Relationship Between Diurnal Changes of Net Photosynthetic Rate and Influencing Factors in Rice under Saline Sodic Stress

The net photosynthetic rate of flag leaves and influencing factors under saline sodic soil conditions were investigated at the full heading stage of rice. The net photosynthetic rate of rice leaves showed a double-peak curve in a day in both non-saline sodic and saline sodic soil treatments. The first peak of the net photosynthetic rate appeared at 9：00-10：00 and 9：00 in the saline sodic and non-saline sodic soil treatments, respectively, whereas the second peak both at 14：00. The midday depression of the net photosynthetic rate always appeared regardless of non-saline sodic or saline sodic soil conditions. In addition, the net photosynthetic rate significantly decreased in all day under saline sodic conditions compared with that under non-saline sodic conditions. Some differences were observed in correlation characters between the net photosynthetic rate and all influencing factors during 9：00-13：00. Under non-saline sodic conditions, the diurnal changes of the net photosynthetic rate in a day were mainly caused by stomatal conductance, and the limitation value and the stomatal factors served as determinants; whereas under saline sodic stress, the diurnal changes of the net photosynthetic rate in a day were mainly caused by non stomatal factors including light intensity and air temperature.

Effect of Hydrochloric Acid on the Structural of Sodic-Bentonite Clay

The objective of this work is to determine changes of surface properties of a bentonite after acid activation, using hydrochloric acid solutions (HCl) at room temperature. XRD, FX, FTIR, MEB, and BET analyses of the samples have been carried out to examine the structure of bentonite before and after acid activation. It is found that the raw bentonite is composed of dioctahedral montmorillonite with predominant quantity and certain amounts of quartz, albite and illite, etc. It has an cation exchange capacity (CEC) of 74.32 meq/g which allows it to be characterized as typical sodium bentonite. The changes, at low acid concentrations, are the result from from cation exchange (exchangeable cations with H+ ions). Differences of surface area at high acid concentrations (0.25 - 0.4 M) were caused by structural changes and partial decomposition of the samples. Data of surface area measurements have showed that with increase of concentration of hydrochloric acid, the surface area increased. The maximum value (837.11 m2/g) was reached by the sample activated with 0.4 M HCl. By against, activation with higher concentration (0.6 M) caused a decrease in the surface area.

Genesis of the Cenozoic Sodic Alkaline Basalt in the Xiahe–Tongren Area of the Northeastern Tibetan Plateau and its Continental Dynamic Implications

Objective The Cenozoic Indo-Asian collision caused significant crustal shortening and plateau uplift in the central Tibet. The extrusion tectonic model has been widely accepted to explain the strike-slip faults around the Tibetan Plateau. Previous studies indicate that the lower crust flow is the main drive force of the extrusion tectonics. Whether mantle extrusion process occurred during the Cenozoic uplift is a major problem to be addressed, which is significant for understanding the uplift mechanism and tectonic evolution of the Tibetan Plateau.

Genesis and Behavior of Sodic Soils in Humid Climates

Sodic soils are typically located in semi-arid to arid climates. However, sodic soils in continental humid climates are rare. As with sodic soils in dry climates, sodic soils in wetlands pose management difficulties for agriculture, forestry, or wild-life habitat. The typical practice of gypsum application is problematic given inability to provide drainage. Natraqualfs located in southeastern Missouri present an acid argillic horizon superimposed on a natric horizon, where the exchangeable sodium percentage and an alkaline reaction are characteristic attributes. Ferrolysis is an active soil process that is slowly degrading the natric horizon because of exchangeable Al3+ and H+ generation and re-stabilization of the soil structure, permitting leaching of the sodium.

Review of Sodic Soil Reclamation with a Snapshot of Current Research Activity

For centuries, reclamation of sodic soils has been an essential part of cropping practices in several parts of the world. Parallel to increasing population, the need for new cropland constantly re-evaluates land suitability concepts. Therefore, the importance of sodic soils as potential croplands is increasing worldwide. Although theoretically farmers can choose from a wide variety of reclamation options, according to profitability, business plans, and human and financial resources, in practice, few reclamation methods are applied at large scale. This article touches on the early history, 20th Century intensive research, and current trends of sodic soil reclamation. New approaches such as leaching, chemical amendments, addition of organic material, and biological and microbial improvements are discussed, and also brand-new approaches are reviewed. The early history is reviewed using historical books, the achievements of the last hundred years using basic technical literature, mostly books, and the current approaches of our time with fresh publications, mostly papers and two very recent conferences published in English.

