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Background Ridge-furrow mulching farming systems (RFMs) aim to increase field productivity and improve water use efficiency. To explore environment-friendly and efficient farming systems is a central aspect of rainfed wheat field management in Kenya where rainfall utilization is at a low level. We introduced RFMs (including plastic film and grass straw mulching) to semiarid Kenya to evaluate the effects on field productivity, rainwater utilization, soil quality and economic profitability using old and modern wheat cultivars from 2012 to 2013. Results Across the cultivars, the RFMs increased grain yield, aboveground biomass and water use efficiency by 74-163%, 36-104% and 89-273%, respectively, compared with conventional flat planting (control). RFMs significantly shortened the vegetative period while prolonging the reproductive period. The net economic output under RFMs was 74-165% higher than that of the control. Grass straw mulching achieved the highest economic output to input ratio, almost 45% higher than plastic film mulching, despite the former harvested only 82% of the maximum field productivity of the latter. Compared with the control, grass straw mulching promoted the contents of soil organic carbon, total nitrogen and C:N ratio by 14%, 8% and 5%, respectively, while obviously decreased values of these parameters were observed under plastic mulching. Conclusions Through reducing soil water loss, and improving rainwater use efficiency and soil quality, ridge-furrow grass straw mulching would be a sustainable option for boosting field productivity and thus ensuring local food security in rainfed agricultural areas of Kenya. © 2020 Society of Chemical Industry.

The dry bean,Phaseolus vulgaris(L.) production is constrained by various factors in the environment. A survey was carried out to determine incidence of various foliage diseases and possible influence by whitefly vectors among other environmental factors on bean grain yield. Highest farmer cultivar preference was a tie of improved KAT Bean 1 (B1) and local cultivar (Mwitemia) at 24% as total of each category. Production level was 0.3-1.6 t ha-1per farm. Dominant whitefly species wasBemisia tabaci(Genn.) in over 90% of the farms. Laboratory analyses showed that disease incidence among the varieties showed improved varieties bearing highest incidence of both fungal and viral diseases compared to the local cultivars. Disease incidence showed little influence on bean grain yield. The updated information here is useful to breeding programmes to focus on local cultivars for higher disease-tolerant bean genotypes.

To explore low–cost, high–yielding and environment–friendly rainfed farming technology is critical for sustainable agricultural development in semiarid east African Plateau (EAP). An innovative ridge–furrow mulching system (RFMS) was first introduced to EAP, with a two–year field experiment using maize cultivar KDVI in a typical semiarid site of Kenya from 2012 to 2013. Nine treatments were designed including ridge–furrow cultivation with black plastic mulching (RFB), straw mulching (RFS) and without mulching (RF) under high (375 kg ha−1), conventional (225 kg ha−1) and zero fertilization rates. We found RFB and RFS significantly increased soil water storage (0–40 cm) by 10.2% and 4.8%, while lowered evapotranspiration rate and improved thermal status, compared to RF across two growing seasons. Importantly, RFB and RFS increased soil organic carbon and C/N ratio (soil organic carbon/soil total nitrogen) by 7.8% and 4.9%, 7.2% and 5.1% respectively, following two growing seasons of farming practice. As expected, grain yield and water use efficiency (WUE) were averagely increased by 63.3% and 63.8%, 27.5% and 35.9% in RFB and RFS than those of RF respectively. Additionally, net income and economic output–to–input ratio were significantly greater in RFB and RFS than those of RF. On the other hand, conventional fertilization rate achieved similar grain yield and WUE as high fertilization did. Considering environmental and economic benefits, the RFMS farming system with conventional fertilization may act as a promising option to upgrade local dryland agricultural system in EAP.

