Cowpea Monoculture Research Articles

Can natural undisturbed revegetation restores soil organic carbon to levels under native climax vegetation under tropical semiarid climate?

AbstractLand‐use change has driven soil carbon stock losses in ecosystems worldwide. Implementing agricultural crops and exploiting forest resources trigger the breakdown of soil aggregates, thus exposing organic matter to microbial decomposition and enhancing carbon dioxide emissions, especially in biomes more susceptible to climate extremes as in the tropical semiarid regions. This study was based on the hypothesis that the undisturbed soil from the dry forest (Caatinga biome under natural revegetation in Brazilian semiarid) would have an improvement in the mass of macroaggregates and recover more than 50% of the soil C stock within 10 years. Thus, a field experiment was conducted to investigate soils from the Caatinga biome under native vegetation, “cowpea cropping” for over 30 years, and soil under natural revegetation for over 10 years, after conventional soil cultivation of maize and cowpea, to determine soil and soil‐aggregates carbon stocks and to estimate the recovery rate of these stocks. The proportional mass of aggregates of different sizes and the total stock of particulate organic carbon (POC) were also quantified. The results showed that soil under preserved native vegetation of dry forest Caatinga biome had higher total soil C stock (50.9 Mg ha−1) than that under cowpea cropping (23.2 Mg ha−1) and natural revegetation (45.1 Mg ha−1). The proportional mass of large macroaggregates was higher in soil under native vegetation for all depths. However, soil under cowpea cropping had lower C stocks in macroaggregates, and recovered roughly 63% of the original C stocks, while revegetation recovered 78% of the stock in 10 years. Although the conventional management system for cowpea monoculture aggravated losses in soil carbon stock by more than 50% of the original C stocks, dry forest under natural revegetation recovered 79% of this stock and almost 100% of POC stock in 10 years (~12 Mg ha−1). Furthermore, soil under undisturbed Caatinga dry forest achieved C stock levels equivalent to that of the global average range for semiarid tropical environments. The high recovery rate of C stock in forest soil under natural revegetation indicates the resilience potential of organisms responsible for structural protection of aggregates and the encapsulated soil organic matter content.

English

Intercropping is considered as an improved system of multiple cropping systems which safeguards crop stand and improves crop production. The main goal of intercropping is to produce high yield from piece of a land by judicious use of available resources which otherwise may not be exploited by a single crop. A study was executed to investigate productivity and resource use in a maize–grain legume intercropping at University of Agriculture, Faisalabad during 2017 and 2018. Experimental treatments included maize, mungbean, mash-bean, and cowpea monocultures (sole crops), and intercropping combinations of maize + mungbean, maize + mash-bean, and maize + cowpea. Highest maize grain yield was observed in maize sole cropping (6520 and 6813 kg ha-1) and maize + mungbean intercropping (6375 and 6542 kg ha-1) during 2017 and 2018 growing seasons, respectively. Maximum seed yield in grain legumes was observed in mung and mash bean sole cropping during both years. Land equivalent ratio (LER) was maximum in maize + cowpea (1.83 and 1.87) and maize + mungbean intercropping (1.77 and 1.80) during both years, respectively. Maximum net economic return (ER) of PKR 134158 ha-1 (≈900 USD) was obtained from maize + mash bean intercropping system with highest benefit cost ratio (2.03) during 2017 while PKR 149358 ha-1 (≈1003 USD) along with benefit cost ratio (2.15) during 2018. Overall, LER and ER results indicated that maize-grain legume intercropping systems were beneficial in terms of land resource utilization and economic returns. The maize-grain legume intercropping systems are more sustainable option for small land-holding farmers in Pakistan. © 2021 Friends Science Publishers

GROWTH AND RESULTS OF CORN AND NUTS IN THE INTERCROPPING SYSTEM

The purpose of this study was to determine the growth and yield of corn and cowpea after planting in the intercropping system. Conducting research at the Kalitirto Agricultural Research and Development (KP4) Educational Garden, Berbah, Yogyakarta friend. A Complete Randomized Block Design with 3 replications was used in the study. Experimental intercropping of corn and cowpea based on additive series system. The first factor is the population of cowpea is without cowpea, 1 row, 2 rows, and 3 rows of cowpea. The second factor is the spacing is 100 cm x 20 cm and 80 cm x 25 cm. Research on cowpea monoculture as a comparison.The results obtained (1) insertion of cowpea, and spacing of corn did not affect the yield of corn per hectare, but affect the yield of cowpea. (2) The combination of 100 cm x 20 cm corn spacing treatment with the insertion of 2 rows of cowpea gives the highest Land Equity Ratio value of 1.42.

