This paper assesses farmer adoption of rice varieties and new genotypes introduced through participatory varietal selection (PVS) in villages which represent submergence- and drought/submergence-prone villages in eastern Uttar Pradesh, India. It focuses on the involvement of women farmers in participatory research for screening improved varieties for areas which suffer from abiotic stresses. It further assesses the impact on the decision-making authority (or women's empowerment) on rice varietal choice, seed acquisition and disposal, and crop management after participating in PVS trials. It suggests strategies to empower women farmers in making sound and timely decisions on farm-related matters and to enhance their roles in accelerating the adoption of new varieties.

Under rainforest vegetation, the central Amazonian Ferralsols are characterized by relatively high availability of N in relation to other nutrients. After forest clearing, several tree crops also have not shown yield responses to N fertilizer. To elucidate the mechanisms of this apparent N sufficiency, the mineralization of soil N was measured under three tree crops and a leguminous cover crop (Pueraria phaseoloides) in a multi-strata agroforestry system at two fertilizer input levels on a Xanthic Ferralsol in central Amazonia. In situ incubations of topsoil (0–10 cm) were carried out using the buried-bag method on five occasions over ten months. The highest mineralization rates were found under the cover crop, intermediate rates under rubber trees (Hevea brasiliensis) where the soil was also covered by the cover crop, and lowest rates under peach palm (Bactris gasipaes) and cupuaçu (Theobroma grandiflorum) with no cover crop. The increased N mineralization under the cover crop was due to more total N in the soil, higher soil moisture and, presumably, a larger pool of readily mineralizable soil N compared with the soil under the tree crops. Other fertility parameters also differed significantly between sampling positions within the plots, but this had no major influence on net N mineralization. Also, the input of NPK fertilizer and dolomite had no significant influence on N mineralization, indicating that N mineralization was not nutrient-limited. High total N mineralization rates in the soil (approximately 350 kg ha−1 a−1 at 0–10 cm depth) explained earlier observations of nitrate leaching into the subsoil under multi-strata agroforestry at this site. Considering the spatial patterns of N mineralization with maximum values under the cover crop, the exploration of the soil volume by crop roots should be maximized to increase the uptake of mineralized soil N by the crops and reduce nitrate leaching. Appropriate measures are narrow tree spacing, use of annual and semi-perennial intercrops and encouragement of the lateral root development of the trees. In addition, the mineralization of soil N close to the tree crops can be influenced through the management of the cover crop. In view of the high total N mineralization rates in the system and unclear yield responses of tree crops to N fertilizer, the application of N fertilizer to tree crops with well-developed root systems and a well-managed cover crop may often be unnecessary on this soil type. This may facilitate the further development of tree crop agriculture in the region.

The effect of variations in the relative sowing time and density of component crops in a maize/cowpea intercrop were examined in two experiments. In the first experiment, maize and cowpea were sown together, and either 10 or 21 days before or after each other. Maize yield was reduced when sown at the same time or after cowpea; intercrop cowpea yields were less than sole cowpea yields at all sowings. In the second experiment, maize densities of 35, 50 and 70 × 103 plants ha−1 were combined with cowpea densities of 70, 100 and 140 × 103 plants ha−1. Increasing the density of either crop in the mixture resulted in increases in total yield. Maize reduced cowpea yields more than the effect of cowpea on maize yields. In terms of LER and total seed protein yield, there was no advantage of either staggered sowings over simultaneous sowing or of the various intercrop density combinations, except between the lowest and the highest densities of either maize or cowpea. The LERs appeared to follow the trends in cowpea yields and total seed protein yields the trends in maize yields.

Sweet potato virus disease (SPVD) causes strap-shaped leaves, vein-clearing, puckering, chlorosis and stunting in susceptible sweet potato varieties and yields are much reduced. To investigate the tolerance of genotypes and obtain a better appraisal of yield loss caused by SPVD, eight sweet potato varieties showing symptoms of SPVD were studied for two years in an area where SPVD is severe. Two varieties, although showing symptoms, were tolerant of the disease; their yields were not significantly depressed by SPVD. Among the remaining six varieties, storage root fresh yields were reduced by 56–90% in plants showing SPVD symptoms. Marketable yields, as well as total and marketable numbers of storage roots were similarly depressed by SPVD in the less tolerant varieties. Significant correlations were found between disease severity rating and yield reduction among cultivars.

