A Climate-smart agriculture approach using double digging, Zai pits and Aquacrop model in rain-fed sorghum cultivation at Wiyumiririe location of Laikipia County, Kenya

Peter Mwangi Muchiri; William Okelo Ogara; Fredrick Kamande Karanja; Jacinta Mwende Maweu

Peter Mwangi Muchiri Department of Agricultural Economics & Extension, University of Embu, Kenya
William Okelo Ogara Institute for Climate Change and Adaptation, University of Nairobi, Kenya
Fredrick Kamande Karanja Department of Meteorology, University of Nairobi, Kenya
Jacinta Mwende Maweu Institute for Climate Change and Adaptation, University of Nairobi, Kenya

Keywords: Aquacrop model, Double digging, Zai pits, Representative Concentration Pathways (RCP), Biomass, Water productivity

Abstract

The smallholder farmers of Wiyumiririe in Laikipia County are food insecure and highly vulnerable to climate related hazards owing to dearth of resources and over reliance on rain-fed agriculture. A preliminary reconnaissance pre-field visit of the area showed that there were no tangible CSA measures in place that could significantly improve the farmers’ adaptive capacity in a way that would make them food secure. This study therefore sought to investigate how double digging, Zai pits and Aquacrop model would be applied to help the community overcome food insecurity and adapt to climate change. The researcher identified experimental plots that were set out based on the split plot design. The field trials were done from January 2016 to February 2019. Daily weather data, soil water content, above ground biomass and percent canopy cover measured at regular intervals formed input data to calibrate Aquacrop model. The validated model was then used to determine the impacts of climate change on Sorghum crop yields at Wiyumiririe and to prepare scenarios for policy makers. The findings show that the interventions had significant impact because farmers who adopt either double digging or Zai pits and farmyard manure at 5 tons/ha, can obtain yields of approximately 9tons per hectare under current weather conditions and in future under climate change. This is because the attainable yields of 9 tons/ha are more than double the average production in Kenya of 4 tons/ha. Furthermore, the model output showed sorghum crop yields will generally increase in future mainly due associated increased carbon dioxide fertilization. However, the increase in yields needs to be taken with caution. This is because the compounding effects of water stress which is likely to cause a 61% reduction in canopy expansion, 31% closure in stomata and temperature stress of 31% is not yet fully understood. Moreover, the impacts of altered weather patterns to crop physiology, soil chemical properties and; prevalence of crop pests and diseases are still obscure.