scholarly journals Cover crop diversity for weed suppression and crop yield in a corn–soybean production system in Tennessee

age ◽  
2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Manuel J. Sabbagh ◽  
Sindhu Jagadamma ◽  
Lori A. Duncan ◽  
Forbes R. Walker ◽  
Jaehoon Lee ◽  
...  
Author(s):  
Laura Stefan ◽  
Nadine Engbersen ◽  
Christian Schoeb

Implementing sustainable weed control strategies is a major challenge in agriculture. Intercropping offers a potential solution to control weed pressure by reducing the niche space available for weeds; however, available research on the relationship between crop diversity and weed pressure, and its consequences on crop yield is not fully conclusive yet. In this study, we performed an extensive intercropping experiment using eight crop species and 40 different species mixtures to examine how crop diversity affects weed communities and how the subsequent changes in weeds influence crop yield. Field experiments were carried out in Switzerland and in Spain, which differ drastically in terms of climate and soil, and included monocultures, 2- and 4-species mixtures, and a control treatment without crops. Weed communities were assessed in terms of biomass, species richness and evenness, and community composition. Results indicate that intercropping per se does not reduce weed performance or diversity, but crop species composition does. In particular, the presence of cereals in crop mixtures significantly reduced weed biomass and diversity. Despite the lack of crop diversity effect on weeds, crop yield increased with crop species richness, particularly in Switzerland. Moreover, in Switzerland, where soil resources were abundant, increasing crop yield correlated with increased weed suppression and reduced weed diversity. In Spain, where water and nutrients were limited, crop yield was not related to weed biomass or diversity. Synthesis and applications: We demonstrate that in our study, increased crop yield in mixtures was not due to increased weed suppression in diverse crop communities, but must be the result of other ecological processes. We also show that crop-weed relationships vary across environmental conditions, which emphasizes the need for a better understanding of weed communities' assembly mechanisms, as well as locally adapted weed management strategies.


Weed Science ◽  
2020 ◽  
Vol 68 (3) ◽  
pp. 301-310
Author(s):  
Kara B. Pittman ◽  
Jacob N. Barney ◽  
Michael L. Flessner

AbstractCover crop residue can act as a mulch that will suppress weeds, but as the residue degrades, weed suppression diminishes. Biomass of cover crop residue is positively correlated to weed suppression, but little research is available regarding the composition of cover crop residue and its effect on weed suppression. Field experiments were conducted to determine the impact of cover crop residue properties (i.e., total carbon, total nitrogen, lignin, cellulose, and hemicellulose) on summer annual weed suppression and cash crop yield. Cover crop monocultures and mixtures were planted in the fall and designed to provide a range of biomass and residue properties. Cover crops were followed by corn (Zea mays L.) or soybean [Glycine max (L.) Merr.]. At termination, cover crop biomass and residue components were determined. Biomass ranged from 3,640 to 8,750 kg ha−1, and the carbon-to-nitrogen (C:N) ratio ranged from 12:1 to 36:1. As both cover crop biomass and C:N ratio increased, weed suppression and duration of suppression increased. For example, a C:N ratio of 9:1 is needed to suppress redroot pigweed (Amaranthus retroflexus L.) 50% at 4 wk after termination (WAT), and that increases to 16:1 and 20:1 to have 50% suppression at 6 and 8 WAT, respectively. Similarly, with biomass, 2,800 kg ha−1 is needed for 50% A. retroflexus suppression at 4 WAT, which increases to 5,280 kg ha−1 and 6,610 kg ha−1 needed for 50% suppression at 6 and 8 WAT, respectively. In general, similar trends were observed for pitted morningglory (Ipomoea lacunosa L.) and large crabgrass [Digitaria sanguinalis (L.) Scop.]. Corn and soybean yield increased as both cover crop biomass and C:N ratio increased where no weed control measures were implemented beyond cover crop. The same trend was observed with cash crop yield in the weed-free subblocks, with one exception. This research indicates that cover crop residue composition is important for weed control in addition to biomass.


