A pathway for sustainable development of mixed crop-livestock systems in semi-arid Kenya :an integrated approach to soil nutrient management

Abstract

Rainfall variability and declining soil fertility are predicaments to sustainable food production. The vagaries of rainfall and the limitations of soil nutrient are mostly felt among the smallholder farmers within arid and semi-arid areas (ASAL) of Sub-Saharan Africa. Over 70% of Kenya’s landmass is either arid or semi-arid. Marsabit-central Sub-County is located within ASAL areas of Kenya and rain-fed production systems provide the primary source of livelihoods. However, the pattern of land use, and the changeability of forage biomass with the rainfall variability has received little attention. Furthermore, the crop production practices, characteristics of soils, and particularly the nutrient balance, has lacked conclusive study. This study employed remotely sensed data to reveal the land use classes. Additionally, rain gauges and spatial modelling were used to unveil the variability of rainfall and forage biomass. Using field measurements, the characteristics of soils and farmer’s crop yields were investigated. Field assessments also included quantification of nutrient flows, and thereby nutrient balance in the crop fields. Finally, by scenario analysis, this work explored alternatives for sustainable food production based on integrated crop and livestock systems. This study showed that crop fields and grazing lands are important land use classes in Marsabitcentral. The spatio-temporal variability of rainfall influenced production of forages, the number of livestock fed and availability of manure. Nitrogen is the deficient soil nutrient and the measured nitrogen balance ranged from -41.7 to -66.3 kg/ha/season in maize fields and -28.8 to -30.2 kg/ha/season in bean fields. Nevertheless, the collectable livestock-mediated manure is 5.0-12.0 x 106 kg and 1.5 x 106 kg in long and short median rain seasons, respectively. Better use of livestock manure can sustain the nitrogen balance and also improve maize grain yields from current 1.1 t/ha to 2.0-4.0 t/ha and bean grain yields from current 0.7 t/ha to 0.8- 1.5 t/ha. Sustainable food production in Marsabit-central farms lie in integrated crop-livestock systems, and manure plays a central role in reclaiming the declining soil fertility.