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The improvement of saline-alkali land plays a key role in ensuring food security and promoting agricultural development. Saline soils modifies the response of the soil microbial community, but research is still limited. The effects of applying phosphogypsum with rice cultivation (PRC) on soil physicochemical properties and bacterial community in soda saline-alkali paddy fields in Songnen Plain, China were studied. The results showed that the PRC significantly improved the physicochemical properties of soil, significantly reduced the salinity, increased the utilization efficiency of carbon, nitrogen, and phosphorus, and significantly increased the activities of urease and phosphatase. The activities of urease and phosphatase were significantly correlated with the contents of total organic carbon and total carbon. A redundancy analysis showed that pH, AP, ESP, HCO3−, and Na+ were dominant factors in determining the bacterial community structure. The results showed that PRC could improve soil quality and enhance the ecosystem functionality of soda saline-alkali paddy fields by increasing nutrient content, stimulating soil enzyme activity, and regulating bacterial community improvement. After many years of PRC, the soda-alkali soil paddy field still develops continuously and healthily, which will provide a new idea for sustainable land use management and agricultural development. [ABSTRACT FROM AUTHOR]

With the continuous increase in saline–alkali land, sustainable development of the global environment and ecology have been seriously affected. This study compared the absorption and accumulation patterns of 11 elements in different parts (roots, stems and leaves) of different leaf Na regulation strategies of the pioneer plant Chenopodiaceae in saline–alkali land and evaluated the effects of soil nutrient status and soil salinity on the distribution of plant elements. The results showed that the changes in the content of Ca, Mg and Na in plants are affected by the salt-tolerant type and on different parts. Soil salinity had no significant effect on element concentrations in different parts of plants. The Pearson correlation coefficient showed that the correlation between plants and soil elements was different, and different parts of plants had the characteristics of selective absorption of soil elements. The salt tolerance type and soil mineral element concentrations explained most of the variation observed in element concentrations in Chenopodiaceae plants; the soil salinity property played only a minor role. It was concluded that the genetic factors are the prerequisite in the composition pattern of leaf elements in Chenopodiaceae, and soil factors are the key to determining element accumulation. These conclusions provide an effective reference for evaluating plant breeding and its response to environmental change in saline–alkali arid areas in Hulunbuir grassland and other parts of the world. [ABSTRACT FROM AUTHOR]

Restoring and reconstructing the salt-affected degraded ecosystem is receiving more and more attention in many parts of the world, especially semi-arid areas. Unfortunately, knowledge about the potential role of natural arbuscular mycorrhizal (AM) fungi was limited. This work examined the regional factors that drove the variations in AM fungal diversity in Songnen Plain, a typical saline-sodic degraded grassland. Soils were sampled in 45 random sites, 150 operational taxonomic units (OTUs) belonging to Glomeromycota were identified. Among these OTUs, 129 and 103 OTUs were classified to Glomerales and Glomus, respectively. The coefficients of variation of total diversity index were 35.61% and the total effects of soil salinity and nutrients collectively accounted for 31.2, 11.8, 47.3, and 64.2% of the variations in Sobs, Chao, Shannon, and Simpson indices, respectively. The climatic variables and geographical location had no significant effects on the variations of AM fungal diversity. Multiple linear regression models showed that soil pH, electrical conductivity (EC), available N and organic C were the most main influencing factors. This research highlighted the wide distribution of AM fungi and thus might promote the development of new techniques that apply natural AM fungi to restore saline-sodic degraded grasslands. [ABSTRACT FROM AUTHOR]

Soil salinity and sodicity can not only directly restrain crop growth by osmotic and specific ion stresses, it also may reduce grain yield indirectly by impacting plant absorption of essential nutrients. Ensuring adequate nitrogen is an important management aspect of rice production in saline-sodic soils. The objective of this study was to investigate the interaction of soil pH, salinity and nitrogen application on rice yield and nutrient absorption. We conducted a rice experiment in containers in a greenhouse. The soils were first leached with 9 target salt solutions of pH 7, 8 and 9 and electrical conductivity (EC) of 2, 6 and 10 dS m −1 . Nitrogen application rates were 100, 200 and 300 kg N ha −1 . Rice grain yield and shoot weight significantly decreased with increasing soil pH and increasing soil EC, and significantly increased with increasing nitrogen application ( P < 0.001). However, at high EC and/or high pH yield was not significantly increased by increased N. High pH and high EC in soil significantly influenced the mineral nutrient content of rice shoots ( P < 0.05). High soil pH and soil EC stresses were superimposed on each other, the negative effects on rice were compounded. The results by stepwise regression analysis showed that soil pH very significantly and adversely impacts grain yield and was the major factor impacting rice grain yield (R 2 = 0.565, P < 0.001). Nitrogen application provided a positive response under control and pH 7 at all salinity values, and at pH 8 under low salinity only. There was no significant response to additional N under pH 8 and elevated EC and no significant response at pH 9 for all EC values. Thus, adequate nitrogen application is an important technical measure for improving rice yield and promoting nutrient absorption in rice of high EC soils but not of high pH soils where pH is the major limiting factor for rice production in saline-sodic soils. [ABSTRACT FROM AUTHOR]

