Abstract
The adverse effects of climate change and increasing human population have put pressure on scarce water resources used in crop production. This consequently threatens the food and nutritional security of the growing human population. Vegetables are short season crops that are sensitive to water deficits during growth, leading to low productivity, poor marketability and reduced household incomes. Use of controlled irrigation in production of vegetables is considered a sustainable route for enhancing input use and productivity. This study sought to evaluate the effects of crop variety and drip irrigation schedules on productivity and profitability of cabbage grown in humic nitisols in Embu County, Kenya. The study applied a split plot laid in Randomized Complete Block Design (RCBD) in which the drip irrigation schedules were allocated the main plot and crop varieties were allocated the sub-plot treatments. The test varieties investigated were Riana F1, Gloria F1 and Triperio F1. The four irrigation schedules were arranged as follows: application twice a week as S1, application once a week as S2, application once after every two weeks as S3 and a control (no irrigation at all) as S4. The treatments were replicated three times. Data was collected on the amount of irrigation water used, production cost, yield and income from the cabbages. The data were subjected to Analysis of Variance using SAS version 9.4. Mean separation was done using Fischer's least significant difference at P=0.05. An accounting profit approach was used to assess profitability from the selected irrigation schedules and varieties. The findings revealed that the yields of different cabbage varieties were not significantly different. Irrigation schedule 1 (S1) produced the highest average yield of 65.66 t ha-1 followed by S2 with 52.26 t ha-1 , S3 with 38.75 t ha-1 and S4 with 24.87 t ha-1 . Water use efficiency was significantly different across the four irrigation schedules. The control treatment plots recorded the highest water use efficiency at 70% in season one and 77% in the second season. Irrigation schedule 1 (S1) recorded the lowest water use efficiency of 46% in season one and 49% in season two which indicates that water productivity and efficiency reduced as the amount of water applied increased. In terms of production cost, S1 had the highest production cost ($2,103) but also gave the highest net revenue of $ 5,947 in season one and $ 4,460 in the second season. S4 recorded the least production cost ($1854) and net revenue ($1,575 in season one and $2,011 in season two). There were no significant differences among the three cabbage cultivars assessed in terms of production cost and net revenue in the second season. However, in season one, the cost of production for Triperio F1 variety ($2,019) was significantly different from that of Riana F1 and Gloria F1 cultivars ($1,959) while the latter two cultivars were not statistically different from each other. Net revenue for statistically different between Gloria F1 ($3,853) and Triperio F1 ($3,028) varieties but there were no significant differences between Gloria F1 and Riana F1 as well as Riana F1 and Triperio F1. These findings were significant for quantifying the impact of irrigation scheduling decisions with regard to water management in cabbage farming. The study therefore recommends adoption of irrigation schedule (S1) in order to optimize on cabbage yield reflected by the head weight and better stand count of the three cabbage varieties. There were no significant effects on the test cabbage varieties among the productivity parameters assessed under different irrigation schedules thus farmers may select any of the three cabbage varieties based on other production factors (agronomic variations, customer preference, and marketability)