The impact of traditional land use management on soil quality in Northeastern Himalayas (India)

Gaurav Mishra,Jesús Rodrigo-Comino

doi:10.7163/gpol.0195

Abstract

n the Northeast Himalayas (NEH) region, four major conventional land-use types are forest, Jhum lands, fallow Jhum lands and plantations, but little is known about their sustainability and responses to changes. We collected soil samples at two uniform depths (0-15 and 15-30 cm) from the Zunheboto district of Nagaland (India). The dataset was statistically analyzed by conducting an ANOVA-one way, principal component analysis (PCA) and calculating an additive soil quality index (SQIa). Our results confirmed that sand content, bulk density (BD), porosity, soil organic carbon (SOC), cation exchange capacity (CEC), exchangeable calcium and potassium showed significant statistical differences among soil depths depending on the land use management. PCA results showed that soil texture, BD, porosity, SOC and exchangeable cations could be consideredthe major indicators to define soil quality. After estimating the SQIa, Jhum soils showed the highest values at the surface, while at 15-30 cm soil depth, fallow Jhum soils phase showed the highest ones. The conversion from natural forest to plantation does not hamper the SQ, but their conversion into Jhum may even increase it, for a shorter duration. However, after 1-2 year of cultivation and conversion from Jhum into fallow Jhum land, soil quality could be reduced.

Highlights

The topic of human impact on soil quality in cultivated mountainous areas in non-developing regions using traditional methods since decades to subsist by changing the land use types is poorly studied
Our results confirmed that sand content, bulk density (BD), porosity, soil organic carbon (SOC), cation exchange capacity (CEC), exchangeable calcium and potassium showed significant statistical differences among soil depths depending on the land use management
A similar dynamic is registered in fallow Jhum lands, where an increase in BD generates a decrease of porosity, showing statistical differences between soil depths (p < 0.050)

Summary

Introduction

The topic of human impact on soil quality in cultivated mountainous areas in non-developing regions using traditional methods since decades to subsist by changing the land use types is poorly studied. An example of this type of areas is the North-Eastern Hilly region of India (NEH). The NEH is one of the twelve biodiversity hot spots in the world due to its geographical position, favourable climate and biodiversity richness (Choudhury et al, 2016) It is covered by forests (65%), agricultural land (16%) and fallow lands (Saha et al, 2012). In the last few decades, Jhum cultivation led to a rapid change in land uses in Nagaland (Chase & Singh, 2014; Sulieman et al, 2018), as the fallow period is decreasing, due to increase in population and food demand

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