Apparatus was built to screen sorghum and pearl millet for seedling emergence through a hot soil surface. Seeds were sown in soil in long clay pots arranged in a steel water tank so that the top 7 cm of the pots was above the water level. The soil in the pots was heated with infra-red lamps fitted to a frame above the tank. By adjusting the height of the frame the temperature of the soil could be changed. The system allows emerging plumules to be subjected to high soil temperatures (up to 50°C) but without water stress. Both crops exhibited genotypic differences in emergence.

In sub-Saharan Africa (SSA), rainfed agriculture is the dominant source of food production. Over the past 50 years much agronomic crop research has been undertaken, and the results of such work are used in formulating recommendations for farmers. However, since rainfall is highly variable across seasons the outcomes of such research will depend upon the rainfall characteristics of the seasons during which the work was undertaken. A major constraint that is faced by such research is the length of time for which studies could be continued, typically ranging between three and five years. This begs the question as to what extent the research was able to ‘sample’ the natural longer-term season-to-season rainfall variability. Without knowledge of the full implications of weather variability on the performance of innovations being recommended, farmers cannot be properly advised about the possible weather-induced risks that they may face over time. To overcome this constraint, crop growth simulation models such as the Agricultural Production Systems Simulator (APSIM) can be used as an integral part of field-based agronomic studies. When driven by long-term daily weather data (30+ years), such models can provide weather-induced risk estimates for a wide range of crop, soil and water management innovations for the major rainfed crops of SSA. Where access to long-term weather data is not possible, weather generators such as MarkSim can be used. This study demonstrates the value of such tools in climate risk analyses and assesses the value of the outputs in the context of a high potential maize production area in Kenya. MarkSim generated weather data is shown to provide a satisfactory approximation of recorded weather data at hand, and the output of 50 years of APSIM simulations demonstrate maize yield responses to plant population, weed control and nitrogen (N) fertilizer use that correspond well with results reported in the literature. Weather-induced risk is shown to have important effects on the rates of return ($ per $ invested) to N-fertilizer use which, across seasons and rates of N-application, ranged from 1.1 to 6.2. Similarly, rates of return to weed control and to planting at contrasting populations were also affected by seasonal variations in weather, but were always so high as to not constitute a risk for small-scale farmers. An analysis investigating the relative importance of temperature, radiation and water availability in contributing to weather-induced risk at different maize growth stages corresponded well with crop physiological studies reported in the literature.

Biochar has received attention due to its potential for mitigating climate change through carbon sequestration in soil and improving soil quality and crop productivity. This study evaluated the effects of rice straw biochar (RSB) and rice husk ash (RHA) each applied at 5 Mg ha−1 and four N levels (0, 40, 80, and 120 kg ha−1) on soil fertility, growth, and yield of rice and wheat for three consecutive rice–wheat rotations. RSB significantly increased electrical conductivity, dehydrogenase activity, and P and K contents when compared to control (no amendment) up to 7.5 cm soil depth. Both RSB and RHA did not influence shoot N concentration in wheat plant but significantly increased P and K concentrations at 60 days after sowing. Grain yields of both rice and wheat were significantly higher in RSB as compared to control (no amendment) and RHA treatments. While the highest grain yields of rice and wheat were observed at 120 kg N ha−1 in RHA and no biochar-treated plots, a significant increase in grain yields was observed at 80 kg N ha−1 in RSB treatment, thereby saving 40 kg N ha−1 in each crop. Both agronomic and recovery N efficiencies in rice and wheat were significantly higher in RSB-amended soil compared to control. Significant positive correlations were observed between soil N, P, and K concentrations and total N, P, and K concentrations in aboveground biomass of wheat at 60 days after sowing. This study showed the potential benefits of applying RSB for improving soil fertility and yields of rice and wheat in a rice–wheat system.

This paper addresses the current and future contributions of plant genetic resources and plant improvement to sustainable agriculture with reference to the activities of the International Center for Agricultural Research in the Dry Areas (ICARDA) in association with national programmes in West Asia and North Africa. These regions constitute the primary centres of diversity of crops such as wheat, barley, chickpea and lentil. Genetic erosion is being curtailed by germplasm collection and preservation. Selection for low-input cultivars of barley is conducted under low input conditions, and new cultivars of lentil and barley are often intentionally heterogeneous to stabilize their performance in dry rainfed areas. The importance of genetic differences in the cultivars on subsequent crops in the rotation and on straw quality for livestock is under study. Insect pests and diseases contribute to yield instability. Because of the potential adverse impact of pesticides on the fragile ecosystems of the region, integrated control strategies based on agronomic management, host plant resistance, biological control agents and strategic use of selective insecticides are being developed.

