施用土壤pH改良剂对弱碱性荔枝园土壤性质及荔枝生长的影响

Effects of soil pH improver on property of alkalescent soil in litchi orchard and litchi growth

【目的】研究比较不同土壤pH改良剂在弱碱性荔枝园土壤的施用效果,为该类荔枝园土壤pH的改良提供参考依据。【方法】采集四川省泸州市弱碱性荔枝园土壤(pH 7.53±0.10),分别添加硫磺(2 g/kg)、硫酸铝(4 g/kg)和硫铁矿(4 g/kg),以不加改良剂为对照,同时进行土壤培养试验和荔枝盆栽试验,比较不同改良剂对土壤性质及荔枝生长的影响。【结果】培养试验结果表明,施用硫磺能显著降低土壤pH、土壤脲酶活性和碱性磷酸酶活性(P<0.05,下同),显著提高土壤磷、钙、镁、铁、锰和铜等多种元素有效性,且作用持久;施用硫酸铝和硫铁矿降低土壤pH作用不显著(P>0.05,下同)且时效短,对土壤养分及土壤酶活性的影响则与养分和酶的种类有关。盆栽试验结果显示,施用改良剂对移栽230 d后的荔枝叶片光合特性和叶绿素指数均无显著影响,但在移栽300 d后,对照及施用硫酸铝和硫铁矿处理的大部分荔枝植株已逐渐枯死;施用硫磺虽然较对照显著促进荔枝生长,但与移栽时相比,收获时其生物量增量仅为9.55±5.08 g/株,长势仍显著弱于酸性土壤中的荔枝长势。【结论】在弱碱性荔枝园土壤即使施用大量酸性改良剂,其促进荔枝生长的效果也不理想。建议在弱碱性土壤上谨慎规模种植荔枝。

【Objective】The roles of application of different soil pH improvers on properties of alkalescent soil in litchi orchard and litchi growth were compared,with the aim to guide the selection of suitable soil pH improver for alkalescent soil in litchi orchard.【Method】Alkalescent soil(pH 7.53±0.10)collected from Luzhou,Sichuan was used to conduct a soil incubation and a litchi pot experiment simultaneously in the greenhouse.Three soil pH improvers including sulfur(2 g/kg),aluminum sulfate(4 g/kg)and iron purite(4 g/kg)were amended into the soils,respectively.Soils without any improvers were used as the control.The response of soil properties and litchi plant growth to soil improvers were investigated.【Result】The incubation experiment showed that sulfate application significantly and durably decreased soil pH and the activities of soil urease and alkaline phosphatase(P<0.05,the same below),significantly and durably increased the bioavailability of soil phosphorus(P),cadmium(Ca),magnesium(Mg),iron(Fe),manganese(Mn)and copper(Cu).Addition of aluminum sulfate and iron purite did not significantly lowered soil pH(P>0.05,the same below),with a shortterm effect.Moreover,the effect of both soil pH improvers on soil nutrient and enzyme activity was dependent on nutrient and enzyme types themselves.The pot experiment indicated that the addition of all soil improvers did not significantly affect the pho-tosynthesis characteristics and leaf chlorophyll index of litchi at 230 d after transplanting,but most of the litchi plants growing in the control soils and soils amended with aluminum sulfate and iron purite were dead at 300 d after transplanting.Sulfur addition significantly promoted the growth of litchi plants,with the harvested biomass increment of 9.55±5.08 g/plant compared to those at transplanting.However,the plant growth performance in soils applied with sulfur was still significantly worse than those growing in acid soils.【Conclusion】Litchi plants growth promotion effect is not obvious in alkalescent soil even a great amount of soil pH improver is amended.It is suggested that commercial litchi plantation should be carefully considered in alkalescent soil.