crop treatments. Therefore, combining crimson clover with grass and certain brassica species can improve total root biomass production, and root distribution compared to crimson clover monocultures, whereas reducing the C:N ratio of roots compared to grass species monocultures. The five species mixture led to greater cumulative carbon inputs compared to monoculture treatments, which was due to greater cover crop biomass C and its influence on the following corn crop's biomass C.

HortScience ◽  
1998 ◽  
Vol 33 (7) ◽  
pp. 1163-1166 ◽  
Author(s):  
John R. Teasdale ◽  
Aref A. Abdul-Baki

Hairy vetch (Vicia villosa Roth), crimson clover (Trifolium incarnatum L.), and rye (Secale cereale L.) and mixtures of rye with hairy vetch and/or crimson clover were compared for no-tillage production of staked, fresh-market tomatoes (Lycopersicon esculentum Mill.) on raised beds. All cover crops were evaluated both with or without a postemergence application of metribuzin for weed control. Biomass of cover crop mixtures were higher than that of the hairy vetch monocrop. Cover crop nitrogen content varied little among legume monocrops and all mixtures but was lower in the rye monocrop. The C:N ratio of legume monocrops and all mixtures was <30 but that of the rye monocrop was >50, suggesting that nitrogen immobilization probably occurred only in the rye monocrop. Marketable fruit yield was similar in the legume monocrops and all mixtures but was lower in the rye monocrop when weeds were controlled by metribuzin. When no herbicide was applied, cover crop mixtures reduced weed emergence and biomass compared to the legume monocrops. Despite weed suppression by cover crop mixtures, tomatoes grown in the mixtures without herbicide yielded lower than the corresponding treatments with herbicide in 2 of 3 years. Chemical name used: [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one](metribuzin).


1988 ◽  
Vol 34 (3) ◽  
pp. 201-206 ◽  
Author(s):  
C. S. Rothrock ◽  
W. L. Hargrove

The influence of winter legume cover crops and of tillage on soil populations of fungal genera containing plant pathogenic species in the subsequent summer sorghum crop were examined in field studies. Legume cover crops significantly increased populations of Pythium spp. throughout the sorghum crop compared with a rye cover crop or no cover crop. This stimulation of the populations of Pythium spp. was not solely due to colonization of cover-crop residue, as populations were significantly greater at the time the legume cover crop was desiccated. Removal of aboveground residue generally decreased populations of Pythium spp. in soil. Incorporation of residue by tillage increased populations of Pythium spp. at some sampling dates. Legumes differed in the magnitude of stimulation, with hairy vetch stimulating Pythium spp. more than crimson clover. Cover crop treatments did not consistently influence soil populations of Fusarium spp., Rhizoctonia solani, Rhizoctonia-like binucleate fungi, or Macrophomina phaseolina. Macrophomina phaseolina populations were significantly greater under no tillage.


2018 ◽  
Vol 32 (3) ◽  
pp. 227-235 ◽  
Author(s):  
Matheus G. Palhano ◽  
Jason K. Norsworthy ◽  
Tom Barber

AbstractCover crop acreage has substantially increased over the last few years due to the intent of growers to capitalize on federal conservation payments and incorporate sustainable practices into agricultural systems. Despite all the known benefits, widespread adoption of cover crops still remains limited due to potential cost and management requirements. Cover crop termination is crucial, because a poorly controlled cover crop can become a weed and lessen the yield potential of the current cash crop. A field study was conducted in fall 2015 and 2016 at the Arkansas Agricultural Research and Extension Center in Fayetteville to evaluate preplant herbicide options for terminating cover crops. Glyphosate-containing treatments controlled 97% to 100% of cereal rye and wheat, but glyphosate alone controlled less than 57% of legume cover crops. The most effective way to control hairy vetch, Austrian winterpea, and crimson clover with glyphosate resulted from mixtures of glyphosate with glufosinate, 2,4-D, and dicamba. Higher rates of auxin herbicides improved control in these mixtures. Glufosinate alone or in mixture controlled legume cover crops 81% or more. Paraquat plus metribuzin was effective in terminating both cereal and legume cover crops, with control of cereal cover crops ranging from 87% to 97% and control of legumes ranging from 90% to 96%. None of these herbicides or mixtures adequately controlled rapeseed.


Agronomy ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1760
Author(s):  
Paul Cottney ◽  
Lisa Black ◽  
Ethel White ◽  
Paul N. Williams

The aim of this study is to identify species of cover crops that cause an increase in biomass and total nutrient accumulation in response to manure/slurry. This could improve nutrient efficiency and intensify the benefits from over-winter cover crops in arable rotations and improve following commercial crop yields. In a pot experiment, sixteen cover crops were grown for 100 days in response to slurry. Growth and nutrient (N, P, K, Mg and S) accumulation were measured, and then residue was reincorporated into the soil with spring barley (Hodeum vulgare L.) sown and harvested for yield. In response to slurry, tillage radish (Raphanus sativus L.) increased N accumulation by 101% due to a significant increase in biomass and % N (p < 0.05) over its relative control plots. Significant interactions between species and the application of slurry were found in cover crop biomass, cover crop and spring barley nutrient uptake, as well as cover crop carbon accumulation, particularly in the brassica species used. Slurry integrated with cover crops both reduced the cover crop C:N ratio and enhanced nutrient cycling compared to the control when soil mineral nitrogen (SMN) and spring barley crop N offtake were pooled. However, this was not observed in the legumes. This study shows that slurry integration with cover crops is a promising sustainable farming practice to sequester N and other macro-nutrients whilst providing a range of synergistic benefits to spring barley production when compared to unplanted/fallow land rotations. However, this advantage is subject to use of responsive cover crop species identified in this study.


