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Salt-Affected Soils
Published in A. Monem Balba, in Arid Ecosystems, 2018
The available soil water ranges from the field capacity to the permanent wilting point (PWP). The salt concentration in the soil water increases with the decrease of this water by evaporation and transpiration. At PWP, the salt concentration is about double its concentration at the field capacity. Accordingly, the adverse effect of salts is expected to increase. Also, the soil water potential increases, making it more difficult for the plant to absorb its need of water. Thus, as the available soil water decreases, between irrigations or when water is short, the water deficit and osmotic effects become greater. Crops vary in their water requirements, optimum growth season, rooting depth, and cultural requirements. Soil salinity is affected by soil and water practices suitable for various crop rotations. Crops which require flooding or more frequent irrigations reduce soil salinity, while others which require a long period without irrigation in hot dry seasons before harvesting will increase soil salinity.
Desertification and Land Degradation Processes
Published in Ajai, Rimjhim Bhatnagar, Desertification and Land Degradation, 2022
Nutrient depletion in soil takes place when its export from an agricultural field exceeds its inputs. Nutrient exports from an agricultural field include extraction of nutrients by crop/plants, losses due to soil erosion and leaching, and volatilization and denitrification. Inputs include application of organic manures and fertilizers, returned or restitution of crop residues, nitrogen fixation by legume crops, atmospheric deposition in rain and dust, and enrichment through weathering of soil minerals. Nutrient depletion is often related to the decrease in soil organic matter. Soil organic matter is important because it is the prime source of nutrients and it helps in enhancing the retention capacity of soil water (Middleton and Thomas 1997).
Flood Management
Published in Saeid Eslamian, Faezeh Eslamian, Flood Handbook, 2022
U.C. Sharma, Vikas Sharma, Saeid Eslamian
Land-use changes have altered runoff-generation processes and the flooding regimes of river basins (Bronstert et al., 2002; Ghosh and Dutta, 2011; Ramesh, 2013; Beckers et al., 2013; Santato et al., 2013). Modern land-use practices have accelerated runoff byreducing the infiltration capacity of soils or obstructing the natural drainage system. Quite likely, man-made land-cover changes have disturbed erosion and sediment dynamics. Historically, it becomes evident that floodplain zones have been a preferred area for human settlement as they offer several opportunities in terms of available natural resources in the economic, social, or environmental domains. Although living on floodplains has great advantages, their occupants are exposed to many disturbances, as well. Land use is playing an important role in flood exposure and susceptibility to damage; there is a need to interlink and harmonize land-use management and flood risk management. The World Meteorological Organization (2006, 2012) indicated that rainfall, cyclonic storms, temperature, soil moisture, groundwater level, surface infiltration rate as affected by vegetation, soil texture, density, structure, soil moisture, and land-use activities such as urbanizationcontribute to increased runoff volume and rate and flow obstruction, as well as a decrease in the conveyance of the river channels due to sediment deposition. In addition to environmental, social, and economic aspects, forests play an important role in hydrological processes within the basin. Loss of vegetation and forest clearing increase runoff and erosion by decreasing soil water-retention capacity. Significant changes to those parameters, such as excessive logging, conversion of forested areas to other land-use types, and conversion of land through forest fires, have an impact on the runoff generation, erosion, and sediment processes, in particular at smaller spatial scales (FAO, 2005). Konrad (2014) mentioned that non-structural measures such as runoff control or capacity enhancement of rivers can be included in land-use planning programs to reduce runoff-generation processes and flood hazards.
Evaluation of regional soil water retention (SWR) characteristics for soils in Central India
Published in Journal of Applied Water Engineering and Research, 2020
R. K. Jaiswal, J. V. Tyagi, R. V. Galkate, A. K. Lohani
The soil water retention is one of the important hydraulic properties of soil that governs availability of water for plant growth, chemical and water transport in the subsoil. The soil water retention depends primarily on soil texture, bulk/dry density and organic matter present in the soil. To plan the optimal supply of water for irrigation in the command, the knowledge of field capacity, wilting point and distribution of moisture retention are important but these are overlooked in the management part. In the study, detailed soil analysis for textural and other soil properties on seventeen sites have been carried out in two adjoining commands (Benisagar and Rangawan reservoirs) of Central India to fit sixteen PTF based and five analytical SWC models. The analysis suggested that the soils in these commands can be classified into two broad groups for soil water retention. The analytical model of Durner, 1994 (A-DB) performs more closely with observed data on each site and in regional analysis. In the analysis, two regional analytical and PTF based equation have been given for the development of SWC in the commands. This study suggests that in the absence of measured data, PTF based models using soil physical properties can be used for irrigation planning and nutrient transport in the region.
Evaluating the status of phytochemicals within Catharanthus roseus due to higher metal stress
Published in International Journal of Phytoremediation, 2021
V. Soumya, A. Sowjanya, P. Kiranmayi
The presence of heavy metals (viz. arsenic, lead, nickel, chromium, cadmium, copper, zinc, iron and mercury) was tested in all the soil samples (Table 2). The maximum and minimum contamination was found in the soil sample collected from Shipyard and Garden respectively. Other physiochemical properties were similarly recorded and tabulated (Table 2). All the observed soil samples, indicated colors that belonged to the Yellow-Red (YR) category of Munsell’s color chart showing varying range of darkness. The observed colors of the soil are usually a result of its composition like the amount of organic matter, moisture or metals. While calculating the organic matter and moisture content in the soil samples, it was found that both the parameters were consistent within each sample, showing highest percentage in soil collected from garden, followed by HPCL, pharmacy, steel plant, dockyard, shipyard in the order. Soil samples with larger amounts of organic matter held more moisture than soils with lower organic matter, indicating a direct proportionality between soil water retention and organic content. Adequate moisture improves organic matter decomposition within soil. The texture of the soil sample depended on the ratio of different sizes of particles present in it. All the observed soil samples had greater ratio of silt when compared to other soil particles. Samples with greater silt and clay had greater moisture content as well, indicating good water retention and air circulation for plants to thrive in silty soil. While measuring the pH and electrical conductivity, it was observed that as the pH went down closer to being neutral, the EC decreased, indicating that EC in soil solution is related to the number of ions available to plants in the root zone. The highest EC was observed in soil collected from garden and the lowest in shipyard. The soils with higher basicity had higher electrical conductivity.
A hyperspectral detection model for permeability coefficient of debris flow fine-grained sediments, Southwestern China
Published in International Journal of Digital Earth, 2023
Qinjun Wang, Jingjing Xie, Jingyi Yang, Peng Liu, Dingkun Chang, Wentao Xu
Soil porosity, the percentage of soil pores in unit volume, is the place for soil water movement and storage, and the key factor influencing soil permeability. Detailed steps of the porosity measurement experiment can be seen in Wang et al. (2022a).