The traditional management of cattle manure in a cropping system in the savanna zone of central Nigeria is discussed in conjunction with the agronomic benefits and problems of manure use. Nitrogen and phosphorus contents of the manure varied seasonally. On-farm trials showed that maize grain yields were about 1 t ha−1 more and weed growth 90% greater in manured than in non-manured areas. It is important to reduce the competition between crops and weeds if grain crops are to obtain the full benefit of manure in such cropping systems.

Traditional cultivars of arabica coffee (Coffea arabica) are susceptible to coffee leaf rust (CLR, Hemileia vastatrix) and coffee berry disease (CBD, Colletotrichum kahawae). CLR is of worldwide importance, while CBD is still restricted to Africa. Host resistances present in C. canephora to both destructive diseases have been successfully introgressed into C. arabica, after several decades of breeding and selection notably in Brazil, Colombia, India and for CBD resistance in East Africa. CLR resistant cultivars have since been grown on hundreds of thousands of hectares in Latin America and elsewhere, while CBD (and CLR) resistant cultivars are now increasingly being planted in East and South Eastern Africa. They contribute to ecologically sustainable coffee production and to considerable socio-economic benefits for the coffee growers. Nevertheless, some representatives of the international coffee trade continue to be sceptical about the cup quality of these modern cultivars. This paper presents an overview of the considerable amount of scientific evidence accumulated over the years showing that, with all environmental factors at optimum level, disease-resistant cultivars can produce quality coffees as good as those from the best traditional varieties.

The mineral N (NH4 + NO8) in soils at a savanna site was low at the time of crop planting except after groundnuts and when dung had been used. Nitrification occurred whatever the previous crop, but the numbers of nitrifying bacteria were small and varied with the level of substrate ammonium.

The contents of the volatile flavour compounds and the flavour index of black teas vary with localities. The magnitude and order of the variations are clonally dependent, the relative performance of clones varying with location. For a comprehensive breeding programme to improve black tea quality, it is suggested that tea clones should be evaluated in the areas of potential release before they are made available to tea growers.

To enhance the diversification of rice varieties for the specific needs of farmers through a participatory varietal selection (PVS) approach, four pre-release and one released chaite rice varieties were distributed in 20 villages of the Western Hills of Nepal in 1991. A survey conducted during June 1993 found that varietal diversity increased in all locations and in 80% of the study area at least two new rice varieties were reported where only CH 45 was grown before the distribution. On-farm varietal diversity was further enhanced by farmer-to-farmer dissemination of new rice varieties. All the rice varieties tested were adopted, but the adoption level varied between locations. Of the households surveyed 37% were growing the new rice varieties and a further 57% were aware of those varieties within two years of introduction. The PVS approach provided farmers with the benefits of new genetic materials five to six years in advance of the formal system and with minimum effort. Institutionalization of the PVS approach and the use of the farmers' network of information and seed exchange, involving relevant grassroots level institutions, can improve the effectiveness of the variety evaluation system.

In the semi-arid Mwea Division of Kenya's Eastern Province, the modern pigeonpea (Cajanus cajan) variety Nairobi Pigeonpea 670 (NPP 670) had become known to all farmers and was being grown by 68% of them within a period of 12 years. The only injection of this seed to the area was from a single on-farm demonstration. Three-quarters of farmers found out about the variety from observing it growing in the field, and obtained seed primarily from other farmers in the village. Factors favouring the diffusion of the variety included its attractiveness as a cash crop, the ease with which it could be distinguished from other varieties, the low seed rate, and the relative ease with which growers were able to maintain seed purity. Farmers expressed a willingness to pay for fresh seed, which suggests that more effort needs to be made to involve the formal seed sector. The present regulatory system does not favour the development of a formal supply system. NPP 670 was released more than 10 years after it was first tested.

