How different soil moisture levels affect the microbial activity

Luiz Gustavo De Oliveira Denardin,Filipe Selau Carlos,João Augusto Coblinski,Cícero Ortigara,Marcelo Raul Schmidt,Ibanor Anghinoni,Cézar Augusto Gama De Toni,Flávio Anastácio De Oliveira Camargo,Bruna Winck,David Clay,Lucas Aquino Alves

doi:10.1590/0103-8478cr20190831

Luiz Gustavo De Oliveira Denardin, Filipe Selau Carlos + Show 9 more

Open Access

https://doi.org/10.1590/0103-8478cr20190831

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Abstract

ABSTRACT: The lowland soils are characterized by high susceptibility to water saturation. This anaerobic condition is usually reported in paddy fields and alters the decomposition process of soil organic compounds. The aim of this study was to evaluate the soil microbial and enzymatic activity of a lowland soil at different soil moisture contents. A poorly drained Albaqualf cultivated with irrigated rice was used to evaluate microbial and enzymatic activity in treatments with different levels of soil moisture, being: i) 60% of field capacity (FC) (60%FC); ii) 100% of FC (100%FC); iii) flooded soil with a 2 cm water layer above soil surface, and iv) soil kept at 60%FC with late flood after 29 days the incubation. The greater soil microbial activity was observed in the 100%FC treatment, being 41% greater than 60%FC treatment and only 2% higher than flooded treatment. The enzymatic activity data by fluorescein diacetate (FDA) hydrolysis corroborated the higher CO2 release in treatments with higher soil moisture content. Differently from the results reported, the main methodologies to evaluate microbial activity still recommend maintenance of the soil with a moisture content close to 60% of the FC. However, in lowland soil with history of frequent paddy fields, the maintenance of moisture close to 60% of the FC can limit the microbial activity. The soil respiration technique can be used to evaluate the microbial activity in flooded soil conditions. However, further studies should be conducted to understand the effect of the cultivation history on the microbial community of these environments.

Highlights

IntroductionThe lowland soils are characterized by high susceptibility to saturation, due both to their position in the landform and their physical characteristics
The lowland soils are characterized by high susceptibility to saturation, due both to their position in the landform and their physical characteristics.it possesses water excess on its surface during the growth of annual crops (BRINKMAN & BLOKHUIS, 1986)
The soil microbial activity and the mineralization rates of soil organic matter (SOM) responded to different Ciência Rural, v.50, n

Summary

Introduction

The lowland soils are characterized by high susceptibility to saturation, due both to their position in the landform and their physical characteristics. It possesses water excess on its surface during the growth of annual crops (BRINKMAN & BLOKHUIS, 1986). The process of decomposition of SOM is not limited by the flooding, it is impaired, mainly due to lower energy efficiency of microorganisms under anaerobic or hypoxic conditions (Reichardt et al, 2001). The SOM decomposition through anaerobic respiration, together with the fermentation processes, is metabolically less efficient and result in partial decomposition of the organic substrate (Duchaufour, 1998)

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