Adaptation Strategies to Increase the Yield in Green Gram Production in Makueni County Under a Changing Climate

Abstract

Climate change effects are causing numerous challenges in agricultural production systems. These effects are location specific and more severe in areas where farmers have low adaptive capacity. This study investigated climate change adaptation strategies to increase the yield in green gram (Vigna radiata) production under a changing climate in Makueni County. The specific objectives were: a) to investigate historical and future rainfall and temperature trends in Kibwezi East Sub- County b) to determine agricultural interventions and climate change adaptation strategies to increase green gram production in the study location and c) to examine a habitat suitability model and a crop production simulation model for green gram production in Kibwezi East Sub County. The study adopted a mixed methods approach including quantitative and qualitative data. Primary data was collected using a household survey, Focus Group Discussions and Key Informant Interviews. A desk top analysis of secondary historical (1990-2020) and future (2040-2070) climate data was used for secondary data collection. Trends for historical and projected future climate data were analyzed using Least Squares and non-parametric approaches based on Mann- Kendall statistics. Descriptive statistics and thematic analysis were used to analyze the qualitative data. The crop production model was parameterized and simulated using APSIM Model while the habitat suitability model was run using an ensemble of Species distribution models in R statistical software using the sdm and dismo packages. The results showed no trend in the rainfall time series data with p = 0.95 for historical, P=0.38 under RCP 4.5 and P=0.23 under RCP 8.5 climate scenarios. The historical monthly rainfall data analysis showed a bimodal rainfall trend while the predicted data showed a deviation from the normal pattern. The annual historical temperature data showed a significant trend whereby both maximum and minimum temperature had (P=0.0091). The predicted maximum temperature data under RCP 4.5 had a (p = 0.19) and minimum temperature data had a (p = 0.32) showing no significant trend. Under RCP 8.5, both maximum and minimum temperature data had a significant trend (P=0.05). Future climate data for the 2060s revealed an increase in rainfall and temperature levels compared to historical climate data under all climate scenarios. There was significant correlation (p < 0.05) between the social-demographic characteristics of the study population and increase in green gram production. The major challenges were prolonged droughts and increased incidences of crop pests. There was significant correlation between adaptation measures and increased green gram production (P< 0.05). There was low adoption of climate change adaptation strategies at the house hold level. Changing the green gram variety and integrated pest management were more prioritized . There was significant vi correlation between government interventions and increased green gram production (P< 0.05). Simulated results from APSIM model showed that variety KS 20 performed better than the other two varieties under all climate scenarios. The formulated crop model had an accuracy of R2 (0.50- 0.84) implying that it was robust and could be used to predict future green gram yields. The habitat suitability model had a good prediction accuracy whereby R2 = (0.87 - 0.98) implying that it was robust and could be used for modelling. The prediction results showed that habitat suitability for green gram production in Kibwezi East would decrease under all climate scenarios. Thange ward had the highest suitability for green gram in the present scenario but its suitability was predicted to decrease in the 1960s due to climate change if no interventions were employed. Due to the present and predicted changes in climate, there was need for farmers to increase adoption of timely planting and choice of drought tolerant and early maturing varieties like KS 20 and Biashara. Use of integrated pest control methods was recommended due to the increasing incidences of crop pests. Water management especially harvesting and conservation at farmer level was recommended. Soil improvement through regeneration, minimum tillage and use of organic fertilizers was recommended. The cutting down of trees should be minimized and more trees planted for environmental protection as well as provision of timely climate information for seasonal plantings. These activities will help to enhance climate change adaptation.