2013 ◽  
Vol 27 (1) ◽  
pp. 193-203 ◽  
Author(s):  
Steven B. Mirsky ◽  
Matthew R. Ryan ◽  
John R. Teasdale ◽  
William S. Curran ◽  
Chris S. Reberg-Horton ◽  
...  

Cover crop–based organic rotational no-till soybean production has attracted attention from farmers, researchers, and other agricultural professionals because of the ability of this new system to enhance soil conservation, reduce labor requirements, and decrease diesel fuel use compared to traditional organic production. This system is based on the use of cereal rye cover crops that are mechanically terminated with a roller-crimper to create in situ mulch that suppresses weeds and promotes soybean growth. In this paper, we report experiments that were conducted over the past decade in the eastern region of the United States on cover crop–based organic rotational no-till soybean production, and we outline current management strategies and future research needs. Our research has focused on maximizing cereal rye spring ground cover and biomass because of the crucial role this cover crop plays in weed suppression. Soil fertility and cereal rye sowing and termination timing affect biomass production, and these factors can be manipulated to achieve levels greater than 8,000 kg ha−1, a threshold identified for consistent suppression of annual weeds. Manipulating cereal rye seeding rate and seeding method also influences ground cover and weed suppression. In general, weed suppression is species-specific, with early emerging summer annual weeds (e.g., common ragweed), high weed seed bank densities (e.g. > 10,000 seeds m−2), and perennial weeds (e.g., yellow nutsedge) posing the greatest challenges. Due to the challenges with maximizing cereal rye weed suppression potential, we have also found high-residue cultivation to significantly improve weed control. In addition to cover crop and weed management, we have made progress with planting equipment and planting density for establishing soybean into a thick cover crop residue. Our current and future research will focus on integrated multitactic weed management, cultivar selection, insect pest suppression, and nitrogen management as part of a systems approach to advancing this new production system.


2021 ◽  
Vol 5 ◽  
Author(s):  
Vivian M. Wauters ◽  
Julie M. Grossman ◽  
Anne Pfeiffer ◽  
Rodrigo Cala

Intensive production practices characterizing vegetable farming contribute to high productivity, but often at the expense of supporting and regulating ecosystem services. Diversification with cover crops may support increased resilience through soil organic matter (SOM) contributions and physical soil protection. Vegetable farming often includes spring and fall production, limiting establishment and productive potential of over-wintered cover crops that are more widely used in the USA. In northern climate vegetable systems, warm-season cover crops planted during short summer fallows could be a tool to build resilience via ecosystem service enhancement. This project evaluated summer cover crops in the northern USA (MN and WI) for biomass accumulation, weed suppression, and contribution to fall cash crop yield. Our study included four site years, during which we investigated the effects of four cover crop species treatments, grown for 30 (short duration, SD) or 50 days (long duration, LD) alongside bare fertilized and unfertilized control treatments: buckwheat (Fagopyrum esculentum) and sunn hemp (Crotalaria juncea) monocultures, and biculture of chickling vetch (Lathyrus sativus) or cowpea (Vigna unguiculata) with sorghum-sudangrass (sudex) (Sorghum bicolor x S. bicolor var. Sudanese). To quantify cover crop quantity, quality, and weed suppression capacity, we measured cover crop and weed biomass, and biomass C:N. To quantify effects on cash crops, we measured fall broccoli yield and biomass. Mean total biomass (cover crop + weeds) by site year ranged from 1,890 kg ha−1 in MN Y1 to 5,793 kg ha−1 in WI Y2 and varied among species in Y1 for both the SD and LD treatments. Most cover crops did not outcompete weeds, but treatments with less weeds produced more overall biomass. Data from Y1 show that cover crops were unable to replace fertilizer for fall broccoli yield, and led to reduced fall crop yield. Broccoli in Y2 did not reach maturity due to fall freeze. Summer cover crops, because of their biomass accumulation potential, may be used by farmers in northern climates to fit into cropping system niches that have historically been left as bare soil, but care with timing is necessary to optimize weed suppression and mitigate tradeoffs for cash crop production.


