Most cocoa farms in Ghana are cultivated in complex agroforest systems, with plant growth and cocoa productivity being affected. The objective of this study was to investigate how shade trees affect cocoa yield, temperature and soil nutrients in low-input cocoa systems. Establishing plots on 24 farms in four locations (districts) in Ghana, we assessed the influence of varying canopy cover and fertilization on cocoa yields. Results showed no relationship between canopy cover and cocoa yields in the light crop season (February to August). For the main crop season (September to January), there was an interaction between shade and yields: Yields were higher on no-shade plots than on shaded plots in two districts, whilst there were no differences at the two other districts possibly due to differences in precipitation and soil nutrient status. On the other hand, there was a positive effect of increased canopy cover on yields within the shaded plots. Soil nutrient analyses revealed no significant differences between shaded and no-shade plots and adequate levels of N, K+, Fe2+, Cu2+ and Zn2+ were recorded. However, soil contents of P, C, Mg2+ and Ca2+ were below recommended values. Peak temperatures recorded in the cocoa canopies were above the recommended range for this species. Although shade trees had a slight modifying effect on peak temperatures, the magnitude appeared too small to have any practical effects.

Cotton–wheat is an important cropping system in South Asia. Introduction of BT cotton has caused the time conflict between sowing of BT cotton and wheat harvest in this cropping system. Wheat is harvested in late April but the best planting time of BT cotton is mid-March, which indicates a time conflict of 30–45 days between two crops in the region. However, this conflict can be managed by raising the cotton nursery and transplanting 30–45 days old seedlings in the field after wheat harvest. This two years field study was conducted to assess the economic feasibility of transplanting BT cotton in BT cotton–wheat cropping system at two locations (Multan, Vehari) in the cotton belt of Punjab, Pakistan. The BT cotton–wheat cropping systems included in the study were; flat sown wheat (FSW) – zero-tilled cotton (ZTC), FSW – conventional-tilled cotton (CTC), ridge sown wheat (RSW) – ridge-transplanted cotton (RTC) (30 days old seedlings), RSW – RTC (45 days old seedlings), bed sown wheat (BSW) – bed-transplanted cotton (BTC) (30 days old seedlings) and BSW – BTC (45 days old seedlings). BSW produced more grain yield than RSW and FSW during both years at both locations. Likewise, BTC (45 days old seedlings) had higher production at both sites during both years. The overall productivity of BT cotton–wheat, in terms of net income, benefit: cost ratio and marginal rate of returns, was the maximum from transplanting 45 days old cotton seedlings on beds after BSW during both years at both sites. Sowing cotton as ZTC following FSW was the least productive cropping system. In conclusion, transplanting 45 days seedlings of BT cotton on beds during late April after harvest of BSW wheat may be opted to manage the time conflict and improve the productivity of BT cotton–wheat cropping system in Punjab, Pakistan.

The main objective of this research was to utilize pollen monitoring methodology to predict olive yields in three Mediterranean olive cultivation areas (Spain, Italy and Tunisia) and their relationships with the olive oil price dynamics. Moreover, olive yield and olive oil production compared with olive oil price trends in the last two decades was evaluated. The statistical analyses confirmed that biological parameters such as the pollen emission, the pollen season start (Pss), the full flowering (Ff) date or the pollen season length (Psl) showed positive correlation values with productive parameters, especially the Pollen Index (Pi). However, the difficulty to define clear relationships with oil price for optimizing the marketing strategies can be due to the olive sector European policy and to the complex international olive oil market situation. The occurrence of unharvested trees was increased and the reduction in agricultural operations as well as non-harvesting could become more widespread above all in traditional extensive systems.