Adaptive management on rainfed agricultural ecosystem is crucial to improve field productivity and soil carbon sequestration under climate change, particularly in semiarid east African Plateau (EAP). We first introduced ridge-furrow (RF) farming system with plastic mulching and balanced fertilization into EAP to explore its effects on maize growth, yield formation, water use and soil carbon sequestration in a typical semiarid site of EAP in long but cool (2012) and short but warm (2013) rainy seasons. Local maize ( Zea mays L.) hybrid, KCB was used in field experiments including three farming patterns: 1) conventional flat planting (FP); 2) RF with transparent polyethylene film (RFT) and 3) RF with black polyethylene film (RFB), in which each pattern was exposed to high fertilization (compound fertilizer) (375 kg ha −1 ), conventional fertilization (225 kg ha −1 ) and zero fertilization respectively. The results indicated that RFT and RFB treatments significantly increased soil water storage in the depth of 0–120 cm, aboveground biomass, grain yield and water use efficiency over two growing seasons. On average, fertilization treatments further increased biomass accumulation, grain yield, leaf area index and WUE by 24.3%, 13.1%, 18.7% and 9.6%, respectively on the basis of sole RFM treatment. Across two seasons, RF mulching with fertilization averagely increased soil organic carbon and C/N ratio (soil organic carbon/soil total nitrogen) by 5.1% and 10.7% respectively. Critically, increased root biomass resulted in more root residue import into soil system due to improved hydro-thermal balance, which may account for biological carbon sequestration effects in this system. In addition, our field demonstration suggested that local farmers benefited from higher economic return from this integrated farming system, showing a high acceptance extent. Taken together, this system could serve as a promising adaptive management on increasing agricultural carbon fixation and maize productivity to cope with food security and climate change in semiarid EAP and other similar areas of Africa.

Gliricidia sepium is a fast growing legume shrub or tree with a wide range of environmental adaptation. Pruning of bushes at 1 m tall provides a source of crop nutrients. However, the value of pruning for increased agricultural productivity is not fully known. A study was carried out in a high rainfall humid tropical environment to investigate the contribution of Gliricidia sepium prunings (leaves and roots) and subsequent fallow with prunings to nitrogen (N) release pattern, sweet corn yield, nitrogen uptake and the N use efficiency (NUE) of the prunings. 15N atom excess dilution and litter bag incubation techniques were used to partition N uptake and estimate N-release pattern of the leaves and roots. The prunings were applied as smooth stems and leaves at a rate of 120 kg N/ha in two split applications, 7–30 days after sweet corn germination. The crop was harvested after 75 days at the physiological maturity. The results showed that Gliricidia Sepium leaves and roots significantly (p ≤ 0.05) increased sweet corn dry matter yield (3158 kg/ha) over the control (898 kg/ha). However, this was not significantly different from those treatments with leaf or root prunings in the presence of hedgerows. Use of root prunings as fallow showed significantly (p ≤ 0.05) higher sweet corn dry matter (2175 kg/ha) yield than that (1082 kg/ha) obtained from leaf prunings application. Nitrogen partition using 15N atom excess dilution showed that Gliricidia sepium fallow and leaf prunings contributed 25.9% and over 100% of total sweet corn N uptake and yield (as total dry matter), respectively. The incubation experiment showed that Gliricidia sepium leaves mineralize very fast, faster than roots, and should be re-applied within 20 days to maintain N-supply from the leaf prunings. It was concluded that Gliricidia sepium pruning and fallow contribute to the N uptake, growth and yield of the sweet corn with 5–9% NUE of the prunings. Further research is required to increase N use efficiency of Gliricidia sepium prunings and fallow in this study environment.

In semiarid Kenya, field productivity of maize has been at a low integrity level due to insufficient use of rainwater use. From 2012 to 2013, an innovative ridge-furrow mulching system (RFMs) was tested using local maize (Zea mays L.) hybrid, KCB in KARI-Katumani Farm, Kenya in long and short rainy seasons. Field experiments were conducted in a randomized complete block design with four treatments: 1) RFMs with transparent polyethylene film (RFT), 2) RFMs with black polyethylene film (RFB), 3) RFMs with grass straw mulching (RFS), and 4) RFMs without mulching (CK). Soil moisture & temperature, grain yield, water use and economic benefit were determined and analyzed. The results indicated that both RFT and RFB treatments significantly increased soil water storage amount in the depth of 0-60 cm. Grain yield and water use efficiency (WUE) in both treatments were increased by 66.5-349.9% and 72.9-382% respectively, compared with those of CK over two growing seasons. In addition, grain yield and WUE in RFS treatment were only increased by from 4.2-127.1% compared with those of CK. Particularly, two types of plastic films displayed different effects on modifying topsoil temperature. Transparent film mulching significantly increased topsoil temperature by 1.3 degrees C (p < 0.05) higher than CK, to facilitate growth and grain formation in long (but cool) growing season. In contrast, black film mulching lowered soil temperature by 0.3 degrees C lower than CK in short (but warm) growing season, which led to better soil thermal balance. Overall, RFMs with film mulching could serve as an effective solution to increase maize productivity, and hence a promising strategy to cope with food security under climate change in semiarid Kenya. (C) 2016 Elsevier B.V. All rights reserved.

