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Soil salinization can decrease soil productivity and is a significant factor in causing land degradation. Precision mapping of salinization in agricultural fields would improve farmland management. This study focuses on the cropland in the Manas River Basin, located in the arid region of northwest China. It explores the potential of a soil mapping method, the Soil–Land Inference Model (SoLIM), which only requires a small number of soil samples to infer soil salinization of farmlands in arid areas. The model was utilized to create spatial distribution maps of soil salinity for the years 2009 and 2017, and changes in the distribution were analyzed. The research results indicate: (1) Through the analysis of sample point data, it was observed that soil salinity in the study area tends to accumulate in the surface layer (0–30 cm) in spring and in the subsoil layer (60–90 cm) during the crop growing season, with significant spatial variability. Therefore, it is necessary to conduct detailed salinity mapping. (2) Using field measurements as validation data, the simulation results of the SoLIM were compared with spatial interpolation methods and regression models. The SoLIM showed higher inference accuracy, with R2 values for the simulation results of the three soil layers all exceeding 0.5. (3) The SoLIM spatial inference showed salt accumulation in the northern part and desalination in the southern part. The findings of this study suggest that the SoLIM has the potential to effectively map soil salinization of croplands in arid areas, offering an efficient solution for monitoring soil salinity in arid oasis croplands. [ABSTRACT FROM AUTHOR]

Elevated CO2 concentration [e(CO2)] often promotes plant growth with a decrease in tissue N concentration. In this study, three experiments, two under hydroponic and one in well-watered soil, including various levels or patterns of CO2, humidity, and N supply were conducted on wheat (Triticum aestivum L.) to explore the mechanisms of e[CO2]-induced N deficiency (ECIND). Under hydroponic conditions, N uptake remained constant even as transpiration was limited 40% by raising air relative humidity and only was reduced about 20% by supplying N during nighttime rather than daytime with a reduction of 85% in transpiration. Compared to ambient CO2 concentration, whether under hydroponic or well-watered soil conditions, and whether transpiration was kept stable or decreased to 12%, e[CO2] consistently led to more N uptake and higher biomass, while lower N concentration was observed in aboveground organs, especially leaves, as long as N supply was insufficient. These results show that, due to compensation caused by active uptake, N uptake can be uncoupled from water uptake under well-watered conditions, and changes in transpiration therefore do not account for ECIND. Similar or lower tissue NO 3 - -N concentration under e[CO2] indicated that NO 3 - assimilation was not limited and could therefore also be eliminated as a major cause of ECIND under our conditions. Active uptake has the potential to bridge the gap between N taken up passively and plant demand, but is limited by the energy required to drive it. Compared to ambient CO2 concentration, the increase in N uptake under e[CO2] failed to match the increase of carbohydrates, leading to N dilution in plant tissues, the apparent dominant mechanism explaining ECIND. Lower N concentration in leaves rather than roots under e[CO2] validated that ECIND was at least partially also related to changes in resource allocation, apparently to maintain root uptake activity and prevent more serious N deficiency. [ABSTRACT FROM AUTHOR]

Abstract: Soil depth reflects the quantity and ecosystem service functions of soil resources. However, there is no universal standard to measure soil depth at present, and digital soil mapping approaches for predicting soil depth at the regional scale remain immature. Using observation of soil profile morphology, we compared the soil depth nomenclatures from the World Reference Base for Soil Resources, Chinese Soil Taxonomy, and Soil Taxonomy. For this study, shallow soils were defined as those with an effective soil depth < 100 cm. Based on legacy data and field soil survey, the spatial distribution of shallow soils in Xinjiang, China, and the main controlling environmental factors were explored. Results showed that shallow soils in Xinjiang are mainly distributed in high altitude regions such as the Tian Mountains. At the regional scale, significant correlations were observed between soil depth and climate factors, as well as between soil depth and vegetation fractional coverage. Contrary to previous conclusions at small spatial scales, terrain attributes could not explain soil depth variation at the regional scale. This study addressed knowledge gaps on soil depth prediction at regional scales while elucidating climate‐vegetation‐soil coevolution. [ABSTRACT FROM AUTHOR]