Intercropped Watermelon for Weed Suppression in a Low-input Organic System

The inclusion of a smother crop used as a cash crop in an intercropping system may be an effective cultural control strategy for the management of weeds in organic production systems. In addition, a multilayered canopy created when intercropping species with different growth forms may limit germination cues for weed seeds and can allow for a more efficient utilization of resources that reduce competition to target crops from weeds. Watermelon (Citrullus lanatus) was evaluated for its ability to reduce weeds in a low-input organic system in Texas when planted alone or in various intercropping combinations that also included peanut (Arachis hypogaea), okra (Abelmoschus esculentus), cowpea (Vigna unguiculata), and hot pepper (Capsicum annuum). Watermelon significantly reduced total weed biomass when planted in monoculture and in all intercropping combinations compared with peanut, okra, cowpea, and pepper monocultures in year 1 of the 2-year study. Total weed biomass was reduced by 81%, 83%, 88%, and 92% in treatments containing watermelon on average as compared with pepper, peanut, okra, and cowpea grown in monoculture, respectively. Less effective weed suppression was obtained with watermelon in year 2. Pepper grown in monoculture had significantly higher weed biomass than all other treatments in year 2. Broadleaf weeds were effectively suppressed across all intercropping treatments in year 1, but nutsedges (Cyperus sp.) were consistently reduced both years, particularly when compared with monocrops with small leaf area such as pepper. The three and four species intercropping combinations consistently had high leaf area index (LAI) values, whereas pepper monoculture had significantly lower LAI values than all other treatments except for cowpea monoculture. There was a significant negative relationship between LAI and total weed biomass 33 d after last planting (r = −0.51, P < 0.01). There was a significant negative relationship between total weed biomass and total fruit yield in year 1 (r = −0.64, P < 0.01) but no significant relationship in year 2. Although findings were inconsistent in year 2 because of changes in precipitation amounts and in relative planting dates, these findings suggest that incorporating a multifunctional intercropping system that includes a low-growing vining crop such as watermelon or at least an architecturally complex mixture can optimize canopy density to reduce weed pressure from resilient perennial weeds such as nutsedge. This may offer organic producers another management tool for the control of perennial weeds.

English

Intercropping of maize and cowpea is widely used by Brazilian family farmers. The aim of this work is to compare the grain yield of two maize cultivars, and one cultivar of cowpea in organic system. Treatments of monoculture of cowpea (Poços de Caldas) and maize ('BR106' and 'AG1051') and intercropping were used. A randomized block design with four replicates in an area under conversion to organic production system was used. The experiment was conducted in the period of October 2012 to March 2013, corresponding to the periods of spring/summer. The maize alone was on average, 26.5 cm taller and grain yield was 28% higher than in the intercropping. The cowpea intercropped with maize 'AG 1051' was 3.8 cm taller than the intercropped with 'BR 106'. In monoculture, the cowpea presented more (0.7 and 1.2 grain per pod when intercropped with 'AG 1051' and 'BR 106', respectively). The cowpea monoculture resulted in 2.4 pods per plant than in intercropping and productivity was 5.4 times higher than that of the intercropping. The cowpea intercropped with 'BR 106' was efficient, while that with 'AG1051' was inefficient in terms of land equivalent coefficient. Key words: Vigna unguiculata, Zea mays, land equivalent coefficient.

Nitrogenase Activity and Nodule Biomass of Cowpea (Vigna unguiculata L. Walp.) Decrease in Cover Crop Mixtures

Legume cover crops are often used to build soil nitrogen (N) fertility and there is increasing interest in cover crop mixtures. The objective of this mechanistic greenhouse study was to determine the effect of cover crop community diversity and soil fertility on nitrogenase activity and nodule biomass of cowpea. Cover crops were grown for 42–53 days, aboveground biomass was harvested, and nitrogenase activity was estimated with the acetylene reduction assay. Roots were then excavated to determine nodule and root biomass. Nitrogenase activity and nodule biomass per plant were greatest in cowpea monoculture and reduced by 71–98 percent in four-species mixtures. Reduced capacity for N2 fixation was partially driven by lower cowpea biomass in mixtures. The ratio of root nodule / shoot biomass increased by 81–297 percent in low-fertility relative to high-fertility soils, which contributed to increased nitrogenase activity. Results suggest cowpea monocultures in low-fertility soils have the greatest potential for N2 fixation.

