红壤性水稻土Eh动态变化及其影响因素初探

The dynamic change of Eh of reddish paddy soil and the preliminary study of its impact factors

通过田间原位测定长期定位试验20cm和80cm地下水位下3种施肥处理水稻土氧化还原电位值(Eh值),阐明已培肥红壤性水稻土晚稻生长期间Eh的动态变化,并初步探讨影响水稻土Eh变化的主要因素。研究结果表明,在晚稻生育期间,各处理Eh变化趋势一致,基本上在水稻生长返青期处于最低水平,分蘖初期和分蘖盛期、拔节抽穗期、扬花期和灌浆期处于较低水平且变幅较小,至烤田期排水落干,Eh出现明显增幅;其中,在淹水期和烤田期,供试土壤Eh平均值分别在-144.79^-107.05mV和140.27~372.60mV之间。方差分析结果表明,观测时期(组内效应)对Eh变化有显著意义,表明影响水稻土Eh的众因素变化较大,在不同时期对Eh的综合影响显著不同。水分是决定Eh变化的关键因素,土壤水分与水稻土Eh有极显著的负相关性(r=-0.364^(**),n=126),且水位对水稻土Eh变化影响显著(p<0.05),水位越低,Eh越高,低水位处理Eh值平均高出高水位处理Eb值37.4%左右,且水位对水稻土Eh的影响较稳定。施肥对整个生育期Eh变化也有显著影响(p<0.05),但施肥对Eh的影响不稳定,仅在返青期、分蘖初期和烤田期对Eh变化起显著作用,有机肥能降低返青期至分蘖初期水稻土Eh。高、低水位下3种施肥处理在晚稻不同生育期近根点Eh均值均大于远根点,表明水稻根系能小幅提高水稻土Eh值。此外,Eh变化与5cm处土温显著相关,而土壤有机碳对Eh变化的影响因被有机肥掩盖,二者之间相关性不显著。

The oxidation reduction potential （Eh） of three kinds of fertilization paddy soil under high （20 cm） and low （80 cm） underground water level in a long-term fertilization experiment was on-site measured to clarify the paddy soil Eh dynamics during the late rice growing period and preliminarily explore the main factors that effect paddy soil Eh. The results indicated that the Eh variation tendencies of all treatments were similar, which reached the lowest level in the turning-green stage, being low level and small variation in the early tillering stage, tillering stage, jointing stage, flowering stage and filling stage, finally significantly increased until the roast field stage; the tested soil Eh average value during the flooding period and roast field peri- od were respectively between - 144. 79～ - 107.05 mV and 140. 27 ～372. 60 mV. Repeated anova analysis showed that the observation period （group effect） had significant effect on Eh, which showed that the change of factors which influencing paddy soil Eh was drastic and their effects on Eh were significantly different in different periods. The test results showed that moisture was the key factor that determined change of Eh, soil water and soil Eh was significantly negative correlated （r= -0. 364, n = 126）, and the ground water level of paddy soil had significant effect on Eh change （p 〈0. 05）. The lower the water level, the higher the Eh, the Eh of low ground water level treatments were about 37.4% higher than those of the high ground water level treatments, and the influence of ground water level on Eh was relatively stable. The effect of fertili- zation also had a significant effect on Eh during whole growth period （ p 〈 0.05）, but the influence of fertilization on Eh was unstable, which had significant effect on Eh change only at the turning-green stage, early tillering stage and roast field stage; organic fertilizer reduced the soil Eh during the turning-green period and early tillering stage. The near-root Eh was greater than far-root Eh in all treatments at different growth stages of the late rice, indicating that rice root could slightly increase the paddy soil Eh. In addition, changes in Eh was significantly related with soil temperature in 5 cm depth and had no significant correla- tion with soil organic carbon content with the masking of organic fertilizer.