Different Approaches to Reduce Salinity in Salt-Affected Soils and Enhancing Salt Stress Tolerance in Plants

Salt stress is one of the most harmful environmental stresses in recent times and represents a significant threat to food security. Soil salinization is caused by spontaneous natural processes of mineral dissolution and human activities such as inappropriate irrigation practices. Natural geological progressions like weathering of rocks, arid climate, and higher evaporation, as well as anthropogenic activities, including the use of brackish water for irrigation, and poor tillage operations, are the foremost causes of soil salinization. Typical characteristics of saline soils are salt stress, high pH, and lack of organic carbon, as well as low availability of nutrients. Disruption of precipitation patterns as well as high average annual temperatures due to climate change additionally negatively affects the process of soil salinization. Productivity and ability to support crop growth are reduced on saline soil. Salinity-induced stress reduces plant growth by modulating the antioxidative system and nutrient orchestration. The aim of this work is to show that the mentioned problems can be alleviated in several ways such as the addition of biochar, exogenous application of several elicitors, seed priming, etc. Research has shown that the addition of biochar can significantly improve the recovery of saline soil. The addition of biochar has no significant effect on soil pH, while the cation exchange capacity of the soil increased by 17%, and the electrical conductivity of the saturated paste extract decreased by 13.2% (depends on the initial salinity and the type of biochar raw material). Moreover, biochar enriched with silicon increases the resistance of bananas to salt stress. In addition, exogenous application of several elicitors helps plants to alleviate stress by inducing stress-related physicochemical and molecular changes (selenium, sulfur, silicon, salicylic acid). Finally, seed priming showed positive effects on metabolomics, proteomics and growth of plants subjected to abiotic stress. Priming usually involves immersing the seed in a solution for a period of time to induce physiological and metabolic progression prior to germination.

Changes in Soil Properties Under the Influences of Cropping and Drip Irrigation During the Reclamation of Severe Salt-Affected Soils

Reclamation of salt-affected land plays an important role in mitigating the pressure of agricultural land due to competition with industry and construction in China. Drip irrigation was found to be an effective method to reclaim salt-affected land. In order to improve the effect of reclamation and sustainability of salt-affected land production, a field experiment （with reclaimed 1-3 yr fields） was carried out to investigate changes in soil physical, chemical, and biological properties during the process of reclamation with cropping maize and drip irrigation. Results showed that soil bulk density in 0-20 cm soil layer decreased from 1.71 g·cm-3 in unreclaimed land to 1.44 g ·cm^-3 in reclaimed 3 yr fields, and saturated soil water content of 0-10 cm layer increased correspondingly from 20.3 to 30.2%. Both soil salinity and pH value in 0-40 cm soil layer dropped markedly after reclaiming 3 yr. Soil organic matter content reduced, while total nitrogen, total phosphorus, and total potassium all tended to increase after cropping and drip irrigation. The quantities of bacteria, actinomycete, and fungi in 0-40 cm soil layer all greatly increased with increase of reclaimed years, and they tended to distribute homogeneously in 0-40 cm soil profile. The urease activity and alkaline phosphatase activity in 0-40 cm soil layers were also enhanced, but the sucrase activity was not greatly changed. These results indicated that after crop cultivation and drip irrigation, soil physical environment and nutrients status were both improved. This was benefit for microorganism＇s activity and plant＇s growth.

Long-Term Fertilization Effect on Fertility of Salt-Affected Soils

The long-term effects of annual fertilizer applications on the fertility of salt-affected soils under the rotation system of wheat （Triticum aestivum L.） and maize （Zea mays L.） are not well documented. In 1984, research plots were established to test the effects of annual applications of different rates of nitrogen （N） and phosphorus （P） fertilizers on the fertility of a salt-affected soil （Typic Ustochrept） at the Quzhou Experimental Station, Quzhou County, Hebei Province, China. In October 2001, composite soil samples （0-20 and 20 40 cm） were collected from each plot and analyzed for soil fertility indices. Seventeen years of N and P fertilizer applications increased the soil organic matter （SOM） in the surface layer. With combined N, 270 （N1） and 540 （N2） kg N ha^-1 year^-1, and P, 67.5 （P1） and 135 （P2） kg P205 ha^-1 year^-1, fertilizer applications, total soil N mostly significantly decreased （P〈0.05）. Soil total P in the 0-20 cm layer of the P2 treatment significantly （P （0.05） increased as compared to those of the other treatments. Rapidly available P （RP） in the 0-20 cm layer of the N1P2 treatment was significantly higher than those in the other treatments except the P2 treatment; and RP in the 0-20 cm layer of the P2 treatment significantly increased as compared to those of the other treatments except the P1 and N1P2 treatments. RP in the subsurface soil layer （20-40 cm） of the P2 treatment （4.2 mg P kg^-1） was significantly （P〈0.05） higher than those in the other treatments. Nevertheless, long-term N fertilization did not significantly increase the alkali-hydrolyzable N in the soil. However, in the salt-affected surface soils the application of combined N and P fertilizers over 17 years significantly （P〈0.05） decreased rapidly available potassium （K）. The results suggested that while under long-term fertilizer applications some soil fertility parameters could be maintained or enhanced, careful monitoring of soil fertility was necessary as other nutrients such as K could become depleted.

