scholarly journals Screening Cover Crops for Weed Suppression in Conservation Agriculture

2017 ◽  
Vol 6 (4) ◽  
pp. 124
Author(s):  
Mutondwa M. Phophi ◽  
Paramu L. Mafongoya ◽  
Alfred O. Odindo ◽  
Lembe S. Magwaza

The use of herbicides amongst smallholder farmers is minimal because herbicides are expensive and they require specialized application equipments. Weeds are problematic in conservation agriculture where herbicides are expensive for smallholder farmers. The use of cover crops can help to suppress weed growth and development by creating an environment which is not suitable for weeds survival. Cowpea (Vigna unguiculata (L.) Walp) dolichos lablab (Lablab purpureus L.) and velvet bean (Mucuna pruriens (L.) DC) were evaluated for biomass accumulation and weed suppression under conservation agriculture system in two contrasting experimental sites: Ukulinga and Bergville in KwaZulu-Natal. Bare plot and herbicide treatments served as controls. Treatments were laid in a randomized complete block design, replicated three times. Mucuna pruriens (L.) DC had the highest biomass accumulation in both sites Bergville (0.72 t/ha) and Ukulinga (1.59 t/ha). Cowpea had the lowest biomass accumulation in Bergville (0.59 t/ha) and lablab was the lowest in Ukulinga (0.88 t/ha). Lablab was effective in suppressing weed biomass in Bergville (P < 0.05). Cowpea performed best in suppressing weed biomass in Ukulinga (P < 0.05). The results suggest that cowpea and lablab can be effective for weed suppression and therefore can be recommended for use in conservation agricultural systems.

2017 ◽  
Vol 6 (4) ◽  
pp. 142 ◽  
Author(s):  
Mutondwa M. Phophi ◽  
Paramu L. Mafongoya ◽  
Alfred O. Odindo ◽  
Lembe S. Magwaza

Soil health is important for sustainable crop production. Frequent soil cultivation has a negative impact on soil health, resulting in loss of soil macrofauna. Conservation agriculture can be practiced to improve soil health by improving the abundance of soil macrofauna. Three leguminous cover crops were tested for soil macrofauna abundance Vigna unguiculata, (cowpea) Lablab purpureus L. (dolichos lablab) and Mucuna pruriens (L.) DC (velvet bean). The experiment was done in two contrasting experimental sites of KwaZulu-Natal (Ukulinga and Bergville) in a randomised complete block design replicated three times. Bare plot and herbicide treatments served as controls. Natural fallow was used to make a comparison to all the other treatments. Cowpea (39 species) had the highest soil macrofauna abundance in Bergville. Lablab (57 species) had the highest soil macrofauna in Ukulinga. Cowpea (0.75 species) and lablab (0.61 species) improved soil macrofauna diversity respectively in Bergville. Natural fallow (0.46 species) had the lowest soil macrofauna diversity in Bergville. Lablab (0.56 species) and velvet bean (0.74 species) had high soil macrofauna species diversity in Ukulinga. Bare plot (0.3 species) had the lowest soil macrofauna species diversity respectively. It can be concluded that cowpea and lablab can be recommended for improving soil macrofauna abundance in conservation agriculture.


Author(s):  
Katja Koehler-Cole ◽  
Christopher A. Proctor ◽  
Roger W. Elmore ◽  
David A. Wedin

