Saline-alkali Soil Research Articles

Elaeagnus angustifolia can improve salt-alkali soil and the health level of soil: Emphasizing the driving role of core microbial communities

Saline-alkali environments are widely distributed in China and significantly hinder the development of agriculture. This study characterizes the long-term effects of planting Elaeagnus angustifolia (E. angustifolia) on the physical and chemical properties, enzyme activities and microbial community characteristics of saline-alkali soil in the Songnen Plain (1, 2 and 3 years). The results showed that planting E. angustifolia reduced soil pH and electrical conductivity (EC) and increased soil total phosphorus (TP), total nitrogen (TN), nitrate nitrogen (Nni), total potassium (TK), dissolved organic C (DOC), dissolved organic matter (DOM) and available potassium (AK) content and catalase, urease, polyphenol oxidase, phosphatase, sucrase and cellulase enzyme activities, and the results peaked in the 3 year. High-throughput sequencing showed that the bacterial abundance and diversity were as follows (from high to low) y3 > y2 > y1 > CK. E. angustifolia resulted in an increase in the relative abundance of the dominant bacteria. Proteobacteria and Pseudomonas were the major phylum and genus, respectively. Redundancy analysis showed that changes in the soil microbial community significantly affect the physical and chemical properties of the soil, with Proteobacteria members being the key microorganisms that reduce soil salinity. Network analysis showed that Pseudomonas (Proteobacteria) participated in the synthesis of key soil enzymes. 16S rRNA sequencing predicted that the expression of genes related to carbon (rbcL, acsA, acsB, Pcc and accA) and nitrogen (amoA/B, nxrA, hao, gdh, ureC and nosZ) transformation increased, and Pseudomonas members were key regulators of carbon and nitrogen dynamics. In conclusion, the planting of E. angustifolia could improve the physical and chemical properties of the soil by releasing root exudates into the soil and increasing the diversity and richness of soil microbial communities to improve saline-alkali soil, providing a theoretical basis for improving saline-alkali soil and promoting the sustainable development of modern agriculture.

Response of soils properties and archaea community to saline-sodic soils under long-term rice-based cropping system

ABSTRACT Understanding the soil microbiology and physico-chemistry may contribute to efficient land utilization. A 10-year field experiment was conducted in Songnen Plain, China. High-throughput sequencing and quantitative PCR of 16S rRNA and methyl coenzyme M reductase A (mcrA) genes were performed to investigate the dynamic changes in archaeal community following long-term rice planting. Ten-year rice planting significantly decreased soil salinity and alkalinity, including pH (7.6%), electrical conductivity (23.9%), sodium absorption ratio (33.1%), and exchangeable sodium percentage (33.5%) and significantly increased soil organic carbon (70.5%) and mineral nutrient concentrations. Rice planting increased α-diversity, and reshaped the archaea community structure of saline-alkali soil. The archaea community compositions during the 10-year period were divided into three stages: 1) shift in abundance from ammonia-oxidizing archaea to methanogenic archaea, 2) methanogenic archaea (e.g. genera Methanosarcina, Methanosaeta, Methanobacterium, Methanocella, Methanomassiliicoccus) established superiority, and 3) methanogenic archaea genes copy numbers increased and the community became stable. Redundancy analysis showed that the decrease in pH caused by long-term flooding was the main factor responsible for the changes in archaea community structure. The results highlighted that the rice planting could be a beneficial approach for maintaining ecological stability and reclaiming severe saline-alkali soil.

Genome-Wide Association Analysis of Salt-Tolerant Traits in Terrestrial Cotton at Seedling Stage.

