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Abstract Dryland agriculture is fundamental to global crop production and vital to food security. Conservation tillage is extensively practiced in USA wheat cultivation. Meanwhile, the adoption of conservation tillage by Chinese farmers is limited. This meta-analysis compared the yield and nitrogen use efficiency (NUE) between conservation tillage and conventional tillage (CT) with different types of cropping systems, mulching methods, levels of nitrogen fertilizer (NF), and addition of manure. The meta-analysis presented that conservation tillage at high-NF enhanced the yield and NUE, and reduced the yield and NUE at low-NF, compared to CT. The interaction of conservation tillage with leguminous cover crops (LCC) and manure application increased the yield and NUE at low-NF, compared to CT. Non-leguminous cover crops (NLCC) increased the yield and NUE under high-NF than low-NF. The interaction of conservation tillage with management practices showed that the no-tillage (NT) with leguminous cover crops (LCC) significantly increased wheat yield by 58% and NUE by 47% under low-NF compared to CT. However, increasing the rate of NF did not increase the yield under such interaction. Cropping systems, mulching types, and manure application mainly determined the effects of conservation tillage on wheat yield and NUE. The adverse impact of CT on yield and NUE could be alleviated with the application of LCC and manure under moderate NF. We demonstrate that adding LCC and manure have a generally substitutive relationship with N fertilizer, resulting in a significant increase in wheat yield and NUE at low-NF doses as at high N fertilizer dosages. Therefore, based on the obtained results, moderate NF with LCC and manure application is recommended for growing winter wheat in dryland regions of the USA and China.

Modern rice production faces the dual challenges of increasing grain yields while reducing inputs of chemical fertilizer. However, the disequilibrium between the nitrogen (N) supplement from the soil and the demand for N of plants is a serious obstacle to achieving these goals. Plant-based diagnosis can help farmers make better choices regarding the timing and amount of topdressing N fertilizer. Our objective was to evaluate a non-destructive assessment of rice N demands based on the relative SPAD value (RSPAD) due to leaf positional differences. In this study, two field experiments were conducted, including a field experiment of different N rates (Exp. I) and an experiment to evaluate the new strategy of nitrogen-split application based on RSPAD (Exp. II). The results showed that higher N inputs significantly increased grain yield in modern high yielding super rice, but at the expense of lower nitrogen use efficiency (NUE). The N nutrition index (NNI) can adequately differentiate situations of excessive, optimal, and insufficient N nutrition in rice, and the optimal N rate for modern high yielding rice is higher than conventional cultivars. The RSPAD is calculated as the SPAD value of the top fully expanded leaf vs. the value of the third leaf, which takes into account the non-uniform N distribution within a canopy. The RSPAD can be used as an indicator for higher yield and NUE, and guide better management of N fertilizer application. Furthermore, we developed a new strategy of nitrogen-split application based on RSPAD, in which the N rate was reduced by 18.7%, yield was increased by 1.7%, and the agronomic N use efficiency was increased by 27.8%, when compared with standard farmers’ practices. This strategy of N fertilization shows great potential for ensuring high yielding and improving NUE at lower N inputs.

Soil provides essential nutrients for plant growth, but excess salts hinder development, making crops more vulnerable under climate change conditions. Soil microorganisms play a significant role in nutrient cycling. However, limited information is available on microbial behavior/community changes, and functional diversity in different soil types (normal, sodic, and highly sodic) and cropping systems [rice-wheat (RW); rice-wheat-mungbean (RWMb); maizewheat-mungbean (MWMb)] and management practices in the north-western Indo-Gangetic Plains of India. We investigated the influence of different soil types on physical and chemical properties at the surface level (0-15 cm) in relation to soil microbial population, activities, and functional diversity, focusing on community-level physiological profiling (CLPP) under different agriculture systems. Seven treatment combinations of soil types, cropping systems, and management practices were evaluated. Soil pHs were found to be lower in zerotill (ZT)-based sodic soil than in conventional-till (CT) sodic soil. Soil organic carbon (SOC) (0.91 and 0.90%) content and available N (154.46 and 132.74 kg ha-1) were higher with the ZT-based system under normal (N) soils (ZT-RWMb-N and ZT-MWMb-N) than in CT-based normal soil (0.67 and 121.04 kg ha-1). Similarly, higher SOC and N (0.85 and 76.11 kg ha-1) were found under ZT management in sodic soils (S) than under CT management (0.73% and 121.05 kg ha-1). Substrate utilization (amino acids, amines, carbohydrates, carboxylic acids, phenolic compounds, and polymers) increased with the incubation period. During 0-120 h of incubation, the highest utilization of amino acids, amines, carboxylic acids, phenolic compounds, and polymers was observed for ZT-MWMb-S soils, while the lowest was recorded for ZT-MWMb-N soils. Under high salt conditions, soil enzymatic activities (dehydrogenase, acid phosphatase, alkaline phosphatase, etc.) declined significantly compared to normal soils, affecting soil chemical and physical conditions. Microbial population and enzyme activities decreased with increasing salt stress across all cropping systems. These findings suggest that adopting efficient crop management practices can help mitigate the adverse effects of soil salinity on microbial diversity and soil health, thereby enhancing sustainable agricultural productivity in salt-affected regions. [ABSTRACT FROM AUTHOR]

