Secondary Salinization Research Articles

CELL SELECTION WITH BARIUM IONS FOR OBTAINING GENETICALLY MODIFIED TOBACCO

Introduction. The salinity is one of the most aggressive environmental factors. It provokes the wide range of pathological changes in the plant tissues. The drastic decrease of K + cations in plant cells due to salt toxicity is the main feature of injury. The lands with secondary salinization increase. Fresh water in many regions transforms to the product of deficit even to the public. So the problem of obtaining plant forms with elevated levels of salt tolerance becomes extremely significant. Genetic effects that increased the genotype tolerance abilities are the aims of various investigations. Cell selection with heavy metal ions is the appropriate biotechnology for obtaining plant forms that challenged the salinity. The scientific interest to Ba 2+ ions is due to its interaction with K + cations. There was shown that Ba 2+ interrupted the K + inward transport Purpose. The obtaining glycophyte-derived salt tolerant forms (cell lines – regenerants – progeny )via cell selection. Methods. Selective systems with lethal doses of barium ions (Ba 2+ ) for obtaining tobacco cell forms tolerant to salt stress are proposed and elaborated. The minimum of Ba 2+ doses that eliminate wild type cell population was established as lethal doses. Primary calli cultures were initiated from tobacco leaves on B5 cultural agar medium. Cell suspension was cultivated in liquid B5 medium. Cell suspension (wild type) was placed between two layers of agar selective medium with the addition of lethal doses of barium ions (“plating procedure”). Only Ba-resistant cells survive under such stress pressure. The survived cells formed primary minicolonies. Such colonies are considered to be tobacco Ba-resistant cell lines (Ba-RCL). Ba-RCL grew at Ba 2+ ions presence during 3 passages . Then callus was cut and transferred to fresh media: basal medium (normal conditions) and selective media (stress conditions). Resistant cell variants were tested under lethal salinity. Salt stress was simulated by the addition of sodium chloride or sodium sulfate. There were established three variants of selective systems: medium with the addition of Ba 2+ cations, (stress I); cultural media with the addition of salinity (stress II, III). Genetic basis of combined stress resistance was confirmed via media rotations. The changes were: normal conditions → stresses I, II, III; stresses I, II, III → normal conditions; stress I → stress II or stress III or other way roads. The type of cultural medium and the number of passages were always free. As proliferation marker calli relative fresh mass growth (RFW, Δm) was used. Regenerants and plants of R1 seed progeny were cultivated in vitro at presence of sea water salts. Result. Tobacco cel lines with combined resistance to lethal ion and chloride and sulfate stresses were obtained via cell selection with Ba 2+ cation. Ba-RCL maintained their viability under any stress pressure. The calli relative fresh mass growth (RFW, Δm) was always positive. Regenerants from selected cell lines and R1 seed progeny were cultivated at presence of sea water salts (2,5%) in vitro. During such cultivations tested plants formed new roots and leaves. After transfer to control (salt free) medium plants adapted to normal conditions. Originality of the investigation and its priority was in the promotion of cell selection with Ba 2+ cations for obtaining tobacco variants tolerant to lethal salinity. Conclusion . Cell selection with heavy metal ions is the perspective approach for obtaining genetically modified plant forms. Barium cation is appropriate agent for selection variants with higher tolerance to salinity. Tobacco is a classic glycophyte. From such initial tissues tobacco plant forms (cell lines → regenerants → progeny) that survive under lethal salinity were obtained. This approach is suitable for other genotypes.