Soil salinization is the main abiotic stress factor affecting agricultural production worldwide, and salt stress has a significant impact on plant growth and development. Cotton is one of the most salt-tolerant crops. Therefore, the selection and utilization of salt-tolerant germplasm resources and the excavation of salt resistance genes play important roles in improving cotton production in saline–alkali soils. In this study, we analysed the population structure and genetic diversity of a total 149 cotton plant materials including 137 elite Gossypium hirsutum cultivar accessions collected from China and 12 elite Gossypium hirsutum cultivar accessions collected from around the world. Illumina Cotton SNP 70 K was used to obtain genome-wide single-nucleotide polymorphism (SNP) data for 149 elite Gossypium hirsutum cultivar accessions, and 18,430 highly consistent SNP loci were obtained by filtering. It was assessed by using PCA principal component analysis so that the 149 elite Gossypium hirsutum cultivar accessions could be divided into two subgroups, including subgroup 1 with 78 materials and subgroup 2 with 71 materials. Using the obtained SNP and other marker genotype test results, under salt stress, the salt tolerance traits 3d Germination potential, 3d Radicle length drop rate, 7d Germination rate, 7d Radicle length drop rate, 7d Germination weight, 3d Radicle length, 7d Radicle length, Relative Germination potential, Relative Germination rate, 7d Radicle weight drop rate, Salt tolerance index 3d Germination potential index, 3d Radicle length index, 7d Radicle length index, 7d Radicle weight index and 7d Germination rate index were evaluated by GWAS (genome-wide association analysis). A total of 27 SNP markers closely related to the salt tolerance traits and 15 SNP markers closely related to the salt tolerance index were detected. At the SNP locus associated with phenotyping, Gh_D01G0943, Gh_D01G0945, Gh_A01G0906, Gh_A01G0908, Gh_D08G1308 and Gh_D08G1309 related to plant salt tolerance were detected, and they were found to be involved in intracellular transport, sucrose synthesis, osmotic pressure balance, transmembrane transport, N-glycosylation, auxin response and cell amplification. This study provides a theoretical basis for the selection and breeding of salt-tolerant upland cotton varieties.

Alteribacter salitolerans sp. nov., isolated from a saline-alkaline soil.

A Gram-positive strain APA H-16(1)T was isolated from a saline-alkali soil sample collected from Heilongjiang Province, China. Cells were rod shaped, non-motile, endospore forming, and aerobic. Growth occurred at 10-45°C (optimum, 35°C), pH 7.0-10.5 (optimum, pH 9.5), and could tolerate NaCl up to 15.0% (w/v). Strain showed low 16S rRNA gene sequence similarities with Alteribacter natronophilus (97.8%), Alteribacter aurantiacus (97.7%), and Alteribacterpopuli(97.1%). The cell wall peptidoglycan was meso-diaminopimelic acid. The predominant menaquinone was MK-7. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, unidentified aminophospholipids, unidentified phospholipid, and unidentified lipid. The major fatty acids were anteiso-C15:0, and iso-C15:0. The genomic G + C content was 45.1%. The average nucleotide identity and digital DNA-DNA hybridization values between strain APA H-16(1)T and the most closely related species were below the cut-off level (95-96%; 70%) for species delineation. Based on phenotypic, phylogenetic, chemotaxonomic, and genome comparison, strain APA H-16(1)T represents a novel species of the genus Alteribacter, for which the name Alteribacter salitolerans sp. nov. is proposed. The type strain is APA H-16(1)T (= KCTC 43228T = CICC 25092T).

Dynamics of Spring Regrowth and Comparative Production Performance of 50 Autumn-Sown Alfalfa Cultivars in the Coastal Saline Soil of North China.

Alfalfa (Medicago sativa L.) production is affected by many factors, including management practices, soil conditions, and the environmental elements of the target area. Varietal differences, in terms of agronomic performance and forage yield, among 50 alfalfa cultivars under six harvest systems following regrowth were evaluated during the growing season of 2019–2020 under non-irrigated rainfed conditions in a coastal saline-alkali soil region of North China. Days to harvesting, plant height, canopy area, growth rate, and forage yield were assessed to rank the cultivars. Furthermore, the key factor influencing the regrowth of the second year after over-wintering was identified based on the growth status before over-wintering by using the Boston Matrix method. Results showed significant (p < 0.05) differences among cultivars and harvests regarding plant height, canopy area, and forage yield. Alfalfa forage yield ranged between 24.2 t ha−1 yr−1 and 32.7 t ha−1 yr−1. The highest forage yield was obtained in cultivar Guochan No.1, and was lowest in cultivar Magnum 601. Forage yield reached the greatest values for the first harvest, and then decreased gradually and changed stably. The forage yield of the third, fourth, fifth, and sixth harvest ranged from 3.4 t ha−1 to 4.3 t ha−1 (averaged across 50 cultivars), which represented 10.8% to 15.2% of the annual total forage production. We also observed that forage yield correlated strongly, but negatively, with the growth rate. According to subordinate function value analysis, Womu No.1, WL440HQ, Weston, Surprise, and WL354HQ proved optimum cultivars for general cultivation in this coastal area. In future, development of alfalfa cultivars with improved regrowth and tolerance to heavy saline-alkali soil and early spring drought would be necessary to increase forage yield under rainfed conditions in coastal saline-alkali areas of North China.

