粤北低山坡地营造梯田对土壤磷组分及有效性的影响

Effect of Terracing in Low Mountain Sloping Land on the Components and Availability of Soil Phosphorus in Northern Guangdong

【目的】探明粤北低山坡地营造梯田对土壤磷形态分布特征和有效性的影响。【方法】选择该区域花岗岩发育的自然林地(FL)、旱作梯田(UT)和稻作梯田(PT)土壤为对象,对土壤剖面不同土层理化性质、磷组分含量及有效性进行测定。【结果】与自然林地FL相比,旱作梯田UT和稻作梯田PT土壤0-20 cm土层有效磷和磷活化系数(PAC)明显增加,以PT最高;3种利用方式土壤有机磷(OP)和无机磷(IP)在剖面中总体表现为“C”字型变化趋势,且均以表层土壤含量最高;与FL相比,UT和PT土壤以IP为主,Fe-P和O-P所占比例较高,其中O-P的比例从7.69%-13.58%上升到22.97%-41.96%;通径分析和冗余分析结果显示,OP是该区域土壤磷有效性的敏感磷源,而游离铁和有机碳是驱动土壤磷组分转化的关键性因子。【结论】粤北低山坡地营造梯田改变了磷在土壤剖面中的分配格局,提高了磷的有效性,也增加了土壤无效态磷的比例。

【Objective】The study was conducted to explore the effect of terracing in low mountain sloping land on the distribution characteristics and availability of soil phosphorus in northern Guangdong.【Method】The forest land(FL),dry land terrace(UT)and paddy terrace(PT)soils developed from granite in this area were selected as research objects,and the physicochemical properties,phosphorus content and availability of different soil layers in the soil profile were determined.【Result】Compared with FL,available phosphorus and phosphorus activation coefficient(PAC)of UT and PT 0-20cm soil increased significantly,and PT soil had the highest value.Soil organic phosphorus(OP)and inorganic phosphorus(IP)of three land uses in the profile showed a C-shape trend,and those of topsoil were the highest.Compared with FL,UT and PT soils were dominated by IP,and Fe-P and O-P accounted for higher proportion.The proportion of O-P increased from 7.69%-13.58%to 22.97%-41.96%.The results of path analysis and redundancy analysis showed that OP was sensitive phosphorus for the availability of soil phosphorus in this area,and free iron and organic carbon were the key factors to drive the conversion of soil phosphorus components.【Conclusion】The terracing in low mountain sloping land in northern Guangdong changed the distribution pattern of phosphorus in the soil profile and increased the availability of phosphorus and the proportion of soil ineffective phosphorus.