The effect of land use change on soil fertility parameters in densely populated areas of Kenya

Daniel Kyalo Willy,Milu Muyanga,Joseph Mbuvi,Thomas Jayne

doi:10.1016/j.geoderma.2019.02.033

Daniel Kyalo Willy, Milu Muyanga + Show 2 more

Open Access

https://doi.org/10.1016/j.geoderma.2019.02.033

Copy DOI

Abstract

The current study seeks to assess sustainability of agricultural land use by identifying the effect of land use change on soil quality using cross-sectional data collected through a household survey among 525 farm households in densely populated areas of Kenya. Soil samples were collected, analyzed and compared across three land use types: undisturbed, semi-disturbed and cultivated. To achieve these objectives, descriptive, Nutrient Index approach and Classification and Regression Tree (CART) analysis methods were used. Results indicate that within a period of five decades, agricultural land use has led to a decline in Total Organic Carbon (−72%), Magnesium (−65%) and Boron (−61%), Iron (−22%) and Total Nitrogen (−15%). The drivers of deterioration identified were cutting across inherent properties such as soil chemical (pH), physical (soil mapping unit) and biological (organic carbon) attributes, farmer practices (agricultural commercialization) and exogenous factors (population density and Agro-ecological zones). The study concludes that indeed conversion of land from natural vegetation is associated with deterioration in soil quality and therefore policy needs to create incentives for the build-up of soil organic matter, replenishment of soil macro and micro nutrients. Blending of commercial fertilizers with targeted micro-nutrients, maintenance of soil conservation techniques and long term fallowing are encouraged.

Highlights

The sustainable Development Goals (SDGs) aim to end poverty, protect the planet and ensure prosperity for all by 2030 among other aspirations (UN General Assembly, 2015)
Plots located in areas with population densities exceeding 877 persons/km2 had about 22% lower Total Nitrogen compared to plots in less densely populated areas
Population density is a proxy for agricultural intensification characterized by intensive cultivation and reduced fallows which could explain the reduction in Total Nitrogen content

Summary

Introduction

The sustainable Development Goals (SDGs) aim to end poverty, protect the planet and ensure prosperity for all by 2030 among other aspirations (UN General Assembly, 2015). It has been noted that at higher population densities, the gains associated with sustainable agricultural intensification can be reversed as a result of land management practices that undermine soil conservation (Willy et al, 2019). In comparison to the changing land use, global SOC stocks within 15 cm depth at sites without any land use change have reportedly increased by 0.19% C y−1 over recent decades (Chen et al, 2015). This clearly shows the land use change can have effects on soil fertility as confirmed by more recent studies

Methods

Results

Conclusion