Low-cost methods for enhancement of seed longevity may facilitate biodiversity conservation especially in resource constrained situations. Longevity of 13 cucurbitaceous seed lots belonging to 12 species with mean moisture contents 9.3±0.7% was studied in hermetic storage (HS) and in a liquid consisting of 20% (w/w) CaCl2 in glycerol, following seed to preservative ratio of 1:1 (v/v), at ambient temperature for 24 years. The liquid preservative (LP) was not absorbed by the seeds over the storage period and was harmless to them, drying seeds to about 5% of moisture and maintaining them at this state throughout the storage period. The seeds lost viability in HS in 3.8±0.4 years, while in LP viability was lost in 14–16 years in eight species and the seeds were still viable in five species after 24 years. LP-preserved seeds and also fresh seeds of three species were planted under field conditions. The results validated the use of LP in seed storage for 24 years. The liquid preservation extended longevity of the cucurbit seeds at ambient temperature by drying them and probably maintaining them in oxygen-free environment.

In order to assess the response of four popularly grown black gram (Vigna mungo L.) genotypes (T9, PU 19, USJD 113, KU 301) under osmotic stress, the present study was carried out by monitoring the changes in relative leaf water content (RLWC), carotenoid, total soluble protein (TSP), membrane lipid peroxidation (MDA), H2O2 scavenging capacity, and the activities of superoxide dismutase (SOD) and catalase (CAT). Osmotic stress was applied by withholding irrigation for 15 consecutive days at vegetative, flowering and pod filling stages. Under stress condition, several fold increase in the content of MDA, H2O2 scavenging activity and antioxidant enzyme activity was recorded while, RLWC, carotenoid and TSP were found to decrease. Flowering stage was found to be most sensitive in terms of economic yield. The genotype T9 experienced lowest reduction in yield (12.10–33.91%) with maximum value of drought tolerance index (DTI) (7.48) which can be attributed to its higher tolerance capacity to drought. On the other hand, USJD 113 had the highest yield loss (26.48–60.99%) and lowest DTI (6.07) value, indicating its susceptibility towards osmotic stress.

Improving farmers’ knowledge of new technologies and creating conducive learning opportunities, with particular attention to the marginalized poor (women and youth), are major factors in the move towards sustainable agriculture. To explore the gender gap in agricultural knowledge acquisition and adoption in West Africa, we used baseline data collected in 2013 and 2014 in five countries (Benin, Côte d'Ivoire, Niger, Nigeria and Togo) with 499 surveyed households. The t-test and Kruskal–Wallis test were used for analysis. The most quoted source for acquiring knowledge on rice farming methods was ‘other farmers’, showing the importance of social capital for rural African farmers. In Benin, a gender gap was noted in rice farmers’ access to agricultural knowledge sources, with women being more advantaged. In Côte d'Ivoire, Niger, Nigeria and Togo, no significant gender gap was observed in rice farmers’ access to agricultural knowledge sources. Regarding the level of knowledge and use of rice farming methods in Côte d'Ivoire and Niger, significant gender gaps were observed. The gender approach to rural development is having impact in West Africa with regard to farmers’ access to agricultural information. However, interactive rural learning approaches (such as farmer-to-farmer video) need to be resorted to make the technologies’ principles well known and improve the ability of marginalized poor to adopt and or innovate with local or limited resources. This study leads to a better understanding of the relationship between gender, knowledge and use of agricultural technologies in order to enhance marginalized farmers’ adoption of improved innovations.

The crop rotation is a practice to protect and improve the soil properties and an alternative to improve the quality of crop residues is the application of fertilizers at the planting of cover crops. Thus, we evaluated the effect of fertilization with nitrogen, phosphorus and potassium (NPK) on organic matter production and chemical composition of cover crops succeeding the corn crop. The treatments consisted of the cultivation of Avena sativa L., Lupinus albus L., Pennisetum glaucum L., Raphanus sativus L. and Sorghum bicolor L. with (200 kg ha−1 of NPK [08-28-16] applied by broadcast seeding) and without fertilization at planting. Organic matter production by all cover crops, as well as concentrations of neutral detergent fibre (NDF) in shoots and roots of A. sativa L. and R. sativus L. were higher when they were fertilized. L. albus L. showed higher NDF and acid detergent fibre (ADF) contents than the other cover crops, with and without fertilization. Nitrogen concentration increased, but the carbon/nitrogen ratio (C/N) in the shoots of L. albus L., R. sativus L. and S. bicolor L. decreased when fertilization was applied. The use of N by the A. sativa L. and P. glaucum L. and of P and K by S. bicolor L. was 16, 54, 82 and 20% more efficient, respectively, when fertilization was applied. The A. sativa L., P. glaucum L. and R. sativus L. showed higher NDF/N, ADF/N and hemicellulose/N ratios in the fertilized treatment. Although the results obtained in this study are highly satisfactory, more research should be conducted to evaluate the decomposition of crop residues from cover crops fertilized with NPK, and the effects of this strategy on corn crops in succession.

