The Effects of Drip Fertigation in Citrus Orchards on Decreasing Soil pH Value
Hamlin sweet orange (Citrus sinensis) trees on Carrizo citrange rootstock were planted in calcareous purple soil with pH values between 7.9-8.3 in the fall of 2000, and their fertigation trial was conducted from 2002 to 2004. The nutrient combinations for fertigation were N, NK or NKP, and the pure N application rates for each tree were 250g, 350g and 450g for 3 consecutive years. For NK or NKP combinations, the pure K and pure P application rates were 80％ and 40％ of pure N, respectively. As to each nutrient combination, annual fertigated applications were made 4 times, 10 times and 16 times, respectively. N(urea) and K(potassium sulphate) were dissolved in irrigation water for fertigation, and P (superphosphate) was single applied in band at 30cm depth in the soil in each late June. At the beginning of each year, drip emitters were relocated to fit the expanded root system. Soil was sampled for pH value test at different depth in Nov. at various distances from the emitters. Results showed that, for most treatments, the pH of soil at 20cm or 5cm distance from the emitters decreased significantly, and the closer to the emitters, the lower of soil pH. For N, NK or NKP treatments, the annual decrease of pH was generally 0. 4 - 0. 5 units for soil at 15 - 85cm depth and 20cm distance from the emitters, and 0.6 0. 8 units for soil at 15 -85cm depth and 5cm distance from the emitters. There was no obvious difference of pH decrease for soil at 15cm to 85cm depth for N treatments. But for NK and NKP treatments, the pH decrease was faster for soil at 15 -45cm than 60 -85cm depth at 5cm distance form the emitters. The pH of soil at 40cm or further distance from the emitters was not affected by fertigation. As the annual amount of fertigated fertilizer increased, the pH of soil showed no trend of proportional decrease, and there was no clear relationship between soil pH decrease and annual feitigation frequency. Soil pH decrease showed no significant differences among N, NK and NKP treatments, and urea has strong acidification effect in calcareous purple soil.
Hamlin sweet orange (C. sinensis) Drip fertigation Calcareous purple soil Acidification pH
Liangzhi Peng Changpin Chun Li Cao Ting Lei
Citrus Research Institute, Chinese Academy of Agricultural Sciences,National Engineering Research Ce Chongqing Citrus Engineering Research Center , Zhongxian ,Chongqing, 404303, P. R. China
国际会议
11th International Citrus Congress(第11届国际柑橘大会)
武汉
英文
932-935
2008-10-01（万方平台首次上网日期，不代表论文的发表时间）