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661.
D. E. Walling A. L. Collins H. M. Sichingabula G. J. L. Leeks 《Land Degradation u0026amp; Development》2001,12(5):387-415
In many developing countries, the management of sediment‐related environmental problems is severely hampered by a lack of information on sediment mobilization and delivery in river basins. The sediment budget concept represents a valuable framework for assembling such information, which can, in turn, be used to assist with the design and implementation of soil erosion and sediment control policies. However, the information necessary to construct a catchment sediment budget is difficult to assemble. Against this background, an integrated approach to establishing a catchment suspended sediment budget, involving a river monitoring station, the use of 137Cs measurements to estimate soil erosion and deposition and floodplain accumulation rates within the catchment, and sediment source fingerprinting, has been developed and tested in the 63 km2 catchment of the upper Kaleya River in southern Zambia. The approach developed not only provides detailed information on individual components of the suspended sediment delivery system, but also permits the establishment of the overall catchment sediment budget. A sediment budget for the upper Kaleya catchment is presented and both its key features and its wider implications for catchment management are discussed. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
662.
Yasuo Kitagawa 《Soil Science and Plant Nutrition》2013,59(4):321-324
Many scientists have attempted to discern the chemical composition and the structure of allophane (2, 4–6). Yoshinaga (7) presented the chemical composition of eighteen samples of pure allophane in detail, and concluded as follows: All samples consisted principally of silica, alumina, and water. The silica-alumina molecular ratio ranged from about 1.3 to 2. Molecular ratios of ignition loss (+H20) and total water (±H2O) to alumina were nearly constant, with the averages about 2.5 and 5.7, respectively. The chemical composition of soil allophane fell into a relatively narrow range, and the change in the percentage composition of the three major elements had a regularity. 相似文献
663.
《Communications in Soil Science and Plant Analysis》2012,43(6):763-780
Artificial neural networks (ANN) and adaptive neuro-fuzzy inference systems (ANFIS) provide an alternative by estimating soil parameters from more readily available data. In this article, multilayer perceptron (MLP) and radial basis function (RBF) of ANN and ANFIS models were described to estimate soil cation exchange capacity and compared to traditional multiple regression (MR). Moreover, to test the accuracy of previous functions that estimate cation exchange capacity (CEC), five pedotransfer functions (PTFs) were surveyed. The results showed that the accuracies of ANN and ANFIS models were similar in relation to their statistical parameters. It was also found that ANFIS model exhibited greater performance than RBF, MLP, MR, and PTFs to estimate soil CEC, respectively. Finally, sensitivity analysis was conducted to determine the most and the least influential variables affecting soil CEC. The performance comparisons of used models showed that the soft computing system is a good tool to predict soil characteristics. 相似文献
664.
Asia Nosheen Humaira Yasmin Rabia Naz Asghari Bano Rumana Keyani Ishtiaq Hussain 《Soil Science and Plant Nutrition》2018,64(4):520-525
Effective management of the nutrients and enzyme activity in the soil is necessary for maximum crop growth and productivity. However, the excessive use of chemical fertilizers (CFs) not only adversely affects the soil nutrient status and soil physicochemical properties but also aids pollution to the ecosystem. The objective of present study was to investigate the effect of single as well as combined applications of phosphate-solubilizing bacteria and agrochemicals on important soil enzyme activities and their impact on the growth of kasumbha (safflower). Pseudomonas putida (P. putida;106 cells/mL) was applied as seed inoculation prior to sowing, and CFs were applied as full, half, and quarter doses during sowing to modulate the growth of kasumbha host plants. P. putida in combination with half dose of CFs (PH) increased the soil urease and phosphatase activities, while P. putida combined with quarter dose of CFs (PQ) augmented the soil invertase activities. Moreover, the PQ treatment exhibited the maximum colony-forming units of P. putida. Leaf chlorophyll, carotenoids, protein contents, and root lengths were increased by PH treatment. Whereas, shoot length and leaf area were improved by PH and PQ treatments, respectively. Leaf protease activity was enhanced by P. putida in combination with full dose of CFs and PQ treatments, while leaf phosphate contents were significantly improved by PQ treatment. It can be concluded that P. putida in combination with half as well as quarter doses of CFs is a promising approach for the improvement of soil enzyme activities and growth of kasumbha and replacing 50% of the use of CFs. 相似文献
665.