Soil provides essential nutrients for plant growth, but excess salts hinder development, making crops more vulnerable under climate change conditions. Soil microorganisms play a significant role in nutrient cycling. However, limited information is available on microbial behavior/community changes, and functional diversity in different soil types (normal, sodic, and highly sodic) and cropping systems [rice-wheat (RW); rice-wheat-mungbean (RWMb); maize-wheat-mungbean (MWMb)] and management practices in the north-western Indo-Gangetic Plains of India. We investigated the influence of different soil types on physical and chemical properties at the surface level (0–15 cm) in relation to soil microbial population, activities, and functional diversity, focusing on community-level physiological profiling (CLPP) under different agriculture systems. Seven treatment combinations of soil types, cropping systems, and management practices were evaluated. Soil pHs were found to be lower in zero-till (ZT)-based sodic soil than in conventional-till (CT) sodic soil. Soil organic carbon (SOC) (0.91 and 0.90%) content and available N (154.46 and 132.74 kg ha−1) were higher with the ZT-based system under normal (N) soils (ZT-RWMb-N and ZT-MWMb-N) than in CT-based normal soil (0.67 and 121.04 kg ha−1). Similarly, higher SOC and N (0.85 and 76.11 kg ha−1) were found under ZT management in sodic soils (S) than under CT management (0.73% and 121.05 kg ha−1). Substrate utilization (amino acids, amines, carbohydrates, carboxylic acids, phenolic compounds, and polymers) increased with the incubation period. During 0–120 h of incubation, the highest utilization of amino acids, amines, carboxylic acids, phenolic compounds, and polymers was observed for ZT-MWMb-S soils, while the lowest was recorded for ZT-MWMb-N soils. Under high salt conditions, soil enzymatic activities (dehydrogenase, acid phosphatase, alkaline phosphatase, etc.) declined significantly compared to normal soils, affecting soil chemical and physical conditions. Microbial population and enzyme activities decreased with increasing salt stress across all cropping systems. These findings suggest that adopting efficient crop management practices can help mitigate the adverse effects of soil salinity on microbial diversity and soil health, thereby enhancing sustainable agricultural productivity in salt-affected regions.

Among the essential plant nutrients, nitrogen (N) is the most important and universally deficient in rice cropping systems worldwide. Despite different practices available for improvement of N management, nitrogen use efficiency (NUE) is still very low in rice, particularly under conventional management practices. This study was conducted to assess the effect of two crop management practices including the system of rice intensification (SRI) versus conventional management practices (CP) with four N application levels (60, 90, 120, and 150 kg N ha−1) and absolute control (i.e., without N application) on rice growth, grain yield, and NUE. Experiments were established in split-plot randomized complete block design in three replicates. Crop management practices and N levels were treated as the main effect of main-plots and sub-plots, respectively with replicate blocks treated as random factors. Results indicated that deploying of SRI increased rice grain yield by 17.5 and 52.4% during wet and dry seasons, respectively compared with the CP. Rice grain yield was significantly (p < 0.05) higher in SRI than in CP at all levels of N application compared. The application of N at 120 and 60 kg ha−1 resulted in the increase in rice grain yields by 49 and 46.5%, respectively, relative to the absolute control during wet and dry seasons. Nitrogen application had a significant effect (p < 0.05) on agronomic nitrogen use efficiency (ANUE) and partial factor productivity (PFP). Results also indicated that agronomic nitrogen use efficiency (ANUE) was higher (27.2 kg grain kg−1 N) during the wet season with an application of 60 kg N ha−1. Furthermore, higher ANUE (23.8 kg grain kg−1 N) was recorded during dry season with an application of 90 kg N ha−1. The significant (p < 0.05) interaction effects of treatments were recorded on PFP between SRI and 60 kg N ha−1 during the wet (116.7 kg grain kg−1 N) and dry (105.8 kg grain kg−1 N) seasons. This study revealed that ANUE and PFP decreased with N application at the levels of 120 and 150 kg N ha−1 under SRI and CP during the two cropping seasons. The findings of the present study provide potential information that rice grain yield and higher NUE could be achieved at low N inputs under SRI, and thus reducing costs resulted from fertilizer inputs without compromising other environmental benefits.

