ASSESSMENT OF THE ECONOMIC BENEFIT OF CABBAGE PRODUCTION UNDER DIFFERENT IRRIGATION LEVELS AND SOIL AMENDMENTS IN A SEMI-ARID ENVIRONMENT

Crop production in small-scale farming communities in semi-arid Central Namibia faces significant challenges due to the high costs associated with irrigation and fertilizers. This study evaluated the impact of different irrigation levels (full and reduced) and six types of soil amendments—biochar, compost, zeolite, NPK, Be-Grow Boost (L) hydrogel, hoof and horn combined with a bone meal (HHB meal), and control on the economic benefits of cabbage production and assessed their feasibility. In the first experiment, irrigation was implemented at 79.6 m³ (100% of the water requirement) for four days a week, classified as full irrigation, and at 39.6 m³ (50% of the water requirement) for two days a week, termed reduced irrigation. Among the fully irrigated treatments, Be-Grow Boost (L) hydrogel, zeolite, and NPK demonstrated the highest Benefit-Cost Ratios (BCRs) at 3.81, 3.67, and 3.65, respectively. In the second experiment, irrigation schedules were adjusted to five and four days per week, using a total of 136.0 m³ (170% of the water requirement) and 124.8 m³ (150% of the water requirement) of water. The compost, HHB meal, and NPK application rates were also modified. The fully irrigated Be-Grow Boost (L) hydrogel, NPK, and reduced irrigation with HHB meal achieved the highest and comparable yields of marketable cabbage heads per hectare, with BCRs of 3.43, 3.24, and 3.29, respectively. In conclusion, utilizing fully irrigated Be-Grow Boost (L) hydrogel, NPK, and reduced irrigation with HHB meal could be effective practices for sustainable crop production in the semi-arid, sandy soil conditions typical of Central Namibia. Moreover, local biochar production could enhance sustainability by reducing overall production costs.