Evaluation of Establishment, Biomass Productivity and Quality of Improved Fallow Species in a Ferralic Arenosol at Coastal Region in Kenya

Abstract

Inherent low soil fertility, continuous cultivation without nutrient inputs, nutrient losses through leaching and unsustainable farming methods of slash and burn leading to nutrient losses are some of the major causes of low crop yields at the coastal region. Short-term improved fallow technology has been successfully associated with soil fertility improvement and increase in crop yields in several parts of Kenya but has not been adequately evaluated at the coastal Kenya to give firm recommendations. An on-farm experiment was established in Malindi District as a randomized complete block design with eight treatments replicated thrice in 2006. Six species were evaluated at two intervals: 6 and 12 months after planting (MAP) for their site adaptability, biomass productivity, nutrient accumulation and leaf quality. The objective of the study was to determine the quantity of biomass produced, nutrient accumulation and leaf quality of improved fallow species. The data were analyzed using ANOVA procedures, and mean comparisons were done using orthogonal contrasts. Mucuna pruriens gave significantly (p 2.5%, with phosphorus and potassium contents being low in all species. Lignin contents were <15% except in Tephrosia species, but all species had low polyphenol contents of <4% at 6 MAP. Tephrosia candida and M. pruriens had N contents of over 100 kg N/ha in the leaf biomass. These were substantially large amounts for recycled N by improved fallow species. In conclusion, M. pruriens, T. candida and Tephrosia vogelii were potential species for the coastal region, and their production can be enhanced in order to have recyclable amounts of nutrients that can be used to ameliorate the inherent low-fertility soils at the coast and subsequently enhance crop yields.