Soil salinization can directly affect crop production, and threaten the sustainable utilization of irrigated land. This problem is particularly prominent in Xinjiang Uyghur Autonomous Region, where has much uncultivated arable land, and soil saline and secondary salinization after land development. In this study, field experiments were conducted to investigate the influence factors and characteristics of soil salt movement, as well as elution desalination in different improvement measures treatments of severe saline soil through 3-year experiment. Five improvement treatments were designed including agricultural improvement (mainly including mulched with plastic film, deep plowing, returning straw and organic fertilizer), salt-isolation to root zone plus agricultural improvement, subsurface pipe drainage plus agricultural improvement, chemical modified plus agricultural improvement, and control without any human activity on new reclamation farmland in Xinjiang Province. The results indicated that salt content of the soil was mainly affected by evaporation, irrigation amount and groundwater depth; the soil salt content was significantly negative correlated with irrigation amount (correlation coefficient=-0.871, P=0.0039) and groundwater depth (correlation coefficient=-0.831, P=0.0072), positively correlated with monthly evaporation (correlation coefficient=0.754, P=0.0084), but not significantly correlated with mean monthly temperatures; The effect of irrigation amount on the 0-80 cm soil salinity in entire growth period was the most prominent. In the 3-years, dynamic changes in soil saline content varied with different improvement methods: high salt content accumulated in the top and deep layers of soil throughout the growing period for agricultural improvement treatment; obvious salt accumulation in the top layer of soils for salt-isolation to root zone plus agricultural improvement; the salt content at the deep layer higher than in subsurface layer for pipe drainage plus agricultural improvement, and chemical modified plus agricultural improvement treatment. The desalination rate of soils after the first-year was not satisfactory, and that after the second-year was significantly improved. The desalination rate of soil in the treatment of salt-isolation to root zone plus agricultural improvement and subsurface pipe drainage plus agricultural improvement treatment was up to 44% in the second year, but was significantly decreased in the third-year due to the reduction of the total salt content of the soil. Overall, all the treatments could result in the decrease of soil salt content. Among them, the soil desalinization rates of agricultural improvement plus subsurface pipe drainage and salt-isolation to root zone plus agricultural improvement were 61.33% and 59.37% respectively in the 0 to 80 cm layers, which were better than the other treatment. The soil desalinization rate of chemical modified plus agricultural improvement treatment was 55.32% in the 0 to 40 cm layers, higher than agricultural improvement 45.42%. The results can provide valuble information for saline soil improvement and rational development and effective utilization of saline soils in the Xinjiang arid zone. [ABSTRACT FROM AUTHOR]

A novel Gram-positive strain, B1 T , was isolated from uranium-contaminated soil. The strain was aerobic, rod-shaped, spore-forming, and motile. The strain was able to grow at 20-45 °C, at pH 6.0-9.0, and in the presence of 0-3 % (w/v) NaCl. The complete genome size of the novel strain was 3 853 322 bp. The genomic DNA G+C content was 45.5 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain B1 T has the highest similarity to Aneurinibacillus soli CB4 T (96. 71 %). However, the novel strain showed an average nucleotide identity value of 89.02 % and a digital DNA-DNA hybridization value of 37.40 % with strain CB4 T based on the genome sequences. The major fatty acids were iso-C 15 : 0 and C 16 : 0 . The predominate respiratory quinone was MK7. Diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, unidentified phospholipids, an unidentified aminolipid and an unidentified lipid were identified as the major polar lipids. The phylogenetic, phenotypic, and chemotaxonomic analyses showed that strain B1 T represents a novel species of the genus Aneurinibacillus , for which the name Aneurinibacillus uraniidurans sp. nov. is proposed. The type strain is B1 T (=GDMCC 1.4080 T =JCM 36228 T ). Experiments have shown that strain B1 T demonstrates uranium tolerance.