琯溪蜜柚园土壤酸化特征研究

【目的】为了研究蜜柚园土壤的酸化特征,从而为蜜柚园土壤改良提供参考依据。【方法】采集福建省平和县319个蜜柚园的土壤样品和25个蜜柚园土壤剖面表土层(0~20 cm)、亚表土层(20~40 cm)和底土层(40~60 cm)的土壤样品,分析了蜜柚园土壤pH值的分布特征、影响蜜柚园土壤酸化的因素和土壤pH值与盐基饱和度和交换性钙、交换性镁含量间的关系。【结果】平和县319个蜜柚园土壤pH值的变幅为3.26~6.22,其平均值为4.34,有89.97%的果园其土壤pH值低于柑橘生长适宜pH值的下限(pH为5.0),其中pH<4.5的强酸性果园占67.71%。25个蜜柚园剖面土壤pH平均值不同土层的高低顺序是表土层>亚表土层>底土层,与表土层土壤的pH值相比,亚表土层和底土层pH<4.5的土壤占比分别提高了50.00%和35.71%。土壤的酸化提高了土壤交换性氢、交换性铝的含量,相关分析结果表明,土壤pH值与土壤盐基饱和度及交换性钙、交换性镁含量间均呈极显著的正相关,说明酸化会减弱土壤的保肥能力,导致土壤钙、镁元素的缺乏。蜜柚园土壤的酸化程度随蜜柚树种植年限、土壤碱解氮含量及氮肥施用量、土壤有效硫含量的增加而降低。【结论】平和县蜜柚园土壤酸化现象严重,且园土亚表土层和底土层的酸化问题较表土层更为突出,氮肥和硫肥的过量施用是引起土壤酸化的原因。鉴于蜜柚园土壤的酸化特性,文中提出了降低果园氮素和硫素的投入、结合果园深翻改土施用碱性土壤改良剂、增施有机肥等防治蜜柚园土壤酸化的措施。

Research on soil acidification characteristics of Guanxi pomelo orchards

【Objective】In order to provide some references for soil improvement in pomelo orchards,soil acidification characteristics of pomelo orchards were studied.【Method】Soil samples from 319 pomelo orchards and from top layer(0-20 cm),middle layer(20-40 cm)and bottom layer(40-60 cm)of 25 soil profiles were collected in Pinghe county,Fujian province,soil pH distribution characteristics,factors affecting soil acidification and relationship of soil pH with salt base saturation,exchangeable Ca content and exchangeable Mg content were analyzed.【Result】Soil pH values in 319 pomelo orchards of Pinghe county are from 3.26 to 6.22,and average pH is 4.34.Soil pH values in 89.97%pomelo orchards are lower than minimum pH(5.0)for citrus growth,and soil pH values in 67.71%pomelo orchards are lower than 4.5.Based on average pH values of soil profiles from 25 pomelo orchards from high to low,order of different soil layer is top layer soil,middle layer soil,bottom layer soil.Compared with top layer soil,soil proportion with pH<4.5 in middle layer soil and bottom layer soil are increased by 50.00%and 35.71%,respectively.Soil acidification increased contents of exchangeable hydrogen and exchangeable aluminum in soil.The results of correlation analysis show that soil pH value is very significantly positively correlated with salt base saturation,exchangeable calcium content and exchangeable magnesium content,indicating soil acidification can reduce soil nutrient preserving capability and result in deficiency of calcium and magnesium in soil.Soil acidification degree in pomelo orchards is increased with increase of planting time length,alkali-hydrolyzable nitrogen content in soil,nitrogen fertilizer application and available sulfur content in soil.【Conclusion】Soil acidification in pomelo orchards of Pinghe county is serious,and acidification of middle layer soil and bottom layer soil is more significant than that of top layer soil.Soil acidification is caused by excessive application of nitrogen fertilizer and sulfur fertilizer.In view of soil acidification characteristics in pomelo orchards,some measures for soil acidification amelioration are put forward,for example,decreasing application of nitrogen and sulfur fertilizers,using alkaline conditioners combined with deep-ploughing and increasing application of organic fertilizer.