ФАКТОРЫ, УСИЛИВАЮЩИЕ ОТРИЦАТЕЛЬНОЕ ВОЗДЕЙСТВИЕ ДЛИТЕЛЬНОГО ОРОШЕНИЯ НА СВОЙСТВА ЧЕРНОЗЕМА ОБЫКНОВЕННОГО

Purpose: to identify factors enhancing the negative impact of long-term irrigation on soil fertility. Materials and methods. The influence of mineralization and quality of irrigation water on ordinary chernozems (Neklinovsky district), the level of groundwater table on the reclamation state and soil fertility of ordinary chernozems (Bagaevsky district of Rostov region), the structure of crop rotations was studied, and optimal moisture levels for different irrigation modes were established. Results. Long-term use of sulphate-sodium low-mineralized water led to the degradation of ordinary chernozems. They acquired the properties of medium alkaline and medium solonized soils: alkalinity – 1.29 mmol(eq)/100 g, solonetzicity – 7 % of exchangeable sodium from the total soil absorbing complex (SAC), soil bulk density – 1.34 t/m³, humus content decreased by 23 % during its transformation from fulvate-humate to humate-fulvate. The close ground waters table and their mineralization of 5 g/dm³ contributed to secondary salinization. Fertility reproduction is observed only with the introduction of organic fertilizers. The increase in humus content in the alfalfa-corn crop rotation was 0.68 % with the introduction of 60 t/ha of manure after 4 years of corn cultivation in comparison with the humus content after 3 years of alfalfa cultivation, and in the grain feed – 0.55 %. It was found that with an increase of irrigation rate up to 30 %, leaching of exchangeable calcium is observed with a simultaneous increase in the content of exchangeable sodium up to 4 % of the total SAC, which contributes to an increase in bulk density of ordinary chernozem to 1.38 t/m³. In the variant with over-irrigation, the humus content decreased by 0.22 % over 4 years of regular irrigation, and in the variant with the optimal and reduced by 40 and 60 % rates, its amount decreased from 0.04 to 0.07 %, as in dry land. Conclusions. The investigated factors enhance under certain conditions the negative impact of long-term irrigation on the properties of ordinary chernozem.

Probabilistic assessment of the role of the soil degradation main factors in Kuban rice fields

As a result of reclamation systems for rice cultivation construction, the conditions of genesis and landscapes soil formation were radically violated. This led to the leaching of active humus and calcium, colloidal particles, nutrients from arable layer to underlying horizons, as a result of which there is a tendency to secondary salinization and solonization of soils. The development of the eluvial glue process and physicochemical parameters change of soils causes a change in the morphological soil profile. Currently relevant are preventing land degradation problems, maintaining and restoring soil fertility. In the article, the authors propose to characterize the rice irrigation system functioning mode from probabilistic point of view. They offer to evaluate the consequences of anthropogenic load, considering operational activities by Poisson stream of a certain intensity. This approach allows to consider uncertainty in terms of probability distributions. The function, characterizing soil quality S(t) was introduced. The function S(t) assumed to be monotonously decreasing. The probability R(S) of achieving a certain soil quality was considered. In case of minimum amount of humus Sm the soil is degrading. In these assumptions the average value expression and probability density of particular soil condition onset duration was received.

Tissue damage to wheat seedlings (<i>Triticum aestivum</i>) under salt exposure

High content of mineral salts reduces crop yields. Agricultural areas are being reduced due to the secondary salinization of land. Wheat is one of the main crops, however, wheat is a type of plant that is sensitive to the toxic effects of mineral salts. Therefore, the identification of cytological and biochemical markers for determining resistant and sensitive wheat varieties to abiotic stress caused by the toxic effects of mineral salts is one of the important tasks of agriculture. Methods of fluorescence, cytophotometry, electrophoresis, and light-optical microscopy produced suitable cytological markers for creating a test system for the early diagnosis of wheat sensitivity to the tested salts. Different wheat genotypes of Triticum aestivum Host. (varieties Agata, Uchitel’, and Zhemchuzhina Povolzh’ya) underwent treatment to investigate their reaction to the toxic effects of sodium chloride and sodium sulfate. The varieties responded differently to the presence of the salts; these were reflected in changes in biometric data, the passage of the cell cycle, features of ROS accumulation, and a quantitative assessment of the viability of seedling cells. In the genotypes sensitive to sodium chloride and sodium sulfate (varieties Zhemchuzhina Povolzh’ya and Uchitel’), tissue damage was observed in root cells under toxic effects, while in the resistant genotype (variety Agata) cell damage was minimal. The developed complex of intravital markers of various wheat genotypes in the early development stages can be effectively used to characterize wheat with different tolerance to chloride and sulfate salinization.