2017 ◽  
Vol 31 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Cody D. Cornelius ◽  
Kevin W. Bradley

The recent interest in cover crops as component of Midwest corn and soybean production systems has led to the need for additional research, including the effects of residual corn and soybean herbicide treatments on fall cover crop establishment. Field studies were conducted in 2013, 2014, and 2015 in Columbia, Missouri to investigate the effects of common residual herbicides applied in corn and soybean on establishment of winter wheat, tillage radish, cereal rye, crimson clover, winter oat, Austrian winter pea, Italian ryegrass, and hairy vetch. Cover crops were evaluated for stand and biomass reduction 28 d after emergence (DAE). Rainfall from herbicide application to cover crop seeding date was much greater in 2014 and 2015, which resulted in less carryover in these years compared to 2013. When averaged across all herbicides evaluated in these experiments, the general order of sensitivity of cover crops to herbicide carryover, from greatest to least was Austrian winter pea=crimson clover>oilseed radish>Italian ryegrass>hairy vetch>wheat >winter oat>cereal rye. Cereal rye had the fewest instances of biomass or stand reduction with only four out of the 27 herbicides adversely effecting establishment. Pyroxasulfone consistently reduced Italian ryegrass and winter oat biomass at least 67% in both the corn and soybean experiments. In the soybean experiment, imazethapyr- and fomesafen-containing products resulted in severe stand and biomass reduction in both years while flumetsulam-containing products resulted in the greatest carryover symptoms in the corn experiment. Results from these experiments suggest that several commonly used corn and soybean herbicides have the potential to hinder cover crop establishment, but the severity of damage will depend on weather, cover crop species, and the specific herbicide combination.


2019 ◽  
Vol 34 (1) ◽  
pp. 48-54
Author(s):  
Kara B. Pittman ◽  
Charles W. Cahoon ◽  
Kevin W. Bamber ◽  
Lucas S. Rector ◽  
Michael L. Flessner

AbstractCover crops provide a number of agronomic benefits, including weed suppression, which is important as cases of herbicide resistance continue to rise. To effectively suppress weeds, high cover crop biomass is needed, which necessitates later termination timing. Cover crop termination is important to mitigate potential planting issues and prevent surviving cover crop competition with cash crops. Field studies were conducted in Virginia to determine the most effective herbicide options alone or combined with glyphosate or paraquat to terminate a range of cover crop species. Results revealed that grass cover crop species were controlled (94% to 98%) by glyphosate alone 4 wk after application (WAA). Overall, legume species varied in response to the single active-ingredient treatments, and control increased with the addition of glyphosate or paraquat. Mixes with glyphosate provided better control of crimson clover and hairy vetch by 7% to 8% compared with mixes containing paraquat 4 WAA. Mix partner did not influence control of Austrian winter pea. No treatment adequately controlled rapeseed in this study, with a maximum of 58% control observed with single active-ingredient treatments and 62% control with mixes. Height reduction for all cover crop species supports visible rating data. Rapeseed should be terminated when smaller, which could negate weed suppressive benefits from this cover crop species. Growers should consider herbicide selection and termination timing in their cover crop plan to ensure effective termination.


2017 ◽  
Vol 31 (4) ◽  
pp. 514-522 ◽  
Author(s):  
Cody D. Cornelius ◽  
Kevin W. Bradley

The recent interest in cover crops as a component of Midwest corn and soybean production systems has led to a greater need to understand the most effective herbicide treatments for cover crop termination prior to planting corn or soybean. Previous research has shown that certain cover crop species can significantly reduce subsequent cash crop yields if not completely terminated. Two field experiments were conducted in 2013, 2014, and 2015 to determine the most effective herbicide program for the termination of winter wheat, cereal rye, crimson clover, Austrian winter pea, annual ryegrass, and hairy vetch; and cover crops were terminated in early April or early May. Visual control and above ground biomass reduction was determined 28 d after application (DAA). Control of grass cover crop species was often best with glyphosate alone or combined with 2,4-D, dicamba, or saflufenacil. The most consistent control of broadleaf cover crops occurred following treatment with glyphosate +2,4-D, dicamba, or saflufenacil. In general, control of cover crops was higher with early April applications compared to early May. In a separate study, control of 15-, 25-, and 75-cm tall annual ryegrass was highest with glyphosate at 2.8 kg ha−1or glyphosate at 1.4 kg ha−1plus clethodim at 0.136 kgha−1. Paraquat- or glufosinate-containing treatments did not provide adequate annual ryegrass control. For practitioners who desire higher levels of cover crop biomass, these results indicate that adequate levels of cover crop control can still be achieved in the late spring with certain herbicide treatments. But it is important to consider cover crop termination well in advance to ensure the most effective herbicide or herbicide combinations are used and the products are applied at the appropriate stage.


