AGRICULTURE AND BIOLOGY JOURNAL OF NORTH AMERICA ISSN Print: 2151-7517, ISSN Online: 2151-7525, doi:10.5251/abjna.2013.4.2.137.144 © 2013, ScienceHuβ, http://www.scihub.org/ABJNA Effect of Teak (Tectona grandis) and Rubber (Elaeis guineensis) Plantations on Soil Physico-Chemical Properties of Alfisol and Ultisol in Parts of Nigeria 1* Anthony I. Iwara, 2 Fatai O. Ogundele and 2 S.G. Odewumi 1 Dept. of Geography, University of Ibadan, Nigeria 2 Dept. of Geography and Planning, Lagos State University, Nigeria *Corresponding author’s email: iwaradream2008@yahoo.com ABSTRACT The study examined the effects of tree crops on soil properties in the southwestern and south- southern ecological zones of Nigeria. The objective of the study was to investigate the effect of teak and rubber plantations on soil properties in the south-western and south-southern ecological zones of Nigeria. Soils were sampled under teak and rubber plantations of 50 and 41 years as well as in a 3 year-old fallow and a secondary forest soils. Result showed that organic matter (OM) was rated low (below 2%) in the 3 year-old fallow soil and rated high (above 3.0%) in the teak and rubber soils including the secondary forest soils. The high OM and moderate total nitrogen content in the teak and rubber soils was attributed to the absence of cultivation resulting in the build-up of biomass. The content of available phosphorus was moderate in all the studied soils (below 15mgkg -1 ). The study reveals that irrespective of the ecological zones and the type of tree crops grown, tree crops if properly managed mostly in the south-southern ecological zone of Nigeria where rainfall is high, can help to conserve soil nutrient by reducing soil erosion and its associated losses. Keywords: Tree Crops, Soil Properties, Alfisol, Ultisol INTRODUCTION Plantation agriculture has assumed increasing importance and acceptance in tropical countries like Nigeria where they are grown in large commercial scale, as one of the possible ways of meeting the increased demands for wood and latex production as well as ensuring environmental conservation among others. In Africa, monoculture plantation agriculture has been embraced by farmers, and it contributes a significant proportion of export earnings (Aweto and Enaruvbe, 2010). In Nigeria, several studies in the literature have either looked at the effect of teak, rubber, oil palm, gmelina, pines, and eucalyptus and cocoa plantations on soil properties with particular reference to a particular ecological zone, but studies that investigate the effect of dominant tree crops on soil properties across different ecological zones of Nigeria are not well documented. Studies carried out on tree crops include cocoa (Adejuwon and Ekanade, 1987: 1988; Ekanade, 1988; Aikpokpodion, 2010), kola nut (Egbe 1973; Ekanade and Egbe, 1990), rubber (Aweto, 1987; Attoe and Amalu, 2005); oil palm (Aweto and Ekuigbo, 1994; Ogidiolu, 1997, 2000; Aweto and Enaruvbe, 2010); cashew (Aweto and Isola, 1995), teak (Samndi, 2006; Samndi et al., 2007; Ogunkunle and Awotoye, 2011), gmelina (Olaleye et al., 2005; Onyekwelu et al., 2006; Awotoye et al., 2009) and duka nut (Musa et al., 2009). Though, plantations as forms of agro-forestry practice are meant to satisfy different needs of man, they however, result in the modification or degradation of the environment. However, in Nigeria, soil fertility restoration for improved agricultural production is a recurrent issue of immense importance mostly with her ever increasing population currently above 150 million. On this note, identifying sustainable ecological practice to improve soil fertility is one of the possible ways to enhance crop production (Amiolemen et al., 2012). The decline in soil fertility has been attributed to population pressure resulting in the shortening of fallow period (Oke and Kadeba, 2001). Since, this problem is persistent mostly with the changing land use and increasing population; plantation agriculture is thus seen as an alternative land use system of soil management and environmental protection. For instance, teak (Tectona grandis) and cocoa (Theobroma cacao) are some of the predominant tree crops grown in the south-