Low soil pH and associated soil infertility problems are considered to be amongst the major challenges to barley production in the highlands of Ethiopia. In response to this, an experiment was conducted at low soil pH (< 5 H2O) site on the effects of different levels of lime and phosphorus (P) fertilizer on soil pH, exchangeable aluminium (Al3+), grain yield and yield components of barley during 2010 and 2011 cropping seasons. The experiment comprised factorial combinations of five lime rates (0, 0.55, 1.1, 1.65 and 2.2 t ha−1) and four P rates (0, 10, 20 and 30 kg ha−1) in a randomized complete block design in three replications. The amount of lime that was applied at each level was calculated on the basis of Al3+. Results of soil analysis after 2 years of liming showed that liming significantly (P < 0.05) increased soil pH, and markedly reduced exchangeable Al3+. Liming at the rate of 0.55, 1.1, 1.65 and 2.2 t ha−1 decreased Al3+ by 0.88, 1.11, 1.20 and 1.19 mill equivalents per 100 g of soil, and increased soil pH by 0.48, 0.71, 0.85 and 1.1 units, respectively. Amongst the liming treatments, liming at the rate of 1.65 and 2.2 t ha−1 gave significantly (P < 0.05) the highest grain yield and yield components of barley. However, grain yield obtained by applications of 1.65 and 2.2 t ha−1 lime was statistically comparable. By additions of 10, 20 and 30 kg P ha−1, grain yield of barley increased by about 29, 55 and 66% as compared to control (without P). During 2010, however, the combined applications 1.65 t ha−1 lime and 30 kg P ha−1 gave 133% more grain yields of barley relative to control (without P and lime). Therefore, sustainable barley production on acid soils in the central highlands of Ethiopia should entail combined applications of both lime and P fertilizer.

Cowpea (Vigna unguiculata L. Walp) is the most important food grain legume in Africa. Cowpea is nodulated by rhizobium bacteria in almost all soils of the tropics, but studies performed in the 1970s and 1980s in Nigeria suggested only modest responses of grain yield in the field to inoculation of selected rhizobium strains. More recently, experiments performed in Brazil have shown that cowpea responded to inoculation of rhizobium selected locally and grain yields increased by up to 30%. We tested some of the Brazilian strains on cowpea at a site in northern Mozambique and at several sites in Northern Ghana. At all sites phosphorus fertilizer (26 kg P ha−1) was added to all plots. At the site in Mozambique despite considerable damage to the crop by the parasitic yellow witchweed (Alectra vogelii), grain yields were more than doubled by inoculation of one of the Brazilian strains and reached 1.4 Mg ha−1. In on-station experiments conducted in 2012 in June and August in northern Ghana using the local cowpea variety Padi-Tuya as the test crop, nodule weight at 35 days after planting (dap) tripled with rhizobium strain BR 3299 (530 mg plant−1) in August with the other inoculants (BR 3267 and a mixture of BR 3267 and BR 3299) also increased nodule weight to over 300 mg plant−1. In the first on-station experiment, grain yields were doubled by the inoculation of any of the three rhizobium strains, and in the second experiment, significant increases in grain yield ranged from 39% to 57% and reached over 2.0 Mg ha−1. Similar increases in nodulation and grain yield due to inoculation were observed in 22 on-farm trials. Nitrogen fertilizer application promoted vegetative growth but did not increase grain yield and nodulation. Inoculating cowpea with highly effective rhizobium strains can therefore enhance grain yield of smallholder farmers in Africa.

