Microbial response of distinct soil types to land-use intensification at a South-Indian rural-urban interface

Virna Estefania Moran-Rodas,Suvarna V. Chavannavar,Rainer Georg Joergensen,Christine Wachendorf

doi:10.1007/s11104-021-05292-2

Virna Estefania Moran-Rodas, Suvarna V. Chavannavar + Show 2 more

Open Access

https://doi.org/10.1007/s11104-021-05292-2

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Abstract

AimsRural-urban dynamics are leading to agricultural intensification practices, which affect microbial ecosystem functions in a soil-specific way. This study aimed to investigate what effects agricultural intensification has on soil microbial communities.MethodsThe effects of N fertilization level (low and high) and crop type (maize and finger millet) on microbial communities were investigated, using a two-factorial split-plot design, at two fields (irrigated and rainfed) on typical soil types (Nitisol and Acrisol) mimicking an intensification gradient in the rural-urban interface of the Indian Megacity Bangalore.ResultsThe Nitisol had higher pH and clay content than the Acrisol. In combination with irrigation, this led to higher aboveground plant biomass (APB), soil organic carbon (SOC), microbial biomass (MB), fungal ergosterol and microbial necromass. High APB resulted in low total P content, due to P export in APB and high soil C/P and MB-C/P ratios in the Nitisol. Crop type and N fertilization level did not affect microbial parameters in the irrigated Nitisol, whereas crop type affected ergosterol and MBP and N fertilization level affected basal respiration in the rainfed Acrisol. Particulate organic matter (POM) was a major explanatory factor for most microbial parameters in both soils. In the Acrisol, drought reduced metabolic demand, which counteracted negative effects of low pH and clay on the MB. This was indicated by similar metabolic quotients and MBC/SOC ratios in both soils.ConclusionsThese results indicate the current need for water and high-quality fresh plant inputs to improve the microbial contribution to soil fertility at Bangalore.

Highlights

Urbanization of rural areas leads to a higher resource demand and agricultural intensification, altering soil microbial dynamics globally, especially in the tropics1 3 Vol.: (0123456789)(Elmqvist et al 2013; Steinhübel and von CramonTaubadel 2021)
The irrigated Nitisol contained between 20% (MurN) and 80% (MBC, MBN, fungal GlcN, and GalN) more of the microbial biomass and necromass markers than the rainfed Acrisol (Table 3)
Microorganisms in typical soil types at Bangalore are C and nutrient limited under major cereal cropping systems

Summary

Introduction

Urbanization of rural areas leads to a higher resource demand and agricultural intensification, altering soil microbial dynamics globally, especially in the tropics1 3 Vol.: (0123456789)(Elmqvist et al 2013; Steinhübel and von CramonTaubadel 2021). A higher C input may not promote C storage per se It is the soil microbial activity and demand for C and nutrients that drives soil organic matter (SOM) decomposition or stabilization (Sinsabaugh et al 2009; Manzoni et al 2010; Stone et al 2013; Vidal et al 2021). In terms of soil microbial community structure, growth and activity, there is evidence to suggest contrasting N addition effects (Wallenstein et al 2006; Treseder 2008; Padbhushan et al 2021; Wang et al 2021; Huang et al 2021) In this context, the metabolic quotient (qCO2), which is the ratio of basal respiration to microbial biomass C (MBC), is an important index of SOM utilization to satisfy the microbial demand for maintenance energy

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