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Effects Of Modifiers On Water And Salt Transport And Cron Growth In Coastal Saline-alkali Land

Posted on:2021-01-17Degree:MasterType:Thesis
Country:ChinaCandidate:X J LiFull Text:PDF
GTID:2370330611953549Subject:Agricultural Soil and Water Engineering
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Coastal saline land is an important land reserve resource,and its improvement is an important way to ease the pressure on agricultural land.Therefore,it is very important to choose the appropriate type of modifier and the amount of application.However,the first issue is to grasp its impact on water and salt transport,and ultimately provide technical support for production and application.To this end,a combination of indoor soil column test and field field test was carried out to carry out a one-dimensional vertical infiltration test with different horizontal treatments,and the relationship between the infiltration characteristics under the condition of modifier and the amount of modifier applied was analyzed;The influence on the parameters of infiltration model and water and salt transport law;analysis of the indoor soil surface evaporation test constant temperature and constant humidity)to establish an evaporation model suiTab.for the application of modifiers in coastal saline-alkali land.To study the influence of the coastal saline-alkali soil on the growth characteristics of corn after applying the modifier,in order to provide a theoretical basis for the coastal saline-alkali land improvement and agricultural development guidance.The main conclusions are as follows:(1)At the same time of infiltration,after the application of humic acid(HA)and sodium carboxymethylcellulose(CMC),the cumulative infiltration volume and infiltration rate both decrease,and are inversely proportional to the application rate.At the same depth of infiltration,the application of both modifiers prolongs the infiltration time,and the time required for infiltration is proportional to the amount applied,indicating that both modifiers have the effect of reducing infiltration.The amount of HA applied had a negative linear relationship with the absorption rate S,and had a positive linear relationship with the overall shape factor ?.When CMC treatment is applied,the absorption rate S and the comprehensive property coefficient ? have a quadratic polynomial relationship with the application rate,and the absorption rate S is negatively correlated with the application amount of the modifier,and the comprehensive property coefficient is inverse.The algebraic model can well calculate the moisture distribution of the soil profile under the conditions of the two modifiers,and the relative error between the calculated value and the measured value is less than 5%.(2)Both HA and CMC have an inhibitory effect on soil evaporation and reduce the accumulation of salt to the surface layer;the amount of modifier application is positively correlated with the average water content;the mathematical model of evaporation can better describe the law of soil water evaporation.As the amount increases,the evaporation model parameter K shows a decreasing trend and has a linear relationship with the amount applied.The application of HA and CMC can promote the leaching of salinity and increase the soil desalination rate.With the increase of the amount of improver,the desalination rate shows an increasing trend;after the application of HA and CMC,the soil organic matter content increases;with the application of HA,the soil pH decreases.(3)After applying HA,the plant height,leaf area,stem thickness,above-ground biomass,etc.all increased,with the increase of the application amount showed an increasing trend;compared with the application of CMC,the increase was more significant.With the increase of the application rate,the corn harvest index showed a trend of increasing first and then decreasing.After the application of humic acid,the inflection point was 25 g/m2,and the CMC inflection point was2 g/m2.(4)The relative change rate of the soil desalination rate,the relative change rate of organic matter,the relative change rate of yield,and the relative change rate of pH under the application of HA are all larger than that of sodium carboxymethyl cellulose.The application rate of humic acid in the range of 277.8?428.6 kg/hm2 can increase the profit,when the application rate is 277.8 kg/hm2,the highest benefit can be obtained.
Keywords/Search Tags:improver, coastal saline-alkali soil, water and salt transport, humic acid, sodium carboxymethyl cellulos
PDF Full Text Request
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