Abstract Replacing tillage with cover crops (CC) for weed management in corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] systems with mechanical weed control has many soil health benefits but in the western Corn Belt, CC establishment after harvest is hampered by cold temperatures, limited labor and few compatible CC species. Spring-planted CC may be an alternative, but information is lacking on suitable CC species. Our objective was to evaluate four spring-planted CC with respect to biomass production and weed suppression, concurrent with CC growth and post-termination. Cover crop species tested were oat (Avena sativa L.), barley (Hordeum vulgare L.), brown mustard [Brassica juncea (L.) Czern.] and yellow mustard (Brassica hirta Moench). They were compared to no-CC treatments that were either tilled pre- and post-planting of soybean (no-CC tilled) or not tilled at all (no-CC weedy). CC were planted in late March to early April, terminated 52–59 days later using an undercutter, and soybean was planted within a week. The experiment had a randomized complete block design with four replications and was repeated for 3 years. Mustards and small grains produced similar amounts of biomass (1.54 Mg ha−1) but mustard biomass production was more consistent (0.85–2.72 Mg ha−1) than that of the small grains (0.35–3.81 Mg ha−1). Relative to the no-CC weedy treatment, mustards suppressed concurrent weed biomass in two out of 3 years, by 31–97%, and small grains suppressed concurrent weed biomass in only 1 year, by 98%. Six weeks after soybean planting, small grains suppressed weed biomass in one out of 3 years, by 79% relative to the no-CC weedy treatment, but mustards did not provide significant weed suppression. The no-CC tilled treatment suppressed weeds each year relative to the no-CC weedy treatment, on average 87%. The ineffective weed control by CC reduced soybean biomass by about 50% six weeks after planting. While spring-planted CC have the potential for pre-plant weed control, they do not provide adequate early season weed suppression for soybean.


Author(s):  
Akpa, Ogonnaya Esther ◽  
Udensi Ekea Udensi ◽  
Omovbude, Sunday ◽  
Orluchukwu, Joseph Amadi

Maize is one of the most commonly cultivated arable crops in the rain forest zone of South Eastern Nigeria. Globally soil fertility and weed pressure are the most important constraints limiting increase productivity of Maize especially in Sub Saharan Africa (SSA). Unavailability and cost of inorganic fertilizer as well as cost of labour for weeding have engendered low productivity of maize. Hence this trial was conducted to evaluate the efficacy of maize-legume systems on weed suppression and maize performance. The trial was carried out at the Teaching   and Research  Farm of Faculty of Agriculture, University of Port Harcourt, Nigeria located within latitude 04°54’N and longitude 6°55’ E). The trial was conducted between April 4th and July 5th, 2017. The experiment was a 3 x 3 factorial arrangement fitted into a randomized complete block design (RCBD) consisting of 3 types of legume systems (Mucuna pruriens, Lablab purpurens and No legume) and three levels of NPK 15:15:15 fertilizer (0, 15, and 30 kg NPK/ha). The 9 treatment combinations were replicated thrice to give 27 plots.  Data collected were on maize yield and yield components, weed and legume parameters at 4, 8 and 16 weeks after sowing (WAS). Result showed that legume significantly reduced weed biomass when compared to the natural fallow. The effect of weed biomass reduction was Mucuna 34.8% >Lablab 29.2%. The legume system significantly suppressed weed compared to natural fallow and the weed suppression ability average 56% and 30% respectively for Mucuna and Lablab whether or not they received NPK. Result of this trial also revealed that within 8 weeks after sowing legumes (8 WASL) 26% N and 22% N can be harvested by integrating this legume cover in cropping system and that NPK application has little or no effect in the performance of these legumes. Mucuna was not sensitive to fertilizer application while Lablab responded to fertilizer application. Maize was sensitive to Mucuna due to early integration; hence, it is recommended that these legumes be integrated at six weeks after sowing maize.


Weed Science ◽  
2017 ◽  
Vol 65 (3) ◽  
pp. 426-439 ◽  
Author(s):  
Jeffrey A. Liebert ◽  
Antonio DiTommaso ◽  
Matthew R. Ryan