EVALUATION OF MORPHOLOGICAL AND BIOCHEMICAL RESISTANCE PARAMETERS TO CHLORIDE SALINATION IN DIFFERENT WHEAT GENOTYPES

Determining salt tolerance potential in wheat is one of the most important problems in breeding practice for areas with primary and secondary salinity. Presence of large areas of saline soils results in inhibition of growth, development and stability in obtaining high yields of agricultural plants. Therefore, there is a need for a comprehensive studying and improving of diagnostic methods during early growth stages. Different genotypes of wheat Triticum aestivum Host. and Triticum durum Desf. were used to identify salt tolerance markers. Both morphometric and some biochemical indicators of wheat varieties were used as salt tolerance markers. At this stage, it was shown that a comprehensive description of wheat varieties is needed to assess resistance of wheat varieties to chloride salinity.

Investigation of the possibility of green bean production under unfavourable agro-ecological conditions in lysimeters

Abstract There are extended agricultural areas in the world that can be utilized only with irrigation for crop production. Improper irrigation may induce unfavourable processes in the soil (e.g. secondary salinization). To investigate this problem existing in Hungary as well, 12 simple drainage lysimeters – which are useful equipment for the investigation of the water and salt balance of the soil – were used in an irrigation experiment in the Research Institute of Karcag. The basic goal was to investigate the possibility of the production of a salt-sensitive crop (green bean) in areas with unfavourable agro-ecological conditions. 6 lysimeters were irrigated with deionized water, while the other 6 with saline water of 1,600 mg/l salt content. We also used a soil conditioner (Neosol) during the experiment. Analysing the effect of the irrigation quality on the plant height of green beans, it can be established that the plants irrigated with deionized water were averagely 5.3 cm taller than the plants irrigated with saline water. Similar tendencies were characteristic of the average biomass (deionized: 93.5, saline: 62.5 g), the average root mass (deionized: 9.5 g, saline: 8.2 g), the number of pods (deionized: 17.1, saline: 11.9), and the pod yield (deionized: 137.9 g, saline: 85.9 g) values. However, all these values can be improved by soil conditioning combined with the optimization of irrigation.

Snowdrift Redistribution as the Main Factor of Regulation of Water Availability for Forest Cultures in Steppe Conditions

Abstract—The applicability and necessity of analysis of snowdrift redistribution features for optimizing moisture availability for both forest cultures and adjacent territories are recommended when creating artificially planted protective forest belts in previously treeless territories. The average distance traveled by individual snowflakes by wind, which usually does not exceed several hundred meters, is the most important parameter of snow cover formation. This particular mechanism regulates the amount of snow accumulation in forest belts, controls the width of the snow-gathering area, and contributes to the even distribution of snow on flat lands without forests. By analyzing the ratio of potential evaporation and the average volume of additional snow-melt water per unit length of the forest belt, some specific features of moisture accumulation and peculiarities of tree desiccation on various types of soils were revealed. Evidence is given for the impossibility of the creation of stable close-planted forests on light chestnut soils in semidesert and dry steppe regions due to the weak accumulation of snow masses and the losses of significant amounts of spring infiltration water due to secondary salinization. Ways are disclosed to optimize the water availability for cultures in chernozem steppes by adjustment of the width of the forest belt according to the mechanics of snowdrift redistribution. The research conducted shows the possibility of mathematical calculation of the optimal parameters and spatial configuration of newly planted forest belts on reclaimed territory. The impossibility of increasing the life cycle of artificial forest stands with the help of only traditional agrotechnical and silvicultural techniques without considering these criteria has been proved.

