The Integrated Effect of Microbial Inoculants and Biochar Types on Soil Biological Properties, and Plant Growth of Lettuce (Lactuca sativa L.).

Hua Ma,Vyacheslav Shurigin,Jeane Aril Dela Cruz,Dilfuza Jabborova,Stephan Wirth,Dilfuza Egamberdieva,Thomas Edison Dela Cruz,Sonoko Dorothea Bellingrath-Kimura

doi:10.3390/plants11030423

Abstract

Numerous reports confirm the positive effect of biochar application on soil properties and plant development. However, the interaction between root-associated beneficial microbes and different types of biochar is not well understood. The objective of this study was to evaluate the plant growth of lettuce after the application of three types of biochar in loamy, sandy soil individually and in combination with plant-beneficial microbes. Furthermore, total microbial activity in rhizosphere soil of lettuce was measured by means of fluorescein diacetate (FDA) hydrolase and enzyme activities linked to carbon, nitrogen, and phosphorus cycling. We used three types of biochar: (i) pyrolysis char from cherry wood (CWBC), (ii) pyrolysis char from wood (WBC), and (iii) pyrolysis char from maize (MBC) at 2% concentration. Our results showed that pyrolysis biochars positively affected plant interaction with microbial inoculants. Plant dry biomass grown on soil amended with MBC in combination with Klebsiella sp. BS13 and Klebsiella sp. BS13 + Talaromyces purpureogenus BS16aPP inoculants was significantly increased by 5.8% and 18%, respectively, compared to the control plants. Comprehensively, interaction analysis showed that the biochar effect on soil enzyme activities involved in N and P cycling depends on the type of microbial inoculant. Microbial strains exhibited plant growth-promoting traits, including the production of indole 3-acetic-acid and hydrogen cyanide and phosphate-solubilizing ability. The effect of microbial inoculant also depends on the biochar type. In summary, these findings provide new insights into the understanding of the interactions between biochar and microbial inoculants, which may affect lettuce growth and development.

Highlights

Biochar is produced from agricultural residues or other bio-waste, e.g., wood chips or sewage sludge, by pyrolysis under low or in the absence of oxygen [1], and is considered to improve soil health and crop productivity and discussed as a strategy for carbon sequestration [2,3]
The objectives of this study were: (1) to evaluate the response of growth of lettuce to the application of three types of biochar applied in loamy, sandy soil individually and in combination with plantbeneficial microbes; (2) to determine the total microbial activity as measured by fluorescein diacetate (FDA) hydrolase in the rhizosphere soil of lettuce; and (3) to analyze rhizosphere enzyme activities linked to carbon, nitrogen, and phosphorus cycling
There was a slight increase in plant biomass grown in soil amended with MBC, but no effect was observed in soil with CWBC or WBC addition

Summary

Introduction

Biochar is produced from agricultural residues or other bio-waste, e.g., wood chips or sewage sludge, by pyrolysis under low or in the absence of oxygen [1], and is considered to improve soil health and crop productivity and discussed as a strategy for carbon sequestration [2,3]. Biochar application enhanced plant growth of various crops such as pepper and tomato [9], soybean and chickpea [10,11], maize [12], and wheat [13]. Such positive effects by biochar application were often explained by enhanced diversity of soil microbial communities, which exhibits plant-beneficial traits and their improved activities involved in nutrient cycling [9,14,15,16,17]. Due to carbon and nutrient concentrations in biochar types, soil microbial activity may vary in response to biochar addition [18]

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