Soil aggregation, an ecosystem function correlated with the concentration of glomalin-related soil protein (GRSP), is highly disturbed in saline soil. However, few studies have focused on differences in amount, composition, and ion binding capacity of GRSP in typical sodic-saline soils. In this study, a field study was performed in Songnen Plain. Combined indicators of soil salinity (Q value) were significant negatively correlated with GRSP concentration by Principal Component Analysis. Multiple linear regression models showed that soil salinity might account for 46%, 25% and 44% variation in total GRSP (T-GRSP), easily-extractable GRSP (EE-GRSP) and difficultly-extractable GRSP (DE-GRSP), respectively. Soil bulk density had most important impact on GRSP concentration, followed by the pH, soil EC had the weak influence. Comparative analysis was carried out between low-salinity and high-salinity soil. Purified T-GRSP of high-saline soil contained higher N content (13.13%), lower C content (43.41%) and lower functional groups relative content (e.g. C O and Si O Si). Purified T-GRSP of high-salinity soil had a greater binding capacity with calcium and phosphorus, the binding capacity could compensate the GRSP loss about 29.8% and 14.1%, respectively. Our findings suggested that sodic salinization of the soil led to a decrease in GRSP concentration and a change in the component percentages. This change in composition might be related to adaptation of fungi-plant systems to varied environments. The calcium and phosphorus binding capacity had a positive dependent of soil salinization, which was possible to develop ecological management or recovery technology in the future. [ABSTRACT FROM AUTHOR]

• Soil salinization in the west of Jilin province for a long term was monitored. • Meteorological conditions are the most relevant and important factors in soil salinization. • The implementation of government policies reversed the saline soil expansion. • Salinized soil was mainly converted to grassland and cropland. Soil salinization is a serious land degradation phenomenon that significantly affects regional economies and agricultural development. Since the 1980s, the state of soil salinization has been constantly changing due to various climatic conditions, human activities, and the application of soil improvement measures. In this study, the Landsat-5 TM and Landsat-8 OLI satellites, launched in 1984 and 2013, respectively, were used to track changes in soil electrical conductivity (EC), a key indicator of soil salinity. A remote-sensing inversion model for the EC of saline-sodic soil was established (R = 0.5), and the soil EC in western Jilin Province from 1989 to 2019 was inverted. Then, the temporal and spatial variation characteristics of the soil salinization degree were counted, and the related variables and influencing factors were analyzed. The results are in good agreement with the conclusion that meteorological conditions are the most relevant and important factors in soil salinization. The area of saline soil increased continuously in the natural state (from 1989 to 1999), and the implementation of government policies (1999 to 2019) reversed the saline soil expansion, converting large areas of saline soil to grassland and cropland. This study is the first to quantitatively analyze the degree of soil salinization and its influencing factors in western Jilin Province from 1989 to 2019; this work also successfully predicted and monitored the variation in soil salinization. This provides data support for the study of the dominant elements in soil salinization changes and the rational development of land. [ABSTRACT FROM AUTHOR]

Abstract: Field experiments were conducted to investigate the effects of drip irrigation on seed germination and Puccinellia tenuiflora growth in saline-sodic soils in the Songnen Plain, northeast China. The experiment included five treatments in which the soil matric potential (SMP) at 0.2m depth was controlled at −5, −10, −15, −20 and −25kPa after the P. tenuiflora germinated. Consequently, the total water applied increased with increased matric potential. The results showed that drip irrigation influenced the water content, electrical conductivity of saturated-soil extract (ECe) and pH distributions, and inhibited the buildup of salts in the root zone, which enabled seeds to germinate and emerge. The ECe and pH in the whole soil profiles decreased as the SMP increased. After two years of the experiment, the tiller numbers, height, spike number and length, aboveground biomass and coverage of P. tenuiflora all increased greatly; and the growth of −15 and −20kPa treatments were better than other treatments. Taken together, these results indicate that drip irrigation can be used to provide suitable conditions for the germination of P. tenuiflora seeds in the Songnen Plain and induce good growth, and the SMP of −15 and −20kPa at a depth of 0.2m immediately under a drip emitter can be used as an indicator for saline-sodic P. tenuiflora grassland restoration in Songnen Plain. The results provide theoretical and technological guidance for reclamation and use of salt-affected soil, as well as for easy and quick restoration and reconstruction of saline-sodic grasslands. [Copyright &y& Elsevier]