Abstract Background Climate change without adaptation is projected to impact strongly the livelihoods of the rural communities. Adaptation to climate change is crucial for least developed country like Ethiopia due to high population and dependency on agriculture. Hence, this study was initiated to examine the barriers to and determinants of the choice of crop management strategies to combat climate change. The Intergovernmental Panel on Climate Change concepts of climate change response provided the framework. Stratified and snowball sampling techniques were employed to select a sample of 398 households. The household survey was employed to collect data on current adaptation strategies. Logistic regression was used to analyse the determinants of the choice of adaptation strategies. Logistic regression analyses were carried out at p ≤ 0.05. Results Small farmland size, agro-ecology, farmland location, financial constraints, and lack of skills were the major barriers to adoption of crop management strategies. Age, farming experience, income, family size, government experts’ extension services, agro-ecology setting, and crop failure history of households significantly affect the choice of most of the crop management strategies. Conclusions Socio-economic and institutional factors determined rural communities’ ability and willingness to choose effective adaptation strategies. Policy priority should be given based on agro-ecology and households demand of policy intervention such as providing extension services and subsidizing the least adopted strategies due to financial constraints.

Chickpea (Cicer arietinum L.) production in Ethiopia is exclusively rainfed. The average national yield remains low comparing to the potentially attainable yield because of the common notion among producers that the crop does not need any nutrient inputs. The newly developed high-yielding cultivars have brought significant yield gains. However, their genetic potentials are still hampered by the traditional crop management practices used and the problematic Vertisol growing conditions. Yields of chickpea grown on Vertisols are limited by poor drainage when sown early and by drought when sown late. This calls for optimization of the balance with minimum tradeoffs in key economic traits. Here, we review research progress on chickpea over the past five decades in Ethiopia, with particular emphasis on crop management practices. The paper gives a comprehensive overview of research findings and information generated on the Vertisol cropping systems, where chickpea is the principal rotational crop under cereal-legume cultivation entailing substantial role in cropping system intensification. It has been noted that the productivity of Vertisol-grown chickpea is largely constrained more by lack of the use of best bet crop management practices than the genetics of a given cultivar. For instance, raised-bed method as compared to the conventional flatbed increased grain and biomass yields by about 74% and 58%, respectively. The current average farm yield of chickpea in Ethiopia is about 55% of the yield potential of the crop, suggesting that farmers can still have rooms to substantially increase yield using improved practices. Based on the cumulative evidences, it can be concluded that the yield potentials of genetically elite cultivars may not be realized without synergistic combination of improved management practices and adequate nutrient use. We, therefore, recommend the integrated use of improved crop management strategies, while the soil physical properties still deserve utmost research attention. [ABSTRACT FROM AUTHOR]

Feeding the world in 2050 requires us to find ways to boost yields of the main local crops. Among those crops, cowpea is one of the grain legumes that is playing an important role in the livelihood of millions of people in West Africa, especially in Benin. Unfortunately, cowpea on-farm yields are very low. In order to understand the main factors explaining cowpea yield gaps, we collected and analyzed detailed survey data from 298 cowpea fields in Benin during the 2017, 2018 and 2019′s rainy seasons, respectively. Composite soil samples were collected from cowpea fields and analyzed in the laboratory. Data on farm field management practices and field conditions were recorded through interviews with 606 farmers. Average cowpea grain yields were low and seldom surpassed 700 kg ha−1 on farmer’s fields. Significant differences were observed between cowpea grain yields from northern to southern Benin (p < 0.05), and the lowest yields were observed in northern Benin. These low yields are related to crop management practices, soil nutrient contents, and the interaction of both. According to the model of regression tree from northern to southern Benin, the use of mineral fertilizer, insecticide sprays to control pests, and the improvement of phosphorus, nitrogen, potassium (P, N, K) and cation sum content in the topsoil would increase cowpea grain yields. Insect pests, diseases, and soil fertility decline are the largest constraints limiting grain yield in Benin. Future research should focus on formulating site-specific fertilizer recommendations for effective cowpea cultivation in Benin, as well as the control of insect pests and diseases.