Salt Tolerance and Desalination Abilities of Nine Common Green Microalgae Isolates

In recent years, decline of freshwater resources has been recognized as one of the main environmental problems on global level. In addition to the increasing extent of primary salinization due to climate change, secondary salinization caused by human interventions is also a significantly increasing problem, therefore, the development of various chemical-free, biological desalination and removal procedures will become increasingly important. In the present study, the salinity tolerance, salinity, and nutrient reducing ability of nine common freshwater microalgae species from the genera Chlorella, Chlorococcum, Desmodesmus, Scenedesmus, and Monoraphidium were investigated. Our results proved that the studied green microalgae species are halotolerant ones, which are able to proliferate in environments with high salt concentrations. Furthermore, most of the species were able to reduce conductivity and remove significant amounts of chloride (up to 39%) and nutrients (more than 90% nitrate). The results proved that nitrate removal of the studied species was not influenced by salt concentration, only indirectly via growth inhibition. However, the results also highlighted that N:P ratio of the medium has primarily importance in satisfactory phosphorous removal. It can be concluded that assemblages of the studied microalgae species could be able to adapt to changing conditions even of salt-rich wastewaters and improve water quality during bioremediation processes.

Secondary Salinization of Reclaimed Solonetzes and Its Aftereffect

The studies were performed at the long-term stationary experiment on crusty hydromorphic solonetzes of the Baraba Plain during 1986–2017. In the humid year of 2013, the ground water level drastically rose from a depth of 250 cm to 50 cm, and secondary salinization was recorded. The content of soluble salts increased, their composition changed, the soil pH shifted to higher values, and the exchangeable sodium percentage increased. After lowering of the ground water table, salts were gradually washed out from the soil profile in the reclaimed solonetzes, and the positive effect of gypsum was partially restored. The soil adsorption complex was dominated by Mg2+ in the control variant and by Ca2+ in the reclaimed solonetzes. This phenomenon should be taken into consideration when reclaiming solonetzes, because the positive effect of gypsum application is preserved after secondary salinization.

Changes in floodplain soils of the Nizhny Don under the influence of flow regulation and anthropogenic load

Formation of hydromorphic floodplain soils of the valley of the Nizhny Don occurs mainly under the influence of anthropogenic erosion and due to lowering the water content of the floodplains below the dams as the result of the construction of the Tsimlyansk reservoir. Road transport and overgrazing contribute to the degradation of natural meadow vegetation until its complete destruction. As a result, the properties of soils, as well as the content and composition of humus, significantly change, the water-physical properties of soils deteriorate and the processes of secondary salinization develop with the nearby proximity of mineralized groundwater.

Appraisal and Mapping of Soil Salinity and Sodicity Problems In Sector One of Watari Irrigation Scheme, Kano State.

One of the main reasons for the loss of productive land in irrigated fields is the buildup of salinity in the soil. In the watari irrigation Scheme, no systematic ap- praisal and mapping have been made before within the sector. The study area was selected after a reconnaissance survey based on the farmer's complaint about the low production. Global positioning system (GPS) was used to record the coordi- nate, and delineate the boundary of the study site. The coordinates of the deline- ated boundary were Geo tagged on Google Image to obtain the image of the study site. Grids of 100 x 100m were superimposed on the Geo tagged image and were used as sampling points. A total of 234 samples were obtained from 160 ha of land for the study; within each grid, four soil samples were collected at a depth of 0 – 20cm, and mixed them into one sample from each grid. The collected sam- ples were processed and analyzed using standard laboratory procedures for salini- ty and sodicity evaluation. Standard methods were followed to measure pH, elec- trical conductivity (EC), and soluble cations. Arc GIS 10.3 was used to map out the varying degree of salinity and sodicity. The extent of the area of the classes and percentage coverage indicated that the non-saline area covers about 28.80% (46 ha) of the total land size. But 25.50% (40 ha) of the sector were slightly sa- line, moderate salinization problem within the sector occupied 34.10% (54.6 ha) of the land area. Only 11.6% (18.6 ha) of the total land size had both salinity and sodicity hazards of the sector with ECe dSm-1 and SAR values greater than 4 dSm-1 and 13, respectively. Based on the findings, the extent of soil salinity and sodicity of the study area revealed that substantial parts were consistently and continuously affected by salinity problem 71.2% (114 ha). Specific proportions of the irrigated land need special attention so as to prevent and control secondary salinization. The sodic soil should be controlled at the earliest before the soil structure is entirely destroyed since only 28.80% (46 ha) is free. The water table control by rehabilitating the subsurface drainage system seems to be the only feasible way to improve the sustainability of the scheme.