Amelioration effects of coastal saline-alkali soil by ball-milled red phosphorus-loaded biochar

There is a great demand for amelioration of coastal saline-alkali soil, which requires efficient and economical amendments. Biochar has been proven to be a promising soil amendment and newly modified biochar is competitive for amelioration of coastal saline-alkali soil. Herein, a novel biochar (BPBC) was successfully prepared by ball milling and red phosphorus (P) loading. Ball milling could effectively grind pristine biochar into submicron particles, load uniform and nanoscale P-containing particles on biochar, and hence markedly improve the special surface area, P loading amount, and P-containing functional groups contents. Meanwhile, the oxidative conversion of red P into phosphorus oxides and phosphate was promoted, which could be ascribed to reactions with the minerals and O-containing functional groups of biochar. These reactions also occurred in the amended soil, thus significantly decreasing the soil electrical conductivity and salinity by phosphate precipitation between BPBC and soluble salt ions, and decreasing the soil pH and alkalinity by acid-base neutralization. BPBC improved the soil quality and fertility by enhancing organic carbon content, cation exchange capacity, soil nutrients (e.g., N, P, K), and soil enzyme activities. Moreover, amendment of biochar, especially BPBC, could improve the microbial community structure and promote the germination and growth of maize. Overall, BPBC is a novel, efficient, and eco-friendly soil amendment that is able to ameliorate soil salinity and alkalinity, improve soil quality, and promote plant productivity in coastal saline-alkali soil.

Mechanism of Saline–Alkali land improvement using subsurface pipe and vertical well drainage measures and its response to agricultural soil ecosystem

Salinization is recognized as a threat to agricultural productivity and land resources in global arid desert regions. To date, field soil improvement schemes have met with minimal success to date. We aimed to improve saline–alkali soils by assessing the effects of combining subsurface pipe (Pa) and vertical well (Sa) drainage measures on agricultural soils ecosystem. In a five-year field experiment, soil was sampled 0.5 m, 5 m, 7.5 m horizontally away from the Pa, and 0.5 m, 30 m, 60 m horizontally away from the Sa. Findings indicate that the soil electrical conductivity (EC) decreased from 16 dS m−1 to 3 dS m−1 at a 0–80 cm depth, and the soil desalination efficiency was great at the 0–300 cm depths (≥ 32%) than at the 400–700 cm depths (−14%–74.7%). The combined Pa and Sa drainage measures significantly decreased the species richness and quantity of soil microbial communities, and their negative impact on observed species was irreversible within 1 year. The farther the horizontal sampling conducted from the Pa and Sa, the greater the structural similarity of the microbial community at the genus level, higher the catalase, acidic protease, and neutral phosphatase activities, and lower the alkaline phosphatase activity. The overall decrease in groundwater level from 2016 to 2020 was 5.7 m. The seed cotton yield increased by 3.2 t ha−1. The results suggest that the value of saline–alkali soil can be improved by combining Pa and Sa drainage measures. Our research provides guidance for further effective utilization of agricultural water and soil resources and the sustainable development of the soil ecosystem in arid desert areas.

Evaluation the Effect of Different Soil Amendments on Physicochemical Property of Soda Saline-alkali Soil and Crop Yield in Northeast of China