Biomass and bio-energy production of ten multipurpose tree species planted in sodic soils of indo-gangetic plains

Ten multipurpose tree species, Terminalia arjuna, Azadirechta indica, Prosopis juliflora, Pongamia pinnata, Casuarina equisetifolia, Prosopis alba, Acacia nilotica, Eucalyptus tereticornis, Pithecellobium dulce and Cassia siamea, were raised in a monoculture tree cropping system on the sodic soil of Gangetic alluvium in north India （26° 47° N： 80°46′ E） for 10 years to evaluate the biomass and bio-energy production. The soil was compact, sodic and impervious to water associated with nutrient deficiency or toxicity. Maximum plant height was recorded with E. tereticornis followed by C.equisetifolia and P. juliflora. A. nilotica performed better than the other species in terms of diameter at breast height （DBH） with a basal area of 13.04 m^2·ha^-1, followed by P. juliflora and C. equisetifolia. P. juliflora and A. nilotica produced nearly similar biomass of 56.50 and 50.75 Mg·ha^-1, respectively, at 10 years; whereas, A. indica, P. pinnata, C. siamea and P. alba did not perform well. P. juliflora scored maximum in net biomass production and nutrient demand. Nutrient （N, P, K, Ca, and Mg） concentrations were higher in leaf component of P. juliflora. However, in woody components, there was little variation between the species. N removal for production of one ton of wood was lowest in Acacia nilotica, P in T. arjuna, K in P. dulce and Ca and Mg in P. juliflora. P. juliflora gave the highest energy production of 1267.75 GJ.ha^-1 followed by A. nilotica with 1206 GJ.ha^-1 and the lowest ofA. indica （520.66 GJ.ha^-1）.

Response of Salt-Tolerant Rice Varieties to Biocompost Application in Sodic Soil of Eastern Uttar Pradesh

Sodic soils have immense productivity potential, if managed through proper technology interventions. Biocompost is prepared by composting pressmud (a sugar industry byproduct) received from cane juice filtration and spent wash received from distilleries through microbial aerobic decomposition and can be used to reclaim sodic soils. Field experiments were conducted during the wet season of 2011 and 2012 to study the effect of incorporation of biocompost in sodic soil with four treatments: T1—Control, T2—Biocompost at 2 t ha-1, T3—Biocompost at 4 t ha-1 and T4—Biocompost at 6 t ha-1. The two promising salt tolerant rice varieties preferred by farmers, Narendra usar 3 and NDR 359 were used as test crops, which can produce yields ranging between 2-4 t ha-1 in soil having a pH range of 9.2 to 10.5. Among the different doses of biocompost tested, application of biocompost at 6 t ha-1 registered highest yields, enabled by a higher biomass, ear bearing tiller (EBT), and grain fertility in both varieties. Narendra usar 3 was more responsive to treatments even at lower doses of biocompost than NDR 359, but NDR 359 yielded slightly higher than Narendra usar 3 in all treatments. Soil health was also improved evidently on better fertility and low soil pH and EC at harvest. Thus, biocompost can be considered as a commercially viable, environmentally acceptable and practically enforceable option for improving the crop productivity and soil fertility status.

GROUND WATER QUALITY IN THE INDUS PLAINS OF PAKISTAN AND ITS USE FOR CROP PRODUCTION DURING RECLAMATION OF SALINE-SODIC SOILS

The Indus Plains of Pakistan lies between 23°to 37°latitude and 61°to 76°longi-tude in the northern hemisphere. The total Canal Commanded Area (CCA) is about 13.50million hectares of which 11.21 million hectares are cultivated. At present, 103 millionacre-feet river flow is diverted into irrigation canals. In addition, 42 million acre feet of thegroundwater are being pumped through 257697 tubewells to supplement the canal supplies.