Land Management Effects on Biogeochemical Functioning of Salt-Affected Paddy Soils

Most lowlands in Northeast Thailand(Isaan region)are cultivated with rice and large areas are affected by salinity, which drastically limits rice production.A field experiment was conducted during the 2003 rainy season to explore the interactions between salinity and land management in two fields representative of two farming practices:an intensively managed plot with organic inputs and efficient water management,and one without organic matter addition.Field measurements,including pH,Eh,electrical conductivity(EC),and soil solution chemistry,were performed at three depths, with a particular focus on Fe dynamics,inside and outside saline patches. High reducing conditions appeared after flooding particularly in plots receiving organic matter and reduction processes leading to oxide reduction and to the release of Fe and,to a lesser extend,Mn to the soil solution.Oxide reduction led to the consumption of H^+ and the more the Fe reduction was,the higher the pH was,up to 6.5.Formation of hydroxy-green rust were likely to be at the origin of the pH stabilization.In the absence of organic amendments,high salinity prevented the establishment of the reduction processes and pH value remained around 4.Even under high reduction conditions,the Fe concentrations in the soil solution were below commonly observed toxic values and the amended plot had better rice production yield.

Feasibility and Prospect about the Cultivation of Apocynum venetum L. in Coastal Salt-affected Soils

[Objective]The aim of this paper was to analyze the feasibility and prospect of Apocynum venetum L.cultivation in coastal salt-affected soils.[Method]The habitat and distribution of Apocynum venetum L.in coastal area of north China were studied.A method to integrate the charicteristics of Apocynum venetum L.（Luobuma） with the utilization of salt-affected soils in this region was proposed.[Result]The introduction,domestication and growth of plants on coastal salt-affected soils can realize the protection of endangered wild species,and achieve the purpose of improving soil.The characteristics of Apocynum venetum L.can produce optimum economic and ecological benefits.[Conclusion]The implementation will provide references for the protection and exploitation of wild plant,and it is of positive significance for the integration of soil and plant resources.

Identification of microRNAs regulating grain filling of rice inferior spikelets in response to moderate soil drying post-anthesis

The grain filling of inferior spikelets is much less complete than that of superior spikelets in rice cultivars with large panicles and numerous spikelets and is promoted by moderate soil drying(MD)post-anthesis.A growing body of evidence has shown that microRNAs function in regulating grain development.However,little is known about the mechanism of microRNA control of grain filling of inferior spikelets in response to MD.In this study,grain filling of inferior spikelets was promoted by MD treatment in Nipponbare.Small-RNA profiling at the most active grain-filling stage was conducted in inferior spikelets under control(CK)and MD treatment.Of 521 known and 128 novel miRNAs,38 known and 9 novel miRNAs were differentially expressed between the CK and MD treatments.Target genes of differentially expressed miRNAs were involved in multiple developmental and signaling pathways associated with catalytic activity,carbohydrate metabolism,and other functions.Both miR1861 and miR397 were upregulated by MD,leading to a decrease in OsSBDCP1 and OsLAC,two negative regulators of SSIIIa activity and BR signaling,respectively.In contrast,miR1432 abundance was reduced by MD,resulting in upregulation of OsACOT and thus an elevated content of both ABA and IAA.These results suggest that both starch synthesis and phytohormone biosynthesis are regulated by differentially expressed miRNAs in inferior spikelets in response to MD treatment.Our results suggest the molecular mechanisms by which miRNAs regulate grain filling in inferior spikelets of rice under moderate soil drying,providing potential application in agriculture to increase rice yields by genetic approaches.