Soil amendment is one of the most effective method to improve saline-alkali soil. In this paper, we verify the effect of 13 kinds of amendments and its combination on soil pH, metal cations content, exchangeable Na+, exchangeable sodium percentage (ESP) in the lab, and then choose the most 5 effective amendments Zeolite (Z), Acidified zeolite (ZH), Aluminum sulfate (AL), Aluminum sulfate + zeolite (AL + Z) and Aluminum sulfate + acidified zeolite (AL + ZH), both applying in both dry and paddy field to evaluate their improvement on soda saline-alkali soil and crop yield. The results showed that AL, AL + Z and AL + ZH treatments could significantly reduce the pH in soil solution and increase the content of metal cations. Z and ZH treatments could adsorb metal cations in soil. Both in dry and paddy fields, all treatment could increase the soil saturated hydraulic conductivity (Ks), increased from 9.63 mm d-1 to 60.02 mm d-1 and 0.18 mm d-1 to 33.25 mm d-1, respectively; All treatments could reduce the content of exchangeable Na+ in soil, and decrease by 38.62% - 61.33% and 25.24% - 71.53%, respectively; All treatments could reduce soil exchangeable sodium percentage, and decrease by 0.14 - 0.22 and 0.14 - 0.41, respectively; AL, AL+Z and AL+ZH treatments could improve soil organic matter content; All treatments could effectively improve the yield of crops, and increase 23.98% - 60.75% and 52.51% - 260.21%, respectively. The effect of AL treatment was the best in dry field and AL + ZH treatment was the best in paddy field of soda saline-alkali soil.

Pig farm biogas slurry can effectively reduce the pH of saline-alkali soils

ABSTRACT Pig farm biogas slurry is being increasingly used as a potent organic fertilizer for sustainable agriculture under circular economy. However, the effect of biogas slurry on soil pH is currently controversial, and the underlying mechanisms especially in saline-alkali soils are not well understood. A saline-alkali soil (pH = 9.2, EC = 2.0 ms/cm) was selected for soil column (0–50 cm) experiments with (BS) and without (CK) addition of pig farm biogas slurry to investigate the soil pH change and its driving factors. Our results show that the soil pH under CK ranged between 9.1 and 9.5 across different soil depths. Compared to CK, the BS-treated soil had lower pH at 0–20 cm depth and higher pH at 20–30 cm depth (P < 0.01). The soil concentrations were negatively correlated with pH values under BS (P < 0.01), indicating that the oxidation of ammonium mainly contributed to the decrease of soil pH. Interestingly, the anions, such as Cl−, and , were accumulated in the topsoil (0–20 cm) under BS, resulting in the changed correlations of these anions with Na+ when compared to the control. FT-IR and 13C-NMR spectra uncovered that carboxyl, amide C, and total alkyl C groups may be responsible for reducing pH of the saline-alkali soil tested. The soil surface morphology confirmed a much tighter granular aggregate microstructure when mixing the biogas slurry with the soil. Overall, we concluded that from the perspective of soil pH, the utilization of biogas slurry for improving saline-alkali soil is feasible and sustainable.

Contrasting effects of biochar- and organic fertilizer-amendment on community compositions of nitrifiers and denitrifiers in a wheat-maize rotation system

This research investigated the N2O fluxes and community compositions of nitrifiers and denitrifiers in a winter wheat-summer maize rotation system on the North China Plain. The experiment included three treatments: 1) a control treatment (CK); 2) biochar at 10.0 t ha–1 yr−1 (C); and 3) organic fertilizer at 7.5 t ha−1 yr−1 (M). The application of biochar reduced the cumulative N2O emissions by 47.7% and 62.2% in the maize and wheat seasons, respectively, compared with those of the CK treatment. Organic fertilizer increased the cumulative N2O emissions by 311.1% in the maize season and had no significant effects on them in the wheat season. Organic fertilizer reduced the cumulative N2O emissions by 39.8% in the nonfertilizer period of the maize season. The cumulative N2O emissions in the maize season accounted for 75.2–90.0% of the annual emissions among all the treatments. Biochar and organic fertilizer affected soil N2O emissions mainly by changing soil denitrifiers. In the maize season, the lower abundances of Candidatus Nitrosoarchaeum (AOA-amoA), Nitrosomonas (AOB-amoA), Mesorhizobium (nirK), Magnetospirillum (nirS) and Halomonas (nirS) may result in lower N2O emissions in the biochar treatment, and organic fertilizer had a similar influencing mechanism on N2O emissions during the nonbasic fertilizer and nontopdressing periods of the maize season. In the wheat season, the dominant genus Alicycliphilus (nosZ) was the major contributor to decreasing N2O emissions in the biochar treatment, while there was no biomarker related to N2O emissions in the M treatment. The soil pH, NO3−-N content and water-filled pore space (WFPS) were the key factors shifting the community compositions of nitrifiers and denitrifiers in this study. The application of biochar could be a better practice to improve saline-alkali soil with lower N2O emissions. These findings will improve our understanding of the nitrifiers and denitrifiers response to biochar and organic fertilizer.