A Practical Model for Desodification of Saline-Sodic Soils of Central Khuzestan Plains, Khuzestan Province

The most important task in leaching practices is assessment of water quantity required for leaching of saline and saline-sodic soils. Therefore, reliable estimation of the required leaching water quantity is vital for reducing soil salinity to a desirable level. The present study aimed to investigate desodification of saline and sodic soils in central area of Khuzestan Province. Consequently, a large area of 3216 ha with S4A3 salinity/sodicity class in Khuzestan, Iran, was selected to obtain the required data. This experiment was conducted with two treatments and tree replicates. In the first treatment, the experiment was conducted by applying just 100 cm water depth in four 25 cm intervals. In the second treatment, 5000 kg/ha Sulfuric Acid was applied prior to salt leaching together with leaching water. The intermittent ponding method was conducted with double rings in a rectangular array. The required physical and chemical analyses were performed on the collected data. The leaching water was supplied from Shotait River. Four mathematical models were applied to the collected experimental data to derive a suitable empirical model. The results for large scale applications indicated that the proposed logarithmic model can estimate the capital leaching requirement much than the previously proposed models.

Carbon stock estimation in halophytic wooded savannas of Uruguay:An ecosystem approach

Savannas constitute a mixture of trees and shrub patches with a more continuous herbaceous understory.The contribution of this biome to the soil organic carbon(SOC)and above-ground biomass(AGB)carbon(C)stock globally is significant.However,they are frequently subjected to land use changes,promoting increases in CO_(2) emissions.In Uruguay,subtropical wooded savannas cover around 100,000 ha,of which approximately 28%is circumscribed to sodic soils(i.e.,subtropical halophytic wooded savannas).Nevertheless,there is little background about the contribution of each ecosystem component to the C stock as well as site-specific allometric equations.The study was conducted in 5 ha of subtropical halophytic wooded savannas of the national protected area Esteros y Algarrobales del Rio Uruguay.This work aimed to estimate the contribution of the main ecosystem components(e.g.,soil,trees,shrubs,and herbaceous plants)to the C stock.Site-specific allometric equations for the most frequent tree species and shrub genus were fitted based on basal diameter(BD)and total height(H).The fitted equations accounted for between 77%and 98%of the aerial biomass variance of Netuma affinis and Vachellia caven.For shrubs(Baccharis sp.),the adjusted equation accounted for 86%of total aerial biomass.C stock for the entire system was 116.71±11.07 Mg·ha^(-1),of which 90.7%was allocated in the soil,8.3%in the trees,0.8%in the herbaceous plants,and 0.2%in the shrubs.These results highlight the importance of subtropical halophytic wooded savannas as C sinks and their relevance in the mitigation of global warming under a climate change scenario.

苏打盐碱地稻米品质研究进展与展望

水稻是苏打盐碱地改良的先锋作物,稻米品质是水稻特征的重要指标。当前研究多关注盐碱地治理及水稻产量,有关盐碱胁迫下稻米品质的研究相对较少。本文从稻米的加工、外观、营养及感官食味品质4个方面系统梳理了苏打盐碱地条件下稻米品质特征,并总结苏打盐碱地水稻品种以及典型改良及栽培措施对稻米品质的影响。研究发现,苏打盐碱地条件下,稻米品质整体表现为较低的整精米率、精米率、糙米率及直链淀粉含量,较高的垩白粒率、垩白度及高蛋白质含量的特点,具有糙米蛋白含量高(更高的营养价值)、半透明颗粒少、淀粉低、钠等金属离子含量高等优点。研究提出未来需要进一步探讨苏打盐碱地条件下水稻品质形成、优异种质资源挖掘、产量与品质的协同提升,以期为苏打盐碱地水稻食味品质提升与特色品质的挖掘提供理论与实践参考。