Weed Science ◽  
2014 ◽  
Vol 62 (1) ◽  
pp. 125-137 ◽  
Author(s):  
Emily R. Bernstein ◽  
David E. Stoltenberg ◽  
Joshua L. Posner ◽  
Janet L. Hedtcke

Grower adoption of no-tillage (NT) approaches to organic soybean production has been limited, in part because of the perceived risks of ineffective cover crop management and lack of season-long weed suppression. We conducted research in 2008 and 2009 to assess those risks by quantifying the effects of winter rye cover-crop management (tilling, crimping, or mowing), soybean planting date (mid May or early June), and row width (19 or 76 cm) on weed recruitment, emergence patterns, season-long suppression, and late-season weed community composition in transitional organic production systems. The weed plant community consisted largely of summer annual species in each year, with velvetleaf or common lambsquarters as the most abundant species. Seedling recruitment from the soil seedbank varied between years, but velvetleaf recruitment was consistently greater in the tilled rye than in the NT rye treatments. Weed emergence tended to peak early in the season in the tilled rye treatment, but in the NT rye treatments, the peak occurred in mid or late season. More-diverse summer annual and perennial species were associated with the NT rye treatments. Even so, weed suppression (as measured by late-season weed shoot mass) was much greater in crimped or mowed rye NT treatments than it was in the tilled treatment. Weed suppression among NT rye treatments was greater in 19- than in 76-row spacing treatments in each year and was greater for mid May than it was for early June planted soybean in 2009. The NT planting of soybean into standing rye before termination (crimping or mowing) facilitated timely planting of soybean, as well as effective, season-long weed suppression, suggesting that those approaches to rye and weed management are of less risk than those typically perceived by growers. Our results suggest that NT systems in winter rye provide effective weed-management alternatives to the typical tillage-intensive approach for organic soybean production.


Author(s):  
John E. Sawyer ◽  
Jose L. Pantoja ◽  
Daniel W. Barker

Author(s):  
John E. Sawyer ◽  
Jose L. Pantoja ◽  
Daniel W. Barker

Author(s):  
John E. Sawyer ◽  
Jose L. Pantoja ◽  
Daniel W. Barker

2021 ◽  
Vol 12 (1) ◽  
pp. 157-172
Author(s):  
Shankar G. Shanmugam ◽  
Normie W. Buehring ◽  
Jon D. Prevost ◽  
William L. Kingery

Our understanding on the effects of tillage intensity on the soil microbial community structure and composition in crop production systems are limited. This study evaluated the soil microbial community composition and diversity under different tillage management systems in an effort to identify management practices that effectively support sustainable agriculture. We report results from a three-year study to determine the effects on changes in soil microbial diversity and composition from four tillage intensity treatments and two residue management treatments in a corn-soybean production system using Illumina high-throughput sequencing of 16S rRNA genes. Soil samples were collected from tillage treatments at locations in the Southern Coastal Plain (Verona, Mississippi, USA) and Southern Mississippi River Alluvium (Stoneville, Mississippi, USA) for soil analysis and bacterial community characterization. Our results indicated that different tillage intensity treatments differentially changed the relative abundances of bacterial phyla. The Mantel test of correlations indicated that differences among bacterial community composition were significantly influenced by tillage regime (rM = 0.39, p ≤ 0.0001). Simpson’s reciprocal diversity index indicated greater bacterial diversity with reduction in tillage intensity for each year and study location. For both study sites, differences in tillage intensity had significant influence on the abundance of Proteobacteria. The shift in the soil bacterial community composition under different tillage systems was strongly correlated to changes in labile carbon pool in the system and how it affected the microbial metabolism. This study indicates that soil management through tillage intensity regime had a profound influence on diversity and composition of soil bacterial communities in a corn-soybean production system.


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