CW-Department of Agricultural Sciences and Technology

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Browsing CW-Department of Agricultural Sciences and Technology by Author "Gitari, Harun I."

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    Crop Water Productivity and Economic Return of Rain Fed Potato-Legume Intercropping Systems
    (University of Montenegro, 2020) Gitari, Harun I.; Kamau, Solomon; Nyawade, Shadrack
    Reliance on rain-fed potato-legume intercropping systems among resource constrained smallholder farmers is usually ineffective without considering their economic viability. A field experiment conducted at the University of Nairobi, Kenya, in the growing seasons of 2014 to 2016 evaluated the effect of intercropping potato with legumes on soil moisture content (SMC), evapotranspiration (ET), potato equivalent yield (PEY), net income and crop water productivity (CWP) based on PEY (CWPPEY) and economic returns (CWPE). The treatments comprised of pure potato (Solanum tuberosum L.) stand (PS), potato-dolichos (Lablab purpureus) (PD), potato-garden pea (Pisum sativum) (PG) and potato-bean (Phaseolus vulgaris) (PB). Results showed significantly higher SMC values at tuber initiation stage: 77, 69, 67 and 62 mm in PD, PG, PB and PS, respectively. Fresh tuber yield was highest in PS (36 t ha−1) and PD (35 t ha−1) and lowest in PG (29 t ha−1). PEY was higher under intercropping than monocropping systems. The lowest ET values that were recorded in PS (630 mm) and PG (631 mm) differed significantly from those in PB (636 mm) and PD (642 mm). Potato-dolichos was the most profitable cropping system with a net income of 9,174 US$ ha−1 and a BCR of 5.7 compared to PS (7,436 US$ ha−1) with a BCR of 5.1. CWPPEY varied significantly between cropping systems in the order of PD (6.2 kg ha−1 m−3) > PB (4.7 kg ha−1 m−3) > PG (4.3 kg ha−1 m−3) > PS (2.3 kg ha−1 m−3). A similar trend was observed for CWPE with values of between 1.3 US$ ha−1 m−3 for PD and 1.5 US$ ha−1 m−3 for PS. The study shows that dolichos is a viable legume crop that could be integrated into potato cropping systems to improve their CWP without compromising the tuber yield.
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    Intercropping Potato with Grain Legumes for Enhanced Productivity and Climate Change Adaptation in Smallholder Farms, Kenya
    (Regional Universities Forum for Capacity Building in Agriculture, 2018) Nyawade, Shadrack; Gitari, Harun I.; Karanja, Nancy N.; Gachene, Charles K. K.; Geldermann, E.; Parker, M.
    This study evaluated the effect of potato-grain legume intercropping systems on best land equivalent yield ratios, crop water productivity and net profits in field trials conducted in three agro-ecologies of Kenya: upper highland with seasonal rainfall of 592 mm and altitude of 2550 m, lower highland (505 mm, 1879 m) and lower midland (356 mm, 1522 m) in 2017 rainy seasons. Shangi and Unica the most common potato variety in Kenya, and a drought and heat tolerant variety, respectively, were grown alone and intercropped with the deep rooting legumes, Dolichos (Lablab purperous) and Lima bean (Phaseolus lunatus). Whereas the potato varieties had similar yields in the traditional highland growing zone, the heat and drought tolerant Unica performed significantly better in a typical semi-arid midland agro-ecology. Intercropping systems with lima bean and Unica potato variety increased crop water productivity by 38% compared to the pure Unica cropping system and maintained soil moisture content above 33% during flowering and tuberization stages at all sites. This resulted in significantly higher dry matter equivalent yields of 3.21 ± 0.12 ha-1 compared to pure stands (1.98 ± 0.21 ha-1) and when intercropped with Dolichos (1.11 ± 0.23 ha-1) in the low midland zone. This system (Unica + Lima bean) recorded the highest net profits of USD 3,324 ± 143 ha-1 across the three agro-ecologies. These results reveal a strong effect of Unica potato genotype and environment interaction, and show that intercropping a heat and drought tolerant potato variety with lima bean is an excellent option for improved resource use efficiency in non-mechanized smallholder farming systems. This strategy can diversify potato production to mid-elevation agro-food systems and mitigate events of climate change in traditional growing regions.
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    Silicon Exerts Additive Effects on Phosphorus Acquisition by Potato Intercropped with Chickpea
    (University of Montenegro, 2020) Nyawade, Shadrack; Gitari, Harun I.; Kamau, Solomon
    The role played by silicon (Si) and legume intercropping in nutrient acquisition by potato crop has been neglected in most studies. A field trial integrating potato (Solanum tuberosum L.) with chickpea (Cicer arietinum L.) in intercropping system was conducted over six (6) growing seasons in the upper midland (1552 m above sea level) agro-ecological zone of Kenya. The intercropped chickpea secreted enzyme phosphatase into the rhizosphere (5.1–27.1 mol g–1 fwt h–1) thus mobilizing organic (4.2–18.9 mg kg–1 soil) and inorganic phosphorus (6.9–42.8 mg kg–1 soil). This increased phosphorus availability and acquisition by the intercropped potato. Chickpea took up more cations than anions, resulting in net proton efflux (43–105 mmol kg soil–1) with a significant decrease in rhizosphere pH. This acidic medium enhanced Si solubilization, increasing Si+ ions, which competed with Fe3+ and Al3+ ions for specific soil phosphorus sorption sites. Provision of sustainable seed supply systems for chickpea and market linkages for water-soluble silicon are necessary for adoption of this innovation.
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    Soil and water conservation and nutrient use efficiencies in smallholder potato-legume intercropping systems
    (APA, 2019) Nyawade, Shadrack; Karanja, Nancy; Gachene, Charles K. K.; Gitari, Harun I.; Kamau, Solomon; Atieno, Elly; Sharma, Kalpana; Schulte-Geldermann, Elmar; Parker, Monica L.
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    Unlocking Legume Intercropping Technology in Smallholder Potato Farming Systems for Climate Change Adaptation
    (University of Montenegro, 2020) Nyawade, Shadrack; Gitari, Harun I.
    A large portion of sub-Saharan Africa is situated in belts of uncertain rainfall and is characterized by low soil fertility with limited capacity to adapt to and mitigate the impacts of climate change. A study was conducted in semi-humid potato growing belt of Kenya to test the effect of legume intercropping and water soluble silicon (Si) on soil erosion control, and on use efficiency of light and water. Two forage legumes, Dolichos (Lablab purpureus L.) and hairy vetch (Vicia sativa L.), were intercropped with a heat and water stress tolerant potato (Unica) in a 2: 2 row arrangement. Silicon was applied to each cropping system in granular form at planting and as foliar at vegetative stage of potato growth and compared with no Si treatments. Intercropped potato subjected to Si application maintained significantly higher (p ≤ 0.05) relative leaf water content, higher concentrations of chlorophyll and greater leaf area index. These treatments accumulated significantly higher proline content and thus alleviated heat load on potato. Intercropping reduced soil loss by up to 80% compared to sole potato. Yield measured in terms of potato equivalents was 2–3 fold greater in intercropping relative to sole potato. Productivity of water and light were 35–75% greater in intercropping than in sole potato and increased with Si application. Combined application of Si and legume intercropping is a novel technology to conserve soils, increase resource use efficiency, and thus adapt farmers to adverse effect of climate change
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    Water Use Efficiency and Yield of Potato in Potato-Legume Based Intercropping Systems in a Semi-Humid Region, Kenya
    (European Association for Potato Research, 2017) Gitari, Harun I.; Gachene, Charles K. K.; Karanja, Nancy; Schulte-Geldermann, Elmar