In the oil palm plantations of Ecuador, two factorial trials (namely CP06 and CP08) were used to assess the effects of N, P and K fertilization on the soil chemical characteristics after 10 years of fertilizer application. The use of ammonia-based fertilizers has resulted in a drop in soil pH, which has reached 1.2 units in one of the two trials. A drop in cation exchange capacity (CEC) was also found, and a loss of exchangeable cations that probably reflected leaching of excess N as nitrates. The use of KCl enriched the soil in K, which contributed to impoverishment in Ca and Mg. In both trials, the highest N and K application rates had no significant effect on yield in comparison with an intermediate fertilization rate; however, their effects on the fertilized soil significantly increased the risk of N and cation leaching towards the deep soil layers. We also compared the effects of the N, P and K factors on soil properties outside the fertilizer application zone. In both trials, the mineral reserves played a major role in meeting the needs of the control palms, which had not been fertilized for 10 years, as no significant yield drop has been observed except in trial CP06 when no KCl was applied. However, uptake of nutrient in the control plots did not lead to significant impoverishment of the soil.

The yield gap has arisen again as a focus for agricultural research to ensure food security and economic growth for farmers around the world. To examine this renewed interest, we carried out a review of key literature in the field of yield gap analysis to identify important gaps in research and analysis. In so doing, both the complexities in yield gap studies emerged along with some significant omissions. Much of the literature and research on the yield gap has been framed by larger concerns and initiatives to raise agricultural productivity. This focus has led to an emphasis on technical solutions such as crop breeding, fertilizer application and other methods to increase production. However, this concentration on the technical usually ignores the wider social, economic and political context that shapes farmer decision-making about agricultural production. This context can either discourage or enable farmers to close their yield gap. Additionally, the impact of increased agricultural production through certain technical solutions also often overlooks the wider impact on the landscape and the ecosystem services which underpin agricultural production and livelihoods. We argue that increasing agricultural productivity, and closing the yield gap, must be addressed with this broader approach.

Water stress is arguably the most limiting factor affecting cereal productivity in the world and its effects are likely to increase due to climate change. It is therefore imperative to have a wide-ranging understanding of water stress effects on crop physiological processes so as to better manage, improve and adapt crops to future climates. A field study was carried out to investigate the influence of four moisture levels on the following: (1) flag leaf CO2 assimilation and flag leaf carbon content; (2) the utility of flag leaf spectral reflectance to monitor leaf water status and as an indicator of biomass and grain yield; and (3) biomass and grain yield performance of four spring triticale genotypes in a dry winter environment (steppe, arid climate). The experiment was carried out in a factorial arrangement of four moisture levels and four spring type triticale genotypes). Soil moisture level significantly influenced biomass accumulation, grain yield, CO2 assimilation, flag leaf carbon content and spectral reflectance. Grain yield levels ranged from 0.8 to 3.5 t ha−1 in 2013 and 1.8 to 4.9 t ha−1 in 2014. CO2 assimilation was significantly higher under well-watered (WW) conditions (9.92 µmol m−2 s−1 in 2013; 11.64 µmol m−2 s−1 in 2014) and decreased gradually with moisture level to 1.82 and 4.74 µmol m−2 s−1 under severe stress (SS) in 2013 and 2014, respectively. Flag leaf carbon content was significantly higher under water limited conditions compared to WW. Normalised Difference Vegetation Index (NDVI), Normalised Difference Water Index (NDWI) and Water Index (WI) were significant and positively correlated to biomass and grain yield. WI was particularly strongly correlated to biomass (0.72***) and grain yield (0.55***). However, no clear varietal effects were detected. This study revealed that carbon tends to accumulate in flag leaves under water stress and that flag leaf carbon content is influenced more by the export capacity of the flag leaves than on CO2 assimilation rate. WI was found to be superior index in monitoring water stress in triticale compared to NDVI and NDWI. Above all, spring triticale proved to be adaptable to steppe (dry) climate of Limpopo and that livestock farmers in the province can successfully grow triticale for silage under MS conditions.