A survey targeting smallholder households was carried out in Mumbuni and Ndovoini sub-locations in the semi arid Makueni County, Kenya, to identify agroforestry types and practices and their level of adoption and socio-economic factors influencing adoption of agroforestry. The study involved a survey of 234 households using a structured questionnaire. The collected data was subjected to descriptive statistical analysis and binary logistic regression model. Results obtained revealed that more than 90% of the households practised agroforestry. It was also observed that significantly (P

Micro-field rain-harvesting farming system (MRFS) has demonstrated great potentials to enhance field productivity and profitability of dryland wheat (Triticum aestivum L.) in semiarid eastern Asia, yet little is known whether this system results in desired effects in semiarid Africa such as Kenya. A two-year field experiment was conducted during 2012 and 2013 growing seasons to evaluate the effects of introduced MRFS on water availability, field productivity and economic benefits using a local wheat (T. aestivum L.) cultivar DUMA in a semiarid site of Kenya. Five treatments were designed as: 1) ridge and furrow with transparent plastic mulching (RFT); 2) ridge and furrow with black plastic mulching (RFB); 3) ridge and furrow with grass straw mulching (RFS); 4) ridge and furrow without mulching (RF); and 5) traditional flat planting (CK). The results showed that mulching treatments (RFT, RFB and RFS) significantly decreased the evapotranspiration (ET) by 11.4–88.5 mm, increased wheat grain yield by 60%–163%, above-ground biomass by 58%–104% and water use efficiency for grain by 68%–271%, compared with CK over two growing seasons. RFT and RFB treatments resulted in maximal soil water storage at 1-m depth and the greatest harvest index among all treatments. Linkage analyses indicated that grain yield showed significantly positive correlation with plant height, leaf area and major spike components (P ≤ 0.05), suggesting that plant type of wheat was altered for better yield production as a result of MRFS operation. More importantly, economic ratios of output to input were also calculated and compared. The average ratio of output to input for CK was 3.86, slightly lower than 4.28, 4.06, 5.86 and 5.34 for RFT, RFB, RFS and RF, respectively across two growing seasons. In particular, net incomes in MRFS (RFT, RFB, RFS and RF) were increased by 145%, 128%, 117% and 82% respectively, compared with that of CK. In conclusion, on-field rain-harvesting farming system provides an innovative management to boost the productivity and profitability of dryland wheat, and a potential solution to cope with food security in semiarid Kenya.

Sorghum (Sorghum bicolor L.) is an important cereal crop in Kenya. Despite the crops importance, the yields attained by farmers in Eastern, Coastal and Nyanza regions of Kenya remain low. Access to good quality seeds of sorghum is one of the constraints facing the subsistence farmers. Good quality seed is important for increasing yield to attain food security. The aim of this study was to evaluate quality attributes of the seed used by farmers. A total of 108 germplasm accessions were obtained from 76 farmers. The seeds were tested for time and percentage of germination, seed vigour index, shoot and root dry weight. Data collected was subjected to analysis of variance. Means were separated using Fisher’s Least Significance Difference test at p ≤ 0.05. Seed samples of 26 accessions attained germination percentage below stipulated standards by Seeds and Plant Varieties Act CAP 326. Majority of seeds showed longer mean germination time with only nine accessions germinating in less than ten days. Seed vigour index was relatively high in most of the accessions, while biomass accumulation varied from high to very low among accessions. Though most of the seeds attained a high germination percentage, about 92% of seeds showed longer mean germination time. The environmental conditions in the fields, pre and post harvest handling practices impact on the seed quality hence the wide variability in germination percentage, germination time, seed vigour index and dry matter accumulation. Therefore the need to improve quality of seeds used by subsistence farmers by providing extension services on best pre and post harvest handling practices. Increasing production of sorghum in these regions will contribute significantly towards realizing food security. Further analysis could be carried out on genetic and sanitary quality aspects of the seeds planted by farmers in Eastern, Nyanza and Coastal regions.

In Proceedings of the 2nd International Conference on Food and Agricultural Engineering, held on 11-13, May, 2016, Copenhagen, Denmark.

