WATER SAVING AND WATER PRODUCTIVITY UNDER BURIED CLAY POT AND DRIP IRRIGATION SYSTEMS FOR CABBAGE IN RWANDA

This research evaluated the effects of Clay Pot Irrigation System (CPIS) on water saving and water productivity compared with Drip Irrigation System (DIS) as microirrigation systems in cabbage production in Rwanda. This research was conducted at the Rwanda Polytechnic/Integrated Polytechnic Regional College Huye (RP/IPRC Huye) farm (2°35′48″ S and 29°44′21″ E, Elevation of 1769 m above sea level), in Huye district of Rwanda. The experimental designed was a Randomized Complete Block Design (RCBD) with three treatments and three replications. The experimental treatments were Clay pot irrigation system, Drip irrigation system, and the control treatment (No irrigation). The soil type was a sand clay loam. The clay pots used were manufactured by mixing clay and sand at the ratio of 4:1 and dried with burning dry grass. Pots were buried under the soil up to their necks, with about 2 cm of their top above the surface of the surrounding. The crop variety used for the study was Zawadi F1 of cabbage produced by the East African Co. Seed, which is adaptable under the agroclimatic conditions of the Huye district of Rwanda. Crop water requirement and irrigation scheduling were estimated by using CROPWAT 8.0 software. Organic manure (20 tons ha-1) was applied for whole trial during tillage, Nitrogen-Phosphorous-Potassium/ NPK 17-17- 17 (300 kg ha-1) was uniformly applied around the seedling (ring application) and Urea (300 kg ha-1) was split applied, first after three weeks of transplanting, and the second application was five weeks after transplanting. The water productivity of CPIS was 36.17 kg m-3 for DIS was 25.4 kg m-3, while the control was 31.1 kg m-3. The results of this research show that CPIS increases water productivity and water saving. Water saved is 40.23% when CPIS is compared with DIS. Clay pot irrigation system can be a viable option for water scarce areas, particularly for small-scale farmers looking to improve their productivity with their small holdings of land in sandy and drier environments.本研究针对卢旺达卷心菜生产中的两类微灌溉系统——陶罐灌溉系统（Clay Pot Irrigation System, CPIS）与滴灌系统（Drip Irrigation System, DIS），对比评估了其节水效果与水分生产率表现，同时设置无灌溉对照组。本试验于卢旺达胡伊区卢旺达理工学院/综合理工区域学院胡伊分校（RP/IPRC Huye）农场开展，地理坐标为南纬2°35′48″、东经29°44′21″，海拔1769米。试验采用完全随机区组设计（Randomized Complete Block Design, RCBD），设置3个处理组与3次重复，处理组分别为陶罐灌溉系统、滴灌系统及无灌溉对照。供试土壤为砂质壤土，试验所用陶罐按照黏土与沙子4:1的质量比混合制成，经干草燃烧烘干后，将其埋入土中至罐颈位置，仅保留约2厘米的罐顶露出周围土壤表面。本研究选用东非种子公司（East African Co. Seed）选育的Zawadi F1卷心菜品种，该品种适配卢旺达胡伊区的农业气候条件。作物需水量与灌溉制度通过CROPWAT 8.0软件估算，全试验田在翻耕阶段施用20吨·公顷⁻¹的有机肥，在幼苗根部周围采用环施方式均匀施加300公斤·公顷⁻¹的氮磷钾（NPK 17-17-17）复合肥，尿素（300公斤·公顷⁻¹）则分两次追施，分别于移栽后第3周与第5周进行。本研究测得陶罐灌溉系统的水分生产率为36.17千克·立方米⁻¹，滴灌系统为25.4千克·立方米⁻¹，无灌溉对照组为31.1千克·立方米⁻¹。结果表明，陶罐灌溉系统可提升水分生产率与节水效果，相较于滴灌系统，该系统可实现40.23%的节水率，对于水资源匮乏地区，尤其是砂质干旱环境下拥有小块耕地的小规模种植户而言，陶罐灌溉系统是一项切实可行的高效灌溉方案。