Fisher accessibility and habitat complexity influence the distribution of adult Cherax cainii (Decapoda: Parastacidae) in a water supply reservoir

Abstract Almost one third of all freshwater crayfishes are threatened with extinction. The factors influencing the distribution of freshwater crayfishes in lentic systems are poorly understood, hampering the conservation and enhancement of those populations. Cherax cainii is the third largest freshwater crayfish in the world and is endemic to south‐western Australia. The distribution of the species has declined markedly, largely attributable to secondary salinization and habitat decline. There is the potential for population enhancement through habitat restoration and the restocking of reservoirs that act as important non‐salinized refuges; however, there is limited understanding of the distribution and habitat associations of C. cainii in these systems. Mark–recapture was undertaken to determine the population abundance and fine‐scale distribution of C. cainii in a large reservoir over a 5‐month period, with generalized linear mixed modelling used to determine those factors that explained the variation in its distribution. Cherax cainii distribution in the reservoir was positively associated with complex habitat (large woody material) and the level of inaccessibility to humans, and negatively associated with depth. The population had a non‐uniform distribution within the reservoir with significant hot‐ and cold‐spots present and there was limited distance between recaptures during the coolest period of the year. The findings suggest that C. cainii would benefit from the provision of additional complex habitat in such habitat depauperate reservoirs to provide increased shelter from predators. It may also be vulnerable to localized depletion through legal and illegal fishing pressure. The study highlights the importance of understanding habitat preferences and movement patterns of freshwater crayfish to underpin their conservation.

Potash mining effluents induce moderate effects on histopathological and physiological endpoints of adult zebrafish (Danio rerio)

Stress in fish can be caused by a variety of factors and has the potential to evoke stress responses leading to a reduction of physical condition and of health. The river Werra (Germany) presents a severe case of secondary salinisation caused by potash mining activities. The model organism Danio rerio was exposed to different ion-concentrations depicting current (HT) and future (LT) threshold values of the Werra, as well as to solutions with single-exceeding ions (Mg2+ + K+ (KMg), Mg2+ (Mg) and K+ (K)). After a six-week exposure period, cortisol levels, growth and weight were measured, gills and gonads were histologically analysed and mRNA expression of follicle stimulating hormone (FSH), luteinising hormone (LH), growth hormone (GH) and prolactin (PRL) were determined. Cortisol was still elevated in fish in the HT and K group, indicating moderate stress. However, gills revealed structural changes in zebrafish in all exposure groups, size of oocytes differed in the LT and K group, male FSH mRNA levels were elevated in the HT and LT group whereas PRL mRNA levels were lower in HT and LT for both, male and female fish.These results suggest that ion-stress induces moderate effects on a variety of biological parameters that mainly serve to adapt to elevated ion concentrations. For these reasons current and even future thresholds should be reconsidered, including thresholds for total as well as single ion concentrations. Future research looking at the effects on local fish species is needed, along with regular and long-term monitoring of environmental conditions, species abundance and diversity.

