Irrigation of steppe soils in the south of Russia: Problems and solutions (Analysis of Irrigation Practices in 1950–1990)

Experience in irrigation of chernozems in the steppe zone of Russia for a period from 1950 to 1990 is analyzed. By the end of this period and in the subsequent years, the areas under irrigation reduced considerably, and the soil productivity worsened. This was caused by the improper design of irrigation systems, on the one hand, and by the low tolerance of chernozems toward increased moistening upon irrigation, on the other hand. The analysis of the factors and regimes of soil formation under irrigation conditions shows that irrigation-induced changes in the soil hydrology also lead to changes in the soil physicochemical, biochemical, and other properties. In particular, changes in the composition of exchangeable cations lead to the development of solonetzic process. In many areas, irrigation of chernozems was accompanied by the appearance of solonetzic, vertic, saline, and eroded soils. The development of soil degradation processes is described. In general, the deterioration of irrigated chernozems was related to the absence of adequate experience in irrigation of steppe soils, unskilled personnel, improper regime of irrigation, and excessively high rates of watering. In some cases, the poor quality of irrigation water resulted in the development of soil salinization and alkalization. To improve the situation, the training of personnel is necessary; the strategy of continuous irrigation should be replaced by the strategy of supplementary irrigation in the critical periods of crop development.     

Causal processes of soil salinization in Tunisia,Spain and Hungary

Soil salinization arises due to the build up of soluble salts at or near the soil surface. Salts accumulate by primary and secondary processes that alter the soils physicochemical properties and lead to direct and indirect soil degradation. Results are presented here from the study of three contrasting salt‐affected landscapes. The Chott el Fedjadj, Tunisia, is a naturally salt‐affected basin containing saline sediments deposited during a marine incursion. The endoreic conditions lead to salt recirculation, concentration and reprecipitation. In the Guadalentin Valley, Spain, increased irrigated agriculture has led to aquifer overexploitation releasing gas and salts. Irrigating with the resultant contaminated groundwater has induced soil salinization. The salt accumulation and translocation is dictated predominantly by irrigation method, water quality and quantity. Hungary has the largest expanse of naturally salt‐affected soil in Europe, with the dominant soil type being solonetz. In Hungary the type of salt‐affected soil development is related to the salts present, hydraulic properties of the soil and depth and quality of the watertable. In Tunisia a catenary relationship of increased water and soil salinity towards the centre of the chott is found, whereas in Spain the highest salinities were found under flood irrigation with the valley displaying a complex spatial distribution of soil salinity. The sediment distribution in Hungary dictates that solonchak soils are found mostly in the Danube–Tisza interfluve and solonetz soils in the Tisza floodplain, with localized variations in soil type related to watertable characteristics. Copyright © 2001 John Wiley & Sons, Ltd.     

Effects on soil and paddy–wheat crops irrigated with waters containing residual alkalinity

Degradation of soils by irrigation with ground waters containing residual alkalinity poses a major threat to agriculture in semi‐arid regions, particularly in South Asia. However, there is a lack of indices to define the soil degradation and crop performance under a monsoon climate. Therefore, an experiment was conducted during 2000–2004 to determine the responses of paddy rice and wheat crops in rotation to irrigation with alkaline waters (AW) having similar salinity (electrolyte concentration 30 me L^?1) but varying ionic constituents (sodium adsorption ratio irrigation water, SARiw 10 and 25; adjusted sodium adsorption ratio, adj.R_Na 13.6 and 29.2; residual sodium carbonate, RSC 5 and 10 me L^?1 and Cl:SO₄ 4:1 and 1:4, respectively). The concentration factors, ECe/ECiw (ratio of electrical conductivity of soil's saturation paste extract to that of the irrigation water) were between 1.1 and 1.8 for soils deprived of rainfall, whereas it was almost 1 for soils not sheltered from rain. Similarly, saturation paste extract, SARe, was between 1.6 and 2.0 times SARiw and 2.0–2.3 times SARiw with and without rainfall, and the exchangeable sodium per cent (ESP) 1.0–1.8 times SARiw. Yields of paddy relative to yields of crops irrigated with good‐quality water, averaged 56–74% during the period 2000–2004 compared with 81–88% for wheat, indicating the greater sensitivity of rice to irrigation with AW. Elevated levels of sulphate rather than chloride in the irrigation water lessened the impacts of the residual alkalinity. Production functions showed that the sodicity (ESP) did not solely explain the variation in crop yields because the salinity stress simultaneously inhibited growth. None of the sodicity indices (RSC, SAR and adj.R_Na) adequately defined the relative impacts of AW, although residual alkalinity (RSC) was a better indicator than either of the other two. The monsoon rains played an important role in alleviating the effects of residual alkalinity. Data presented here should support the development of more reliable criteria for the assessment of sodicity/salinity hazards from AW in semi‐arid regions.     

