Abstract:

To reveal the distribution characteristics of pH values and available potassium (AK) contents in Guizhou tobacco fields with different soil types and guide soil conservation, the thickness of plough layer, the distribution of pH values and AK contents were analyzed in typical tobacco-planting fields in Guizhou, and the changes of pH values and AK contents were evaluated after 30 cm deep ploughing. The results showed that the average thickness of soil plough layer was 18.88 cm, which was generally shallow. The average pH value was 6.21 with anthrosols>argosols>cambosols>ferrosols>primosols, and there was no significant difference among the soil types. The average AK content in soil plough layer was 332.81 mg/kg with argosols>ferrosols>anthrosols>cambosols>primosols, AK in argosols and ferrosols were significantly higher than that in anthrosols and cambosols, and there was no significant difference between argosols and ferrosols, and anthrosols and cambosols. The soil pH value and AK content were defined as three modes: decreasing type, increasing type and uniform type, pH was mainly increasing type (72.21%), and AK was mainly decreasing type (72.21%). After deep ploughing, the pH value increased by 0.12 units on average, and the AK content decreased by 49.43 mg/kg. The thickness of plough layer was generally shallow and acidification phenomenon could be observed, but the AK content was generally high in Guizhou tobacco-planting fields. Different soil types had different pH values and AK contents and the profile distribution characteristics affected the changes of soil pH value and AK content after deep ploughing.

Key words: soil types, soil plough layer thickness, pH, available potassium, soil conservation