MODERN STATE, DYNAMICS OF CHANGES AND PROSPECTS FOR THE DEVELOPMENT OF HYDROTECHNICAL RECLAMATIONS IN DNIPROPETROVSK REGION

Formulation of the problem. Irrigation is one of the priority areas of agricultural development for Ukraine. According to numerous studies, it has been determined that restoration of irrigated agriculture is a prerequisite for adapting the agricultural sector of the economy to climate change and ensuring Ukraine's food security. Dnipropetrovsk region was among the territories with the largest area of irrigated land. The vast majority of irrigation systems in the region were built in the 70-80's of the last century and operated for about 50 years, and the last reconstruction of the capital reconstruction was carried out more than 30 years ago. About 198.7 thousand hectares of irrigated land are recorded on the territory of the region, of which 163 thnd ha (82% of available capacity) are not used as irrigated. At the same time, operating systems on the area of 35,7 thnd ha (18% of available) are not working at full capacity. Under the condition of reconstruction of the internal irrigation network, it is promising to restore irrigation on an area of 80.4 thnd. ha.
 Research results. Irrigation of agricultural crops in the Dnipropetrovsk region occurs on the right and left bank of the Dnipro River in 18 administrative districts. An analysis of the dynamics of the change on the right-bank part indicates a trend of reduction of irrigated land by 1.3 times in 2014 as compared to the same indicator in 2004. The irrigated areas of the left-bank part of the Dnipropetrovsk region have a positive tendency to build up. The dynamics of the change in the period of 2004-2014 indicates that the irregular area is slightly but gradually increased 1.36 times.For the purpose of determining the quality of irrigation water and its suitability for irrigation by structural subdivisions subordinated to the regional office of water resources in the Dnipropetrovsk region, 130 samples were sampled at 56 stationary observation points for chemical analysis. Samples of water were selected near the main pumping stations and control basins, in the heads of main channels, from large and small rivers and ponds.The analysis of the results testifies to the threatening tendency of gradual deterioration of the quality of irrigation water. For example, in comparison with the figures for 2004 in relation to 2014, the area of irrigation with water of the 1st class decreased by 2.7 times from 16.85 thnd ha to 6.34 thnd ha. Almost stable trend has the irrigation area, which was watered with 2nd grade water, which increased by 1.35 times and, with the exception of the indicators in 2010, averaging about 12 thnd ha. The most threatening trend is the increase in areas of irrigated water that is not suitable for irrigation without the prior improvement of its physical and chemical parameters. Such territories have grown almost 3 times from 2,2 thnd ha to 6,1 thnd ha.
 Conclusions. The unsatisfactory technical condition of the conducting network of most canals and drainage systems, violation of irrigation regime and outdated irrigation technique, worsens the reclamation state of a significant part of the irrigated lands of the Dnipropetrovsk region. In this regard, it is necessary to introduce a system of detailed monitoring of land prone to secondary salinity, based on technologies of remote mapping WL-methods. In addition, it is necessary to widely apply methods of field simplified operational control of the technical state of the components of irrigation networks. It is necessary to perform repair and renovation works in a timely manner that will reduce unproductive water losses for filtration from irrigation systems and prevent soil salinization, as well as rational use of water resources. Due to the threatening trend, particular attention should be paid to the quality and quantity of irrigation water. In the absence of control by the authorities on volumes, concentrations and major sources of pollution of surface and groundwater, it is possible that irrigation systems in the future should include technological lines to improve the physical and chemical parameters of irrigation water. The economic feasibility of the issue requires further study.