Features of Salt－Affected Soils and Salinization Hazard in East Asia and Its Neighboring Regions

Asia is the largest distribution area of salt-affected soils in the world. Very few countries in Asia couldescape from hazard of salinization. This paper deals with various salt-affected soils spreading in East Asiaand its neighboring regions (including China, Japan, Kampuchea, Democratic People’s Republic of Korea,Republic of Korea, Laos, Mongolia, Burma, Thailand and Vietnam). Principles of occurrence of salinization,and features of salt-affected soils in these regions have been studied in the present paper. Based on studieson types, features and distribution patterns of salt-affected soils, a salt-affected soil map of East Asia andits neighboring regions has been complied. Mechanism and manifestation of the salinization hazard on theregional agriculture and ecological environment, measures of preventing salinization hazard and exploitingsalt-affected soils in these regions are also discussed.

潮土磷库组成及累积磷的消耗转化特征

【目的】长期施用磷肥致使潮土中累积了大量的磷,为精确管控和合理利用累积磷素,我们研究了小麦–玉米连续种植下,停止使用磷肥后磷库的组成和消耗转化特征。【方法】本研究依托位于河南新乡的“国家潮土肥力与肥料效益长期定位试验基地”进行,连续26年施用不同量磷肥,处理间土壤磷积累量差异很大。利用单个处理或两个处理耕层土壤混合的方法,制备Olsen-P含量分别为6.7、14.3、27.6、55.4、72.3 mg/kg的土壤(分别记为L1、L2、L3、L4、L5),用于进行微区耗竭试验,种植制度为冬小麦–夏玉米轮作。在耗竭试验的5年间,测定了土壤全磷、Olsen-P和各磷库组分含量。【结果】潮土磷库中无机磷占比超过90%,L5处理土壤中的有效磷库组分Resin-P、NaHCO_(3)-Pt、NaOH-Pt含量分别为L1的5.0、3.5、2.8倍。L1处理(缺磷土壤)的有效磷组分在全磷中的比例仅为10.4%,而难利用磷组分(C.HCl-Pt, Residual-P)的比例高达24.0%;L5处理(高磷土壤)有效磷组分比例高达20.6%,难利用组分比例低至14.3%。缓效磷组分(D.HCl-Pi)在全磷中的比例基本维持在66%。有效磷水平高于农学阈值(L2处理)之后,Resin-P组分才开始增加,增加量占有效磷库增加量的17.3%~22.6%。磷库耗竭过程中,有效磷库是作物吸收的第一磷库,且以Resin-P、NaHCO_(3)-Pi、NaOH-Pi的先后顺序被利用。Resin-P、NaHCO_(3)-Pi、NaOH-Pi每消耗1 mg/kg,Olsen-P分别减少1.3、0.7和1.0 mg/kg。有效磷库组分与缓效磷库、难利用磷库组分可以互相转化。5年耗竭过程中,L1处理有18.0 mg/kg难利用磷转化为D.HCl-Pi,L2、L3处理分别有22.3和7.2 mg/kg D.HCl-Pi转化为有效态磷,提升了土壤累积磷素的生物有效性;而L4、L5处理分别有29.9和43.1 mg/kg有效态磷组分转化为D.HCl-Pi,降低了土壤累积磷的生物有效性。【结论】随着土壤Olsen-P水平的提高,有效磷库组分Resin-P、NaHCO_(3)-Pt、NaOH-Pt占比增加,难利用磷库占比减少,而缓效磷库占比高且稳定。有效态Resin-P在Olsen-P超过农学阈值后才开始累积。作物吸收可促进缺磷土壤难利用磷库组分转化为缓效磷库组分,中磷土壤缓效磷库组分转化为有效磷库组分,最终土壤累积磷素均被活化利用;而高磷土壤中30%以上的有效磷库组分被转化为缓效磷库组分,作物奢侈吸磷量显著增加,造成一定的磷肥养分浪费。中磷土壤是维持磷资源高效利用和作物高产的最佳磷库组成状态。

有机污染场地土壤化学氧化耦合微生物修复技术

化学氧化耦合微生物修复是通过适度氧化预处理降解转化污染土壤中的高浓度、难降解有机污染物,并增强其生物可利用性,再利用微生物降解有机污染物的技术,在有机污染场地土壤修复中具有良好的应用潜力.本文评述了化学氧化耦合微生物修复技术的研究进展,重点介绍了土壤氧化还原电位精准预测、土著微生物优化或工程菌强化方法,阐述了基于机器学习的土壤污染修复调控策略,以期提升化学氧化耦合微生物修复效率,为有机污染场地土壤绿色、经济、安全、高效修复的工程应用提供参考.