In a field experiment initiated in 1991 kharif season (April–October) on an acidic soil in the Western Himalayas of India, 25% and 50% of the recommended doses of nitrogen were substituted through different organics, viz. farmyard manure (FYM), wheat cut straw and Sesbania aculeata (as green manure) in rice, followed by use of chemical fertilizers in wheat each year. The aim of this work was to study the long-term integrated effect of organics and chemical fertilizers on grain yield of rice–wheat system and soil quality. Based on five years’ moving average values, continuous cropping without fertilization or manuring (control) gave the lowest grain yields of both rice and wheat. Application of 50% N through FYM plus 50% NPK through chemical fertilizers to rice followed by 100% NPK through chemical fertilizers to wheat (T3) maintained the highest productivity of rice and wheat at about 3.4 Mg ha−1 and 3.3 Mg ha−1, respectively, as found from the pooled grain yield over the years. The highest values of organic carbon, cation exchange capacity and available N, P, K were also recorded under this treatment (T3). Soil pH was marginally affected by different treatments, while Diphenyl Triamine Penta Acetic acid extractable micronutrient cations increased over control when chemical fertilizers were applied in conjunction with different organics.

Field experiments were conducted on a Typic Hapludoll (Mollisols) soil in the Indo-Gangetic Plains of India during the 2008 and 2009 rainy seasons to (1) find out the effect of irrigation schedules and plant spacing on physiological parameters, yield and water productivity of two rice cultivars under System of Rice Intensification (SRI), and (2) compare the performance of SRI with conventional transplanting (CT). Treatments under SRI included 12 combinations of three irrigation schedules, viz. irrigation at 1, 3 and 5 day(s) after disappearance of ponded water (DADPW), two spacing intervals (20 × 20 cm and 25 × 25 cm) and two cultivars (‘Pant Dhan 4’ and ‘Hybrid 6444’). The two control treatments were the CT of each cultivar. The experiment was set in a factorial randomized complete block design replicated thrice. The net photosynthetic rate (NPR) of the topmost fully expanded leaf at tillering and that of flag-leaf at flowering stage was affected significantly by irrigation schedules. Irrigating rice crop at 1 or 3 DADPW, being at par with each other, recorded significantly higher NPR than 5 DADPW. The increase in NPR at 1 and 3 DADPW was 17.1% and 8.4% at tillering and 13.6% and 6.1% at flowering stage, respectively, compared with that at 5 DADPW (tillering: 12.78 μmol CO2 m−2 S−1, flowering: 16.01 μmol CO2 m‑2 S−1). At closer spacing (20 × 20 cm) the cultivars did not differ significantly for NPR; however, at wider spacing (25 × 25 cm), ‘Hybrid 6444’ showed significantly higher NPR than ‘Pant Dhan 4’. Between two methods, SRI recoded higher NPR. Dry matter accumulation (DMA) in leaves and grains declined with delay in irrigation from 1 to 5 DADPW. Wider spacing significantly enhanced DMA in stems and grains. ‘Hybrid 6444’ showed higher DMA in all plant parts than ‘Pant Dhan 4’. Grain yield was not affected significantly by irrigation schedules in 2008, while in 2009, irrigation at 1 and 3 DADPW resulted in 12.8% and 8.0% higher grain yield, respectively, than 5 DADPW (5.84 t ha−1). Wider spacing was superior to closer spacing. SRI improved grain yield by 16.9% and water productivity by 18.5% over CT.

Many food production systems in sub-Saharan Africa are constrained by phosphorus (P). We hypothesized that within legume-cereal rotation systems: targeting P to the legume phase leads to higher system productivity, and that use of grain legumes leads to better economic returns than use of herbaceous legumes. Four P application regimes: (i) no P, (ii) P applied every season, (iii) P applied in season 1 only and (iv) P applied in season 2 only were tested for four seasons in three cropping systems (continuous maize, mucuna-maize rotation and soybean-maize rotation) in a split plot experiment set up in Nyabeda, western Kenya. Treatments where P was applied were better than no P treatments. While continuous cereal systems showed the need for application of P every second season, rotation systems involving mucuna and soyabean indicated that application in one out of three seasons could be sufficient. Nitrogen fertilizer equivalence was 52 to >90 kg N ha−1 for soyabean and 37 to >90 kg N ha−1 for mucuna, depending on P fertilization and season. Analysis of marginal rates of return (MRR) showed that soybean-maize rotation with one application of P was the most economically viable option, with an MRR of at least 147% compared to other non-dominated options.