Development of secondary salinity and salt migration in the irrigated landscape of hot arid India

The present paper examines the nature of salt movement by the influence of landscape position and development of secondary salinity in Indira Gandhi Nahar Pariyojana command area of hot arid India. Soil samples were collected along 20 km transect across landscapes of upland, medium land, lowland and wetland. Soil properties, electrical conductivity of saturated extract (ECe), soluble ions in saturated extracts, exchangeable sodium percentage (ESP) and sodium adsorption ratio were determined. Results showed that cation exchange capacity, organic carbon and CaCO3 were significantly increased in lowland and wetland while soil pH, salinity indicators (ECe and ESP) and exchangeable cations and anions such as chloride and sulphate were increased significantly (P < 0.05) in the wetland. The mean exchangeable Na was increased while exchangeable Ca, Mg, and K decreased from upland to wetland landscape. It was found that Cl− imposed an existing and potential threat to sensitive crops in medium to wetland, where Cl− concentrations were greater than 106 me L−1. Principal component analysis helped in the identification of the parameters responsible for soil salinity variation, and the first factor indicated that soil ECe and ESP had a major role in the development of salinity and sodicity, respectively. Cluster analysis grouped four sampling sites into three clusters and members of the third cluster (lowland and wetland) were in close proximity. Under the prevalent arid conditions, improving the management of irrigation water should be the indispensable one to conserve and sustain the already fragile agricultural soils in the hot arid regions of India.

Evaluation of Groundwater Quality and Agricultural use Under a Semi‐arid Environment: Case of Agafay, Western Haouz, Morocco

AbstractWater resources are a priority for economic development, aiming at meeting the increasing needs of agriculture and all socio‐economic sectors. Agriculture is one of the essential pillars of this development in the Haouz Plain. Under a semi‐arid climate, irrigation, consuming more than 85% of available water, is inevitable for most crops. Hence, groundwater is becoming increasingly under pressure.Salinization due to poor irrigation management is one of the main causes of soil degradation. In this context, assessment of groundwater quality and risks of soil salinization was carried out in irrigated citrus orchards located in the western part of Haouz and aimed at understanding the connection between natural context, irrigation practices, and water and soil salinization. The spatial distribution of aquifer potential lines is affected by groundwater over‐exploitation. Moreover, geologically, the Palaeozoic substratum rise constitutes an obstacle for underground flow, which explains the low values recorded and measured around the studied area.The groundwater quality in the study area is characterized by strong mineralization, consequently affecting the soil by secondary salinization due to the intensive use of moderate saline waters from groundwater. Using a mixture of different water origins is a practical measure to reduce the risks of degradation of the soil. © 2019 John Wiley &amp; Sons, Ltd.

Effect of Pyrochar and Hydrochar on Water Evaporation in Clayey Soil under Greenhouse Cultivation.

Greenhouse cultivation consumes large volumes of freshwater, and excessive irrigation induces environmental problems, such as nutrient leaching and secondary salinization. Pyrochar (biochar from high-temperature pyrolysis) is an effective soil amendment, and researches have shown that pyrochar application could maintain soil nutrient and enhance carbon sequestration. In addition to pyrochar from pyrolysis, hydrochar from hydrothermic carbonization is considered as a new type of biochar and has the advantages of low energy consumption and a high productive rate. However, the effect of these two biochars on water evaporation in clayey soils under a greenhouse system has seldom been studied. The relationship between water evaporation and biochar properties is still unknown. Thus, in the present study, water evaporation under pyrochar and hydrochar application were recorded. Results showed that both pyrochar and hydrochar application could inhibit water evaporation in clayey soil under greenhouse cultivation. Pyrochar showed a better inhibition effect compared with hydrochar. Correlation analysis indicated that the water evaporation rate was significantly positively correlated with bulk density of biochar (p < 0.05). Overall, application of pyrochar or hydrochar could both reduce soil bulk density and inhibit soil evaporation, and be available for greenhouse cultivation. However, the inhibition effect depends on the properties of the biochar.

