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闽北地区不同类型茶园土壤硒赋存形态特征及影响因素分析

Selenium Contents and Forms in Soils at Tea Plantations of Different Soil Types in Northern Fujian

  • 摘要: 为探讨闽北典型茶园土壤中硒形态特征,采集了闽北地区4个主要土壤类型(黄壤、红壤、潮砂土、紫色土)的35份茶园表层土壤(0 ~ 20 cm),分析土壤中硒含量、赋存形态及影响因素。结果表明:闽北地区35份茶园土壤全硒含量为0.22 ~ 1.07 mg·kg-1,均值为0.59 mg·kg-1,达到富硒土壤标准(> 0.4 mg·kg-1)比例茶园占82.86%;土壤硒活化率均值为8.34%,土壤中硒的有效度较低。不同土壤类型中以黄壤茶园土壤全硒及各形态硒含量最高,潮砂土含量硒含量最低,但其茶园土壤硒活化率最高。茶园土壤硒形态分布规律表现为有机结合态>残渣态>可交换态及碳酸盐结合态>铁锰氧化物结合态>可溶态,土壤硒的生物有效性较低。相关分析表明,茶园土壤硒形态总体受土壤有机质、氮素形态及pH的影响,土壤有效磷与土壤全硒、有机结合态和残渣态硒之间呈显著或极显著正相关,土壤铁锰氧化物结合态硒与土壤理化性质之间相关性均不显著。总体而言,该区域茶园富硒土壤为发展天然富硒茶提供了物源保证,但硒生物有效性不高,如何提高硒生物有效性还有待进一步研究。

     

    Abstract: Distribution of available selenium (Se) in soils at tea plantations of different soil types in northern Fujian province was determined to analyze the factors that contributed to the variations. Thirty-five specimens of surface soil at the depth of 0-20 cm from tea plantations of yellow soil, red earth, moisture sandy soil, and purple soil types in the region were collected. The chemical analysis showed that the total Se contents of the soils ranged from 0.22 mg·kg-1 to 1.07 mg·kg-1 with an average of 0.59 mg·kg-1. A great majority of the area soil, i.e., 82.86%, belonged to the Se-rich classification. The availability of Se, however, was low, ranging from 1.10% to 31.64% with a mean of 8.34%. Among the different soil types, the yellow soil was the highest in contents of total and various forms of Se, while the sandy soil lowest but most available for plant utilization. The contents of various forms of Se were lower in the order of organic matter-bound Se > residual Se > exchangeable and carbonate-bound Se > iron and manganese oxides-bound Se > soluble Se. The chemical form was critically affected by the organic matters, pH, and nitrogen in the soil with significant positive correlations between available phosphate and total Se and between organic matter-bound Se and residual Se. On the other hand, there were no significant correlations between iron or manganese oxides-bound Se and soil physiochemical properties. In general, the soil in the region was rich in Se for tea cultivation, but the relatively low availability of the element deterred the potential benefit. Hence, improving Se bioavailability at the tea plantations would be a most desired task facing the scientists and industry.

     

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