长春中风化泥岩盾构施工泥饼防治研究

为更好地分析盾构结泥饼风险及渣土塑流性特征,开展旋转剪切试验、三轴试验和坍落度试验,探究长春中风化泥岩渣土黏附强度和抗剪强度特征;基于渣土强度提出长春泥岩渣土合理改良坍落度的建议,并结合实际工程验证其合理性。主要结论如下:1)随着含水率的增大,长春中风化泥岩渣土(界面)黏聚力先增大后减小,(界面)摩擦角逐渐减小。当含水率为22.58%~27.36%时,土-金属间的界面黏聚力大于黏聚力;当含水率为15.99%~24%时,界面摩擦角大于内摩擦角。2)渣土坍落度与强度密切相关,随着坍落度的增大,渣土黏附强度和抗剪强度快速降低。当坍落度大于4 cm时,黏附强度和抗剪强度变化较小;当坍落度为0.5~1 cm时,渣土黏附强度大于抗剪强度,因此建议盾构渣土坍落度不小于1 cm,且尽可能使渣土坍落度大于4 cm,以充分减小渣土强度和增大渣土塑流性。

轻中度盐碱地土壤有机质空间异质性及影响因素分析——以山东省黄河三角洲农业高新技术示范区为例

以黄河三角洲轻中度盐碱地典型分布区(山东省黄河三角洲农业高新技术示范区,以下简称黄三角农高区)为研究区域,于2021年10月采用网格布点法,对该区域土壤进行野外采样调查,利用地统计学和结构方程模型等方法,探究不同土层有机质含量的空间变异规律与影响因素,以期为轻中度盐碱地土壤资源合理利用提供参考。结果表明,黄三角农高区土壤有机质含量[0~20 cm土层为(15.85±5.69) g/kg;20~40 cm土层为(11.51±4.32) g/kg]属于4级,整体呈现中等变异。20~40 cm土层有机质含量的空间相关和自相关性高于0~20 cm土层。有机质含量与土壤粉粒含量和黏粒含量均呈显著正相关,与含盐量呈显著负相关。东部滨海地区有机质含量低于中部地区,呈现耕地>林地>荒地的趋势,人为利用(耕地、林地)提升了土壤有机质含量。离海距离对土壤有机质含量有直接影响,较高的pH值和粉黏比是影响土壤有机质积累的重要因素。本研究明确了黄三角农高区不同土层土壤有机质分布格局,揭示了土地利用类型对有机质含量的影响以及土壤有机质积累的限制因素,可为该区轻中度盐碱地农业生产规划提供参考。

Hydraulic properties of typical salt-affected soils in Jiangsu Province, China

Every year about 1,500 ha of land is reclaimed from the sea along the coastline of Jiangsu Province,China.It is important to characterize the hydraulic properties of this reclaimed land to be able to predict and manage salt and water movement for amelioration of these saline soils.In this paper,we report hydraulic properties of these salt-affected soils.The pressure-plate method,constant head method,the crust method and Klute’s method were used in this study.The satu-rated hydraulic conductivities of the soils ranged from 128.66 to 141.26 cm/day and decreased with increasing soil depth.The unsaturated hydraulic conductivities followed an expo-nential function of pressure head.The soil water retention curves were similar for three soil layers in the soil.The satu-rated water content,field capacity and wilting point decreased with increasing soil depth.Plant available water contents of the three layers in the soil profile were 0.21,0.20 and 0.19 cm3/cm3,respectively.The unsaturated soil water diffu-sivity of the studied soils ranged from 0.07 to 10.46 cm^(2)/min,and was related to the water content via an exponential relationship.