Effect of Soil Conditioning on the Moisture Content and the Salt Profile of the Soil Under Irrigation with Saline Water

Abstract The research work was started on the preliminary knowledge that the risk of secondary salinization is high in the hobby gardens around Karcag as the water of the aquifers used for irrigation is saline, nevertheless irrigation in the drought periods is essential for vegetable production. A complex experiment was set up in 12 simple drainage lysimeters at the lysimeter station of the Research Institute of Karcag in 2012 in order to simulate the conditions of irrigation characteristic in the region with the goal of finding a solution to mitigate the harmful effects by means of optimization of irrigation. In 2017–2018 three approaches were applied for the scientific establishment of the problem studying the effect of different irrigation frequencies, different irrigation water qualities, and soil conditioning on the moisture content and the salt profile of the soil. The soil conditioner (Neosol) applied was found to have a positive effect on the water and salt regime of the soil, partly by creating a more favourable vertical distribution of the soil water, and partly preserving more moisture in the soil.

Effect of Surface Straw Incorporation Rate on Water–Salt Balance and Maize Yield in Soil Subject to Secondary Salinization with Brackish Water Irrigation

Secondary salinization induced by brackish water irrigation has forced agricultural development to increasingly rely on soil management. A two-year field experiment was conducted to explore the effects of different straw incorporation rates (SIRs) within 0 to 20 cm topsoil on the soil water–salt balance, maize yield production, and water use efficiency (WUE) under brackish water irrigation in a naturally non-saline area. Air-dried wheat straw was applied at the rates of 0, 4.5, 9.0, 13.5, and 18.0 t ha−1 (R0–R4) and two salinity levels of irrigation water with the salt content of 1.92 dS m−1 (SL) and 3.20 dS m−1 (SH) were applied for simulating the scenarios of secondary salinization. Results demonstrated that straw incorporation markedly increased the soil water content during two growing seasons, and SIR was directly correlated to the deep percolation, but inversely correlated to the soil water depletion, under both the SL and SH condition. Meanwhile, straw incorporation led to the increase in salt content within the straw incorporation zone, but the total mass of salt deposited in the 0–100 cm soil profile was comparatively reduced as SIR increased due to the increased deep percolation for salt leaching, and such relative alleviation was more pronounced under the SH condition. The significantly increased maize yield and its corresponding WUE were obtained in treatments with high SIR levels. Additionally, an exponential function was used to describe the trend of the yield-increasing rate as SIR increased, and the theoretical maximum of grain and biomass yield calculated from the fitting results were 6483 in 17,282 kg ha−1 under SL, and 5440 and 14,501 kg ha−1 under SH, respectively. Results in this study would be helpful in the adoption of straw incorporation and brackish water irrigation in ways that facilitate soil water availability and reduce the risk of soil salinization.

Physico-Chemical Characterization of Water and Soil of the M’nasra region in the Gharb plain (Northwest Morocco)

The aim of this work is to carry out an evaluation of the quality of agricultural soils and water in the irrigated area of the M’nsara region in the Gharb plain (Northwest Morocco) with the goal of describing the degree of degradation of natural resources and improve the sustainability of the environment and irrigated farming systems of the region through optimal management of these resources. Eighteen water and nineteen soil samples were collected based on existing soil and piezometric maps of the irrigated areas, distributed into 3 different zones: A, B, and C. Characterizations of the main parameters of soil and irrigation water quality were made. Irrigation water salinity varies between 0.5 and 1.3 dS/m. The irrigated soils from the groundwater have shown a secondary salinization superior to that of irrigated soils by the waters of the dam. Cultivated soils present a salinity that reaches 1.90 dS/m in some areas. The results show that 68.4% of the soil samples are poor to moderately poor in organic matter. The sodium adsorption ratio (SAR) shows a minimal risk to accumulate sodium in the soil with 16.7% is slightly alkaline. The soils are weakly to moderately basic and represent respectively 73.7 and 10.5 % of the study area. Potassium and available phosphorus have very low values in the majority of soils which will have a negative impact on the environment. The spatialization of these parameters was performed by the determinsitc method of inverse distance weighted (IDW). In order to delineate areas that are a priori subject to environmental degradation in order to understand the effect of agricultural intensification on the sustainability of natural resources, taking into account the type of management water irrigation in the arid region.