Soil alkalinization and salinization in the djajerud Basin,Iran

The Djajerud Basin is located on the southern slopes of the Elburz Mountains, to the east of Tehran. Near its source, as the River is fed mainly by the melting of the winter snow and flows over tuffs and schists, its carbonate-enriched water can induce soil alkalinization. The Djajerud River runs from its source across a gypsum and marl piedmont. Gypsum is dissolved and modifies the chemical quality of the waters, which lose their alkaline character and get more salty. These sulphate-rich flows are less damaging because soil degradation hazards in the region are related more to salinization than to alkalinization. The Djajerud River waters next seep deep into a permeable deposition fan and feed water-tables which merge into the groundwaters of the Varamin Plain (which are also fed by chloride-rich waters from other sources). The chemical character of the Djajerud-River changes in this section, developing a marked sodium chloride salinity. The soils in this part of the Basin, due to the high groundwater salinity, have poor drainage which prevents any agriculture. The River eventually flows into the highly saline endorrheic Daryachehnamak Lake. The concept of residual alkalinity is used to examine the chemical composition of the Djajerud River along its course and affords the determination of the soil degradation hazard in the various parts of the Basin.     

松嫩平原土壤水盐动态规律研究

对设于松嫩平原嫩江右岸引嫩江水工程区域内的土壤水盐动态观测点多年研究结果表明，基　　　　本无盐渍化的总干段土壤较通水前土壤盐分与ｐＨ值以及地下水ｐＨ值和盐分有减有增，但减多增少，说　　　　明优质、低盐分嫩江水引入后土壤向改善方向发展，而土壤盐渍化重又无排水工程的莎分干段则相反，盐　　　　渍加重重．北部引嫩江水工程是成功的，关键是必需有排水系统和排水出路．     

Assessment of soil degradation in the eastern part of the Nile Delta

This study was performed to quantitatively assess the levels and rates of soil degradation and determine qualitative changes in the soils of the eastern part of the Nile Delta through comparing the literature data obtained in 1997 with the results obtained during a 2010 soil survey on the melioration situation. The results have shown that the key factors in these negative phenomena are salinization of soils and ground waters and alkalinization, water logging, and soil compaction; the key causative factors include inappropriate irrigation, deficiency or poor operation of the drainage system, untimely use of heavy machinery, and the absence of nature-protecting measures.     

灌溉灰钙土水盐动态之初步研究

宁夏南部气候干旱,淡水十分缺乏,但苦水资源尚丰,为了提高农业生产,势必发展苦水灌溉。该区为底层盐化灰钙土,苦水灌后大量盐分积累在上层土壤中,导致表土很快发生次生盐渍化,影响农业生产的进一步发展。土壤盐分随水分而运动,两者在行迹上是密切一致的。土壤的积盐和脱盐,就是土壤水分随着灌水及气候季节变化而运动的结果。     

Salt accumulation and its control on the plains of Central Asia

The water-salt budget on the plains of Central Asia in natural conditions and under significant anthropogenic impact (irrigation and construction of hydraulic engineering systems) is analyzed. It is shown that up to 87.2 million tons of salts are annually transported to the plains of Central Asia from the surrounding mountains. Under natural conditions, the larger part of the salts was discharged into the Aral Sea, Balkhash and Issyk-Kul lakes, and into deep closed depressions (Tuzkan, Sarykamysh, and others). Thus, these salts were generally excluded from the geochemical turnover. Only 40% of the salts entered the deposits and groundwater of the plains. Irrigation has transformed the water-salt budget in the area. The input of salts into the groundwater and soils increased by 30% and induced the development of soil salinization in the region. Measures for salinization control are suggested. It is necessary to stop the discharge of drainage water into the rivers and the use of saline water for irrigation purposes. The existing irrigation systems should be reconstructed, and the irrigated areas should be reduced.     

