Tropical and Subtropical Agroecosystems 25 (2022): #110 Wafula et al., 2022 1 IN-SITU WATER HARVESTING TECHNOLOGIES AND FERTILIZER RATES INCREASE MAIZE AND BEAN YIELDS IN THE SEMI-ARID KATUMANI, KENYA † [LAS TECNOLOGÍAS DE COSECHA DE AGUA IN SITU Y LAS TASA DE FERTILIZANTE AUMENTAN LOS RENDIMIENTOS DE MAÍZ Y FRIJOLES EN EL SEMIÁRIDO KATUMANI, KENIA] Kelvin M. Wafula 1* , Nancy N. Karanja 1 , George N. Karuku 1 and Anthony O. Esilaba 2 1 Department of Land Resource Management and Agricultural Technology, University of Nairobi, P.O Box 29053-00625 Nairobi, Kenya. 2 Kenya Agricultural and Livestock Research Organization (KALRO) Headquarters. P.O Box 57811-00200 Nairobi, Kenya. Email: wafulakelvin2019@gmail.com *Corresponding author SUMMARY Background: Crop production in the arid and semi-arid lands (ASALs) is constrained by erratic rainfall and poor soil fertility. Therefore, climate smart agriculture mechanisms such as in-situ rainwater harvesting technologies and recommended fertilizer rates would be vital for ensuring food security. Objective: To evaluate selected in-situ water harvesting technologies and fertilizer rates on soil water content and yield of maize and beans at KALRO Katumani Research Center in Machakos County, Kenya during the 2019 and 2020 short and long rain seasons, respectively. Methodology: The experiment was established in a randomized complete block design with a split-split plot arrangement, replicated three times, with in-situ water harvesting technologies comprising of zai pits, ngolo pits, contour furrows and conventional tillage, as the main plots, whereas the split plots were varying rates of fertilizer inputs: Di-ammonium phosphate (DAP), goat manure and control. The split-split plots comprised of maize and beans cropping systems. Soil moisture content was assessed at 4, 8, 12 and 16 weeks after emergence, whilst nutrient uptake, use efficiency and crop yields at physiological maturity. Data was subjected to analysis of variance. Results: Soil moisture, maize and beans yields, nutrient uptake and use efficiency were significantly (p ≤ 0.05) increased by in-situ water harvesting technologies and fertilizer inputs. Highest soil moisture content was recorded under zai and ngolo pits and lowest in conventional tillage treatments. Ngolo pits recorded higher maize and beans grain yield. Application of DAP fertilizer increased maize and beans grain yield compared to control. Intercropping maize and beans increased grain yield significantly (p ≤ 0.05) compared to sole maize and sole beans. Implications. There is need for promoting a combination of in-situ rainwater harvesting technologies especially ngolo and zai pits with application of DAP+ manure in semi-arid areas where water is scarce coupled with poor soil fertility. Conclusion: Ngolo and zai pits increased soil water retention capacity while application of DAP fertilizer led to increased crop yield and the study therefore recommends their adoption within the study area and extrapolation to areas of similar conditions. Key words: in-situ water harvesting; ngolo pits; zai pits; nutrients uptake; use efficiency. RESUMEN Antecedentes: La producción de cultivos en las tierras áridas y semiáridas (ASAL) se ve limitada por la irregularidad de las lluvias y la escasa fertilidad del suelo. Por lo tanto, los mecanismos de agricultura climáticamente inteligente, como las tecnologías de recolección de agua de lluvia in situ y las tasas de fertilizante recomendadas, serían vitales para garantizar la seguridad alimentaria. Objetivo: Evaluar tecnologías seleccionadas de recolección de agua in situ y tasas de fertilizantes sobre el contenido de agua del suelo y el rendimiento de maíz y frijoles en el Centro de Investigación KALRO Katumani en el condado de Machakos, Kenia, durante las temporadas de lluvia corta y larga de 2019 y 2020, respectivamente. Metodología: El experimento se estableció en un diseño de bloques completos al azar con un arreglo de parcelas divididas y divididas, replicado tres veces, con tecnologías de recolección de agua in situ que comprenden pozos zai, pozos ngolo, surcos de contorno y labranza convencional, como las parcelas principales. mientras que en las parcelas divididas se variaron las tasas de aportes de fertilizantes: Fosfato diamónico (FDA), estiércol caprino y testigo. Las parcelas divididas fueron constituidas por los sistemas de cultivo de maíz y frijol. El contenido de humedad del suelo se evaluó a las 4, 8, 12 y 16 semanas después de la emergencia, mientras que la † Submitted February 17, 2022 – Accepted June 27, 2022. http://doi.org/10.56369/tsaes.4247 Copyright © the authors. Work licensed under a CC-BY 4.0 License. https://creativecommons.org/licenses/by/4.0/ ISSN: 1870-0462.