Abstract

Very poor reclaimed soil quality and weak microbial activity occur in the reclamation area of a coal gangue landfill in the Loess Hills. The fourth and fifth years after farmland soil was reclaimed were studied, and the changes in and carbon source utilization characteristics of rhizosphere (R) and non-rhizosphere (S) soil microorganisms under organic and inorganic (OF), inorganic (F), and organic (O) fertilizer application and a control treatment (CK) in soybean (S) and maize (M) rotation systems were compared and analysed in Guljiao Tunlan, Shanxi Province, China. Biolog-EcoPlate technology was used to analyse the mechanism of soil characteristic change from the perspective of soil microbial metabolism function to provide a theoretical basis for reclamation and ecological reconstruction in this area. The average well colour development (AWCD) absorption and Shannon-Wiener index values of soybean and maize rhizosphere microorganisms were higher than those of non-rhizosphere microorganisms, and the mean value of the fertilizer treatment was higher than that for CK. Principal component analysis shows the main carbon sources that impact the functional diversity of the soybean rhizosphere and non-rhizosphere soil communities are a-cyclodextrin, a-D-lactose, ß-methyl D-glucoside, and glucose-1-phosphate and L-phenylalanine, while those for the maize rhizosphere and non-rhizosphere soil communities are D-cellobiose, glucose-1-phosphate, ß-methyl D-glucoside, methyl pyruvate, D-galactosate gamma lactone, D-mannitol, N-acetyl-D-glucosamine, D-galactosalonic acid, and L-serine. The comprehensive utilization score of the non-rhizosphere soil carbon source in the maize season increased with respect to that in the soybean season, and the maximum increase was 1.09 under the OF treatment. Redundancy analysis showed that the soil nutrient factors driving the changes in the metabolic function diversity index values of the rhizosphere and non-rhizosphere soil microbial communities in the different crop seasons in the reclamation area differed, but they were all related to the soil organic matter and available phosphorus. This may explain why OF treatment is the most beneficial to soil fertility under the rotation system in mining reclamation areas.

Highlights

  • Land reclamation and ecological reconstruction can ease the tension of cultivated land, ensure food security, improve ecological environment

  • In the soybean planting season in 2017, the average well colour development (AWCD) value of the soybean rhizosphere and nonrhizosphere soil under the different fertilization treatments remained basically unchanged within 0–24 h but increased rapidly after 24 h

  • Canoco 5.0 was used to perform an Redundancy analysis (RDA) of the rhizosphere and non-rhizosphere soil microbial diversity index values and organic matter, total nitrogen (TN), TP, TK, Alkaline nitrogen (AN), available phosphorus (AP), and AK, and we found that in the maize season, the soil microbial diversity index values under the different treatments were effectively related to the soil organic matter, TN, AK, AN, and AP; in the soybean season, the microbial diversity index values for the rhizosphere and non-rhizosphere soil were only related to the soil organic matter and AP

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Summary

Introduction

Land reclamation and ecological reconstruction can ease the tension of cultivated land, ensure food security, improve ecological environment. Soil quality is an important component in the reconstruction of ecosystems due to its physical, chemical and biological (nutrient) support for plant recolonization and establishment [1]. Soil microbial diversity is a sensitive indicator of soil fertility, and soil metabolic activity is an important biological parameter associated with soil functions and is highly affected by agricultural practices [5]. It is crucial for soil nutrient recycling and utilization, energy transmission, ecosystem balance, and sustainable soil use in soil ecosystems [6,7,8,9]. The measurement of microbial diversity may provide important information regarding the function of microbial communities [15]

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