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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.

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.

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.