Effects of Seven-Year Fertilization Reclamation on Bacterial Community in a Coal Mining Subsidence Area in Shanxi, China

The restoration of soil fertility and microbial communities is the key to the soil reclamation and ecological reconstruction in coal mine subsidence areas. However, the response of soil bacterial communities to reclamation is still not well understood. Here, we studied the bacterial communities in fertilizer-reclaimed soil (CK, without fertilizer; CF, chemical fertilizer; M, manure) in the Lu’an reclamation mining region and compared them with those in adjacent subsidence soil (SU) and farmland soil (FA). We found that the compositions of dominant phyla in the reclaimed soil differed greatly from those in the subsidence soil and farmland soil (p < 0.05). The related sequences of Acidobacteria, Chloroflexi, and Nitrospirae were mainly from the subsided soil, whereas those of Alphaproteobacteria, Planctomycetes, and Deltaproteobacteria were mainly derived from the farmland soil. Fertilization affected the bacterial community composition in the reclaimed soil, and bacteria richness and diversity increased significantly with the accumulation of soil nutrients after 7 years of reclamation (p < 0.05). Moreover, soil properties, especially SOM and pH, were found to play a key role in the restoration of the bacterial community in the reclaimed soil. The results are helpful to the study of soil fertility improvement and ecological restoration in mining areas.

Effects of different fertilizer application practices on newly reclaimed soil structure and its nutrient content

Effects of organic fertilizer practice (OF), organic fertilizer combined with chemical fertilizer practice (OC), and conventional fertilization practice (CF) on soil structure were evaluated by combining micro and macro analyses in newly reclaimed cultivated land. Soil organic matter (SOM), cation exchange capacity (CEC), soil bulk density (BD), soil moisture content (SMC), and aggregate stability were also analyzed. The CF soil structure was mainly composed of moderately separated block and angular structures with the minimum SOM (7.08 g/kg) and the highest BD (1.40 g/cm3), and the pore type was mainly simple surface cracks. Compared with CF, OF and OC significantly increased SOM content by 59.3 and 29.6% (p < 0.05) and CEC by 13.5 and 5.2%, respectively. The newly reclaimed soil structure was improved to a moderately separated clump structure and a well-developed aggregated structure, and the number of composite accumulation pores gradually increased. Moreover, OF and OC were associated with higher mean weight diameter (MWD), geometric mean diameter (GMD) values, and lower BD and fractal dimension (D) values. The water-stable macroaggregates (R0.25) and the aggregate stability of newly reclaimed soil were significantly increased, with a stronger improvement observed under OF. These results confirm the benefits of OC and OF practices on the structural stability, water and fertilizer retention characteristics of newly reclaimed cultivated land, and will be conductive to improving the soil quality and achieving sustainable soil development. Bangladesh J. Bot. 50(3): 781-794, 2021 (September) Special

Genetic Mapping Reveals Novel Exotic and Elite QTL Alleles for Salinity Tolerance in Barley

Soil salinity is one of the constraints of crop production in Egypt. The aims of this study were to identify genomic regions associated with grain weight and its related traits along with their salinity tolerance indices and to identify the most salinity tolerant and high-yielding genotypes. Therefore, we evaluated an advanced backcross mapping population of barley in newly reclaimed soil under two salinity levels of groundwater aquifers in South of Sinai, Egypt. We detected significant QTL associated with grain weight related attributes and the salinity tolerance index (STI) distributed throughout the whole genome of barley, which can be used to enhance salinity tolerance. Moreover, the markers bPb-3739 (4H, 96.3 cM), AF043094A (5H, 156 cM), bPb-8161 (7H, 2.22 cM), and bPb-5260 (7H, 115.6 cM), were the most important identified genomic regions corresponding to vernalization, dwarfing and dehydrin genes, which are correlated with salinity tolerance. Additionally, the doubled haploid lines SI001, SI043, SI044, SI028, SI242, SI035, and SI005 had the highest STI values based on yield average. The present study demonstrated that wild and elite barley do harbor novel valuable alleles, which can enrich the genetic basis of cultivated barley and improve quantitative agronomic traits under salinity conditions.