Maximizing cereal rye biomass has been recommended for weed suppression in cover crop–based organic no-till planted soybean; however, achieving high biomass can be challenging, and thick mulch can interfere with soybean seed placement. An experiment was conducted from 2012 to 2014 in New York to test whether mixing barley and cereal rye would (1) increase weed suppression via enhanced shading prior to termination and (2) provide acceptable weed suppression at lower cover crop biomass levels compared with cereal rye alone. This experiment was also designed to assess high-residue cultivation as a supplemental weed management tool. Barley and cereal rye were seeded in a replacement series, and a split-block design with four replications was used with management treatments as main plots and cover crop seeding ratio treatments (barley:cereal rye, 0:100, 50:50, and 100:0) as subplots. Management treatments included high-residue cultivation and standard no-till management without high-residue cultivation. Despite wider leaves in barley, mixing the species did not increase shading, and cereal rye dominated cover crop biomass in the 50:50 mixtures in 2013 and 2014, representing 82 and 93% of the biomass, respectively. Across all treatments, average weed biomass (primarily common ragweed, giant foxtail, and yellow foxtail) in late summer ranged from 0.5 to 1.1 Mg ha−1in 2013 and 0.6 to 1.3 Mg ha−1in 2014, and weed biomass tended to decrease as the proportion of cereal rye, and thus total cover crop biomass, increased. However, soybean population also decreased by 29,100 plants ha−1for every 1 Mg ha−1increase in cover crop biomass in 2013 (P=0.05). There was no relationship between cover crop biomass and soybean population in 2014 (P=0.35). Soybean yield under no-till management averaged 2.9 Mg ha−1in 2013 and 2.6 Mg ha−1in 2014 and was not affected by cover crop ratio or management treatment. Partial correlation analyses demonstrated that shading from cover crops prior to termination explained more variation in weed biomass than cover crop biomass. Our results indicate that cover crop management practices that enhance shading at slightly lower cover crop biomass levels might reduce the challenges associated with excessive biomass production without sacrificing weed suppression in organic no-till planted soybean.


2019 ◽  
Vol 35 (5) ◽  
Author(s):  
Lamara Freitas Brito ◽  
João Carlos Cardoso Galvão ◽  
Jeferson Giehl ◽  
Steliane Pereira Coellho ◽  
Silvane de Almeida Campos ◽  
...  

The decomposition dynamics of cover crop mulch influence the nutrient supply of successor crops and weed suppression. This is even more relevant in organic production systems, due to their limited use of chemical fertilizers and herbicides. As such, the aim of this study was to quantify biomass production, model the decomposition and N, P and K release of the mulch of different cover crops, and assess the weed suppression of cover crops in the form of mulch and in consortium with organic maize. A randomized block design was used, with a 7x2 factorial scheme (7 cover crop management strategies and 2 cropping systems - maize in monoculture and intercropped with jack bean) and 4 replicates. The management practices that produced the most biomass were white lupine intercropped with black oat and the white lupine, black oat and sunflower monocultures. The use of cover crops did not differ from manual weeding in terms of weed biomass, but did affect the relative importance (RI) of nutgrass. Additionally, maize intercropped with jack bean reduced weed biomass in subsequent crop growth stages.


HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 998A-998
Author(s):  
Jose Linares ◽  
Johannes Scholberg ◽  
Carlene Chase ◽  
Robert McSorley ◽  
James Fergusson

Lack of effective weed control may hamper organic citrus establishment. Cover crop/weed biomass (CCW) indices were used to assess the effectiveness of annual and perennial cover crops (CC) in reducing weed growth. The CCW values for perennial peanut (PP) were 0.06, 0.14, 0.4, and 0.5 during 2002, 2003, 2004, and 2005, respectively (very poor to poor weed control). Initial PP growth was slow and repeated mowing was required, but, over time, PP became more effective in controlling weeds. Weed biomass with sunn hemp was 0.3 Mg/ha in 2002 (CCW = 25, outstanding weed control) compared to 1.4 Mg/ha with use of cowpea (CCW = 1) in 2004. In 2004, the dry weights (Mg/ha) for different summer CC were: hairy indigo = 7.6, pigeon pea = 7.6, sunn hemp = 5.3, cowpea = 5.1, alyce clover = 2.9, velvet bean = 1.3, and lablab bean = 0.8. Corresponding 2005 values were: 9.5, 3.7, 12.6, 1.0, 1.9, and 1.4. Respective CCWI values were: 7, 4, 2, 16, 28, 0.6, and 0.3 (2004) vs. 17, 2, 64, 80, 0.5, 2, and 14. In 2004, winter CC production (Mg/ha) was radish (R) = 3.2, crimson clover (CR) = 1.7, oats (O) + lupine = 1.6, and rye (WR)/vetch (V) mix = 1.1. Results for 2005 were: CR + R + WR = 8.0, WR = 6.0; CR + WR = 5.3, CR = 5.0, CR + O + WR = 5.0, R = 4.3, and O = 3.6 Mg/ha. Corresponding values for CCW-indices were 15, 2, 1, and 3 (2004) and 100, 25, 76, 35, 62, 11, and 16 (2005). Although OMRI-approved herbicides showed up to 84% weed injury for selected species, none of these products provided long-term weed control. Combination of repeated tillage, use of compact/reseeding CC mixes in tree rows, more vigorous annual CC and/or perennial PP in row middle and repeated use of organic herbicides near sprinklers and tree trunks are thus required to ensure effective weed suppression in organic citrus.