长期不同施肥措施对盐碱地稻田土壤微生物数量和群落结构的影响

为阐明盐碱地稻田长期不同施肥对表层土壤微生物数量和群落结构的影响,以大安站盐碱地水稻长期定位施肥试验土壤为对象,采用磷脂脂肪酸(PLFA)分析法研究了单施氮肥(N)、无机肥配施(NPK)、有机肥单施(M)、有机肥与无机肥配施(MNPK)和秸秆还田配施无机肥(RNPK)对土壤微生物数量和群落结构的影响。结果表明:不同施肥处理土壤中共检测出57种PLFA生物标记,M、MNPK、RNPK和NPK处理的PLFA含量较N处理分别增加26.47%、29.76%、25.07%和13.20%,其中M、MNPK和RNPK处理显著高于N处理(P<0.05)。MNPK处理土壤中的真菌/细菌的比值最大,较二者之比最小的M处理高6.00%,说明有机肥配施化肥对盐碱地稻田土壤生态系统的稳定性具有更好的改善作用。RNPK处理土壤中革兰氏阳性菌与革兰氏阴性菌之比最小,较二者之比最大的M处理降低了13.71%,说明秸秆还田配施化肥处理的土壤营养胁迫小,能有效改善土壤的营养状况。不同施肥处理微生物群落多样性大小表现为N处理土壤的Shannon-Wiener多样性指数(H)、Pielou均匀度指数(J)和Simpson优势度指数(D)最大,分别较3项指数最小的NPK处理增加10.91%、12.00%和13.79%。冗余分析结果表明,盐分电导率(EC)、有机质和pH对土壤微生物群落变化具有显著影响,解释量分别为54.8%、39.8%和33.1%。因此,长期有机肥与化肥配施、有机肥单施和秸秆还田配施无机肥能有效增加土壤微生物生物量并优化微生物群落结构,进而改善土壤生态环境。

不同种稻年限苏打盐碱土剖面性状及有机碳分布特征

以不同种稻年限苏打盐碱土为研究对象,开展种稻年限对苏打盐碱土剖面形态及有机碳分布和稳定性的影响研究。通过田间试验,以未开垦盐碱地、分别种植水稻1年、5年、10年、15年、20年、40年的苏打盐碱土为研究对象,对其剖面性状、pH值、微团聚体含量及微团聚体中有机碳分布特征、易氧化有机碳含量等指标进行测定并分析。结果表明:与未开垦盐碱地相比,种稻后苏打盐碱土耕作层的颜色暗度随年限增加而加深,各剖面土壤大多呈粒状和棱柱状,土壤的结持性均变疏松。未开垦盐碱地与种稻后苏打盐碱土的碳酸盐含量均较高,各剖面中石灰反应程度不同。种稻后,苏打盐碱土各土层的pH值均有不同程度的降低。在土壤微团聚体中,0.05—0.25 mm的大微团聚体含量最高,种稻使该粒级团聚体分解成<0.05mm的小微团聚体。种稻1—5年,小微团聚体有机碳含量有所增加;种稻10—40年,有机碳富集在大微团聚体中。种稻后,土壤各层次易氧化有机碳含量逐年增加,氧化稳定系数值均低于未开垦盐碱地的。耕作层、亚表层及渗育层中氧化稳定系数分别在种稻40年、种稻15年、及种稻10年达到最小值。总之,长期种稻不仅改良了苏打盐碱土结构,降低其pH值及有机碳的稳定性,还使土壤小微团聚体含量及大微团聚体有机碳含量增加。

苏打盐碱土壤黏粒分散特征研究进展

本文系统总结了黏粒分散特征表征方法,归纳可用于表征黏粒分散程度的主要指标;概述了黏粒分散对土壤物理性质的影响;重点阐述影响黏粒分散的因素,包括:土壤酸碱性、离子浓度、土壤有机质、农业管理措施、外源物质施用等;提出了黏粒分散控制方法。根据Na^(+)、K^(+)、Ca^(2+)和Mg^(2+)不同分散和絮凝能力得出,离子性指数、电荷稀疏性、净分散量、土壤结构稳定性的阳离子比和阳离子交换量等是表征黏粒分散特征的常用指标;电动电位势和浊度与黏粒分散存在密切联系,有待进一步应用于苏打盐碱土壤黏粒分散研究。黏粒分散破坏土壤结构,导致土壤水力传导率下降,严重阻碍土壤正常功能。黏粒分散机理:不同阳离子价态不同和不同土壤溶液浓度不同导致黏粒表面正电荷层厚度不同,引起黏粒之间范德华吸引力和静电排斥力作用效果差异,正电荷层较厚导致黏粒分散。通过明晰黏粒分散机理,有助于掌握影响黏粒分散的主要因素,抑制苏打盐碱土壤黏粒分散,改善土壤结构,以期为苏打盐碱土治理提供理论参考和技术指导。

