Effect Of Oyster Shell Soil Conditioner On The Quality Of Guanxi Pomelo

Pinghe County,Fujian Province is the main producing area of the characteristic fruit Guanxi pomelo.In recent years,the problem of acidification of orchard soil has become increasingly serious due to problems such as excessive use of chemical fertilizers and acid rain.Therefore,it is urgent to take a reasonable and effective method to solve it.Fujian is a large province for oyster production.During the processing of oysters,oyster shells,which account for more than80%of their total mass,are usually discarded directly.While oyster shells contain more than90%calcium carbonate,as well as abundant trace elements and some organic matter.Because of the poor solubility of calcium carbonate,the directly use of pulverized oyster shells for applying fertilizer leads acidic soils to harden.After high temperature calcination,the oyster shell can convert part of calcium carbonate into soluble calcium oxide and produce porous structure,which is more beneficial to improve the physical and chemical properties of acidic soil and the quality of the fruit.In this paper,Guanxi pomelo was the experimental object.In addition,the soil conditioner prepared by high temperature calcined oyster shell was used as the test material and carried out field tirial.The test subjects were treated with four treatments:0 kg/plant?CK?,1.25 kg/plant?T1?,2.50 kg/plant?T2?,and 3.75 kg/plant?T3?.The basic composition and microstructure changes of oyster shells before and after calcination were measured by electron microscopy.It was found that the content of CaCO₃ in oyster shells decreased after high temperature calcination.The micropore structure of oyster shell changed obviously and the size of pores was between 2-10?m after calcination.The adsorption of Cd²⁺and Pb²⁺before and after calcination of oyster shells was determined by flame atomic absorption spectrophotometry.It was found that the adsorption of Cd²⁺and Pb²⁺was significantly better than that of uncalcined oyster shells.The physicochemical properties of the soil of Guanxi pomelo were analyzed.Results showed that the oyster shell soil conditioner can improve the physicochemical indicators of the acid soil.Compared with the initial value,the soil pH of T3 was the most significant increased from 3.23±0.13 to 4.62±0.46.The soil bulk density decreased significantly in the T2,from 1.34 g/cm³ to1.11 g/cm³,which decreased by 17.16%;in terms of organic matter content,increased significantly from 16.85 g/kg to 38.68 g/kg,an increase of 168.24%.At the same time,the increase of available potassium content in T2 had the most significant increase from 93.86 mg/kg to 177.20 mg/kg,which increased by 88.79%.The quality index of Guanxi pomelo fruit was determined.Results showed that the oyster shell soil conditioner can increase the soluble sugar content,soluble solid content and vitamin C content of the fruit,and reduce the titratable acid content and the hardness and fracturability of the fruit juice cells.Compared with CK,the soluble sugar content and soluble solid content of T3increased significantly,which were 9.63%and 11.31%respectively;the vitamin C content in the T2 increased significantly,which was 2.21%higher than that in the CK;the titratable acid content,fruit juice cell hardness and fracturability were all the best in the T3,which decreased by15.52%,37.36%and 70.98%,respectively.The above test results showed that after applying the oyster shell soil conditioner to the soil of Guanxi pomelo,the soil was improved from strongly acidic soil to acidic soil,was changed from a tight state to a suitable crop growth state,and the soil nutrient was increased from four levels to three levels.Moreover,it provided an effective solution for improving the quality and flavor of Guanxi pomelo fruit.At the same time,it also provided a practical solution to the problem of environmental pollution caused by the massive accumulation of oyster shells.