2020 ◽  
Vol 45 (2) ◽  
pp. 256-264
Author(s):  
T. F. Mbahi ◽  
S. Maidadi ◽  
Z. A. Gworgwor ◽  
Y. Danladi

An experiment was conducted to evaluate the effect of growth, biomas yieds and nutritive value of Lablab purpureus, Centrosema pubescens and Mucuna pruriens under rain fed condition in Yola, Adamawa State, Nigeria. The field experiment was laid in a randomized complete block design with the plot divided into three main plots and replicated three times measuring 5x5m with inter and intra row spacings of 0.5m. The five harvesting stages are 6, 8, 10, 12 and 14 weeks, respectively. The growth in height increases with stage of growth and declined with reduction in rainfall. Higher growth were recorded in T3 (3.8 -354.8cm) followed by T2 (2.96-260.20cm) and then T1 (1.50-213.00cm) and the results were presented graphically. The result of the chemical composition of all the legumes showed that the crude protein decreases with stage of growth from weeks 6 -14 (14.40, 12.26, 10.65-10.08, 6.79, 6.49) and ADF and NDF (25.20, 32.15, 27.35-42.13, 40.33, 36.50 and 32.20, 54.45, 47.00- 51.24, 63.53, 66.33), respectively. The biomass yields were significantly different (P<0.05) for all the legumes at different harvesting stages T1 (2744.53-3186.93), T2 (2696.47- 3006.70) and T3 (2843.73-3147.63). It is therefore concluded that legumes could best be harvested between weeks 10 and 12 when the yield and quality are at levels to sustain the animals both for maintenance and production.


Weed Science ◽  
2006 ◽  
Vol 54 (02) ◽  
pp. 326-334 ◽  
Author(s):  
Kevin S. Charles ◽  
Mathieu Ngouajio ◽  
Darryl D. Warncke ◽  
Kenneth L. Poff ◽  
Mary K. Hausbeck

Field studies were carried out in Laingsburg, MI, from 2002 to 2004 on Houghton muck soil to assess the impacts of cover crops and soil fertility regimes on weed populations and celery yield. The cover crops were oilseed radish, cereal rye, hairy vetch, and a bare ground control. The fertility rates were full (180, 90, and 450 kg ha−1nitrogen [N], phosphorus pentoxide [P2O5], and potassium oxide [K2O], respectively), half (90, 45, and 225 kg ha−1N, P2O5, and K2O, respectively), and low (90 kg ha−1N). Each cover crop treatment was combined with the low or half rate of fertilizer. An additional treatment with bare ground plus the full rate of fertilizer was added as standard practice. Treatments were maintained in the same location for the duration of the study. Major weed species were common chickweed, prostrate pigweed, shepherd's-purse, common purslane, and yellow nutsedge. Each year, oilseed radish consistently produced the greatest biomass and provided over 98% early season weed biomass suppression. Hairy vetch and cereal rye provided about 70% weed suppression in early spring. Soil fertility level affected weed populations during the 2004 growing season. In 2004, weed biomass in treatments without cover crops or with vetch increased when greater amounts of fertilizer were applied. Within individual fertility levels, higher celery yields were recorded in the oilseed radish plots. For example, in the low fertility rate, celery yield was 34.8, 29.2, 23.9, and 24.4 ton ha−1in the oilseed radish, cereal rye, hairy vetch, and control plots, respectively in 2003. Overall, the results of this experiment indicate that when included in a system where hoeing and hand-weeding are the only weed control methods, cover crops can successfully improve weed management and celery yield on muck soils, allowing reduced fertilizer inputs.