Effects of Rhizosphere Microbial Composition on the Growth of Cajanus Cajan in Coal Gangue Reclaimed Soil

Planting the economically sustainable Cajanus cajan crop in coal gangue dump as an approach for ecological management has attracted extensive attention from scholars worldwide. Microorganisms play important roles in ecological restoration. However, there have been few reports about the microbial composition and functions of Cajanus cajan root systems planted in plateau waste dumps. In this study, the gangue dump (1,390 m above sea level) in Guizhou Plateau was covered with soil and planted with YN and JX Cajanus cajans. After one year, the Cajanus cajan root system was collected, and high-throughput sequencing was utilized to examine the bacterial and fungal biodiversity. The bacteria in all samples were assigned to six phyla and 60 genera. The unclassified_f_Enterobacteriaceae and Cedecea were the most abundant genera. The fungi were assigned to six phyla and 143 genera and Fusarium was the most abundant genus. Venn and heatmap analyses revealed differences in the dominant root species among Cajanus cajan varieties, Lactococcus and Fusarium. In JX and YN, Pseudoarthrobacter is a unique genus of bacteria; in JX, Robillarda is a unique genus of fungi; and in YN, Scytalidium is a unique genus of fungi. The endophytic fungi mainly play the roles of saprotroph, plant pathogen, and endophyte. Among the bacterial properties, L-arabinose isomerase and adenosine triphosphatase were the most abundant in all samples, while chitinase, catalase, and laccase played important roles in photosynthesis, degradation of lignin, chitin, and chitosan. This study guides the selection of reclamation plants and strategies for the migration and restriction of heavy metals in soil.

Adsorption and Desorption of Cd: Characteristics and Mechanisms in Reclaimed Soil Under the Influence of Dissolved Organic Carbon

Organic acids are widespread in the environment, where they play an important role in the adsorption, desorption, and migration of Cd in soil. This study evaluated the characteristics and mechanisms of Cd adsorption and desorption in reclaimed soil from the Panyi Mine, in the Huainan mining area (China), under the influence of humic acid (HA). The addition of HA inhibited the adsorption of Cd but enhanced its desorption in reclaimed soil. With an increasing concentration of added HA, the adsorption capacity of Cd in the reclaimed soil gradually decreased, while the desorption capacity gradually increased. That is, the adsorption inhibition/desorption promotion effect was stronger under higher concentrations of organic acid. Cd adsorption and desorption dynamics could be described as a logarithmic function of organic acid concentration. Kinetic curves for Cd adsorption and desorption in reclaimed soil under the influence of organic acid showed that both adsorption and desorption involved two stages: a fast reaction stage, followed by a slow reaction stage. The factors influencing the capacity of Cd adsorption and desorption in soil were analyzed by gray correlation analysis, and their resulting rank order was as follows: Cd concentration > HA concentration > pH > temperature. Using linear regression analysis, a multi-factor coupling functional model of soil Cd adsorption and desorption under the influence of DOC was established, in the form of Y = a + bXHA + cXT + dXPH + eXCd.

Effect of Diluted Red Sea Water on Growth Behavior and Chemical Component of Moringa Plants

Background: Moringa tree is a drought resistance tree, fast-growing, Moringa leaves, flowers and pods are a food source for human and animals. It is a rich source of calcium, iron and a good source of vitamins, B, A, C, amino acids. Shortage of water resources for irrigation especially in reclaimed soil considered is one of the great problems to cultivate traditional crops. Thus, nowadays the use of the non-traditional source of water, such as saline water is very important. Results: The obtained data recorded that the lowest level of salinity (4000 ppm) decreased plant height, fresh and dry weight of leaves, the stem fresh and dry weight, stem diameter recorded decreased. Increasing salinity levels up to 16000 ppm high reduction was registered in the previously mentioned parameters except for leaves number. The interaction between salinity and proline concentration exhibited in most cases reduction in total chlorophyll. Carbohydrate content, protein, nitrogen%, calcium%, recorded reduction in most cases under saline condition and their interaction with proline. While, Sodium %, Cl- percentage and proline content recorded increments in most cases under the previously mentioned circumstances. Conclusion: The results were nearly ascending order with increasing of salinity level. Increasing salinity to 16000 ppm decreased significantly the values of vegetative growth and almost all cases of chemicals constituents were reduced.

Adsorption and desorption characteristics and mechanism of Cd in reclaimed soil under the influence of dissolved organic carbon

Organic acids are widespread in the environment and play an important role in the adsorption, desorption, and migration of soil Cd. This study evaluated the characteristics and mechanism of Cd adsorption and desorption in reclaimed soil from Panyi Mine in the Huainan mining area under the influence of humic acid (HA) and citric acid (CA). The addition of HA and CA inhibited the adsorption and enhanced the desorption of Cd in reclaimed soil, with HA having a stronger effect than CA. As the concentration of added HA or CA increased, the adsorption capacity of Cd in the reclaimed soil gradually decreased, while the desorption capacity gradually increased. That is, the adsorption inhibition/desorption promotion effect was stronger for higher concentrations of organic acid. Cd adsorption and desorption could be described as a logarithmic function of organic acid concentration. The kinetic curves of Cd adsorption and desorption in reclaimed soil under the influence of organic acids show that both adsorption and desorption involved two stages: a fast reaction stage followed by a slow reaction stage.