2018 ◽  
Vol 32 (3) ◽  
pp. 244-250 ◽  
Author(s):  
Taïga B. Cholette ◽  
Nader Soltani ◽  
David C. Hooker ◽  
Darren E. Robinson ◽  
Peter H. Sikkema

AbstractGlyphosate-resistant (GR) and multiple herbicide–resistant (groups 2 and 9) Canada fleabane have been confirmed in 30 and 23 counties in Ontario, respectively. The widespread incidence of herbicide-resistant Canada fleabane highlights the importance of developing integrated weed management strategies. One strategy is to suppress Canada fleabane using cover crops. Seventeen different cover crop monocultures or polycultures were seeded after winter wheat harvest in late summer to determine GR Canada fleabane suppression in corn grown the following growing season. All cover crop treatments seeded after wheat harvest suppressed GR Canada fleabane in corn the following year. At 4 wk after cover crop emergence (WAE), estimated cover crop ground cover ranged from 31% to 68%, a density of 124 to 638 plants m–2, and a range of biomass from 29 to 109 g m–2, depending on cover crop species. All of the cover crop treatments suppressed GR Canada fleabane in corn grown the following growing season from May to September compared to the no cover crop control. Among treatments evaluated, annual ryegrass (ARG), crimson clover (CC)/ARG, oilseed radish (OSR)/CC/ARG, and OSR/CC/cereal rye (CR) were the best treatments for the suppression of GR Canada fleabane in corn. ARG alone or in combination with CC provided the most consistent GR Canada fleabane suppression, density reduction, and biomass reduction in corn. Grain corn yields were not affected by the use of the cover crops evaluated for Canada fleabane suppression.


2016 ◽  
Vol 30 (2) ◽  
pp. 415-422 ◽  
Author(s):  
Matthew S. Wiggins ◽  
Robert M. Hayes ◽  
Lawrence E. Steckel

Glyphosate-resistant (GR) weeds, especially GR Palmer amaranth, are very problematic in cotton-producing areas of the midsouthern region of the United States. Growers rely heavily on PRE residual herbicides to control Palmer amaranth since few effective POST options exist. Interest in integrating high-residue cover crops with existing herbicide programs to combat GR weeds has increased. Research was conducted in 2013 and 2014 in Tennessee to evaluate GR Palmer amaranth control when integrating cover crops and PRE residual herbicides. Cereal rye, crimson clover, hairy vetch, winter wheat, and combinations of one grass plus one legume were compared with winter weeds without a cover crop followed by fluometuron or acetochlor applied PRE. Biomass of cover crops was determined prior to termination 3 wk before planting. Combinations of grass and legume cover crops accumulated the most biomass (> 3,500 kg ha−1) but by 28 d after application (DAA) the cereal rye and wheat provided the best Palmer amaranth control. Crimson clover and hairy vetch treatments had the greatest number of Palmer amaranth. These cereal and legume blends reduced Palmer amaranth emergence by half compared to non–cover-treated areas. Fluometuron and acetochlor controlled Palmer amaranth 95 and 89%, respectively, at 14 DAA and 54 and 62%, respectively, at 28 DAA. Cover crops in combination with a PRE herbicide did not adequately control Palmer amaranth.


2017 ◽  
Vol 31 (3) ◽  
pp. 348-355 ◽  
Author(s):  
Matthew S. Wiggins ◽  
Robert M. Hayes ◽  
Robert L. Nichols ◽  
Lawrence E. Steckel

Field experiments were conducted to evaluate the integration of cover crops and POST herbicides to control glyphosate-resistant Palmer amaranth in cotton. The winter-annual grasses accumulated the greatest amount of biomass and provided the most Palmer amaranth control. The estimates for the logistic regression would indicate that 1540 kg ha−1would delay Palmer amaranth emerging and growing to 10 cm by an estimated 16.5 days. The Palmer amaranth that emerged in the cereal rye and wheat cover crop treatments took a longer time to reach 10 cm compared to the hairy vetch and crimson clover treatments. POST herbicides were needed for adequate control of Palmer amaranth. The glufosinate-based weed control system provided greater control (75% vs 31%) of Palmer amaranth than did the glyphosate system. These results indicate that a POST only herbicide weed management system did not provide sufficient control of Palmer amaranth, even when used in conjunction with cover crops that produced a moderate level of biomass. Therefore, future recommendations for GR Palmer amaranth control will include integrating cover crops with PRE herbicides, overlaying residual herbicides in-season, timely POST herbicide applications, and hand weeding in order to achieve season-long control of this pest.


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