The effects of rainfall on yield of rainfed grain sorghum in a rotation experiment have been investigated over six years. There was a positive association between yield and rainfall during May and from the beginning of July to the first half of September, but a negative association at other times of the year. Total rainfall in August and September, and the annual total, were positively related to yield, while the totals of June and July were inversely related. Variation in monthly rainfall accounted for up to 86 per cent of the variation in yield, while the total rainfall in August and September accounted for up to 96 per cent.

Within the context of participatory varietal selection of peanut (Arachis hypogaea L.) in East Timor, this study investigated an approach to identify yield determinants in farmer-managed varietal trials in a type of exploratory agronomy. A singular increase of 47% in peanut on-farm productivity by variety Utamua over local varieties was recorded across agro-ecologies over 616 farmer-managed trials in five cropping seasons. Utamua has larger (c. 70%) seed than local, which resulted in poor germination initially. Farmers then started seed priming, and, by the last two seasons’ trials, 50% of farmers with on-farm trials seed primed. The volume of trials allied with detailed recording of agro-ecological, household and management conditions allowed the identification of factors affecting yield, such as seeding arrangement (two seeds/hill more productive than one seed/hill) and soil pH (pH 7–8.5 more productive than lower pH), using an unbalanced ANOVA design. Farmer innovations in management could be identified within varietal trials highlighting future agronomic possibilities.

The efficiency of the randomized complete block design, relative to the completely randomized design, is linearly expressed as: Relative efficiency=A+CF, where A and C are constants determined by the number of treatments (t) and blocks (b) and F=calculated F value for blocks in the ANOVA table. For values of t and b ranging from 2 to 10 the constants A and C are estimated. Curves of relative efficiency are given when o≤F≤10 for t values ranging from 2 to 10 when b=4, 6 and 8.

The Mashona cattle of Rhodesia are a strain of the Sanga type, which is found in specific areas of Central and Southern Africa. They are descended from protogenic Bos taurus, Bos indicus and Bos brachyceros cattle which were cross-bred in ancient times. in spite of the pandemics which ravaged herds at the turn of the last century, it seems that Mashona cattle have changed little since first brought to the country. An account is given of the Central African environment and the way it affects the physiological processes of cattle. Because Mashona cattle have lived in the Rhodesian environment for many centurites they are well adapted to it. A description is given of Mashona cattle which are being developed as a distinct breed in Rhodesia.

Cowpea bean (Vigna unguiculata) is usually submitted to pre-harvest burndown with herbicides aiming to an early harvest. We aimed to quantify the residues of paraquat, diquat, glufosinate-ammonium and glyphosate in cowpea grains subjected to two timings of pre-harvest burndown. Three identical experiments were installed in Dourados (Lat. 22° S), Sinop (Lat. 11° S) and Teresina (Lat. 05° S), Brazil, comprising the pre-harvest burndown of cowpea bean with these herbicides, applied either with 50 or 75% of the pods dry and ready for harvest. As hotter and drier the location as slower the herbicide dissipation. Glyphosate should not be used for pre-harvest burndown of cowpea. Herbicide residues were above the maximum levels stated by the Brazilian legislation when applied with 50% dry pods. Burndown herbicides aiming to speed harvest should be applied with at least 75% dry pods in cowpea to ensure safe herbicide residue levels in grains.

Smallholders in Southern Africa continue to grapple with low maize productivity despite this being the staple food crop. This study sought to analyze and isolate the relative contribution of agronomic practices to maize yields obtained by smallholders in Malawi and Mozambique using data generated from on-farm trials testing the performance of conservation agriculture cropping systems. The trials were implemented in two communities, namely Kasungu district in Malawi and Sussundenga district in Mozambique, and ran for seven consecutive growing seasons starting in 2010–2011. Maize yield was measured annually in the on-farm trials, which included a ‘control treatment’ representing an improved farm practice, and in neighboring fields managed by the same farmers on their own, hence representing a ‘true farm practice’. Results indicated that maize yield increased linearly with increasing plant population at harvest at both sites. On average, an increase in plant population at harvest by 1000 plants ha–1 resulted in an increase in maize yield of 90 and 63 kg ha–1 at Kasungu and Sussundenga, respectively. The greatest maize yields were obtained when plant population at harvest exceeded 40 000 plants ha–1. Yet, the plant population at harvest was below the generally recommended optimum for most of the cropping systems studied and in most growing seasons. Furthermore, the use of agronomic practices alone without conservation agriculture (i.e., improved varieties, fertilizer management, and timely weed control) resulted in maize yield gains of as much as 54% and 43% relative to the ‘true farm practice’ at Kasungu and Sussundenga, respectively. Overall, the proportion of these yield increases relative to the ‘true farm practice’ accounted for by agronomic practices amounted to 53–70% and 57–85% at Kasungu and Sussundenga for the highest to the lowest-yielding cropping system. Although conservation agriculture significantly improved maize yield at both sites, such increases were smaller in magnitude compared to the yield gains derived from improved agronomic practices. The study suggests that considerable strides toward narrowing maize yield gaps in Southern Africa can be achieved through improvement of current crop management practices, let alone adhering to the conservation agriculture principles of minimum tillage, residue retention, and crop diversification.

