The Effect Of Carbon Based Materials On Amending The Salt-affected Soil Of The Yellow River Delta

The Yellow River Delta is an important area for economic development in China.The slight and moderate salt-affected soils are important reserved land resources in Shandong Province.It is difficult to ameliorate the salt-affected soils in the Yellow River Delta due to geographical and anthropogenic factors.It has become an urgent social demand to study the effect of soil amendment on alleviating the salinization obstacles to increase fertility of salinized farmlands and provide scientific and technological support for the sustainable use of land.Aiming at the different salinized farmlands in the Yellow River Delta,this study investigated the effect of different carbon-based ameliorators on the change of soil solution components,the alleviation of salt barriers,the improvement of nutrient retention,and crop absorption through the wheat germination experiment,column leaching experiment,soil incubation experiment,and indoors/outdoors pot experiment.The results would provide theoretical and technical support for ameliorating saline soil in the Yellow River Delta and increasing the agricultural yields.The main findings of this study were shown as the followings:1. The effect of carbon-based materials on amending salinized soils?slight,moderate,and heavy?was preliminarily explored.The results showed that the effects of biochar and peat application on saline soil were different due to the different physio-chemical properties of ameliorators.Biochar increased the content of K⁺in soil solution,promoted the intake of K⁺in wheat seedling,and increased K⁺/Na⁺to reduce the resistance of wheat to salt stress.Peat increased the concentration of Ca²⁺and Mg²⁺in soil solution as well as reduced the sodium adsorption ratio.The changed ion composition of soil solution by peat would drive the occurrence of cation exchange between soil/ameliorator particles and soil solution.Therefore,soil environment was improved and the growth of wheat seedling was promoted.2. The effect of different dosage levels of carbon-based ameliorator application on thesaline soil leaching was studied by simulating the rainfall in summer.The results showed that the carbon-based materials promoted the leaching of soil salt,decreased the sodium adsorption ratio of soil solution,and increased the content of organic matter in the soil.The ameliorator with application dosage of 1%had the best effect on amending saline soil.Na⁺was removed by 79.7%in the soil after leaching with the sodium adsorption ratio reduced by 68.1%.The content of soil organic matter was significantly increased with enhanced K⁺/Na⁺in wheat seedling and salt resistance of wheat.3. The effects of carbon-based ameliorators on nutrient transformation,enzyme activityand nutrient absorption of corn seedlings in different salinized soil were studied through an 81-day soil incubation and maize pot experiment.The results showed that the carbon-based ameliorators could promote the hydrolysis of urea and increase the activity of urease and phosphatase.Urease and phosphatase activities in saline soil reached the maximum on the 8th day of soil incubation.The results of maize pot experiment showed that the appropriate carbon-based ameliorators could increase the content of chlorophyll a or b in maize leaves,raise the content of N in maize,and then promote the accumulation and absorption of N in maize.4. Outdoor pot experiment was carried out under the conditions of ensuring stable or increasing yield.The influence of carbon-based ameliorators on alleviating soil salt barrier,promoting crop growth,improving nutrient utilization efficiency,and increasing yield was comprehensively analyzed and discussed.The results showed that carbon-based ameliorators effectively increased the biomass of maize,promoted the accumulation of nutrients?C,N,and P?,improved the efficiency of fertilizer utilization,and raised the K⁺/Na⁺ratio in maize.Treatment of 75%of conventional fertilization with 3‰of carbon-based ameliorator application had the best effect on saline soil amendment.The total dry biomass of maize at this treatment could still reach the similar weight with that of normal fertilization even by reducing 25%of fertilizer application dosage.The maize had the maximum nutrient absorption as well as the highest fertilizer utilization rate of nitrogen and phosphorus.The results were significant for the achievement of reducing fertilizer application and providing practical help for the improvement of saline soil in the Yellow River Delta.In addition,the ameliorator should be applied with a proper range to avoid the decrease in accumulation of crop biomass.