Decomposition dynamics of leaves of six indigenous fruit trees commonly found on croplands of southern Africa

Abstract

Leaf litter decomposition plays a crucial role in the cycling of both nutrients and energy in the tropical croplands. A field experiment was conducted at Botswana College of Agriculture’s Research Farm in 2003 to compare the leaf material decomposition rates among six native tree species: Azanza garckeana, Berchemia discolor, Sclerocarva birrea, Strychnos cocculoides. I'angtieria infausta and Strychnos pungens. The litterbags (20 cm x 25 cm x 2 mm) containing leaves of each species were incubated under field conditions and retrieved after 2, 4, 6, 8, 10 and 12 weeks. During the first 6-8 weeks of incubation, the leaf dry weight loss of I'angtieria infausta increased by 36.8% while that of Jrtwzt/ garckeana increased by 85.4%. At the end of incubation period, both I'angtieria infausta and Azanza garckeana showed the highest leaf dry weight losses (96.2 and 95.0% respectively) as compared with Berchemia discolor (79.3%), Sclerocarva birrea (78.7%), Strychnos pungens (72.3%) and Strychnos cocculoides (71.3%). It is concluded that I'angtieria infausta and Azanza garckeana have high agroforestry potential as sources of organic manure and that application of their foliages can improve both soil fertility and crop productivity. Proper timing of foliage application is important if nutrients released from these sources are to be synchronized with specific agricultural crops demand.