Local Crop Planting Systems Enhance Insecticide-Mediated Displacement of Two Invasive Leafminer Fly

Liriomyza sativae and L. trifolii are highly invasive leafminer pests of vegetable crops that have invaded southern China in recent years. Liriomyza sativae was the first of these species to invade China, but it is now being displaced by L. trifolii. The rate and extent of this displacement vary across southern China. In Hainan, monocultures of highly valuable cowpea are planted and treated extensively with insecticides in attempts to control leafminer damage. In Guangdong, cowpea fields are interspersed with other less valuable crops, such as towel gourd (Luffa cylindrica), which receive significantly fewer insecticide applications than cowpea. To determine how differences in cropping systems influence the Liriomyza species composition, we conducted field trials in 2011 and 2012 in Guangdong where both species were present. We replicated conditions in Hainan by planting cowpea monocultures that were isolated from other agricultural fields, and we replicated conditions in Guangdong by planting cowpea in a mixed crop environment with towel gourd planted in neighboring plots. We then compared leafminer populations in cowpea treated with the insecticide avermectin and untreated cowpea. We also monitored leafminer populations in the untreated towel gourd. Untreated cowpea and towel gourd had comparatively low proportions of L. trifolii, which remained relatively stable over the course of each season. Avermectin applications led to increases in the proportions of L. trifolii, and after three weekly applications populations were >95% L. trifolii in both crop systems. However, the rate of change and persistence of L. trifolii in the mixed crop system were less than in the monocrop. These results indicate that L. trifolii is much less susceptible to avermectin than is L. sativae. Further, L. sativae was able to persist in the untreated towel gourd, which probably enabled it to recolonize treated cowpea.

Effect of intercropping cowpea with maize or cassava on cowpea bacterial blight and yield

The effect of intercropping cowpea (Vigna unguiculata (L.) Walp.) with cassava (Manihot esculenta Crantz) or maize (Zea mays L.) on bacterial blight of cowpea caused by Xanthomonas axonopodis pv. vignicola was investigated in five cropping systems: cowpea monoculture at high density and at low density, cowpea-maize ‘within row’, cowpea-maize ‘in alternate rows’, and cowpea-cassava ‘in alternate rows’, in the forest savanna transition zone of Benin over two years. After inoculation of field border plants, disease severity index and incidence were measured as areas under the disease progress curve (AUDPC). The AUDPCs for disease incidence and severity were reduced in one of four treatments in each of two subsequent years, and one of four treatments in one year, respectively, in the ‘in alternate row’ patterns compared to monoculture at high density. Disease incidence was higher in cowpea monoculture at high density than in cowpea-cassava ‘in alternate rows’ in year 1996, and in cowpea-maize ‘in alternate rows’ in year 1997. The disease severity index was reduced by 50% in the cowpea-cassava ‘in alternate rows’ pattern in 1997, but not in 1996. Highest percentages of leaves with spots or blight occurred only in the cowpea monoculture at high density. Compared with monoculture, cowpea yield was about 60% in intercropping with cassava and about 40% in intercropping with maize. Cassava yielded 45–57% and maize 53–60% compared to monocropped cassava and maize, respectively. Comparing the land efficiency use of cowpea monoculture at high density to intercropping, the land equivalent ratio was similar in the intercropping systems with ‘alternate row’ patterns, and a yield loss of cowpea in intercropping was compensated by the additional yield of the intercrop. Although no stable effect of intercropping on disease reduction was observed, intercropping cowpea with maize or cassava ‘in alternate rows’ reduced bacterial blight in some cases and generally gives the farmer more yield security in case of failure of one crop. Therefore, intercropping as one element of an integrated control strategy for cowpea bacterial blight should not be abolished by farmers in favour of monocropping cowpea.

Farmer-participatory evaluation of cowpea integrated pest management (IPM) technologies in Eastern Uganda

