桉—草复合经营模式的土壤理化性质动态及关联分析

Correlation Analysis and Dynamic of Soil Physicochemical Properties under the Eucalyptus-grass Compound Management Models

以桉树（ Eucalyptus spp．）间种牧草桂牧1号杂交象草（ Pennisetum americanum × P． purpureum）× Penn-isetum purpureum）、山毛豆（ Tephrosia candida）和柱花草（ Stylosanthes guianensis）的6种复合经营模式为处理，以桉树纯林为对照，分别于造林初期、中期和后期，分析桉树人工林间作牧草复合经营模式不同土层土壤理化性质主要因子的变化规律，并运用灰色系统理论方法筛选出对土壤理化性质改良效果较优模式。研究结果表明：同一时期相同土层土壤容重、总孔隙度、毛管孔隙度、田间持水量、有机质、全量氮、磷、钾和速效氮、磷、钾含量在不同模式间的差异均达到显著水平（ P〈0．05）或极显著水平（ P〈0．01）。同一时期，各模式0-20 cm土层的土壤总孔隙度、毛管孔隙度、田间持水量有机质、全氮、速效氮、速效磷和速效钾含量均大于20-40 cm土层，土壤容重则相反。随着造林时期的变化，在相同土层各模式的土壤容重、毛管孔隙度和田间持水量逐渐增加，土壤总孔隙度逐渐减小，而土壤养分含量在不同种植模式不同土层的变化趋势各不相同。桉树（2 m ×3 m）＋山毛豆模式上下层关联度均表现最大，说明A2模式改善土壤物理性质，提高土壤养分含量的综合效果最佳。

Based on 6 kinds of compound management mode about Eucalyptus interplanting grass （ Penn-isetum americanum×P. purpureum ）× Pennisetum purpureum, Tephrosia candida and Stylosanthes guianensis, using Eucalyptus pure forest as control, dynamic of main factors of soil physicochemical prop-erties in different soil layers of Eucalyptus-grass compound management models was analyzed, and the＆amp;nbsp;better model to improve the soil physicochemical properties was selected by the method of gray system. The results showed that during the same period of the same soil layer, the differences of soil bulk density, total porosity and capillary porosity, field capacity, organic matter, total N, P, K and available N, P, K among different models reached significant level （ P 〈 0. 05 ） or extremely significant level （ P〈0. 01） . At the same period, all of the soil total porosity and capillary porosity, field capacity, organic matter, total N, available N, available P and available K of soil layer from 0cm to 20cm were greater than soil layer from 20cm to 40cm, while soil bulk density was opposite. As the change of planting peri-od, soil bulk density, capillary porosity, field capacity of all models at the same soil player were increas-ing, while soil total porosity decreased. Changing trends of the soil nutrient content in the different plant-ing patterns and different soil layers were different. The best model to improve the soil physical properties and soil nutrient content was A2, which was Eucalyptus （2m × 3m） ＋ Tephrosia candida with the high-est upper and lower correlation.