The African ebony (Dalbergia melanoxylon) is a tree that is crucial in making of high value wooden traditional artifacts, however its slow growth in the arid and semi-arid lands (ASALs), poor germination and low seedling growth rate, seed pest predation coupled with overharvesting pause a great threat for the future availability of the species. Unscreened natural methods of seed germination might not sustainably solve the problem of low germination. Overharvesting for wood carving, and low natural regenerative ability of the species and lack of the local and national conservation efforts present a serious threat its availability to the future availability of Dalbergia melanoxylon. Availability of viable seed plays a crucial role the establishment of African ebony. There is need for immediate methods for multiple seedling production for propagation of D. melanoxylon. Our studies showed 2% germination without screening but increased to 40% after screening (p< 0.001). Careful moisture monitoring of the seedling seemed to increase the growth rate in the ASAL region. Therefore, selected propagation methods of this species can rescue it from the current extinction trend which is caused by its low regenerative ability when natural methods are used and over exploitation. There is need to support on farm cultivation of the tree to sustain the carving industry.

Managing grain moisture content is important because maximum economic return can be achieved by marketing at a certain moisture level of grain. Post-harvest management dictates that grains must be dried to certain levels to avoid development of fungal and insect problems, respiration and germination. However, over drying can also a lead to economic losses. Most farmers are aware of fungal development in moist grains but few are aware that they make less profit by over drying. Moreover, there are also bean varieties which genetically retain more water than others and hence can be safer and have more economic returns compared to others. But, this also should be matched to the rain pattern in a growing region. We compared six varieties of beans (KAT B1, KAT B9, and Kakunzu (KKZ), Rose Coco (GLP2/RCC), Kenya Tamu and KAT X56) grown in the South Eastern region of Kenya and found significant differences in dry moisture content, physical properties and grain weights. The Rose Coco and KAT X56 varieties had the highest moisture content retention but the KKZ variety the lowest. This explained why KKZ is favoured more by famers in arid areas with less rain during fruit maturation.

Cowpea is popular in Eastern Kenya where it is attractive to farmers because of its high economic value and the belief that it does not require many external inputs. Farmers are however discouraged to grow the crop in this region due to massive attack by a parasitic weed Alectra vogelii (Benth). Yield losses due to A. vogelii have being estimated to range from 50 to 100% in Mbeere, Kitui and Makueni districts. No single method however is available to farmers in these regions in control of the parasitic weed. Combining several control methods, as in the management of Striga spp in Western Kenya should be a sustainable option. Field studies were conducted in 2010 and 2011 at Kenya Agricultural Research Institute (KARI), Kiboko farm to determine the response of 143 cowpea genotypes to Alectra infestation. The aim for the study was to identify resistant genotypes that could be used in breeding programme. Significant differences were observed amongst cowpea genotypes in days to first Alectra emergence, number of Alectra shoots emerged at 6, 8, 10 and 12 week after planting and grain yield. Cowpea genotypes Kir/Nya-005 and Mbe/Mach-022 showed complete resistance to Alectra while Ken-Kunde, M66 and K80 (all commercial varieties) supported the highest number of Alectra shoots. Grain yield loss in the three susceptible varieties was 80, 79 and 50% respectively. On the other hand, Sia/Cia-004, Mbe/Mach-014 and Kib-006 had high grain yields despite the high number of Alectra shoots present. There was a strong correlation (r = -0.57) between grain yield and number of Alectra shoots emerged at 12 weeks after planting. A significant negative (r = -0.37) correlation was also obtained between pod number per plant and number of emerged Alectra shoots at 12 weeks after planting. This negative correlation proves the high accumulation dry matter in the cowpea roots at the expense of the pods thus decreasing grain yield. This information showed that there is sufficient genetic variability in the cowpea genotypes studied, which can be exploited in breeding improved cowpea varieties for resistance to A. vogelii in Kenya. A great progress towards developing improved cowpea variety that meets farmer’s preferences with durable resistance to A. vogelii can be achieved if the genes from the resistant and tolerant local cowpea cultivars identified in this study could be introgressed into the adapted susceptible improved varieties. This will increase the potential impact of adoption of resistant cowpea varieties in the zones. Key words : Cowpea, Alectra vogelii , Resistance/tolerance and grain yield.

Milk consumption in the semi-arid regions of Kenya is not well understood. A study was carried out on consumption of milk and milk products in the semi-arid region of eastern Kenya. A total of 135 rural and 126 urban households were interviewed. Raw milk was the most popular and was consumed by 99% and 84% of rural and urban households, respectively. Generally as degree of processing increased, the frequency of consumption declined from more than once per day to 1-2 times a week and eventually to occasionally. Richer households consumed significantly (p < .05) more milk and milk products than poor households. Raw milk was preferred over pasteurized, ultra high temperature treated, and powdered milk because it was cheaper and widely available. In order to improve consumption of different milk products, there is need to improve availability particularly in the rural areas.