A three-season study was conducted with the goal of verifying integrated pest management (IPM) technologies developed at Makerere University for management of cowpea field pests. Ten IPM-field schools with 10–20 farmers were run for three consecutive seasons of 2000 A (first rains), 2000 B (second rains), and 2001 A. Each school evaluated seven treatments that included farmers’ practices; cowpea monoculture and cowpea/sorghum intercrop mixtures, and five varying insecticide spray regimes. The key insect pests targeted by the sprays included aphids, Aphis craccivora Koch, flower thrips, Megalurothrips sjostedi Trybom, the legume pod borer, Maruca vitrata Fabricius (formerly M. testularis Geyer), and a range of pod sucking bugs (i.e., Nezera viridula Linnaeus, Clavigralla tomentosicollis Stal., Riptortus dentipes Fab.). The experiment was a randomized complete block design with farms (i.e., field schools) as replicates. Results indicated that combining cultural practices and spraying once each at budding, flowering, and podding stages was more effective and profitable than spraying cowpea weekly throughout the growing season. An IPM practice which combined early planting, close spacing cowpea (30×20 cm 2), and three insecticide applications once each at budding, flowering and podding stages, had the highest yields of 791 kg/ha with a 51% yield gain over the farmers’ traditional practices. Farmer evaluation over the three seasons revealed that this practice was most preferred by farmers, with a farmer preference of 46.4%, 57.1%, 71.4%, and 89.3% at planting, vegetative, flowering and harvesting evaluation stages, respectively.

Sorghum-cowpea Intercropping: An Effective Technique Against Runoff and Soil Erosion in the Sahel (Saria, Burkina Faso)

In the Central Plateau of Burkina Faso, runoff on bare soil amounts to 40% of annual rainfall and soil losses reach 4 to 8 Mg ha-¹ a-¹, despite slopes of under 3%. Several studies have shown that mulching the soil surface can reduce runoff by over 60%. However, the scarcity of straw and the incompatibility of mulching with mechanical soil preparation have prevented the large-scale adoption of the technique. The study conducted in Saria village where annual rainfall is 800 mm,set out to evaluate the efficacy of sorghum-cowpea intercropping in reducing runoff and erosion. The study design comprised five plots set up so as to recover runoff and transported solids, on a Ferric lixisol with a slope of 0.7%. Three years results showed that sorghum-cowpea intercropping reduces runoff by 20-30% compared to a sorghum monoculture and by 45-55% compared to a cowpea monoculture. Soil loss is also reduced with intercropping by at least a half compared to sorghumand cowpea monoculture. Moreover, it transpired that sorghum-cowpea intercropping is also beneficial in agricultural production terms, since the grain yield of the intercropped plots was double that obtained with sorghumor cowpea monocultures. The better crop production can be an asset for the widespread use of this technique in the country. An evaluation of the advantages of the legume in terms of nitrogen supplies to the cereal (N 2 symbiotic fixation) and of added soil OM will be useful in improving the cost-effectiveness of such a technique.

Effect of cowpea monocultures and polycultures with sorghum and greengram on predatory arthropods

SUMMARYPrior to implementing biological control, knowledge on availability of the possible enemies of pest(s) is important. Therefore, as part of a larger on‐farm study whose main objective was to develop a farmer‐friendly package for the management of cowpea pests, the diversity and abundance of insect predators within cowpea cropping systems (sole crops and intercrops) were monitored at three diverse locations in eastern Uganda. Coccinellids, syrphid larvae, spiders, Orius sp. and earwigs were observed at all locations. Abundance of Coccinellids and syrphid larvae were not influenced by the cowpea genotype nor cropping systems. Contrastingly, the abundance of predatory Orius sp., spiders and earwigs differed significantly among the cowpea cropping systems, being more common in the cowpea pure stands and cowpea + greengram than in the cowpea + sorghum intercrops.

Weed interference in maize, cowpea and maize/cowpea intercrop in a subhumid tropical environment. III. Influence of land preparation

SummaryThe influence of no‐tillage and conventional tillage on the outcome of early weed interference in maize (Zea mays L., cv. TZB), cowpea [Vigna unguiculata (L.) Walp, cv. VITA‐5] and their intercrop at populations of 40000, 50 000 and 30 000 + 40 000 plants ha−1 was investigated on a loamy sand Oxic Ustropept in a subhumid tropical environment between April and July 1980. Both tillage treatments received 60 kg N, 30 kg P2O5 and 30 kg K2O ha−1. Although the weed spectrum was wider under no‐tillage, weed weight was only 52% of the weight recorded under conventional tillage 6 weeks after sowing and the average food energy yield reductions caused were 28 and 65%, respectively. Cropping pattern had no effect on plot weediness. With minimum or no weed interference, maize performance was better in conventional than no‐tillage but worse with prolonged weed interference. Cowpea responded more to weed interference than to tillage practice. Regardless of tillage practice and weed interference duration (up to 6 weeks) after sowing, maize monoculture produced the highest food energy yield, followed by maize/cowpea intercrop and cowpea monoculture in that order.