内蒙古河套灌区碱化土壤的发生原因和特性

本文简述了内蒙古河套灌区自然概况，盐渍化演变过程和碱化土壤的改良现状。着重揭示灌区内碱化土壤的发生原因、类型、性质和特点。该地区碱化土壤发生原因：１．灌区内最严重的碱化土壤大部分因地下水含大量残余碳酸钠，在干旱气候条件下经强烈蒸发而成。主要特点是通体碱化度高，改良难度大。２．地下水和地表水中的钠离子，受各种因素影响在土体中富集并进入土壤吸收性复合体而使土壤碱化。这部分碱化土壤一般表层碱化度较高，而     

中国盐渍土研究：历程、现状与展望

盐渍土研究是以盐渍土和盐渍生境作为主要研究对象，以盐渍土和盐渍化的发生与演变过程、环境要素和人类活动对盐渍化的影响与作用机制、盐渍土的治理、改良和利用的理论与技术为主体的研究领域。我国盐渍土面积巨大、种类繁多，盐渍化问题突出，对农业生产和生态环境造成不同程度的影响。我国科学家提出的盐渍土“水盐调控”“水盐平衡”，“淡化肥沃层”和“障碍消减”等理论与技术方法，为发展农业生产、提高土地产能、保障粮食安全、拓展耕地资源等发挥了积极作用。近期我国在土壤盐渍化演变过程的监测与多源数据融合、土壤水盐运移过程模拟与尺度转换、盐渍农田养分循环与减损增效、盐渍障碍的生态消减、盐渍障碍微生物修复、盐渍农田灌排优化管理与边际水安全利用等方面取得了积极的进展和成果。建议今后深入开展盐渍土精准控盐的高效和安全用水、土壤盐渍障碍的绿色消减与健康保育、盐渍农田养分库容扩增与增碳减排、土壤盐渍化与区域生态的耦合响应和协同适应等方面的理论与技术研究。应面向农业、资源、生态、环境等领域和行业，致力于拓展理论和新技术的研究，为国家农业升级、粮食安全、耕地保护、生态安全、高质量发展发挥重要作用。本文回顾了我国盐渍土研究工作的...     

焉耆盆地水资源开发与土壤次生盐碱化防控研究

焉耆盆地水土资源丰富,光热条件充分,是新疆农牧业生产的主要基地之一。但由于长期以来水土资源开发不当,导致本区土壤次生盐碱化日趋严重,严重影响了当地农业的持续发展,且其农业排水直接导致博斯腾湖的水质劣化。本文在分析区域土壤盐分分布的空间特征和土壤次生盐碱化产生的背景条件的基础上,提出了区域水土资源可持续开发的对策,并着重分析在该盆地细土平原带通过竖井灌排开发地下水以降低地下水位的必要性与可行性,从而推动该区农业的稳定发展和环境质量的逐步好转。     

Ameliorative status of irrigated soils in Rostov oblast

The development of irrigation and the ameliorative status of irrigated lands in Rostov oblast are analyzed for a fifty-year-long period (1952–2001). Three stages of irrigation development are specified. The first stage (1952–1982) was characterized by poor operating conditions of irrigated lands. The second stage (1982–1990) was a period of the most intense irrigation and improvement of the ameliorative status of irrigated lands. The third period (1990–2001) was marked by a drop in the area of irrigated lands and exclusion of lands with unsatisfactory ameliorative status from irrigation. The natural and operating conditions of 18 irrigation systems allocated to areas with different lithological and geomorphic features and soils (chernozems, dark chestnut, meadow, alluvial, and other soils) are characterized. It is shown that soil irrigation often leads to the development of negative soil processes, such as salinization, alkalization, and waterlogging. They are related to the natural and operating conditions of irrigated systems. Secondary salinization and waterlogging are most active in irrigation systems used for rice growing independently of the natural conditions. Upon initially weak salinization of soils and rocks, secondary salinization and alkalization are slightly developed. In the secondary saline and solonetzic soils excluded from irrigation, residual solonetzic features are preserved for more than 15–20 years.     

新疆浅层暗管排水降低土壤盐分提高棉花产量

土壤盐渍化问题严重制约着干旱区农业可持续发展,为达到土壤脱盐的效果,增加作物产量,该文针对膜下滴灌棉田,采用完全随机试验方案,在装有暗管的中度和轻度盐渍化土壤上种植棉花,分析暗管降盐技术对轻度和中度盐渍化农田土壤盐分变化规律及棉花产量的影响。结果表明:轻度和中度盐渍化农田土壤盐分剖面特征均由表聚型向脱盐型变化,中度盐渍化土壤0~20 cm土层盐分下降最快,其他土层盐分含量均呈现显著下降趋势;轻度和中度土壤最高脱盐率分别为50.96%和90.89%,中度盐渍化土壤盐分可降低至轻度水平;暗管排水的电导率变化范围为7.53~11.16 dS/m,pH值变化范围7.08~8.20;轻度和中度盐渍化棉田增产幅度分别为25.3%和55%。研究表明与滴灌配套的浅层暗管排水降盐技术可有效治理盐碱土壤,提高作物产量,该研究可为盐渍化土地的可持续利用提供依据。     

