长期单施不同量化肥和有机肥后盐化潮土pH和EC的变化

Changes in pH and EC of salinized fluvo-aquic soil after long-term application of chemical or organic fertilizers

【目的】研究长期单施不同量有机肥和化肥对华北平原盐化潮土区土壤pH和EC的影响,以期为本地区科学实施有机肥替代化肥提供数据支撑和理论依据。【方法】本研究以始于2006年的长期定位试验为研究平台,在冬小麦–夏玉米一年两熟种植制度下,有机肥和化肥处理均设置10个氮水平,N 0、60、120、180、240、300、360、420、500和600 kg/hm^2,共计19个处理,监测了连续施用不同量化肥和有机肥10年共20季作物后潮土的EC和pH值。【结果】单施化肥N 60、120、180、240 kg/hm^2的土壤EC分别为232、280、220和258μS/cm,与不施肥处理CK的243μS/cm差异不显著(P> 0.05);化肥氮量为N 300、360、420、500和600 kg/hm^2处理,土壤EC分别为320、403、513、516和570μS/cm,显著高于CK和N 60~240kg/hm^2处理(P <0.05)。10年20季播种作物后,不施肥处理土壤pH基本在7.97上下波动,化肥处理N从60增加到600 kg/hm^2,土壤pH分别为7.96、7.89、7.88、7.85、7.83、7.72、7.53、7.51和7.42,随着肥料用量的增加呈显著降低趋势(P <0.05)。肥料类型对黄淮海地区盐化潮土土壤EC和pH存在显著影响。化肥氮量为N 60、120、180、240 kg/hm^2处理与有机肥氮量N 60、120、180、240处理土壤EC和pH类似,分别相差为9.90、–15.9、26.4、1.76μS/cm和–0.04、0、0.03、0.02,差异均未达显著水平,但随着肥料投入量的增加,差距越来越明显,且与施肥量呈显著线性相关(P <0.05)。化肥N 300、360、420、500、600 kg/hm^2处理比同量有机肥氮处理的土壤EC值分别高42.1、90.5、195、110、188μS/cm,土壤pH分别低0.08、0.09、0.18、0.18、0.14个单位,差异达显著水平(P <0.05)。【结论】在华北盐化潮土上,化肥和有机肥氮投入量不超过240kg/hm^2范围内,连续施用10年20季作物后,均未发现对土壤EC值和pH有不利影响,施化肥和有机肥的土壤EC值和pH差异不显著。然而,氮投入量超过300 kg/hm^2后,等养分化肥土壤EC值显著高于有机肥,pH显著低于有机肥。因此,要提高盐化潮土的养分投入,应控制化肥用量,依靠有机肥投入,维持土壤pH和土壤EC的稳定。

【Objectives】The change trends of soil EC and pH after long term application of chemical or organic fertilizers were studied, to provide data support for the replacement of chemical fertilizer by reasonable proportion of organic fertilizers in North China Plain.【Methods】The long-term experiment, started from 2006, was located in Lingxian Experimental Station, CAAS, where the planting system was winter wheat–summer maize rotation and the tested soil was salinized fluvo-aquic soil. In the experiment, both organic and chemical fertilizers were separately applied in 10 nitrogen(N) rates, including 0, 60, 120, 180, 240, 300, 360, 420, 500,and 600 kg/hm^2. After 10 years and 20 growing seasons, the soil pH and EC were determined.【Results】In treatments of chemical N 60, 120, 180 and 240 kg/hm^2, soil EC values were 232, 280, 220 and 258 μS/cm,respectively, and there was no significant difference with that in treatment of N 0;while in treatments of chemical N 300, 360, 420, 500 and 600 kg/hm^2, those were 320, 403, 513, 516 and 570 μS/cm, respectively, and were significantly higher than those in N 0–240 kg/hm^2. Soil pH in treatments of chemical N 0, 60, 120, 180, 240, 300,360, 420, 500 and 600 kg/hm^2 fluctuated at 7.97, 7.96, 7.89, 7.88, 7.85, 7.83, 7.72, 7.53, 7.51 and 7.42,respectively, showing a significant linear correlation with inorganic N rates. At N level of 60, 120, 180 and 240 kg/hm^2, the difference of soil EC between organic and chemical fertilizer treatments were 9.9,–15.9, 26.4, 1.8μS/cm, and differences in soil pH were negligible. When the N rates were 300, 360, 420, 500 and 600 kg/hm^2,the difference between the two fertilizer treatments were rapidly increased and became significant. The EC values in chemical N treatments were 42.1, 90.5, 195.1, 110.2, 187.5 μS/cm higher than those in organic fertilizers, and p H values were 0.08, 0.09, 0.18, 0.18, 0.14 lower than those in organic fertilizers, respectively.【Conclusions】In North China Plain, long-term low and proper N input rates of chemical fertilizers will not lead to significant change of soil pH and EC values, but higher than 300 kg/hm^2 will increase soil EC and decrease pH significantly,while organic fertilizer will not produce significant variations in all the tested input levels. When the N input is higher than 300 kg/hm^2, the EC values in soils with chemical fertilizers are significantly higher than those with organic fertilizers, while the pH values are lower. So, when high N input is required in the salinized aquic-fluvo soil in North China, organic fertilizers should be considered and chemical fertilizer should be controlled within a reasonable level.