We developed a protocol for comprehensive evaluation of nutrient management (NM) technologies for production of eggplant taking its yield, produce quality, profitability, energy balance and environmental sustainability in terms of upkeeping soil quality as the goal variables. Fifteen NM technologies comprising of three sources of nutrients viz., organics [vermicompost (VC), farmyard manure (FYM) and mustard oil cake (MOC)], inorganic fertilizations [recommended N–P–K at the rate of 100–22–42 kg ha−1 and 150% of recommended N–P–K (NPK^)] and their selected combinations were tested for growing the plants. Integrated NM technology was proved to be socio-economically sound and environment-friendly practice. It helped to upkeep soil quality by improving soil organic carbon stock, microbial biomass carbon, bulk density and available nutrients in soils. Combining all the parameters by employing non-parametric evaluation of regression factor scores through principal component analysis, the NM technology of VC3 Mg ha−1+NPK^ was found to be the best when considering the marketable fruits (12.27 Mg ha−1), economic return (benefit-cost ratio 3.3; marginal rate of return 8.7), energy conserving efficiency (net energy 113.8 GJ ha−1), soil and crop quality for human welfare. Only organics were less productive and profitable, and energetically less efficient than the integrated and inorganic NM systems and as such may not be sustainable for eggplant production in subtropical India.

The relationship between climate, crop growth and crop yield is complicated. This study aimed to determine the ratio of CO2–C emission to grain yield, the field treatments were initiated in 2003, but the measurements for this analysis were collected during the summer maize-growing seasons of 2011 and 2012 in the North China Plain. The experiment showed that conventional tillage with straw application significantly increased grain yield and the ratio of CO2–C emission to grain yield of summer maize. The mean soil CO2–C emission rate with no tillage was significantly lower than that when conventional tillage was used; however, straw application significantly increased the soil CO2–C emission rate, irrespective of whether tillage was performed or not. This was mainly because straw application changed the soil total porosity and organic carbon content. In conclusion, the results of this study support the hypothesis that the ratio of CO2–C emission to grain yield in the North China Plain can be increased by straw application, whereas no tillage decreases this ratio.

Numerous innovation platforms have been implemented to encourage the adoption of agricultural innovations and stakeholder interactions within a value chain. Yet little research has been undertaken on the design and implementation of innovation platforms focussing on issues other than market access and aiming to encourage agro-ecological intensification. This is the case for the development of Conservation Agriculture (CA) in West Africa, which due to its complex nature calls for technical, organizational and institutional changes at the level of both production systems and village territories. This article analyses the design and implementation process of platforms in three villages in Burkina Faso aiming to develop CA technical references with local stakeholders, and to renew rules of interaction between stakeholders within a territory. The platforms enabled farmers in the three villages to actively participate in the identification of the cropping systems that were tested and to improve their knowledge and mastery of CA. They furthermore promoted networking among producers and facilitated the development of new rules for crop residue use. The platforms thus appear to be relevant mechanisms, enabling complex innovations to be addressed. Diverse modifications and improvements are discussed that would ensure the sustainability of the platforms and the evolution of their objectives and activities beyond those of the project under which they were launched.

Recent literature suggests that to make value chains in changing agrifood systems in sub-Saharan Africa more inclusive, intermediary institutions should foster coordination. The hub concept has been applied as such an intermediary institution that coordinates advisory services, input supply and smallholder access to markets. This study unravels hub coordination in smallholder dairy in Kenya, conceptualising the hub as a mix between a broker of relationships, a one-stop-shop for services and a cluster of producers and service providers, enabling horizontal coordination (between smallholders) and vertical coordination (between smallholders and value chain actors and service providers). Findings indicate that, in resolving challenges that limit smallholders’ integration in value chains, synergies emerged as the hub combined different types of horizontal and vertical coordination. This was done by simultaneously organising clusters of farmers and input and service providers (clustering role) and actively facilitating delivery (broker and one-stop-shop role), where the hub structure stimulated the matching of demand (better articulation) to supply (better organised access). However, tensions emerged in the combination of horizontal and vertical coordination as farmer organisations as hub operators had to balance a role as an honest broker between farmers with the intent of enhancing collective action and as a business-oriented entity which resulted in the exclusion of some farmers who cannot deliver the quantity and quality required to minimise coordination costs. Given these tensions and capacity problems of farmers’ organisations, complementary intermediary arrangements may be necessary to fulfil some coordination roles.