The effect of advancing the sowing date from early February to November on the growth and seed and straw yields of three large seeded and three small seeded lines of lentil (Lens culinaris) was studied under rainfed conditions in northern Syria between 1982 and 1985. The average seed and straw yields from early winter sowing were 838 and 2476 kg ha−1 compared with 679 and 1470 kg ha−1, respectively, from a late sown crop. There were seasonal differences in the advantage in seed yield from early sowing, largely because infestation by Orbanche species limited the use of early sowing. There were no overall differences between the growth and yields of large and small seeded lines, but genetic variation within groups was apparent for all characters. A high rate of dry matter accumulation, manifested as early vigour, was always related to a high final economic biomass.

Fruit and vegetable farming generally involves high levels of chemical inputs despite the fact that consumers are increasingly concerned about the sanitary and organoleptic aspects of fruit quality. Pineapple is largely subject to these issues since it is dominated by conventional monocropping with high levels of agrochemical inputs due to nitrogen (N) and potassium (K) fertilisation, weed management, crop protection and flowering induction. However, low-input pineapple cropping systems are both rare and little documented. Our study aimed at replacing all or part of the chemical fertilisers used with local organic fertilisers. It was conducted on the cultivar ‘Queen Victoria’, without pesticides or herbicides, in Reunion Island. We compared the impacts of three fertilisation treatments on pineapple growth and yield, fruit quality traits, symptoms of two major fungal diseases in fruit and production costs and labour times: (i) conventional: NPK fertiliser at recommended doses (265.5 kg ha−1 N–10.53 kg ha−1 P–445.71 kg ha−1 K); (ii) integrated: Mucuna pruriens green manure (240.03 kg ha−1 N, 18.62 kg ha−1 P, 136.11 kg ha−1 K) incorporated into the soil and a half-dose of NPK fertiliser and (iii) organic: M. pruriens green manure incorporated into the soil and foliar applications of sugarcane vinasse from a local distillery, rich in K (14.44 g L−1). Our results showed that NPK fertilisation could be replaced by organic fertilisers as well as by integrated fertilisation. ‘D’-leaf analysis showed that vinasse supplies a largely sufficient K level for growing pineapples. With organic fertilisation, pineapple growth was slower, 199 days after planting vs. 149 days for integrated or conventional fertilisations, and fruit yield was lower, 47.25 t ha−1 vs. 52.51 and 61.24 t ha−1, probably because M. pruriens green manure provided an early increase in soil mineral N, whereas N requirements are much higher four months after planting. However, the fruit weight (709.94 ± 123.53 g) was still within the size range required for the export market (600–900 g). Interestingly, organic fertilisation significantly reduced Leathery Pocket disease and produced the best quality fruit with the highest total soluble solids contents (TSS) and the lowest titratable acidity (TTA). Fruit quality was also significantly improved with integrated fertilisation, with fruit weight similar to that of conventional fertilisation. To conclude, these findings have implications for the sustainability of pineapple production and could lead to low-input innovative cropping systems that reduce production costs and develop local organic inputs.

In Ethiopia, irrigation is mainly implemented in small-scale irrigation schemes, which are often characterized by low water productivity. This study reports on the efficiency and productivity of a typical small-scale irrigation scheme in the highlands of the Blue Nile, Ethiopia. Canal water flows and the volume of irrigation water applied were measured at field level. Grain and crop residue biomass and grass biomass production along the canals were also measured. To triangulate the measurements, the irrigation farm management, effects of water logging around irrigation canals, farm water distribution mechanisms, effects of night irrigation and water losses due to soil cracking created by prolonged irrigation were closely observed. The average canal water loss from the main, the secondary and the field canals was 2.58, 1.59 and 0.39 l s−1 100 m−1, representing 4.5, 4.0 and 26% of the total water flow respectively. About 0.05% of the loss was attributed to grass production for livestock, while the rest was lost through evaporation and canal seepage. Grass production for livestock feed had a land productivity of 6190.5 kg ha−1 and a water productivity of 0.82 kg m−3. Land productivity for straw and grain was 2048 and 770 kg ha−1, respectively, for teff, and 1864 kg ha−1 and 758 kg ha−1, respectively, for wheat. Water productivities of the crops varied from 0.2 to 1.63 kg m−3. A significant volume of water was lost from small-scale irrigation systems mainly because farmers' water application did not match crop needs. The high price incurred by pumped irrigation positively affected water management by minimizing water losses and forced farmers to use deficit irrigation. Improving water productivity of small-scale irrigation requires integrated interventions including night storage mechanisms, optimal irrigation scheduling, empowerment of farmers to maintain canals and proper irrigation schedules.