不同水稻灌溉模式和氮肥减量对还田麦秸腐解特性及土壤养分的影响

为了探讨不同水稻灌溉模式和氮肥减量对还田小麦秸秆腐解特性及土壤养分的影响,通过田间试验,设置了水稻灌溉模式(常规灌溉,W1;干湿交替灌溉,W2)和施氮水平(不施氮,N0;常量施氮,N1;减量20%施氮,N2)处理,采用尼龙网袋法研究了不同处理下小麦秸秆腐解动态、养分释放规律及土壤养分含量。结果表明,干湿交替灌溉和氮肥施用均可促进还田小麦秸秆的腐解,减量20%施氮处理小麦秸秆累积腐解率低于常量施氮处理。相同施氮水平下,干湿交替灌溉模式小麦秸秆碳与氮磷钾累积释放率高于常规灌溉模式;与常量施氮相比,减量20%施氮处理小麦秸秆碳与氮磷钾累积释放率降低。干湿交替灌溉和施氮使土壤有机质、全氮、碱解氮和有效磷含量提高,而减量20%施氮对土壤养分含量的影响较小。综上可见,干湿交替灌溉和氮肥施用促进了还田小麦秸秆腐解和养分释放,有利于土壤养分提升;而减量20%施氮对小麦秸秆腐解与养分释放以及土壤养分无明显影响。

黑土累积磷的释放动力学特征及主要影响因素

【目的】长期大量施用磷肥致使农田土壤磷快速累积,磷肥增产效率和利用率下降。研究不同施肥措施下土壤累积磷的释放动力学特征及其机制,为累积磷的活化利用和磷肥高效施用提供理论依据。【方法】黑土长期定位试验位于黑龙江省哈尔滨市,在5个不同处理采集土样,分别标记为P1、P2、P3、P4和P5,其Olsen-P含量依次为15.5、20.2、93.2、199和216 mg/kg。采用0.5 mol/L NaHCO3连续浸提法测定5个土壤样品中有效磷的释放量,以5个动力学方程拟合或描述有效磷的释放动力学。采用Hedley法测定了浸提前后土壤活性磷(Resin-P、NaHCO3-Pi、NaHCO3-Po)、中活性磷(NaOH-Pi、Na OH-Po、DilHCl-P)和稳性磷(ConcHCl-Pi、ConcHCl-Po、Residual-P)含量。【结果】连续浸提过程中,供试5个土壤的Olsen-P释放均呈先快后慢的趋势,在浸提1400 min (10次)时基本达到平衡。以米氏方程(Michaelis)、一级方程、Elovich方程、抛物线方程和幂函数方程描述有效磷的释放动力学特征,拟合方程的决定系数(R2)均在0.964及以上(P<0.01),其中又以米氏方程和一级方程为佳,其R2分别为0.9955和0.9922。由米氏方程可知,供试5个土壤的有效磷最大释放量分别为59.8、60.9、332.6、589.7和717.0 mg/kg,随Olsen-P含量的增加而增加,Olsen-P每增加1 mg/kg,磷释放量平均增加3.12 mg/kg;5个土壤有效磷的最大释放量占土壤全磷的比例分别为13.68%、14.86%、45.44%、60.67%和66.45%,也随Olsen-P含量的增加而增加,但土壤浸提残留磷(全磷与可提取有效磷之差)均为373.99 mg/kg左右,说明施磷对土壤残留磷的影响较小,长期施肥累积的磷具有较高的活性。一级方程和Elovich方程表明,黑土有效磷的释放是以扩散为主的动力学过程。连续浸提后,土壤活性磷平均减少了82.9%(67.8%~93.5%),中活性磷平均减少了34.6%(17.2%~52.0%),稳定性磷无显著变化。活性磷中的Resin-P和Na HCO3-Pi显著降低了89.8%(78.5%~96.0%)和84.5%(72.9%~91.3%),这表明Resin-P和Na HCO3-Pi的有效性最高。土壤活性磷库、中稳态磷库、磷释放的动力学方程参数与土壤有机质、Olsen-P、全磷呈显著正相关,与p H呈显著负相关,说明土壤累积磷的释放过程主要受到土壤活性磷、中活性磷、土壤有机质、pH和全磷含量的影响。【结论】黑土固定的残留磷量受施肥的影响较小,施肥累积的磷大部分可以释放,尤其Resin-P和Na HCO3-Pi的有效性最高。黑土中磷的释放符合米氏方程和一级方程,磷释放量随Olsen-P水平的增加而增加。土壤有机质、p H和全磷含量是磷释放过程的主要影响因素。