Nitrogen (N) fertilization affects wheat yield and grain protein concentration; however, its mismanagement can increase plant lodging. While the use of plant growth regulators such as trinexapac-ethyl (TE) can mitigate plant lodging, their effects on seed physiological quality are not well known. The aim of this study was to evaluate the effects of N fertilization and TE on wheat yield, lodging and seed quality of spring wheat varieties. It was carried out in the 2018 growing season in the environments of Londrina and Ponta Grossa, Brazil. A randomized complete block design was used with a 2 × 3 × 3 factorial arrangement to evaluate two wheat genotypes (WT 15008 and WT 15025), three top-dressing N rates (0, 40 and 120 kg ha−1), and three TE rates (0, 50 and 100 g ha−1). Agronomic characteristics related to wheat productivity (hectolitre weight, thousand-grain weight, density of fertile spikes, plant height, lodging and grain yield) and seed physiological quality (seed germination and vigour; length and dry matter of normal seedlings) were evaluated. Increasing N rates up to 120 kg ha−1 increased plant lodging up to 26.4 percentage points for WT 15025 in Londrina. TE impaired some traits of seed physiological quality. Spraying 100 g ha−1 TE on the plants reduced seedling length by 9.4% in the seeds of WT 15008 harvested in Ponta Grossa compared to the TE control (0 g ha−1). The dry matter of the seedlings from the seeds harvested in Londrina declined by 7.2% due to the application of 100 g ha−1 TE, compared to the control. However, a lower rate of TE (50 g ha−1) might be enough to minimize plant lodging without impairing the physiological quality of the seeds, depending on the rate of N fertilization. This study is the first step in providing empirical evidence for the detrimental effects of TE in combination with N on wheat seed quality, suggesting that seed producers should exercise caution in managing TE and N fertilization.

In traditional yam (Dioscorea spp.) production systems in West Africa, finding sole seed yam producers is rare and up to 30% of harvested tubers from the ware tuber crop is reserved to plant an equivalent area of the harvested crop during the next season. Many farmers typically must make a trade-off between food and seed in the use of available tubers. A study was carried out using a factorial experiment in a randomised complete block design to investigate the influence of planting different minisett sizes at different planting periods on the yield of seed yam with the aim of improving the availability of this expensive input and saving more ware tubers for food or sale. Results showed that by doubling or tripling the minisett size from 30 to 60 or 90  g, yields of seed yam increased by 61.1 and 103.3%, respectively. The 90 g minisetts had the highest values for all traits studied but had the least sett multiplication ratio. The early planted crop yielded 137% more than the late-planted crop. Significant interactions between minisett size, planting period and season were found. In 2016, although the highest yield of seed tubers was from early planted 90  g minisetts (35.6 t ha−1), the yield of early planted 30 g minisetts (23.8 t ha−1) was similar to those of 60 g planted mid-season (28.7 t ha−1) and 90 g planted late (20.0 t ha−1). To produce a high proportion of seed size tubers with less planting material, early planting of 30  g minisetts is recommended. Such practice will enhance seed tuber availability and food security by saving 1–2 t ha−1 of tubers that would have been used as seed instead of food.

The limitation of soil amendments and insufficient and irregular rainfall are the main factors accounting for the decline in crop yields in the Sahelian low-input cropping systems. This study explored the agronomic and economic responses of integrated use of millet glume-derived compost with synthetic fertilizer in cowpea-based cropping system. A two-year field experiment was laid out as factorial design arranged in randomized complete blocks with three rates of compost (0, 4000, and 8000 kg ha−1) and three rates of recommended synthetic fertilizer (0, 50, and 100%). Cowpea grain yield increased markedly with combined application of compost and synthetic fertilizer. The combined use of compost applied at 8000 kg ha−1 and 50% of the recommended rate of synthetic fertilizer increased cowpea grain yield by 51% compared to the application of 100% of the recommended rate of synthetic fertilizer. The rainwater use efficiency (RaUE) increased by 52 and 49% with the combined application of compost at 8000 kg ha−1 along with 50% of the recommended rate of synthetic fertilizer when compared to the application of 100% of the recommended rate of synthetic fertilizer in 2013 and 2014, respectively. All treatments induced a positive net income, and the highest value/cost ratio was achieved with combined application of compost and synthetic fertilizer. This study highlights the possibility of improving cowpea productivity through combined use of composted locally available organic input with half of the recommended rate of synthetic fertilizer. This combination would reduce the investment in mineral fertilizer currently made by smallholder farmers in the Sahelian low-input cowpea cropping system and reduce environmental pollution resulting from the current practice of burning the millet glume.

