Effects of Fallow Genealogical Cycles on the Build-up of Nutrients in Soils of the Cross River Rainforest, South-Southern Nigeria

Abstract

The study examined the effect of fallow generational cycles on the buildup of nutrients in the soil. Fallow sequence of 1 st , 2 nd , 3 rd , 4 th and 5 th generations were studied. The quadrat approach of sampling was employed to collect soil samples (surface and subsurface) from five plots of 10m x 10m across the five fallow generational cycles. Result showed that the mean proportions of organic matter (OM), total nitrogen (TN), cation exchange capacity (CEC) and available phosphorus (Av. P) increased substantially in the 1 st and 2 nd generation of fallows probably due to reduced cropping frequency. The PCA result further revealed that topsoil available phosphorus, topsoil exchangeable sodium and topsoil exchangeable potassium constituted the most significant soil properties that progressively increased across the fallow generations. As usual, nutrients in the fallow generations were confined to the topsoil. The increase in soil nutrients was attributed to the increased in tree size, vegetation cover and adequate ground cover which helped to conserve and build-up essential nutrients in the soil by minimizing the loss of nutrients through soil erosion. The study suggested that for efficient conservation practices, fallow land mostly the 1 st generation fallow which was fast approaching climax should be considered for reserve. For this to be feasible, alternative means of livelihoods should be provided to reduce the wanton destruction, concentration and dependence on forest resources for sustenance.

Assessment of the Nutrient Status of Soil under <em>Chromolaena odorata</em> L. (Siam Weed) Fallow in Moniya, Oyo State Southwestern Nigeria

“…The increase in the contents of OM and TN in the 2 nd year fallow is attributed to the increase in C. odorata cover. The increase in cover helps to reduce raindrop intensity and increases litter input which in situ decomposes to form nutrient (Aweto and Dikinya 2003;Offiong and Iwara, 2011). The OM and TN values obtained here also fall with the range of 1.83% and 0.35% in a similar study reported by Yahaya and Edicha (2010).…”

“…Nevertheless, soil fertility continues to be a problem in many parts of the country as a result of the clearing and modification of forest mostly for agricultural production. The clearing of forest coupled with high temperature and precipitation accelerates soil erosion resulting in nutrient elements loss in dissolved and solid bound forms (Offiong and Iwara, 2011). However, after the cultivation of food crops, farmlands are deliberately allowed to fallow, a process for fertility restoration (Styger et al, 1999;.…”

Soil Fertility Status in Relation to Fallow Cycle in Shifting Cultivated Areas of DIMA HASAO

“…The native P was more solubilized with organic acid and root exudates. Similarly, many authors found that soils under long term jhum fallow cycle contain more total N, P and Ca in the surface horizon (0-12 cm)" [27,36,37]. The significant increase in available P was observed from long jhum fallow cycle and statistically at par with undisturbed soil.…”

“…The density of trees/shrubs provides adequate protection, releases root exudates to the soil thereby preventing unproductive nutrient losses. Similarly, many authors found that soils under long term fallow cycle contained more N, P and Ca in the surface horizon [27,41,36]. The exchangeable Ca and Mg as well as sulphur were held with colloidal clay particles thereby leading to their subsequent enhanced concentration in soil solution [42,43].…”

Soil fertility in indigenous swidden fields and fallows in northern Amazonia, Brazil

“…Pinho, unpublished data). In the near future, this can come to compromise soil fertility and other ecological and social characteristics of slash‐and‐burn systems in the studied communities (Fachin et al, 2021; Lawrence et al, 2010; Offiong & Iwara, 2012; Villa et al, 2018). In this sense, the implementation of highly diversified agroforestry systems, which follow the same growth processes as the natural succession of secondary forest (Cezar et al, 2015; Night & Diemont, 2013; Young, 2017), can indeed extend the time of use of slash‐and‐burn systems, without compromising their ecological and social functions, in addition to enhancing soil fertility (Chowdhury et al, 2020; Hands, 2021; Pinho et al, 2012).…”