生物炭与木醋液对中度盐土N_(2)O和NH_(3)排放的影响

为探究生物炭与木醋液对盐土尿素氮的硝化过程、N_(2)O排放和NH_(3)挥发的影响,以甘肃中度盐土为研究对象,设置不施尿素对照(CK)、单施尿素(N)、尿素+生物炭(N+B)、尿素+木醋液(N+WV)和尿素+生物炭+木醋液(N+B+WV)5个处理,开展室内好气培养试验。结果表明:(1)各处理在培养0~14 d的表观硝化率均呈上升趋势,其中N+B+WV处理较其他处理铵态氮含量最高、表观硝化率最低,培养后期表观硝化率明显提高;培养结束N+B+WV处理氨氧化细菌(AOB)amoA基因丰度较N处理显著提高,增幅为76.5%,氨氧化古菌(AOA)amoA基因丰度较CK显著降低,降幅为51.5%。(2)与CK相比,N处理N_(2)O和NH_(3)累积排放量显著增加;与N处理相比,N+WV、N+B和N+B+WV处理N_(2)O累积排放量分别增加10.0%、减少9.5%和减少18.2%,氧化亚氮还原酶nosZ基因丰度分别降低9.3%、26.1%和37.7%,NH_(3)累积挥发量分别减少30.5%、28.9%和49.0%。(3)综合计算各处理N_(2)O和NH_(3)排放的温室效应潜能发现,与N处理相比,N+B+WV处理降低温室效应潜能20.0%,减排效果最显著。综上,在中度盐土区采用生物炭与木醋液配施可以有效减少盐土中N_(2)O和NH_(3)排放,有利于减少土壤氮素损失并降低温室效应潜能。

微咸水灌溉下不同生物炭对盐碱土水盐运移的影响

【目的】合理利用黄河三角洲地区微咸水资源改良盐碱地。【方法】以黄河三角洲地区中度盐碱土为研究对象,进行室内一维入渗试验,探讨在微咸水灌溉基础上掺加小麦/玉米秸秆生物炭对盐碱土水盐运移和pH值的影响。试验共设置10个处理:CK(去离子水)、X1(10 t/hm^(2)小麦秸秆生物炭)、X2(20 t/hm^(2)小麦秸秆生物炭)、Y1(10 t/hm^(2)玉米秸秆生物炭)、Y2(20 t/hm^(2)玉米秸秆生物炭)、W(3 g/L微咸水)、WX1、WX2、WY1、WY2。【结果】微咸水灌溉条件下掺加生物炭提高了土壤入渗能力,增加了土壤保水能力,且掺加小麦秸秆生物炭的入渗性能与保水效果优于掺加玉米秸秆生物炭,其中WX1处理效果最优;微咸水灌溉条件下掺加生物炭有利于土壤盐分的淋洗,含盐量较微咸水灌溉处理降低了7.30%~10.44%,且掺加小麦秸秆生物炭降盐效果优于掺加玉米秸秆生物炭,其中WX1处理脱盐效果最优,脱盐率达53.74%;微咸水灌溉条件下掺加生物炭增加了土壤pH值,但与淡水灌溉无明显差异,且经小麦秸秆生物炭处理的土壤p H值均低于玉米秸秆生物炭,其中WX2处理效果最好。【结论】在3 g/L微咸水灌溉条件下,添加10 t/hm^(2)的小麦秸秆生物炭对黄河三角洲地区中度盐碱土改良效果较好。

Salt-affected marginal lands:a solution for biochar production

The literature has shown that biochar can serve as potential amendment to achieve sustainable agriculture and environment.The accessibility and availability of cheap feedstock are considered as important constraint factors for the widespread application of biochar in agriculture.Marginal lands are widely distributed globally,several times larger than arable land,and hold little value for food production due to poor soil conditions.However,these lands are suitable for growing plants,which can be used as feedstock for biochar production.The salt-affected lands,as one of the main marginal lands,are particularly suitable for cultivating diverse varieties of halophytes that can be pyrolyzed into biochar,bio-gas,and bio-oil.The halophyte-derived biochar is useful to produce a desirable acid soil conditioner due to its high ash and rich bases,and improves soil characteristics under extreme saline conditions.Additionally,syngas and bio-oil hold potential benefits as fuels and industrial raw materials.This study introduces an innovative management technique for marginal lands such as salt-affected land,which can provide all-round benefits in food production,land management,vegetation coverage,carbon sequestration,and climate change mitigation.

