Impact of Minimum Tillage and Crop Rotation as Climate Change Adaptation Strategies on Farmer Welfare in Smallholder Farming Systems of Zambia

摘要

Worldwide, climate change is currently recognized as one of the major challenges to increased food production. The agriculture sector is the main source of livelihoods, growth and foreign exchange earnings in many developing countries including Zambia. However, it is also a sector that is mostly vulnerable to effects of climate change. Smallholder farmers in Zambia have been adopting agricultural related adaptation strategies including minimum tillage and crop rotation to mitigate effects of climate change. There has been contentious debate on whether the two strategies (that are elements of conservation farming) increase crop yields and incomes. Available literature heavily relies on biophysical experiments and show contradictions in the ability of these strategies to improve crop yields. Taking cognizance of the differences in socioeconomic circumstances of the farmers, the purpose of this study was to estimate the impact of minimum tillage and crop rotation on maize yields and incomes for farmers adopting the strategies. The study used cross sectional data collected in 2012/13 from 1231 households across six districts of Zambia and applied propensity score matching techniques and Heckman’s selection estimators to account for observed and unobserved heterogeneity between the adopters and non-adopters. The results showed that about 12 and 19% of the farmers have adopted minimum tillage and crop rotation respectively. The strategies improved on-farm maize productivity by about 26% to 38% for minimum tillage and 21% to 24% for crop rotation. Minimum tillage also improved total household maize production. On the other hand crop rotation did not significantly improve total maize production and gross income from the crop. This could reflect the small proportions of areas allocated to legumes versus the areas subsequently allocated to the maize crop during crop rotation. The impact of crop rotation on the staple maize crop could be boosted by encouraging farmers to increase the areas allocated to legumes. The legumes portfolio in the government sponsored input support programme should be increased. The results from this study generally confirm the potential direct role of agricultural related climate change adaptation strategies in improving crop productivity levels in small holder farming systems.