The contribution is aimed at the assessment of recommended crop management practices of chosen cereals for organic farming. To increase competitiveness, these practices are modified depending on soil and climatic conditions, and on a way of production use. Furthermore, impacts of the recommended crop management practices on economics of growing chosen cereals are evaluated and compared with economic results obtained under conventional farming. It is assumed that achieved results will contribute to the increase in proportion of arable crops in the Czech Republic where organic production offer does not meet current demands.When evaluating results of growing individual cereal species in a selective set of organic farms, triticale, spelt and spring barley (in this ranking) can be considered as profitable crops. Moreover, triticale and spelt have even higher gross margin under organic farming than under conventional farming (by 62 % in triticale). Oat brings losses, however, it is important for livestock production. Winter wheat seems to be also unprofitable since less grain is produced at lower imputs per hectare and only part of it is produced in quality “bio”, i.e. marketed for higher prices. Rye also brings losses under organic farming, particularly due to lower yields, similarly to the other mentioned cereals. Special cereal species that are still neglected in organic farming systems are of potential use. Durum wheat has vitreous kernels with a high content of quality gluten which is used for pasta production. It can be grown in the maize production area on fertile soils only.

Highlights: [•] This is the first experimental test of the impact of crop diversity on biodiversity. [•] Plots with higher crop genetic diversity hosted more diverse arthropod communities. [•] Crop homogenization may thus contribute to biodiversity loss in agroecosystems. [Copyright &y& Elsevier]

Abstract: Computerised integrated models from science contribute to better informed and holistic assessments of multifaceted policies and technologies than individual models. This view has led to considerable effort being devoted to developing integrated models to support decision-making under integrated water resources management (IWRM). Nevertheless, an appraisal of previous and ongoing efforts to develop such decision support systems shows considerable deficiencies in attempts to address the hydro-socio-economic effects on livelihoods. To date, no universal standard integration method or framework is in use. For the existing integrated models, their application failures have pointed to the lack of stakeholder participation. In an endeavour to close this gap, development and application of a seasonal time-step integrated model with prediction capability is presented in this paper. This model couples existing hydrology, agronomy and socio-economic models with feedbacks to link livelihoods of resource-constrained smallholder farmers to water resources at catchment level in the semi-arid Olifants subbasin in South Africa. These three models, prior to coupling, were calibrated and validated using observed data and participation of local stakeholders. All the models gave good representation of the study conditions, as indicated by the statistical indicators. The integrated model is of general applicability, hence can be extended to other catchments. The impacts of untied ridges, planting basins and supplemental irrigation were compared to conventional rainfed tillage under maize crop production and for different farm typologies. Over the 20years of simulation, the predicted benefit of untied ridges and planting basins versus conventional rainfed tillage on surface runoff (Mm3/year) reduction was 14.3% and 19.8%, respectively, and about 41–46% sediment yield (t/year) reduction in the catchment. Under supplemental irrigation, maize yield improved by up to 500% from the long-term average yield of 0.5 t/ha. At 90% confidence interval, family savings improved from between US$ 4 and US$ 270 under conventional rainfed to between US$ 233 and US$ 1140 under supplemental irrigation. These results highlight the economic and environmental benefits that could be achieved by adopting these improved crop management practices. However, the application of various crop management practices is site-specific and depends on both physical and socio-economic characteristics of the farmers. [Copyright &y& Elsevier]

