Nematode Community-Based Soil Food Web Analysis of Ferralsol, Lithosol and Nitosol Soil Groups in Ghana, Kenya and Malawi Reveals Distinct Soil Health Degradations

Haddish Melakeberhan,John W Kimenju,Jiaguo Qi,Zinthuzar Maung,Charles Kwoseh,Jenni Gronseth,George N Karuku,Thomas Adjei-Gyapong,Senol Yildiz,Isaac Lartey

doi:10.3390/d13030101

Abstract

Determining if the vast soil health degradations across the seven major soil groups (orders) of Sub-Saharan Africa (SSA) can be managed on the basis of a one-size-fits-all or location-specific approach is limited by a lack of soil group-based understanding of soil health degradations. We used the relationship between changes in nematode population dynamics relative to food and reproduction (enrichment, EI) and resistance to disturbance (structure, SI) indices to characterize the soil food web (SFW) and soil health conditions of Ferralsol, Lithosol and Nitosol soil groups in Ghana, Kenya and Malawi. We applied bivariate correlations of EI, SI, soil pH, soil organic carbon (SOC), and texture (sand, silt and clay) to identify integrated indicator parameters, and principal component analysis (PCA) to determine how all measured parameters, soil groups, and countries align. A total of 512 georeferenced soil samples from disturbed (agricultural) and undisturbed (natural vegetation) landscapes were analyzed. Nematode trophic group abundance was low and varied by soil group, landscape and country. The resource-limited and degraded SFW conditions separated by soil groups and by country. EI and SI correlation with SOC varied by landscape, soil group or country. PCA alignment showed separation of soil groups within and across countries. The study developed the first biophysicochemical proof-of-concept that the soil groups need to be treated separately when formulating scalable soil health management strategies in SSA.

Highlights

Agricultural Nematology Laboratory, Department of Horticulture, Michigan State University (MSU), Nematology Laboratory, Kearney Agricultural Research and Extension Center, Department of Nematology, University of California (Riverside), Parlier, CA 93648, USA
With a long-term goal of developing soil groupbased scalable soil health management strategies in Sub-Saharan Africa (SSA), this study considered the types and levels of biological degradations associated with Ferralsols, Lithosols and Nitosols in Ghana, Kenya and Malawi
Two regions separated by about 15 km in Ghana and up to 300 km in Malawi were selected for each soil group

Summary

Introduction

Services [7,8,9,10,11,12], developing soil health management models that fit the vast soil degradations in SSA is limited by a) variable standards and outcomes, b) existing knowledge lacking an integrated platform, and c) issues of scale within and across regions where the levels of soil degradations, cropping systems, land use practices, and cultures are highly variable [4,12]. Developing soil health management strategies to that fit the extent of SSA soil degradations will require identifying if the degradations across space fit a one-size-fits-all or a location-specific approach to fix. This paper characterizes the types and levels of soil health degradations in soil groups (orders) and provides a proof-of-concept for a location-specific approach to formulating soil health management strategies in SSA. Recent studies and meta-analyses of the relationships between soil health and ecosystem services in SSA and elsewhere showed highly variable standards and outcomes [10,11,12,13,14,15,16]

Methods

Discussion

Conclusion