Fate of bacterial community, antibiotic resistance genes and gentamicin residues in soil after three-year amendment using gentamicin fermentation waste

Over a three-year field trial, the impacts of composted and raw gentamicin fermentation waste (GFW) application to land on residual soil gentamicin levels, physicochemical properties, bacterial community composition, and antibiotic resistance genes (ARGs) were assessed. In the saline-alkali soil tested, GFW application decreased electrical conductivity (EC) and pH. Importantly, there was no measurable long-term accumulation of gentamicin as a result of GFW addition. Changes in the abundance of Bacillus was primarily associated with degradation of gentamicin in soil, whereas wider (i.e. more general) shifts in bacterial communities over the treatments was linked to alteration of soil physicochemical properties, particularly pH, total nitrogen, dissolved organic carbon, EC, NO3−-N and NH4+-N. Compared with other treatments, soils receiving composted GFW harbored more types of ARGs and significantly higher (P < 0.05) abundances of mobile genes elements (MGEs) (especially IncQ and Int1) and aminoglycoside ARGs (especially aminoglycoside phosphotransferases genes, APH). Finally, the abundances of ARGs in soils receiving raw and composted GFW were 59.60% and 50.26% higher than that in soils only receiving chemical fertilizer, respectively. Specifically, the abundances of APH, especially strB, were significantly higher than other kinds of ARGs (P < 0.05). The results of linear regression and partial least squares path model showed that MGEs, including plasmids, integrons, and transposons, along with soil properties (EC and NH4+-N) were the main factors associated with change in ARGs. Furthermore, different MGEs were involved in different transfer mechanisms of specific ARGs. Our findings demonstrated the potential risks of using raw and composted GFW as fertilizer, and suggest potential solutions to this problem.

Soil salinity variations and cotton growth under long-term mulched drip irrigation in saline-alkali land of arid oasis

The sustainable development and utilization of saline-alkali land are closely related to holding fast the minimum cultivated land area of China. The change of soil salt in cotton field under long-term mulched drip irrigation (MDI) is connected with the development of the national cotton industry. From 2015 to 2019, five cotton fields with different applying years of MDI, which were reclaimed in 2004, 2008, 2010, 2012 and 2015 respectively and were saline-alkali wasteland before, were monitored continuously in the Manas River irrigation area of Xinjiang. By means of continuous location monitoring and spatial–temporal variability (For example, the monitoring data of cotton fields under MDI in 2004, 2008, 2010, 2012 and 2015, and in the year of 2015 were counted as 12, 8, 6, 4 and 1 years, respectively), the spatial–temporal variations of soil salt and ions in cotton field with 1-16a MDI technology were presented. The cotton growth characteristics and its main influencing factors were also analyzed in the study. The results showed that saline-alkali cotton field experienced changed from intensive saline soil to moderate saline soil and finally to non-saline soil under long-term MDI. The change of soil salt and the response of cotton growth to soil salt were divided into three typical stages. Firstly, soil desalinated rapidly in 1-4a MDI cotton field, which the annual average desalination rate was 24.93% in 0–100 cm soil layer (root zone). Additionally, the survival rate of cotton rocketed from 1.48% to 42.04%, and yield increased sharply from 72.43 kg ha−1 to 3075.90 kg ha−1. Soil desalination was lower in 5-11a MDI cotton field, which the annual average desalination rate was 10.92% at the root zone. The annual survival rate and yield of cotton increased by 6.26% and 5.18%, respectively. After 12a MDI, the soil salt in cotton field tended to be generally constant, which the average salt content in root zone was less than 2.49 g kg−1. The survival rate of cotton was stable above 90.39%, and the yield per unit area exceeded 5401.32 kg ha−1. Ions, sodium absorption ratio and Cl− and SO42− equivalent ratio (CSER) in cotton soil also decreased with the extension of MDI. Salt composition changed year by year, but the type of intensive saline soil had always been chloride-sulphate solonchak (0.2 < CSER < 1). In practice, with a higher irrigation quota and ideal irrigation water quality, the soil salt environment of saline-alkali soil MDI cotton field had developed in favor of cotton growth in an oasis irrigation area. However, this management practice caused between 124.21–143.61 mm of water resources waste. Therefore, we should further enhanced the consciousness of water-saving and implemented quota management in practice.

