Dynamics in tropical lowland soil nutrients as influenced by leafy biomass of some agroforestry trees

Abstract

One of the major challenges of the developing countries is the production of sufficient food for the rapidly increasing population, and over cultivation of land resulting to soil infertility. Hence, transfer of nutrients through tree biomass contribute to micro variability in soil fertility and plant growth. A field research was conducted in the forest nursery of the Federal University of Agriculture, Abeokuta (FUNAAB), Nigeria to investigate the response of tropical lowland soil to the application of leafy biomass of some agroforestry tree species; Anogeissus leiocarpus, Enterolobium cyclocarpum, Gliricidia sepium, Leuceana leucocephala and Treculia africana at the rate of 5 tons per hectare (5t ha-1 or 5000 kg ha-1). The soil samples were collected at 2, 4, 6, 8 and 10 weeks after application (WAP). Split plot experimental design was used with the time of soil sampling as main plots, mulch type as sub-plots. Data were statistically analysed using Analysis of Variance (ANOVA) at p =0.05 on pH, organic carbon, total N, P, K, Ca, Mg and Na. L. leucocephala had highest nutrient release values on; total nitrogen (0.019±0.002), calcium (41.07±3.75), sodium (139.0±36.927). Control plots was high in organic carbon (3.12±0.067), as well as pH (6.45±0.029). However, E. cyclocarpus also had highest nutrient contents in potassium (90.0±4.79) and magnesium (152.50±24.575). It is concluded that L. leucocephala had fast decomposition rate and its rapid nutrient release is a good alternative to improving soil nutrients in lowland tropical soil and therefore recommended as a better choice soil improvement agroforestry tree leafy biomass among other species as investigated from the study.