Wei-wei ZHANG Xiao-ying ZHAN Shu-xiang ZHANG Khalid Hamdan Mohamed Ibrahima Ming-gang XU 《农业科学学报》2019,18(3):667-676
The concentration of soil Olsen-P is rapidly increasing in many parts of China, where P budget(P input minus P output) is the main factor influencing soil Olsen-P. Understanding the relationship between soil Olsen-P and P budget is useful in estimating soil Olsen-P content and conducting P management strategies. To address this, a long-term experiment(1991–2011) was performed on a fluvo-aquic soil in Beijing, China, where seven fertilization treatments were used to study the response of soil Olsen-P to P budget. The results showed that the relationship between the decrease in soil Olsen-P and P deficit could be simulated by a simple linear model. In treatments without P fertilization(CK, N, and NK), soil Olsen-P decreased by 2.4, 1.9, and 1.4 mg kg~(–1) for every 100 kg ha~(–1) of P deficit, respectively. Under conditions of P addition, the relationship between the increase in soil Olsen-P and P surplus could be divided into two stages. When P surplus was lower than the range of 729–884 kg ha~(–1), soil Olsen-P fluctuated over the course of the experimental period with chemical fertilizers(NP and NPK), and increased by 5.0 and 2.0 mg kg~(–1), respectively, when treated with chemical fertilizers combined with manure(NPKM and 1.5 NPKM) for every 100 kg ha~(–1) of P surplus. When P surplus was higher than the range of 729–884 kg ha~(–1), soil Olsen-P increased by 49.0 and 37.0 mg kg~(–1) in NPKM and 1.5 NPKM treatments, respectively, for every 100 kg ha~(–1) P surplus. The relationship between the increase in soil Olsen-P and P surplus could be simulated by two-segment linear models. The cumulative P budget at the turning point was defined as the \"storage threshold\" of a fluvo-aquic soil in Beijing, and the storage thresholds under NPKM and 1.5 NPKM were 729 and 884 kg ha~(–1)P for more adsorption sites. According to the critical soil P values(CPVs) and the relationship between soil Olsen-P and P budget, the quantity of P fertilizers for winter wheat could be increased and that of summer maize could be decreased based on the results of treatments in chemical fertilization. Additionally, when chemical fertilizers are combined with manures(NPKM and 1.5 NPKM), it could take approximately 9–11 years for soil Olsen-P to decrease to the critical soil P values of crops grown in the absence of P fertilizer. 相似文献
666.
Franz Schulz Christopher Brock Harald Schmidt Klaus-Peter Franz 《Archives of Agronomy and Soil Science》2013,59(3):313-326
In 1998, the Organic Arable Farming Experiment Gladbacherhof (OAFEG) was started in order to explore the impact of different organic arable production systems (mixed farming, stockless farming with rotational ley, stockless cash crop farming) and of different tillage intensities (conventional plough as a full inversion tillage, two-layer plough, inversion tillage at reduced depth, non-inversion tillage) on sustainability parameters. In this article, we present results on the development of soil organic matter (SOM) levels. Starting with organic mixed farming with approximately 0.7 livestock units (LU) per ha cattle before set-up of the experiment, only the mixed farming system in the experiment was able to maintain SOM levels. The stockless system with ley maintained soil organic carbon (SOC), but lost soil total nitrogen (STN), and the stockless cash crop system had a significant SOM loss in the magnitude of 7.7 t SOM ha?1, or roughly 8.4% of the initial SOM mass. Reducing tillage intensity had no impact on SOM masses, but only on organic matter stratification in soils. We conclude that specialization of organic farms towards stockless arable crop production requires special attention on SOM reproduction to avoid detrimental effects. Further, reduced tillage intensity does not necessarily have a positive effect on SOM. 相似文献
667.
水土保持监理制度在水电工程建设中所起到的作用不可或缺,然而,限于诸多因素制约,水土保持监理制度如何有效实施、监理工作如何顺利开展,目前并无成熟方案形成。通过水电工程水土保持监理实例,总结实施水土保持监理的一些体会,并提出相应建议。 相似文献
668.
Catchments dominated by meltwater runoff are sensitive to climate change as changes in precipitation and temperature inevitably affect the characteristics of glaciermelt/snowmelt, hydrologic circle and water resources. This study simulated the impact of climate change on the runoff generation and streamflow of Chu River Basin(CRB), a glacierized basin in Central Asia using the enhanced Soil and Water Assessment Tool(SWAT). The model was calibrated and validated using the measured monthly streamflow data from three discharge gauge stations in CRB for the period 1961–1985 and was subsequently driven by downscaled future climate projections of five Global Circulation Models(GCMs) in Coupled Model Inter-comparison Project Phase 5(CMIP5) under three radiative forcing scenarios(RCP2.6, RCP4.5 and RCP8.5). In this study, the period 1966–1995 was used as the baseline period, while 2016–2045 and 2066–2095 as the near-future and far-future period, respectively. As projected, the climate would become warmer and drier under all scenarios in the future, and the future climate would be characterized by larger seasonal and annual variations under higher RCP. A general decreasing trend was identified in the average annual runoff in glacier(–26.6% to –1.0%), snow(–21.4% to +1.1%) and streamflow(–27.7% to –6.6%) for most of the future scenario periods. The projected maximum streamflow in each of the two future scenarios occurred one month earlier than that in the baseline period because of the reduced streamflow in summer months. Results of this study are expected to arouse the serious concern about water resource availability in the headwater region of CRB under the continuously warming climate. Changes in simulated hydrologic outputs underscored the significance of lowering the uncertainties in temperature and precipitation projection. 相似文献
669.
穆棱县拍卖“五荒”加快水土流失治理的调查报告郭廷辅,佟伟力,刘家仁,庞志桐（北京水利部水土保持司,１００７６１）（黑龙江省水利厅）编者按：拍卖“五荒”（荒山、荒地、荒滩、荒草、荒水）使用权,加快水土流失治理,挖掘水土资源的生产潜力,既是农村深化改革的... 相似文献
670.
Rawan MLIH 《干旱区科学》2016,8(1):77-92
Countries in the Middle Eastern and North African(MENA) region are among the most water-scarce regions in the world, and their dryland soils are usually poor in organic carbon content(<0.5%). In this study, we summarize examples of how people in the few oases of the MENA region overcome environmental challenges by sustainably managing economically important date production. On the basis of the limited studies found in the existing literature, this mini-review focuses on the role of traditional soil organic matter amendments beneath the soil surface as a key tool in land restoration. We conclude that soil organic matter amendments can be very successful in restoring soil water and preventing the soil from salinization. 相似文献