Potassium application alleviates the negative effects of salt stress on cotton (Gossypium hirsutum L.) yield by improving the ionic homeostasis, photosynthetic capacity and carbohydrate metabolism of the leaf subtending the cotton boll

• Potassium (K) application alleviated the salt stress damage and improved cotton yield. • K application in saline alkali soil maintained the ionic homeostasis of LSCB (leaf subtending the cotton boll). • Under salt stress, K application improved LSCB photosynthetic capacity. • Under salt stress, K application enhanced the carbon metabolism of LSCB. Field experiments were conducted in 2017 and 2018, in order to investigate the effects of potassium (K) application on photosynthetic capacity and carbohydrate metabolism of the leaf subtending the cotton boll (LSCB) under salt stress. Three salinity treatments (EC = 1.68∼1.78, 6.21∼6.42 and 10.59∼11.08 dS m −1 ) with three K levels (0, 150, 300 kg K 2 O ha -1 ) applied in each salinity treatment, were imposed on two cotton ( Gossypium hirsutum L.) cultivars differing in salt sensitivity (CCRI-79, salt tolerant and Simian 3, salt sensitive). The results indicated that under salt stress: (1) K application increased LSCB K + /Na + ratio since Na + concentration decreased and K + concentration increased. Cotton boll (capsule wall, seed and lint) biomass, total boll number, boll weight and seed cotton yield were also increased; (2) K application improved net photosynthetic rates ( Pn ) of LSCB by increasing stomatal conductance rates ( Gs ), chlorophyll a and b concentrations and chlorophyll a / b ratio; (3) K application decreased soluble sugar, sucrose and starch concentrations of LSCB through increases in sucrose phosphate synthase (SPS) and sucrose synthase (SuSy) activities and decreases in sucrose acid invertase (SAI) activity. The results of this study indicated that K fertilizer application rates have a regulating effect on LSCB’s photosynthetic properties and carbohydrate metabolism under salt stress, thus providing a theoretical foundation for increasing cotton yield under salt stress.

Combined Treatment of a Pyroligneous Solution and Soluble Calcium Enhances Cotton Growth Through Improving Soil Quality in Saline-Alkali Soils

Combined Treatment of a Pyroligneous Solution and Soluble Calcium Enhances Cotton Growth Through Improving Soil Quality in Saline-Alkali Soils

Halophyte Planting Improves Saline-Alkali Soil and Brings Changes in Physical and Chemical Properties and Soil Microbial Communities

Halophyte Planting Improves Saline-Alkali Soil and Brings Changes in Physical and Chemical Properties and Soil Microbial Communities

Optimization of irrigation and nitrogen fertilization increases ash salt accumulation and ions absorption of drip-fertigated sugar beet in saline-alkali soils

