Relationships of Zanthoxylum bungeanum yield with topography and soil fertility in Jiulongpo area

The relationships of soil nutrient conditions and topography with production in Jiulongpo Zanthoxylum bungeanum planting areas was studied through a field investigation-based research and lab analysis to provide a theoretical basis for scientific and effective fertilization practices. The characteristics of altitude and slope, and soil pH, organic matter content, macro- and micro-elements content, cation exchange capacity (CEC) and exchange acidity as well as Z. bungeanum yeild in low-, medium and high-yield areas of Z. bungeanum were investigated. The results showed that Z. bungeanum was generally planted at altitudes between 200 and 500 meters in Jiulongpo, and the altitude of the high-yield area was approximately 300 meters. The slope from low-to high-yield areas appeared to be slight increase but not obvious. The soil was acidic, with a pH < 6.5; and soil fertility was high, with large differences in nutrient factors. CEC and available phosphorus, calcium, magnesium, iron, manganese, copper, and zinc were abundant at 27.2 cmol(+)·kg^-1, 35.2 mg·kg^-1, 3 289.8 mg·kg^-1, 271.8 mg·kg^-1, 48.6 mg·kg^-1, 62.1 mg·kg^-1, 1.5 mg·kg^-1, and 4.5 mg·kg^-1, respectively. Organic matter and available nitrogen, potassium and exchange acid were at a moderate levels of 19.1 mg·kg^-1, 114.9 mg·kg^-1, 107.0 mg·kg^-1 and 8.1 cmol(+)·kg^-1, respectively. The content of water-soluble boron was a relatively low 0.28 mg·kg^-1. Z. bungeanum yield exhibited a positive correlation with available calcium, CEC, pH, available manganese, and water-soluble boron. Available calcium, CEC, exchange acidity, and available copper, iron, and zinc were the main influencing factors on yield. An optimal linear regression equation of available calcium (X₆) and yield (Y) was established based on stepwise regression analysis (Y=11.693 + 0.003X₆). In conclusion, soil nutrient in Jiulongpo Z. bungeanum area was imbalanced seriously, more attention should be paid to balancing fertilization, increasing organic fertilizer, improving the physical and chemical properties of soil, and relieving soil acidification.