Black polyethylene tunnels were used to subject Armore and Missionary strawberry cultivars to 21 short-day inductive cycles at either full bloom (7–28 May) or fruit swelling (1–21 June) stages. Regardless of application date, treatments induced a second bloom 8–10 weeks after treatment in both cultivars. The second crop of Armore was as large as the first, but Missionary produced only a small second crop that would not be worth commercial harvesting. Covering plants with black polyethylene reduced the vitamin C content of the first-crop fruits of Armore without affecting yield, while Missionary responded in an opposite way. Treating plants at full bloom hastened the ripening of the first crop of both cultivars by about 1 week and resulted in a larger second crop than was obtained by the later treatment.

Isolation of Colletotrichum gloeosporioides (causal agent of yam anthracnose) from soil is difficult because of the presence of fast growing micro-organisms like Rhizoctonia spp., Rhizopus spp., Penicillium spp. and bacteria. Therefore, a semi-selective medium consisting of antimicrobial agents such as pencycuron 50 mg L−1, tolclofos-methyl 10 mg L−1, streptomycin sulphate 100 mg L−1, chloramphenicol 100 mg L−1 and chlortetracycline 100 mg L−1 was developed using potato dextrose agar as the basal medium. The procedure involved screening of candidate fungicides, developing a suitable combination of antimicrobial agents, assessing the proposed semi-selective medium and adjustment of pH of the medium to 5. The effectiveness of the medium is due to selective inhibition of micro-organisms by the antimicrobial agents and the development of distinct salmon-pink colonies of C. gloeosporioides.

Potassium chloride (KCl) is the most widely used fertilizer in oil palm (Elaeis guineensis) plantations and the rates applied are based on interpretation of leaf K contents. When no positive response on leaf K contents can be detected, no optimum content can be established whatever the yield response to KCl rates. We used data from 13 fertilization trials conducted on several continents to study the responses of leaf K, leaf Cl, leaf Ca and yield to KCl rates as a function of the soil properties of each site. We found that the abundance of exchangeable Ca in the soil expressed as a percent of the cation exchange capacity (CEC) was the best soil variable to predict if leaf K content would increase with KCl rates. In addition, we found that the leaf K contents of unfertilized controls at the end of the trials were also correlated with Ca/CEC. This ratio thus appears to be a better index of soil K reserves than soil exchangeable K content.

The concentrations of total nitrogen and nitrate–nitrogen in yam leaves receiving various levels of nitrogen were determined fortnightly. Nitrate–nitrogen was superior to total nitrogen as an index of nitrogen nutrition. Correlation coefficients between nitrate–nitrogen at various sampling dates and rate of nitrogen application were highest between late June and early July in two seasons, indicating that this is the best time to take single samples for foliar analysis. A relation was demonstrated between nitrate–nitrogen at this period and tuber yield.

Digestibility of the herbage of the indigenous tree Antiaris africana was investigated. Digestion coefficients (%) were—organic matter 67, dry matter 64, crude protein 78, crude fibre 39, nitrogen-free extract 74, ether extract 36 and ash 36. Calculated nutritive values were—starch equivalent 23·2 and digestible crude protein 3·7, giving a nutritive ratio of about 1 : 6. The herbage was young and its palatability high.

Farmers’ access to reliable information is crucial to improving rural livelihoods, food security, and national economies in West Africa. This paper discusses the dynamics of accessing and using agricultural learning videos from commercial channels, vs project and non-project channels in Benin and Mali. Using combinations of different models to assess the effectiveness of agricultural extension programs, the findings showed that farmers were motivated to pay for videos and watch them by themselves, without facilitation. Farmers who watched the videos through project support have also continued to watch on their own if the videos are of interest to them. Nevertheless, farmers were less motivated in the learning process when they received the Digital Video Disc (DVD) free and without support to watch them. We also found that the distribution of learning videos through commercial channels reaches more serious users and increases farmers’ self-determination for learning, and farmers are more motivated to provide feedback than viewers who receive DVDs for free or via project support, Non-Governmental Organizations (NGOs), or farmer organizations. Although buying a DVD is an individual action, they like to watch the videos in groups. After buying the DVD, about 43% of respondent borrowed DVD players and one person in five bought a DVD player to watch the videos. Efforts to promote improved technologies need to expand beyond the conventional focus on research and extension services. Support to agricultural technology dissemination must go beyond assistance to smallholder farmers and NGOs (practical implication). As the private sector has a role to play, both in making technologies available and in teaching farmers how to use them, their contribution would create space for innovation (theoretical implication). Our findings suggest that successful development intervention programs can be sell audiovisual material to farmers, who will use it proactively.

A field experiment was conducted from 1989 to 1992 to investigate the effect of sewage sludge applications on wheat yield under different irrigation regimes. The sewage sludge was applied at rates equivalent to 0, 20 or 60 t ha-1 whenever the available soil moisture reached 30 or 70%. The results showed a significant response in grain yield and its nutrient content with no significant differences between rates of sewage sludge applied. Much higher responses were obtained under the wet than under the dry regime.