• Irrigation and nitrogen effects on dry matter, ash salt accumulation, irons uptake of sugar beet were explored. • Dry matter and ash salt accumulation, Na + , K + , Ca 2+ and Mg 2+ uptake of W 3 were smaller than those of W 1 and W 2 . • Ash salt accumulation, Na + , K + , Ca 2+ and Mg 2+ uptake were proportional to dry matter accumulation. • Binary quadratic equations were fitted between water-nitrogen inputs and dry matter, ash salt accumulation and irons uptake. Sugar beet ( Beta vulgaris L.), as a salt-tolerant plant, has been widely cultivated in saline-alkali soils, e.g. southern Xinjiang of China, due to its effective capability of reducing soil salinity. A two-year field experiment was conducted on drip-fertigated sugar beet under plastic mulch to explore to effects of three irrigation amounts (W 1 : 0.60 ET c , W 2 : 0.80 ET c and W 3 : 1.00 ET c , where ET c is the crop evapotranspiration) and six nitrogen application rates (N 1 : 25 kg N ha −1 , N 2 : 60 kg N ha −1 , N 3 : 120 kg N ha −1 , N 4 : 240 kg N ha −1 , N 5 : 360 kg N ha −1 and N 6 : 480 kg N ha −1 ) on sugar beet growth, ash salt accumulation, plant Na + , K + , Ca 2+ and Mg 2+ uptake. The results showed that the year and the two-way interaction of irrigation and nitrogen fertilization had significant effects on dry matter, ash salt accumulation, plant Na + , K + , Ca 2+ and Mg 2+ uptake, but there was no significant effect of the three-way interaction of year, irrigation and nitrogen fertilization on ash salt accumulation, plant Ca 2+ and Mg 2+ uptake. The dry matter, ash salt accumulation, Na + , K + , Ca 2+ and Mg 2+ uptake of N 1 were significantly lower than those of other treatments. Nitrogen fertilization increased the dry matter and ash salt accumulation, Na + , K + , Ca 2+ and Mg 2+ uptake of sugar beet. The ash salt, K + and Ca 2+ were mainly distributed in the leaf and petiole, while Na + and Mg 2+ were mainly distributed in the taproot. Among the four ions, the average contents of K + and Na + were larger in all treatments, which were 1.79 % and 1.62 % in the two years, respectively. The average content of Mg 2+ was 0.36 % in all treatments in the two years, and the average content of Ca 2+ was lowest in all treatments, which was 0.14 % in the two years. Compared to W 1 and W 2 , W 3 decreased the dry matter and ash salt accumulation, plant Na + , K + , Ca 2+ and Mg 2+ uptake. The ash salt accumulation, plant Na + , K + , Ca 2+ and Mg 2+ uptake increased with the increasing dry matter accumulation. Based on the response surface methodology, the relationships between water-nitrogen inputs and dry matter, ash salt accumulation, plant Na + , K + , Ca 2+ and Mg 2+ uptake were established. The results can provide a theoretical basis for the phytoremediation of sugar beet in southern Xinjiang of China and maybe elsewhere with similar arid and semi-arid climates.

Effects of tillage methods on soil physical properties and maize growth in a saline–alkali soil

AbstractSoil sodicity and salinization is a major issues concerning agricultural production in northeast China. The effects of six treatments—no tillage (NT), no tillage and subsoiling (NTS), rotary and ridge tillage (RT), rotary and ridge tillage and subsoiling (RTS), rotary and flat tillage (FT), and rotary and flat tillage and subsoiling (FTS)—on soil physical and chemical properties and yields were compared from 2016 to 2018. The results showed that compared with the RT treatment, which is the traditional tillage method in this area, and the FT treatment, the NT treatment increased the soil water content (SWC) during the first‐leaf growth stage (V1). The use of subsoiling increased the average daily temperature and the soil thermal time (TTsoil). Subsoiling contributed to the growth and development of deep roots and increased leaf area index (LAI) to intercept more radiation. The NTS treatment increased grain yield of maize (Zea mays L.) by 2.7–15.2%, nitrogen use efficiency (NUE) by 4.2–14.4%, and water use efficiency (WUE) by 5.4–16.5% compared with RT. In conclusion, NTS soil management practices appear to be a sustainable approach to farming in the semiarid region of the Songnen Plain.

Klebsiella variicola improves the antioxidant ability of maize seedlings under saline-alkali stress

BackgroundSaline-alkali soil is mainly distributed in the northern and coastal areas of China. The Songnen Plain, located in the northeast of China, is a region with a relatively high concentration of saline-alkali soil and is also one of the more at-risk areas in the country. Every year, the increasing spread of saline-alkali soil areas has a serious impact on the growth of agricultural crops. The maize crop is sensitive to saline-alkali stress, which seriously affects its growth and development. Our previous study determined that Klebsiella variicola performs a variety of biological functions, as well as improves the rhizosphere microenvironment and promotes the growth and development of maize seedlings in saline-alkali soil environments. The present study further analyzed the mechanism that enables K. variicola to alleviate saline-alkali stress at the level of the antioxidant system.MethodsThe accumulation of O2− was observed directly via histochemical staining. The activities of several antioxidant enzymes were determined using the nitro blue tetrazolium and the guaiacol methods. The contents of non-enzymatic antioxidants were determined using the dithionitrobenzoic acid method.ResultsThe contents of the superoxide anion and hydrogen peroxide in leaves and roots of maize seedlings increased under saline-alkali stress conditions. The higher level of reactive oxygen species increased the degree of membrane lipid peroxidation. There were differences in the degree of oxidative damage and performance of the antioxidant defence system in maize seedlings under saline-alkali stress. Following the application of increasing concentrations of K. variicola, the activity of antioxidant enzymes increased by 21.22%–215.46%, and the content of non-enzymatic antioxidants increased as well, the ratios of ASA/DHA and GSH/GSSG in leaves increased by 4.97% and 1.87 times, respectively, and those in roots increased by 3.24% and 1.60 times, respectively. The accumulation of reactive oxygen species was reduced, and the content of H2O2 decreased by 26.07%–46.97%. The content of O2− decreased by 20.18%–37.01%, which alleviated the oxidative damage to maize seedlings caused by saline-alkali stress.ConclusionK. variicola reduced ROS-induced peroxidation to membrane lipids and effectively alleviated the damage caused by saline-alkali stress by increasing the activities of antioxidant enzymes in maize seedlings, thus enhancing their saline-alkali tolerance. A bacterial concentration of 1×108 cfu/mL was optimal in each set of experiments.