Multilocation experiments were established to determine the best strategy for using inorganic fertilizer in conservation agriculture (CA) systems that use green manure cover crops, namely sunhemp, velvet bean and cowpea grown in rotation with maize. The objectives of the study were to determine (i) the effect of half and full rates of basal fertilizer on maize and legume biomass yields, (ii) the residual effects of unfertilized, half and fully fertilized green manure legumes on maize grown after the legumes, and (iii) the residual effect of unfertilized, half and fully fertilized green manure legumes combined with basal and topdressing fertilizer on maize yields. Experimental design was a randomized complete block with basal fertilizer as a treatment in the green manure legumes phase. Previously, in the maize phase, green manure legume species were the main treatment with basal fertilizer as a subtreatment (sunhemp, velvet bean and cowpea: 0, 75, 150 kg ha−1 and 0, 50, 100 kg ha−1, respectively). Nitrogen was applied in the maize phase at 0, 23, 46, 69 kg N ha−1 as a sub-subtreatment in Malawi. Results showed that inorganic fertilizer is the most effective when applied to the maize, not green manure legumes. Biomass of green manure legumes, sunnhemp 8084 kg ha−1, velvet bean 7678 kg ha−1 and cowpea 4520 kg ha−1, was not significantly affected by application of basal fertilizer. Maize production increased after the application of green manure legumes with maize-after-maize, maize-after-velvet bean, maize-after-sunnhemp and maize-after-cowpea, yielding 3804, 5440, 5446 and 5339 kg ha−1, respectively. Nitrogen increased maize yield regardless of the previously used green manure legumes species. Our results suggest that farmers should apply fertilizer to maize and grow green manure legumes on residual soil in CA systems. Despite growing green manure legumes, smallholders should apply nitrogen topdressing to maize grown using the green manure legumes in some agro-ecologies.

White yam (Dioscorea rotundata) is a major root crop grown throughout West Africa and a major limitation on its production is the availability of good quality (i.e. free of pests and diseases) planting material, notably seed yams. One of the methods developed to address this limitation is the Adapted Yam Minisett Technique (AYMT) and since 2012 the AYMT has been promoted in both Nigeria and Ghana via a Bill and Melinda Gates funded project entitled Yam Improvement for Income and Food Security in West Africa (YIIFSWA). While previously published studies have focussed on the agronomy of the sett-to-seed yam process, there has been no work done on the seed-to-ware yam stage which is critical in terms of farmer income and livelihood. This paper provides the first published evidence obtained under entirely farmer-managed conditions in Africa that shows seed yams produced via the AYMT can generate agronomic benefits in the water yam stage, including better germination, tuber numbers and weights.

Upland rice (Oryza sativa L., UR) could be an option under soybean–maize crop rotation system. However, the recommended row spacing for UR (0.30 m) is shorter than that recommended for soybean and corn (0.40 m), limiting the use of UR in this rotation. We hypothesize that cultivar adaptation to wider than recommended row spacing and local environmental conditions harbour significant potential for overcoming the yield constraints of wider row spacing. We evaluated the row spacing effects on rice grain yield and their components in UR cultivars grown under different water deficit conditions. The experiments were designed as a randomized block in a split–split-plot scheme with sites (the cities of Santo Antônio de Goiás, Porangatu and Formoso) as main plots, row spacing (0.25, 0.35, 0.45 and 0.55 m) as the subplots and UR cultivars (one old and two modern genotypes) as the sub-subplots. We found that, in the less stressful environments, the modern cultivars, BRSMG Curinga and BRS Primavera, presented the highest grain yield. By contrast, in environments with moderate to intense water stress, the traditional cultivar, Douradão, presented the best performance, regardless of row spacing used. We conclude that UR is a viable option for soybean–maize rotation systems, as the UR cultivars tested presented no noticeable yield losses when sown with the same row spacing used for soybean and maize crops (0.40 m). In terms of impact, it can lead to an increase in UR cropped area in Brazil, and decrease in dependence on flooded rice harvested in the south of the country.