2017-2021年吉林大安农田生态系统国家野外科学观测研究站气象数据集

气象数据可以提供准确的天气预警,同时对农业生产有着重要意义。吉林大安农田生态系统国家野外科学观测研究站地处松嫩平原西部,属中温带大陆性季风气候,全年光照充足,雨热同期,有利于农作物生长。但该区大面积分布的盐碱土严重影响了农业发展和生态安全。本数据集利用大安站气象观测场的原始数据,经过数据处理和质量控制,以时尺度、日尺度和月尺度将2017-2021年的气象观测数据汇编成集,内容包括气温、气压、相对湿度、风速、降雨、土壤温度(0-20 cm)、总辐射、反射辐射、光合有效辐射、土壤热通量和日照时数,旨在为研究东北苏打盐碱土,发展盐碱地特色生态农业,保障粮食安全和生态安全提供基础数据,为我国盐碱荒漠化治理与盐碱地综合利用等提供数据支撑。

膨润土同步提纯钠化研究及在球团中应用

基于某企业生产的低品质钙基膨润土,采用多重钠化工艺进行提质改性,系统研究了多重钠化剂种类及用量对膨润土性能指标和收得指标的影响。结果表明,在钠化剂Na2CO3用量为2.0%时,钠化土的收得率为83.55%,其膨胀指数、吸水率和吸蓝量分别由原土的5.0 mL/g、119%/(2 h)和26.9 g/(100 g)提升到22 mL/g、377.1%/(2 h)和39.6 g/(100 g),达到一级钠化土指标。采用多重钠化改性工艺可以显著提升膨润土指标,钠化剂配比为2.0%Na6P6O18和2.0%Na2CO3时,双重钠化土的膨胀指数为77 mL/g,吸水率为631.8%/(2 h),吸蓝量为39.1 g/(100 g),收得率为61.29%。造球实验中添加量为1.8%时,生球落下强度由原土的3.0次/(0.5 m)分别提高至一次钠化土的4.6次/(0.5 m)和双重钠化土的8.6次/(0.5 m)。

Saline-Sodic Soils:Potential Sources of Nitrous Oxide and Carbon Dioxide Emissions?

Increasing salt-affected agricultural land due to low precipitation, high surface evaporation, irrigation with saline water, and poor cultural practices has triggered the interest to understand the influence of salt on nitrous oxide （N20） and carbon dioxide （CO2） emissions from soil. Three soils with varying electrical conductivity of saturated paste extract （ECe） （0.44-7.20 dS m-1） and sodium adsorption ratio of saturated paste extract （SARe） （1.1-27.7）, two saline-sodic soils （S2 and S3） and a non-saline, non-sodic soil （S1）, were incubated at moisture levels of 40%, 60%, and 80% water-filled pore space （WFPS） for 30 d, with or without nitrogen （N） fertilizer addition （urea at 525μg g-1 soil）. Evolving CO2 and N20 were estimated by analyzing the collected gas samples during the incubation period. Across all moisture and N levels, the cumulative N20 emissions increased significantly by 39.8% and 42.4% in S2 and S3, respectively, compared to S1. The cumulative CO2 emission from the three soils did not differ significantly as a result of the complex interactions of salinity and sodicity. Moisture had no significant effect oi1 N20 emissions, but cumulative CO2 emissions increased significantly with an increase in moisture. Addition of N significantly increased cumulative N20 and CO2 emissions. These showed that saline-sodic soils can be a significant contributor of N20 to the environment compared to non-saline, non-sodic soils. The application of N fertilizer, irrigation, and precipitation may potentially increase greenhouse gas （N20 and CO2） releases from saline-sodic soils.

