基于Nemerow法的森林土壤肥力综合指数评价

Assessment of forest soil fertility using an integrated index based on the Nemerow method

以广西国有大桂山林场用材林林地为研究区域,以土壤pH值、全量氮、全量磷、全量钾、速效氮、速效磷、速效钾、有效铜、有效锌、有效硼和有效铁作为评价指标,利用Nemerow法进行土壤肥力综合评价。结果表明,不同样地土壤养分因子变异系数在5.02%~65.69%。有机质平均值为28.75g/kg,处于中等偏下水平。全量N平均含量为1.64g/kg,速效N为135.5mg/kg,处于中等或中等偏上水平。全量P2O5平均含量为0.82g/kg,速效P为1.5mg/kg,均处于贫乏水平。全量K2O平均含量为23.76g/kg,速效K为51.8 mg/kg,均处于中等偏下水平。大量元素氮磷钾因子可以概括为＂富氮、缺磷、中等钾＂。微量元素方面,有效Zn和有效Fe林地平均含量分别为2.03mg/kg和32.11mg/kg,处于中等水平,有效B和有效Cu平均含量分别为0.18mg/kg和0.41mg/kg,属于贫或极贫水平。大桂山林地土壤肥力综合指数为0.85,桉树、松树林地肥力综合指数分别为0.77和0.82,肥力等级均属于Ⅲ级,杉木林地肥力综合指数为0.90,肥力等级属于Ⅱ级。速效P、有效B、有效Cu均处于贫或极贫水平,是影响研究区域土壤肥力的主要限制因子。

This study evaluated soil fertility in a forest utilized for timer production in Daguishan State Forest Farm using the Nemerow method.Soil pH,organic matter,total N,P and K,available N,P,K,Cu,Zn,B and Fe were selected as indicators.The coefficients of variation of these indicators ranged between 5.02%-65.69%.Organic matter content of the studied soil was moderately low with an average of 28.75g/kg.Similarly,total N and available N were moderate or moderately high with averages of 1.64g/kg and 135.5mg/kg,respectively.However,P was very low with an average P2O5 content of 0.82g/kg and an average available P content of 1.5mg/kg.Average K2O and available K contents were 23.76g/kg and 51.8mg/kg,respectively,moderately low.Soil fertility of the forest could be considered as＂nitrogen rich,low phosphorus and moderate potassium＂.Trace elements were also variable;available Zn and Fe were 2.03 mg/kg and 32.11 mg/kg,respectively,suggesting moderate levels while available B and Cu were 0.18mg/kg and 0.41mg/kg,respectively,indicating low or very low levels.The integrated soil fertility index of Daguishan forest was 0.85.The fertility indices of eucalyptus and pine forests were 0.77 and 0.82,respectively,equivalent to gradeⅢ,while fir forest had a fertility index of 0.90,equivalent to gradeⅡ.It was found that soil fertility of the study area was mainly limited by available P,B and Cu.