A glasshouse study was carried out to determine the isotopicdiscrimination (B values) and the isotopic fractionation factors (β)associated with symbiotic nitrogen fixation in stylo (Stylosantheshamata L.) and cowpea (Vigna unguiculata L.Walp). The B values are required to improve the accuracy of estimates ofnitrogen fixation based on the differences in the natural abundance of15N between nitrogen fixing and non-fixing plants. The B values ofplants grown in nitrogen free media for stylo were −1.60, 82 days after planting (DAP) and −1.86, 98 DAP and −1.48, 49DAP and −1.51 for cowpea shoots 73 DAP. Theisotopic fractionation factors for stylo and cowpea were 1.0016, 82DAP and 1.0019, 98 DAP and 1.0018, 49 DAPand 1.0015, 73 DAP, respectively.

Laboratory studies were conducted to investigate the effect of phosphorus concentration in residues of cowpea (t Vigna unguiculata, L. Walp) and stylo (t Stylosanthes hamata, L., cv Verano) on their rate of nitrogen mineralisation when incubated in a soil whose P status was deficient for plant growth. Residues with a range of P concentrations were obtained by applying varying rates of P to soil in which the plants were grown in the field or the glasshouse. Variations in P concentration of field- or glasshouse-grown residues were not accompanied by variations in other chemical components (C:N ratio, lignin and polyphenol concentrations). Both lignin and polyphenol concentrations were higher in the field-grown than in the glasshouse-grown residues. Lignin concentration was greater in cowpea than in stylo, but polyphenols were higher in stylo. Cowpea residues mineralised N less rapidly than stylo. N mineralisation from residues with low P concentration was consistently less than from those of higher P concentration; reduced mineralisation was observed for P concentration in the residues below 1.6 g kg−1. When inorganic P was added to the residue-soil systems, N mineralisation from the residues was increased, though no interaction between the effects of adding inorganic P and P concentration in the residues was observed.

Post-harvest losses in sub-Saharan region in Africa are estimated to be about 30% annually. This review examines the vital role which post-harvest management plays in the management of crop farms and in the mitigation of aflatoxin poisoning. The capitalization of this role offers a cheaper way of improving food production in the sub-Saharan region which is drought prone and has to a large extent, seen as food insecure. Studies have shown that proper post-harvest management, especially the use of the small scale metal silo, contributes to better quality of grains, less pesticide usage and can accelerate agribusiness, therefore directly contributing to rural development and poverty reduction. However, not much effort has being invested in reducing post-harvest food losses especially in staple cereals like maize and legumes, even after many studies have shown that it offers an essential way of increasing food availability without the need of other resources. Furthermore, post-harvest management offers a cheaper way for diet diversification, which is crucial in aflatoxin poisoning reduction. This review also presents a model by which can be used in reducing the entry of toxigenicAspergillus flavusin the grain supply chain.

A total of 74 farms were selected from Machakos, Mwingi and Makueni districts in Kenya, using participatory techniques and classified in three categories on the basis of soil fertility management (low level, medium and high level). Soil fertility management was monitored, using the NUTrient MONitoring methodology, which appears a suitable and appropriate tool for the diagnostic phase of Farming System Analysis and Design in Arid and Semi-Arid Lands of Kenya. The participatory inventory and monitoring procedures applied, involving the farmers in the analysis of their own situation, forced the farmers to think about the processes and flows associated with the nutrient balances and the associated consequences for the quality of their soil resource base. Farmers’ performance during the feedback, through farmers’ workshops, of the results of soil analyses and the discussion on possible solutions for the identified problems, creates confidence that in the participatory learning and action phase, farmers will be equally involved and willing to adopt suggested adaptations. The first results of the quantitative analyses of nutrient balances at farm level show that farm balances for NPK are negative. This is in agreement with earlier work in the high-potential areas of Kenya and elsewhere in East Africa, as well as those from semi-arid regions in West Africa. It has been shown that client characterisation, as an emerging component of a research approach towards design of sustainable agricultural production systems, helps in identifying major potential recommendation domains and related research and development problems and opportunities, and potential interventions on which to focus the research agenda.