Abstract: Oil of conventional oilseed rape (OSR) varieties with 7–10% alpha-linolenic acid content (LAC) might oxidize when heated, resulting into an unpleasant odor. Varieties with low (around 3%) LAC have been bred to provide industries with a new raw material for frying media production. However, high-oleic low-linolenic (HOLL) OSR quality could be compromised by conventional OSR through pollen flow or volunteers. Both nearby fields and volunteers of conventional OSR growing in the HOLL field or in its margins could thus be the cause of a reduced quality. Crop management practices such as regional field pattern, crop rotation, weed control and soil tillage might be decisive. The GeneSys model was initially developed to quantify the effects of cropping systems on gene flow between genetically-modified (GM) and non-GM crops. In this work, it was improved and then used to predict LAC of OSR harvests, particularly HOLL ones, in different situations. Field experiments carried out at the experimental station in Changins (VD), Switzerland, in 2005–2006 showed that LAC was controlled by two additive quantitative genes. Consequently, an additive model was used for calculations with GeneSys. Results also showed that beyond a 20m distance, a field of conventional OSR caused only a minor increase in LAC in a neighbouring HOLL OSR field, meaning that it is highly unlikely that pollen dispersal will compromise HOLL OSR quality under farmers’ conditions. These data were also used to evaluate the prediction quality of GeneSys. Briefly, the final LAC was slightly underestimated by the model, especially in the case of a high amount of conventional OSR volunteers leading to high LAC. Both experiments and simulations showed that the presence of volunteers of conventional OSR in the HOLL field had the most dramatic effect. In a short crop rotation, an important amount of volunteers significantly increased the LAC, but this can be controlled by adequate tillage and weed control in other crops of the rotation. Furthermore, in Switzerland, OSR is usually grown with an interval of at least 4 years in normal crop rotations, which is usually enough to prevent major contamination by volunteers if they are correctly managed. [Copyright &y& Elsevier]

Abstract: An experiment was conducted from spring 2001 to 2005 at Blackville, SC, to determine the impact of no-till and glyphosate-resistant crops on changes in the weed community. Glycine max (L.) Merr. (soybean) was grown in 2001 and 2003, and Zea mays L. (corn) was grown in 2002 and 2004. Tillage each year included no-tillage and conventional tillage (disking and field cultivation prior to crop sowing). Glyphosate-only and nonglyphosate programs were evaluated within each tillage system. Soil cores were collected at 0–5 and 5–10cm depths prior to spring to estimate the seedbank. Weed biomass by species was determined in mid-summer each year, except in 2003. Twenty-seven species were found in soil collected from the test site throughout the study. Digitaria sanguinalis (L.) Scop. (large crabgrass), Amaranthus palmeri S. Wats. (Palmer amaranth), and Mollugo verticillata L. (carpetweed) were the dominant weeds in soil at initiation of the experiment. Summer annual grasses comprised more than 20% of total weed biomass in 2001, but less than 1% of total biomass in 2002 and 2004. D. sanguinalis seed density in soil was reduced rapidly in all management systems and was replaced by Dactyloctenium aegyptium (L.) Willd (crowfootgrass) as the dominant summer annual grass. There was an 80–99% reduction in the A. palmeri seed density (0–5cm depth) during the first year of the study and M. verticillata became the dominant summer annual broad-leaved weed. Perennial weeds comprised <10% of the total weed biomass in 2001, but by 2004, >99% of the total weed biomass was made up of perennial weeds in nonglyphosate systems regardless of tillage treatment. These perennial weeds consisted of Cynodon dactylon (L.) Pers. (bermudagrass), Cyperus rotundus L. (purple nutsedge), and Solanum carolinense L. (Carolina horsenettle). The seed density in soil of most species declined over the four cropping seasons. [Copyright &y& Elsevier]

