不同施肥处理对杉木林土壤水源涵养功能的影响

【目的】林地土壤容重、孔隙度、蓄水性指标和土壤渗透性能反映土壤水源涵养功能大小,以连续施肥6 a的杉木林地为研究对象,研究不同处理的氮、磷肥对杉木林地土壤水源涵养功能的影响,为施肥杉木林地科学经营和水源涵养提供依据。【方法】对杉木林地进行不同的施肥处理:CK、N1 (50 kg·hm^-2a^-1)、N2 (100 kg·hm^-2a^-1)、P (50 kg·hm^-2a^-1)、N1P (50 kg·hm^-2a^-1+50 kg·hm^-2a^-1)和N2P (100 kg·hm^-2a^-1+50 kg·hm^-2a^-1)。试验测定了不同深度表层土壤(0~5 cm、5~10 cm和10~20 cm)容重、孔隙度、蓄水性指标和土壤渗透性指标,分析了土壤水源涵养功能与土壤理化性质的相关关系。【结果】1)在0~20 cm土层当中,P和N1P极显著降低了土壤容重(P <0.01),N1P增加了土壤非毛管孔隙度和总孔隙度,P增加了毛管孔隙度和总孔隙度。随着土层深度的增加,土壤容重逐渐增大。2)N1P和N2P显著增加了土壤有机质碳、有效磷、速效钾,但与N2一样降低了土壤pH值。P显著降低了土壤有机质碳、速效钾含量,但增加了有效磷含量。随着土层深度的增加,有机质碳、有效磷、速效钾含量均显著降低,而pH值显著升高。3)P显著增强了5~20 cm土层的持水能力,N1P显著增强了10~20 cm土层的持水能力;在蓄水量当中,P显著增强了0~20 cm土层的最大蓄水量和毛管蓄水量。4)施肥6 a后杉木林土壤初渗率、稳渗率、平均渗透速率和渗透总量比未施肥杉木林土壤上升29.75%,5.45%,20.99%和10.50%。土层分析当中,土壤渗透性均表现为0~5 cm显著高于5~10 cm和10~20 cm土层,且表现为:初渗率>平均入渗率>稳渗率。5)土壤水源涵养功能与土壤容重呈极显著负相关(P <0.01);土壤蓄水性与毛管孔隙度、非毛管孔隙度、总孔隙度呈极显著正相关(P <0.01);速效钾与毛管蓄水量呈极显著负相关(P <0.01),与最大蓄水量呈显著负相关(P <0.05)。pH值与渗透性呈极显著负相关(P <0.01);有机质碳、有效磷、速效钾、孔隙度与渗透性呈极显著正相关(P <0.01)。【结论】综合6种施肥处理分析土壤水源涵养功能与土壤理化性质的相关关系,由此得出施用低浓度氮肥与磷肥,可以有效地提高杉木人工林涵养水源的能力,为该地区杉木林地持续经营提供理论参考。

Effects of different fertilization treatments on soil’s water conservation function of Chinese fir plantation

【Objective】The soil bulk density,porosity,water storage indexes and soil permeability of the forest land reflect the water conservation function of the soil,and the six-year continuous fertilization of Chinese fir forest is taken as the research object to study the effects of different treatments of nitrogen and phosphorus on the water conservation function of Chinese fir forest.The impact will provide a basis for the scientific management of fertilized Chinese fir land and water conservation.【Method】Subtropical Chinese fir plantation was used as the research object,including CK,N1(50 kg·hm^-2a^-1),N2(100 kg·hm^-2a^-1),P(50 kg·hm^-2a^-1),N1P(50 kg·hm^-2a^-1+50 kg·hm^-2a^-1)and N2P(100 kg·hm^-2a^-1+50 kg·hm^-2a^-1)fertilization treatments.Bulk density,porosity,water retention and soil permeability of surface soil at different depths(0-5 cm,5^-10 cm and 10^-20 cm)were measured.The correlation between soil water conservation function and soil physical and chemical properties was analyzed.【Result】1)In the 0^-20 cm soil layer,P and N1P significantly reduced soil bulk density(P<0.01),N1P increased soil non-capillary porosity and total porosity,and P increased capillary porosity and total porosity.With the increase of soil depth,soil bulk density increases gradually.2)N1P and N2P significantly increased soil organic carbon,available phosphorus and available potassium,but reduced soil pH value as N2P significantly reduced the content of soil organic carbon and available potassium,but increased the content of available phosphorus.With the increase of soil depth,the contents of organic carbon,available phosphorus and available potassium were significantly reduced,while the pH value was significantly increased.3)P significantly enhanced the water holding capacity of the 5^-20 cm soil layer,and N1P significantly enhanced the water holding capacity of the 10^-20 cm soil layer.Among the water storage,P significantly enhanced the maximum water storage and capillary water storage in the 0^-20 cm soil layer.4)After six years of fertilization,the initial infiltration rate,stable infiltration rate,average infiltration rate and total infiltration rate of Chinese fir forest soil increased by 29.75%,5.45%,20.99%and 10.50%compared with the soil of Chinese fir forest without fertilization.In the soil layer analysis,the soil permeability of 0-5 cm is significantly higher than that of 5^-10 cm and 10^-20 cm,and it is shown as:initial infiltration rate>average infiltration rate>stable infiltration rate.5)There was a significant negative correlation between soil water conservation function and soil bulk density(P<0.01).Soil water storage was positively correlated with capillary porosity,non-capillary porosity and total porosity(P<0.01).There was a significant negative correlation between available potassium and capillary water storage(P<0.01),and a significant negative correlation between available potassium and maximum water storage(P<0.05).pH value was significantly negatively correlated with permeability(P<0.01).Organic carbon,available phosphorus,available potassium,porosity and permeability were significantly positively correlated(P<0.01).【Conclusion】The correlation between soil water conservation function and soil physical and chemical properties were analyzed based on six fertilization treatments,which can effectively improve the ability of Chinese fir plantations to conserve water,and provide a theoretical reference for the sustainable management of fir forest land in this area.