Distribution patterns of soluble salts and gypsum in soils under large-scale irrigation agriculture in Central Asia

Abstract

Soil salinization is a serious problem in the arid and semi-arid regions of Central Asia. To address the problems, we analyzed the dynamics and distribution patterns of salts in both rice-based and cotton-based cropping fields in selected farms of southern Kazakhstan and Uzbekistan with special emphasis on the dynamics of gypsum, which had a lower solubility than Na salts, as an index of water-movement regimes in irrigated fields. Most of the rice-based plots and some of the cotton-based plots exhibited no surface accumulation of soluble salts or gypsum because of repeated washing by a huge amount of irrigation water in the former or comfortable drainage in the latter. These soils are probably free from the risk of secondary salinization under present conditions and management practices. In contrast, uncultivated plots near canals accumulate both soluble salts and gypsum in the surface soil layers, and these salts would not be leached out without a drastic change to a predominantly downward pattern of water movement. In the intermediate stages in terms of soil salinization, some soils accumulated substantial amounts of soluble salts in surface layers but relatively low amounts of gypsum. In this case, periodic irrigation could have washed out most of the gypsum and soluble salts in a downward direction and, consequently, it is possible to leach out the accumulated soluble salts by applying additional irrigation water if necessary. However, there were some cases in which soils accumulated large amounts of gypsum in surface layers as well as soluble salts, suggesting that irrigation/drainage is generally insufficient to remove gypsum with a lower solubility and that these profiles are dominated by an overall upward movement of water. For these soils, drainage facilities should be improved to ensure the efficient leaching of accumulated salts on cropping. Thus, the condition of irrigated plots in terms of the direction of water movement and resulting salt regimes can be well understood from the distribution patterns of both soluble salts (or cations) and gypsum.     

Composition of soil lipids in two chinampas agroecosystems from Xochimilco and Tlahuac municipalities,Mexico

Abstract

The Chinampas are important historically and represent a special agroecosystem that has been sustainable for many years. However, their agricultural potential has currently decreased mainly because of irrigation with waste water from Mexico City, leading to progressive salinity and alkalinity problems and the subsequent general alteration on the agroecosystem. Chemical composition of the main groups of lipid molecules in anthropogenic organic soil from Xochimilco and Tlahuac Municipalities (Mexico) were investigated. The analysis performed included physico‐chemical characteristics of the soil and the distribution analysis of free alkanes and fatty acids. The successive accumulation stages of organic materials in these anthropogenic organic soils represent a source of irregular distribution in organic carbon, likewise the concentration of lipid extracts differed noticeably with depth. There is a vertical variability, where hydromorphic environment has played a key role in this variability. The major compounds identified in the soil lipid extracts by gas chromatography‐mass spectrometry include series of linear and satured alkanes, fatty acids, as well as individual components such as sterols and hopanes. Most of the lipid components in these soil seem to have a biogenic origin (higher plants and microorganism biomass).     

THE ALKALINITY OF ALKALI SOILS

The theoretically derived equation: log Alk–pH = log Pco₂–7.82 describes the relation between three easily estimated parameters, viz. the composition (alkalinity), CO, partial pressure and the pH of the soil solution. This equation is also important for understanding the formation of alkaline soils. The concept of residual alkalinity, i.e. the difference between the alkalinity and the total concentration of the divalent cations in the soil solution (on an equivalent basis) is introduced. In a closed basin with excess evaporation over precipitation highly alkaline soils, i.e. soils with a pH above 8 to 8.5, develop if the inflowing water has a positive residual alkalinity. A number of processes, such as weathering, oxidation and reduction, cation exchange, precipitation, addition of neutral salts, evaporation, which may influence the alkalinity and residual alkalinity of natural waters and soils are discussed briefly.     