Among the essential plant nutrients, nitrogen (N) is the most important and universally deficient in rice cropping systems worldwide. Despite different practices available for improvement of N management, nitrogen use efficiency (NUE) is still very low in rice, particularly under conventional management practices. This study was conducted to assess the effect of two crop management practices including the system of rice intensification (SRI) versus conventional management practices (CP) with four N application levels (60, 90, 120, and 150 kg N ha -1 ) and absolute control (i.e., without N application) on rice growth, grain yield, and NUE. Experiments were established in split-plot randomized complete block design in three replicates. Crop management practices and N levels were treated as the main effect of main-plots and sub-plots, respectively with replicate blocks treated as random factors. Results indicated that deploying of SRI increased rice grain yield by 17.5 and 52.4% during wet and dry seasons, respectively compared with the CP. Rice grain yield was significantly (p < 0.05) higher in SRI than in CP at all levels of N application compared. The application of N at 120 and 60 kg ha -1 resulted in the increase in rice grain yields by 49 and 46.5%, respectively, relative to the absolute control during wet and dry seasons. Nitrogen application had a significant effect (p < 0.05) on agronomic nitrogen use efficiency (ANUE) and partial factor productivity (PFP). Results also indicated that agronomic nitrogen use efficiency (ANUE) was higher (27.2 kg grain kg -1 N) during the wet season with an application of 60 kg N ha -1 . Furthermore, higher ANUE (23.8 kg grain kg -1 N) was recorded during dry season with an application of 90 kg N ha -1 . The significant (p < 0.05) interaction effects of treatments were recorded on PFP between SRI and 60 kg N ha -1 during the wet (116.7 kg grain kg -1 N) and dry (105.8 kg grain kg -1 N) seasons. This study revealed that ANUE and PFP decreased with N application at the levels of 120 and 150 kg N ha -1 under SRI and CP during the two cropping seasons. The findings of the present study provide potential information that rice grain yield and higher NUE could be achieved at low N inputs under SRI, and thus reducing costs resulted from fertilizer inputs without compromising other environmental benefits., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s).)

• Mixtures of wheat varieties did not increase abundance and richness of Collembola. • Wheat traits explained 13 % of species assemblages of Collembola. • Wheat traits explained 11 % of trait assemblages of Collembola. • Wheat sensitivity to fungal diseases explained 4.7 % of trait assemblages of Collembola. • Soil features explained 10.8 % of species assemblages of Collembola. The genetic diversity of cultivated crops has decreased continuously since the beginning of the 20th century, because of the gradual replacement of genetically heterogeneous traditional varieties by new genetically homogenous varieties, grown in monospecific stands. The resulting agro-ecosystems are now considered as unsustainable. Increasing within-field genetic crop diversity by using a mixture of varieties could increase the sustainability of these agro-ecosystems. This could also potentially increase non-crop biodiversity. In the present study we used an experimental approach to test whether the number of wheat varieties (genetic diversity), the number of functional groups (functional diversity), the composition of functional groups and wheat traits influence (1) species richness and abundance of Collembola, and (2) species and trait assemblages of Collembola. A total of 104 plots were seeded with either monocultures or mixtures of 2, 4 and 8 wheat varieties. Soil cores were collected in each plot to extract Collembola and measure soil features. The number of wheat varieties and the functional wheat diversity did not influence the abundance and species richness of Collembola. The sensitivity of wheat to septoria leaf blotch was positively related to abundance and species richness of Collembola, while specific root length was positively related to collembolan species richness. Wheat traits related to sensitivity to fungal diseases, (more especially septoria leaf blotch) and characteristics of aerial parts and roots impacted collembolan species and trait assemblages, but these effects were weak. Soil features, especially the proportion of coarse silt, were also influential. Our study did not show a favorable impact of wheat genetic diversity on soil Collembola, which might result from their low abundance. Nevertheless, it suggests correlations between some variety traits and the species richness and abundance of Collembola. [ABSTRACT FROM AUTHOR]

Feeding the world in 2050 requires us to find ways to boost yields of the main local crops. Among those crops, cowpea is one of the grain legumes that is playing an important role in the livelihood of millions of people in West Africa, especially in Benin. Unfortunately, cowpea on-farm yields are very low. In order to understand the main factors explaining cowpea yield gaps, we collected and analyzed detailed survey data from 298 cowpea fields in Benin during the 2017, 2018 and 2019′s rainy seasons, respectively. Composite soil samples were collected from cowpea fields and analyzed in the laboratory. Data on farm field management practices and field conditions were recorded through interviews with 606 farmers. Average cowpea grain yields were low and seldom surpassed 700 kg ha−1 on farmer's fields. Significant differences were observed between cowpea grain yields from northern to southern Benin (p < 0.05), and the lowest yields were observed in northern Benin. These low yields are related to crop management practices, soil nutrient contents, and the interaction of both. According to the model of regression tree from northern to southern Benin, the use of mineral fertilizer, insecticide sprays to control pests, and the improvement of phosphorus, nitrogen, potassium (P, N, K) and cation sum content in the topsoil would increase cowpea grain yields. Insect pests, diseases, and soil fertility decline are the largest constraints limiting grain yield in Benin. Future research should focus on formulating site-specific fertilizer recommendations for effective cowpea cultivation in Benin, as well as the control of insect pests and diseases. [ABSTRACT FROM AUTHOR]