连续两年桉树林下间种3种牧草对土壤肥力及地表径流的影响与评价

Effects and Evaluation of Three Pastures Interplanting in Eucalyptus Plantation for Two Consecutive-Years on Soil Fertility and Runoff

采用山毛豆（Tephrosia candida）、184柱花草（Styiosanthes guianensis）和桂牧1号杂交象草（ Pennisetun americanum × Pennlsetum purpureum ）×Pennisetum purpureum cv．Mott在桉树林下间种，间种方式有2种：桉树密度3m×2m，行间问种牧草；桉树密度6m×2m，行间间种牧草。不间种为对照。目的是探索在桉树林下间种牧草后，对桉树林地土壤肥力，地表径流量的影响。经2年试种，与本底调查情况（种植前）相比，种植密度A（3m×2m）林地土壤pH、有机质、全量N、全量P205、速效P和代换性Mg均表现出不同程度的提高，增幅为7．59％～110．00％；土壤A层有机质含量比桉树纯林平均提高14．47％，比本底调查平均提高35．54％。种植密度B（6m×2m）林地土壤pH、有机质、全量N、全量P205、速效P和代换性Mg均表现出不同程度的提高，增幅为2．78％～135．71％；土壤A层有机质含量比桉树纯林平均提高57．45％，比本底调查平均提高36．76％。桉树间种牧草的地表径流量与桉树纯林相比，2年桉树＋桂牧1号模式地表径流量分别降低了30．82％和21．07％。桉树林下间种牧草，不但可增加土壤矿质元素的含量，而且还能促进桉树的生长，减少了水土流失，保护了生态环境。

Such 3 pastures as Tephrosia candida , StyIosanthes guianensis and （ Penniseturn arneri- canu x Pennisetumpurpureurn ） x Penniseturn purpureurn cv. Mort were interplanted in Eucalyptus plantation. After 2 years, compared with baseline survey, soil pH, organic matter, total N, total P2O5, available P and exchangeable Mg increased at different levels, ranging from 7.59% to 110.00 % with the density of 3m x 2m. Content of organic matter in A layer of soil averagely increased by 14.47 % than that of Eucalyptus pure plantation, 35.54 % higher than baseline survey. Soil pH, organic matter, total N, total P2O5, available P and exchangeable Mg increased at different levels,ranging from 2.78 % to 135.71% with the density of 6m × 2m. Content of organic matter in A layer of soil averagely increased by 57.45 % than that of Eucalyptus pure plantation, 36.76 % higher than baseline survey. Compared with pure plantation of Eucalyptus, runoff of 2-year-old Eucalyptus plantation interplanted with （Pennisetun arnericanum × Pennisetum purpureum ） x Pennisetum purpureum cv. Mort decreased by 30.82% and 21.07% respectively. The model of growing pasture in Eucalyptus plantation not only increased the content of soil mineral substance, but also improved the growth of Eucalyptus, decreased soil and water erosion and protected ecological environment.