南亚热带丘陵赤红壤区农业可持续发展的土壤水分管理探讨

焉耆盆地土壤盐渍化日趋严重,直接影响当地农业发展和生态环境建设。作者运用统计特征值、趋势面分析等方法,探讨了焉耆盆地土壤含盐量、盐分化学组成及其空间分布特征。结果发现:(1)除戈壁砾石带外,区内有近60%的土地处于强盐渍化和盐土状态,且主要为氯化物-硫酸盐型盐渍化;(2)荒地土壤的含盐量远大于农田区土壤;(3)表层土壤盐分具有从扇缘到湖滨逐渐增加的趋势,在灌区内土壤盐分随灌溉和排水而呈现季节性变化,但整体上处于脱盐状态。区内土壤盐渍化是在自然和人类活动共同作用下形成的,通过节水灌溉、合理开发地下水、完善灌排系统等措施可有效地改良盐渍土。     

滨海盐渍土的碱化问题

滨海盐渍土是否有碱化问题,特别是在开垦利用以后,土壤是否会向碱化方向演化,这是很多生产单位所关心的问题。对此,过去已做了不少工作。有人认为滨海盐渍土由于长期受海水浸渍,土壤胶体表面吸附着大量的钠离子,因此有比较高的碱化度,盐渍程度愈重则碱化度愈高,随着土壤脱盐同时脱碱,当不致进一步碱化^[3]。也有人认为滨海盐债土耕垦后不会发生碱化,其碱化度随改良利用年限而降低^[1]。还有人在滨海盐溃土耕垦种稻后,观测到在土壤脱盐过程中,土壤pH值和总碱度有所增高,认为土壤发生了碱化^[2,5]1)。我们就这一间题曾先后对浙江上虞、乐清,江苏东台、大丰、滨海、灌云以及辽宁兴城、锦县、大洼等县的滨海地区进行了调查研究和室内试验。     

Saline-alkali soils of Russia

Diagnostics, methods of evaluation, and geography of saline-alkali (soda) soils are discussed. The saline-alkali soils include soils of different genetic types with the following chemical properties: the pH of the water suspensions equal to or higher than 8.5; the total alkalinity exceeding 1.4 meq/100 g of soil and the sum of water-soluble calcium and magnesium; and the presence of soluble “alkaline” salts in the soil profiles, the hydrolysis of which results in the alkaline reaction of the soils. The chemical properties of the saline-alkali soils are largely related to the presence of soda (Na₂CO₃, NaHCO₃) in the soils. According to their morphological properties, saline-alkali soils are divided into two groups: alkaline soils with an undiferentiated profile and without a morphologically pronounced solonetzic (natric) horizon, and alkaline soils with a pronounced natric horizon (solonetzes). Solonetzes, in turn, are divided into (a) alkaline solonetzes (with soda or with soda and neutral salts), (b) solonetzes salinized with neutral salts (saline soils) with increased alkalinity in the solonetzic and lower lying horizons, (c) saline solonetzes throughout the profile, and (d) leached solonetzes containing no soluble salts in the profile and almost no exchangeable sodium in the soil exchange complex (SEC) (“dead” solonetzes). The latter two groups of solonetzes cannot be ranked among the alkaline soils. The alkalinity of the saline-alkali soils under study is due to carbonate and bicarbonate ions (carbonate alkalinity), organic acid anions (organic alkalinity), and borate ions (borate alkalinity). The carbonate alkalinity is due to both soda (Na₂CO₃, NaHCO₃) and CaCO₃.     

膜下滴灌土壤水盐与玉米产量对节水控盐灌溉模式响应的模拟

土壤盐渍化是干旱灌区农业可持续发展亟待解决的关键问题,膜下滴灌加适宜的节水控盐灌溉制度可有效控制根区土壤盐分,并提升作物产量。该研究以河套灌区玉米膜下滴灌田间试验为基础,应用农业水文模型（Agro-Hydrological & Chemical and Crop systems simulator, AHC）模拟分析了膜下滴灌农田土壤盐分胁迫和玉米产量对不同灌溉制度的响应,以期获得不同程度盐渍化土壤膜下滴灌玉米适宜的节水控盐灌溉制度。结果表明,土壤盐渍化、灌水下限及淋盐灌溉显著影响玉米灌溉制度和玉米耗水、产量与水分利用效率。轻度和中度盐渍化土壤玉米膜下滴灌适宜的节水-控盐-增产灌水下限分别为–25和–15 kPa,次灌水量为对应灌水下限无淋盐处理的灌水量与淋盐水量之和。轻度盐渍化土壤灌水下限为–25 kPa时,与不淋盐处理相比,淋盐处理盐分胁迫系数平均值可提高12.4%,产量可提高16.9%;中度盐渍化土壤灌水下限为–15 kPa时,与不淋盐处理相比,淋盐处理盐分胁迫系数平均值可提高31.1%,产量可提高25.2%。研究结果为河套灌区及类似干旱灌区玉米农田土壤水盐调控与灌溉管理提供科学依据。