湖南典型稻作烟区植烟土壤pH和钙镁硫元素垂直分布特征OA

To explore the vertical variation patterns of pH and calcium-magnesium-sulfur elements in tobacco-growing soil in the typical rice-tobacco areas in Hunan Province,representative soil samples were collected from 0 to 50 cm soil layers(divided into 5 layers,10 cm per layer)in three locations:Chenzhou,Hengyang and Changsha.The contents of major soil nutrients were determined,and the deficiency and sufficiency status and vertical distribution characteristics of soil nutrients were analyzed using classical statistical methods.The results showed that in the 0-50 cm soil layer of typical rice-tobacco areas in Hunan Province,the pH(7.48±0.67)and the mass fraction of exchangeable magnesium((300.46±174.34)mg/kg)were relatively high,while the mass fractions of exchangeable calcium((4 914.45±3 325.86)mg/kg)and available sulfur((58.59±21.33)mg/kg),and the calcium-magnesium ratio(19.31±16.55)were extremely high.In the plough layer(0-20 cm),65.00%of the soil had a calcium-magnesium ratio greater than 10,and in the non-plough layer(>20-50 cm),68.89%of the soil had a calcium-magnesium ratio greater than 10,which could easily cause physiological magnesium deficiency in tobacco plants.The pH and the mass fraction of exchangeable magnesium in the non-plough layer of tobacco-growing soil were significantly higher than those in the plough layer,while the available sulfur showed a surface accumulation phenomenon,and the content in the plough layer was significantly higher than that in the non-plough layer.The mass fractions of exchangeable calcium,exchangeable magnesium and available sulfur in the soil were all in a quadratic relationship with pH.When 5.0<pH≤7.0,their mass fractions increased with the increase of pH,but at the condition of pH>7.0,their mass fractions decreased with the increase of pH.Therefore,tobacco production requires controlled use of limestone,alkaline fertilizers and potassium sulfate,and to construct a balanced plough layer to optimize nutrients and produce high-quality tobacco leaves.