Study on Cultural Technologies and Salt-resistance of Nitraria sibirica in Coastal Areas with Serious Salt-affected Soil

In this research, five Nitraria sibirica provenances such as Dayilu were selected to do experiment of salt-resistance, combining fixed plots test with typical plot investigation, measuring survival rate and growth as main indicators. The experiments of main cultural technology were done on Nitraria sibirica in 4 types of site preparation, 3 types of planting, 3 designs for planting density. The Nitraria sibirica experiments for the effects of curbing salt and improving soil were done by testing soil nutrients, salt content, soil physical properties as focal points in typical site of 3-4 years woods. The experiment results showed that the Nitraria sibirica could survive well with soil salt content of 0.6%, and that survival rate declined distinctively as soil salt content exceeded 0.8%. However, high soil salt content did not influence growth in the year of planting. There were obvious differences in salt-tolerance among Nitraria sibirica provenances; Dayilu was the best on salt-tolerance, the other 4 provenances had no differences, and obviously inferior to Dayilu. The different types of site preparation clearly influenced planting survival rate, conserving rate and growth. The method of two-ploughing-two-harrowing was the best among all 4 types of site preparation. Seed forestation was largely limited, bared-rooted seedling forestation may be popularised when soil salt content was less than 1% and soil moisture content was better in spring. Forestation with container seedling was suited to coastal saline soil in rainy season. The optimum planting density of Nitraria sibirica was 2 505/ha in the Yellow River Delta area in view of coverage rate, yield of fruits and cost of planting. Generally speaking,Nitraria sibirica could effectively refrain soil from accumulation of salt in the surface soil, decrease salt content and increase soil nutrient, and heighten soil capillary pore rate.

Saline-alkali land reclamation boosts topsoil carbon storage by preferentially accumulating plant-derived carbon

Saline–alkali land is an important cultivated land reserve resource for tackling global climate change and ensuring food security, partly because it can store large amounts of carbon(C). However, it is unclear how saline–alkali land reclamation(converting saline–alkali land into cultivated land) affects soil C storage.We collected 189 adjacent pairs of salt-affected and cultivated soil samples(0–30 cm deep) from the Songnen Plain, eastern coastal area, Hetao Plain, and northwestern arid area in China. Various soil properties, the soil inorganic C(SIC), organic C(SOC), particulate organic C(POC), and mineral-associated organic C(MAOC) densities, and plant-and microbial-derived C accumulation were determined.Saline–alkali land reclamation inconsistently affected the SIC density but significantly(P < 0.001)increased the SOC density. The SOC, POC, and MAOC densities were predicted well by the integrative soil amelioration index. Saline–alkali land reclamation significantly increased plant-derived C accumulation and the plant-derived C to microbial-derived C ratios in all saline–alkali areas, and less microbial transformation of plant-derived C(i.e., less lignin degradation or oxidation) occurred in cultivated soils than salt-affected soils. The results indicated that saline–alkali land reclamation leads to plant-derived C becoming the dominant contributor of SOC storage. POC storage and MAOC storage were strongly linked to plant-and microbial-derived C accumulation, respectively, caused by saline–alkali land reclamation.Our findings suggest that saline–alkali land reclamation increases C storage in topsoil by preferentially promoting plant-derived C accumulation.

中风化泥质粉砂岩水泥改良路基回填料适宜性试验研究

中风化泥质粉砂岩遇水易软化、崩解,造成工程性质不稳定。为合理利用开挖产生的大量中风化泥质粉砂岩进而克服碎石回填路基料来源困难、成本高的不足,本文依托华东某重大工程项目,对开挖区典型中风化泥质粉砂岩的物理力学特性和矿物成分进行了分析,然后采用P.O.32.5硅酸盐水泥对中风化泥质粉砂岩进行改良及配合比方案设计,开展了不同水泥掺量及含水量下中风化泥质粉砂岩水泥改良回填料(简称改良回填料)的无侧限抗压强度和击实试验研究,随后利用高分辨率扫描电镜分析了泥质粉砂岩水泥改良回填料微细观结构。研究结果表明:(1)水泥掺量4%~20%范围内改良回填料的应力-应变曲线呈现出软化特征,改良回填料无侧限抗压强度随硅酸盐水泥掺量的增加而增大,且较原状土有大幅提高;(2)含水量10%~20%范围内改良回填料干密度随含水量的增加呈现出先增加后降低的特征,改良回填料最优含水量随水泥掺量增加而呈现降低的变化规律;(3)改良回填料的微细观结构表明水化反应在土颗粒间形成了胶结骨架,且整体结构会随着龄期增长逐渐增强。