Study On The Salt-reducing Effect And Appropriate Dosage Of Carbon Regulators On Secondary Saline Soils Dominated By Nitrates

In this paper,the secondary salinized soil in the greenhouse for melon growing was studied through soil investigation,indoor culture and greenhouse test.The effect of carbon regulator on reducing salt in secondary salinized soil and the suitable application rate were investigated.The results are as follows:Soil salinity is dominated by nitrate.Among the salt ions,the anions are mainly NO3-and SO42-,accounting for 46%and 35%of the total anions respectively,and 33%and 25%of the total salt.Cations were mainly Ca2+,accounting for 50%of the total cations and 14%of the total salt content.The other important soil properties are manifested in serious soil eutrophication and acidification,the soil total nitrogen,total phosphorus,available nitrogen,phosphorus,and potassium are all at a very rich level.The pH was 0.7,lower than the open field.The concentration of soluble salt in soil decreased significantly with the increase of carbon regulator.In a certain range,the decreasing range increased with the increase of the amount of carbon regulator.Under the condition of laboratory culture,,the content of soluble salt decreased by 31.8%,compared with the control CK.The effects of carbon regulators on the ions that make up salt are inconsistent.After the addition of carbon regulator,the concentration of potassium ion in cations increases significantly,the concentration of sodium ion increases slightly,and the concentration of calcium and magnesium ion decreases significantly.After the addition of carbon regulator,the nitrate ion decreased significantly,the sulfate increased slightly,and the chloride ion and bicarbonate ion increased significantly.Compared with the control group,the contents of soil pH,organic matter,available phosphorus,and available potassium increased significantly after the addition of carbon regulator,while the effective nitrogen decreased dramatically,which was mainly caused by the continuous transformation of inorganic nitrogen to organic nitrogen under the action of microorganisms.Greenhouse experiment results showed that applying the right amount of carbon regulator can increase significantly the reduced soil salt content,when the dosage of carbon regulator of 7500 kg ha-1(T1),reducing salt effect is significant,followed by 15000 kg ha-1(T2),excessive application of carbon regulator will increase the content of soluble salt in soil.,When the amount of carbon regulator increased to 22500 kg ha-1(T3),the soil salt content of the two sheds increased by 43.1%and 36.0%.The study on the growth process of melon treated with carbon regulator showed that the application of appropriate carbon regulator could promote the growth of the melon seedlings and significantly increase accumulation of nitrogen,phosphorus,and potassium in plants.The application of appropriate carbon regulator was beneficial for the construction of the melon plant and greatly increased final yield;however it was accompanied by the decrease of the sugar content at the same time.Taking economic benefits and quality indexes into consideration,the amount of carbon regulator recommended in this experiment is 7500 kg·ha-1.