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Effects Of Different Modifiers And Irrigation Methods On Saline-alkali Land Improvement And Greenhouse Gas Emissions

Posted on:2020-10-06Degree:MasterType:Thesis
Country:ChinaCandidate:Y ZhangFull Text:PDF
GTID:2370330578956993Subject:Agricultural Soil and Water Engineering
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As an important commodity grain production base in northern China,Hetao Irrigation District is affected by climatic conditions,poor irrigation and drainage,high groundwater level,resulting in serious soil salinization,low soil productivity,and salt stress seriously restricting local agricultural production and ecological sustainable development.In recent years,the implementation of the saline-alkali land comprehensive treatment project is in line with the country's ecological governance principles and policies,and contributes to the high-quality green development of agriculture.At the same time,multiple improvement measures may have a great impact on the farmland ecological environment.This paper aims at revealing the impacts of different improvement measures and irrigation methods on the water and salt transport,crop growth and greenhouse gas emissions of saline-alkali farmland,so that people could find appropriate saline-alkali land improvement technologies.In this paper,moderate salinized soil was used as the research object and field plot experiment was used as the research method.The salinized soil Physicochemical properties and effects of greenhouse gas emissions from farmland under the combined influences of different modifiers(biochar,gypsum,straw,organic fertilizer)and irrigation methods(groundwater drip irrigation,Yellow River flood irrigation)will be analyzed and comprehensively evaluated.With that conclusion we can not only improve the water and soil environment of salinized farmland,but also realize carbon sequestration and emission reduction.Most importantly it can improve economic and social ecological benefits,which provides a theoretical basis for the comprehensive management and resource utilization of salinized farmland in Hetao Irrigation District.The main conclusions are as follows:(1)All soil amendments under different irrigation modes can increase the water content of soil tillage layer in different degrees.The increase effects are more obvious under drip irrigation condition than that under Yellow River water irrigation condition.Deep burial of straw and biochar under different irrigation modes both can increase the soil temperature of tillage laye.C ompared with blank soil,the temperature of biochar and deep buried of straw soil increased by 0.89%?16.31% and 0.45%?18.06% under drip irrigation,respectively.The temperature of biochar and deep buried of straw soil increased by 0.83%?17.86% and 1.66%?19.65% under border irrigation of the Yellow River,respectively.(2)Under drip irrigation,deep burial of straw,gypsum +organic fertilizer and gypsum can effectively reduce soil pH.And irrigation of Yellow River water has less effects on soil pH.Under the conditions of different improvement measures,the effect of salt reduction is obvious in the second year of improvement.Among this there are some phenomenon worth attentions:fields which applied biochar coal,straw deep burial and gypsum under drip irrigation has a greater reduction in salinity;and the accumulation of salt in fields irrigated by Yellow River water is more than that under drip irrigation.These indicate that drip irrigation combined with improver have a better effect on salt leaching and inhibition of surface salt accumulation.Biochar coal and gypsum had significantly increased soil nutrient contents.(3)All amendments can promote the growth of sunflower.And the growth of sunflower under drip irrigation is better than that under yellow irrigation.The yield of sunflower increased by 20%or so in the second year of improvement.(4)The application of biochar coal and gypsum significantly reduced greenhouse gas emission flux and intensity(GHGI),in which the emission intensity under drip irrigation decreased by 1 6.77%-34.93%.(5)In the first year of improvement,the economic benefit is not obvious.In the second year of improvement,all treatments increase the economic benefit,and drip irrigation treatment is better.And the improvement is bigger under drip irrigation treatment.At the same time,straw,gypsum and biochar as wastes had sustainable benefits for resource reuse and ecological environment improvement.Comprehensively considering the combined effects of amendments and irrigation methods on the physical and chemical properties of moderately saline soils,crop growth characteristics and carbon sequestration and emission reduction,applying biochar(22.5t/hm2) and gypsum(37.5t/hm2) under drip irrigation is a better choice.
Keywords/Search Tags:Salinized farmland, Modifier, Irrigation method, Physical and chemical properties of Soil, Carbon sequestration
PDF Full Text Request
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