陕北风沙区不同植被覆盖下的土壤养分特征

选取了陕北定边县板凳滩风沙区四种典型植被覆盖下的风沙土壤,对其基本养分含量进行了测定。分析不同类型植被覆盖下的土壤养分含量特征、土壤养分含量层次特征以及土壤各层次养分含量之间的相关性,为风沙区土壤生态恢复重建及侵蚀土壤质量的恢复保育提供了科学依据。结果表明:(1)不同植被覆盖下的土壤对有机质、全氮、速效氮、速效磷的保持能力均为:小蒿草>羊草>沙蒿>苦豆子>无植被;对全磷的保持能力,各植被覆盖条件下差异不显著,但小蒿草覆盖下含量最高,羊草最低,且低于无植被;从土壤对全钾的保持能力来看,羊草覆盖下的全钾含量最高,小蒿草最低。(2)不同植被覆盖下的土壤养分含量层次变化除全磷和全钾变化微弱外,土壤有机质、全氮、速效氮、速效磷、速效钾含量均随着土层深度的增加而逐渐下降,且降低速度基本呈现出小蒿草>羊草>沙蒿>苦豆子>无植被。(3)不同植被覆盖下的土壤各层次养分含量之间的相关性以羊草最为密切,大体呈显著中度及以上正相关;沙蒿和苦豆子覆盖下的相关性稍弱,基本呈中度正相关;而小蒿草覆盖下的相关系数正负均有,相关性较为复杂。

Soil nutrient characteristics under different vegetations in the windy and sandy region of northern Shaanxi

The study chose Aeolian sandy soils under four typical vegetations in the Bandeng Beach of Dingbian County in Northern Shaanxi as its subjects and assayed their fundamental nutrients. And by analyzing nutrient content characters in different soil layers under the different vegetations depending on its measurement results of the soil nutrients, it probed into the nutrient patterns in different soil layers underneath the different vegetations as well as the correlations among the nutrient in the different soil layers under the different vegetations so as to provide scientific basis for restoring soil ecologies of sandy lands and rehabilitating and conserving eroded soils. Its results indicated: (1) the capacities of the soils underneath the different vegetations to retain organic matter, total nitrogen, available nitrogen and available phosphorus all ranked in the order of Kobresia pygmaea > Leymus chinensis > Artemisia desterorum Spreng > Sophora alopecuroides L > no vegetation coverage. The capacities of the soils under the different vegetations to retain phosphorus did not significantly differ, but the soil phosphorus content under Kobresia pygmaea was the highest and the soil phosphorus content under Leymus chinensis was the lowes, even lower than that without any vegetation coverage. In light of the capacities of the soils under the different vegetations to retain total potassium the potassium total under Leymus chinensis was the highest, the potassium total under Kobresia pygmaea was the lowest. (2) Under the different vegetations, except for the phosphorous and potassium totals in the different soil layers, which slightly differed, the soil organic matter contents, nitrogen totals, available nitrogen and phosphorus, and potassium contents in the different soil layers gradually decreased as the soil layers went deeper and the rates of their decreases ranked in the order of Kobresia pygmaea > Leymus chinensis > Artemisia desterorum Spreng > Sophora alopecuroides L > no vegetation covering. (3) the nutrients in the different soil layers under Leymus chinensis appeared most closely correlated, moderately at least or significantly positively, the nutrients in the different soil layers under Artemisia desterorum Spreng and Sophora alopecuroide appeared slightly weakly correlated, approximately moderately positively, and the correlation coefficients among the nutrients in the different soil layers under Kobresia pygmaea appeared mixed, positively or negatively correlated.