施加脱硫石膏对盐碱土改良和固碳的影响

【目的】探究脱硫石膏施用对盐碱土改良效果和固碳作用。【方法】以新疆塔里木河流域下游荒漠盐碱土为研究对象,分析脱硫石膏不同施用量(0、10、20、30、40、50 t/hm^(2))对土层厚度为0~40 cm的土壤理化性质及土壤固碳的影响。【结果】与对照组相比,施用脱硫石膏显著降低0~20 cm土层土壤pH,增加土壤盐分含量;施用脱硫石膏量为40 t/hm^(2)的土壤有机碳储量达到最高,比对照组增加0.029 kg/m^(2);与对照组相比,脱硫石膏施用量分别为10、40 t/hm^(2)时,处理土壤的无机碳储量分别增加0.21、0.18 kg/m^(2);从改良时间来看,施用脱硫石膏改良土壤固碳效应的持续时间为0~7 d,其中施用量为40 t/hm^(2)时的效果最好;土壤碳储量受土壤pH、土壤盐分、降水量和蒸散发的影响较大。【结论】从盐碱土的改良效果及固碳作用来看,脱硫石膏施用量为40 t/hm^(2)时能显著降低土壤pH,且过程中具有显著的固碳作用。

Remediation of saline–sodic soil with flue gas desulfurization gypsum in a reclaimed tidal flat of southeast China

Salinization and sodicity are obstacles for vegetation reconstruction of coastal tidal flat soils. A study was conducted with flue gas desulfurization（FGD）-gypsum applied at rates of 0, 15, 30, 45 and 60 Mg/ha to remediate tidal flat soils of the Yangtze River estuary.Exchangeable sodium percentage（ESP）, exchangeable sodium（ExNa）, p H, soluble salt concentration, and composition of soluble salts were measured in 10 cm increments from the surface to 30 cm depth after 6 and 18 months. The results indicated that the effect of FGD-gypsum is greatest in the 0–10 cm mixing soil layer and 60 Mg/ha was the optimal rate that can reduce the ESP to below 6% and decrease soil p H to neutral（7.0）. The improvement effect was reached after 6 months, and remained after 18 months. The composition of soluble salts was transformed from sodic salt ions mainly containing Na~＋, HCO_3^-＋ CO_3^（2-）and Cl-to neutral salt ions mainly containing Ca^（2＋）and SO_4^（2-）. Non-halophyte plants were survived at 90%. The study demonstrates that the use of FGD-gypsum for remediating tidal flat soils is promising.

苏打盐碱化稻田土壤反硝化和氨挥发特征及主要影响因子

为阐明土壤盐碱化程度对氮素气态损失的影响,本研究通过随机采集30个不同盐碱化程度的稻田土壤(0~20 cm)样品,根据盐碱化程度将其划分为轻度(含盐量0.1%~0.3%,碱化度5%~15%)、中度(含盐量0.3%~0.5%,碱化度15%~30%)和重度(含盐量0.5%~0.7%,碱化度30%~45%)盐碱土3类,每个类别中依据最小归类样品数选取盐碱化程度接近的3个土样作为3次重复,进行实验室模拟培养分析,探究不同盐碱化土壤氮素反硝化和氨挥发动态变化特征及其主要影响因素。结果表明,随着土壤盐碱化程度的增加,氮素的反硝化作用显著降低,氨挥发作用显著增加,硝酸还原酶、亚硝酸还原酶和脲酶活性显著降低(P<0.05)。与轻度盐碱土相比,中度和重度盐碱土相同培养时间的氮素反硝化速率分别降低了18.9%和37.8%,累积反硝化氮量分别降低了13.7%和29.4%,氨挥发速率分别增加了30.8%和64.8%,累积氨挥发量分别增加了36.6%和59.4%。逐步回归分析表明,EC、ESP(碱化度)、CO_(3)^(2-)和TN是影响苏打盐碱地稻田土壤累积反硝化氮量的主要因素,EC、CO_(3)^(2-)和SOM(土壤有机质)是影响累积氨挥发量的主要因素。土壤盐碱化虽然抑制了氮素的反硝化作用,但是显著增强了氨挥发作用。