Influence of different phytoremediation on soil microbial diversity and community composition in saline-alkaline land

Soil salinization is one main environmental factor restricting plant growth and agricultural productivity. However, phytoremediation is one of the important means to improve saline-alkali soil by planting halophytes or salt-tolerant plants. In order to study whether there are differences among soil microorganisms in different phytoremediation, the effects of four plants, including alfalfa (MX), oil sunflower (YK), maize (YM) and ryegrass (HMC) on soil physicochemical properties, enzyme activity and microbial community diversity and composition were investigated in this study and the relationships between microbial community structure and soil physicochemical properties, enzyme activity were analyzed. The results showed that all plants treatments significantly decreased pH, TS (total saltinity) and BD (bulk density), while increased OM (organic matter), TN (total nitrogen), AN (available nitrogen), TP (total phosphorus), AP (available phosphorus), TK (total potassium) and TPOR (total porosity), and the number of nitrite bacteria reduced by planting at the same time. Except for YM, other treatments significantly increased the number of nitrifying and denitrifying bacteria compared with CK, while only YK increased that of fungi. Additionally, all plants increased the activity of nitrite reductase and decreased that of urease. More interestingly, plants treatments shifted microbial community compositions, and only YM significantly decreased the bacterial diversity and increased the fungal diversity. Redundancy analysis suggested that TK, pH, BD, TS, AN, OM and nitrite reductase, lignin peroxidase were the key environmental factors that shaped the bacterial community structure, while that of fungi was mainly driven by OM, nitrite reductase, urease and lignin peroxidase. The results indicated that MX and YM are the best choice for remediation of saline-alkali soil. These data can provide certain theoretical basis for the further restoration of saline-alkali land. HIGHLIGHTS The effects of different phytoremediation on microbial diversity and community structure were different. Phytoremediation can significantly decreased pH, TS and BD, while increased OM, TN, AN, TP, AP, TK and TPOR in saline-alkali soil. All plants increased the activity of nitrite reductase and decreased the activity of urease.

Reducing nitrogen rate and hill distance improves rice dry matter production in saline–alkali soils

AbstractThe integrated strategies for nitrogen management and planting density are important for improving rice (Oryza sativa L.) yield in saline–alkali soil; however, the optimal growth conditions for the Songnen Plain, China, are unclear. Here, we studied the effects of nitrogen application rate (NAR) (N0, 0 kg ha−1; N1, 90 kg ha−1; N2, 120 kg ha−1; N3, 150 kg ha−1; N4, 180 kg ha−1) and hill distance (HD) (HD1, 16.5 cm; HD2, 13.3 cm; HD3, 10 cm) on rice dry matter accumulation, translocation, and photosynthetic production in a split‐plot experiment. At NARs below 120 kg ha−1, the number of effective tillers increased significantly with increasing NAR and decreasing HD. The leaf area index (LAI) increased as the NAR increased and HD decreased and was the highest in the N4–HD3 treatment, followed by N3–HD3, at the full‐heading stage. However, dry matter accumulation from the full‐heading to the maturity stage was the highest in the N3–HD3 treatment. The population growth rate in N3–HD3 was the highest from the full‐heading stage to the maximum grain‐filling stage, at 26.46 g m−2 d−1. The high rice yield under N3–HD3 conditions was attributed to the high dry matter accumulation after the full‐heading stage and the high sheath output rate. This study revealed that treatment N3–HD3 resulted in high yield, from the perspective of photosynthetic matter production.