Weed Science ◽  
2021 ◽  
pp. 1-26
Author(s):  
Roberto Botelho Ferraz Branco ◽  
Fernando de Carvalho ◽  
João Paulo de Oliveira ◽  
Pedro Luis da Costa Alves

Abstract Cover crop residue left on the soil surface as organic mulch in no-tillage crop production provides several environmental benefits, including weed suppression. Thus, many farmers who use cover crops attempt to reduce the use of agricultural inputs, especially herbicides. Therefore, our objectives were to study the potential of different cover crop species to suppress weeds and produce an in situ organic mulch, and evaluate the effect of the organic mulch with and without spraying glyphosate on weed suppression for vegetable (tomato (Solanum lycopersicum L. and broccoli (Brassica oleracea L. var. botrytis) growth and yield. Five cover crop treatments (sunn hemp (Crotalaria juncea L.), jack bean [Canavalia ensiformis (L.) DC.], pearl millet [Pennisetum glaucum (L.) R. Br.], grain sorghum [Sorghum bicolor (L.) Moench ssp. bicolor] and a no-cover crop (control)) were used in the main plots; and spraying or no spraying glyphosate on the flattened cover crop in the sub plots of split-plot experimental design. Organic mulch from pearl millet, sorghum and sunn hemp resulted in lower weed biomass during the early season of both tomato and broccoli than jack bean and no-cover crop (control). Spraying glyphosate after roller crimping reduced weed biomass by 103 g m−2 and 20 g m−2 by 45 and 60 days after transplanting (DAT) of tomato, respectively and resulted in a better tomato yield compared to non spraying. Glyphosate reduced weed biomass by 110 g m−2 in the early season of broccoli (30 DAT), but did not affect yield. Terminating high biomass cover crops with a roller crimper is a promising technique for weed management in vegetable crops, which has the potential to reduce or even eliminate the need for herbicide.


Agronomy ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 319 ◽  
Author(s):  
Laura Vincent-Caboud ◽  
Léa Vereecke ◽  
Erin Silva ◽  
Joséphine Peigné

Organic farming relies heavily on tillage for weed management, however, intensive soil disturbance can have detrimental impacts on soil quality. Cover crop-based rotational tillage (CCBRT), a practice that reduces the need for tillage and cultivation through the creation of cover crop mulches, has emerged as an alternative weed management practice in organic cropping systems. In this study, CCBRT systems using cereal rye and triticale grain species are evaluated with organic soybean directly seeded into a rolled cover crop. Cover crop biomass, weed biomass, and soybean yields were evaluated to assess the effects of cereal rye and winter triticale cover crops on weed suppression and yields. From 2016 to 2018, trials were conducted at six locations in Wisconsin, USA, and Southern France. While cover crop biomass did not differ among the cereal grain species tested, the use of cereal rye as the cover crop resulted in higher soybean yields (2.7 t ha−1 vs. 2.2 t ha−1) and greater weed suppression, both at soybean emergence (231 vs. 577 kg ha−1 of weed biomass) and just prior to soybean harvest (1178 vs. 1545 kg ha−1). On four out of six sites, cover crop biomass was lower than the reported optimal (<8000 kg ha−1) needed to suppress weeds throughout soybean season. Environmental conditions, in tandem with agronomic decisions (e.g., seeding dates, cultivar, planters, etc.), influenced the ability of the cover crop to suppress weeds regardless of the species used. In a changing climate, future research should focus on establishing flexible decision support tools based on multi-tactic cover crop management to ensure more consistent results with respect to cover crop growth, weed suppression, and crop yields.


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