添加玉米和水稻秸秆对淹水土壤pH、二氧化碳及交换态铵的影响

通过温室土壤培养试验，研究了不同添加量玉米和水稻秸秆对淹水土壤pH、CO₂及交换态铵的影响.结果表明：在接近中性的土壤中加入秸秆可使土壤pH值降低，4 g·kg^-1玉米和水稻秸秆处理的土壤pH值均与对照差异显著（P＜0.05），而1 g·kg^-1玉米和水稻秸秆处理与对照差异不显著（P＞0.05）.土壤溶液中的CO₂含量随秸秆添加量的增加而增大，1 g·kg^-1玉米和水稻秸秆处理的土壤溶液CO₂含量最大值分别为35.9％和31.9％（v/v），与对照（25.8％）差异达显著水平（P＜0.05），但两者间差异不显著（P＞0.05）；4 g·kg^-1玉米和水稻秸秆处理的土壤溶液CO₂含量最大值分别为54.2％和41.8％（v/v），与对照差异极显著（P＜0.01），两者间差异也达显著水平（P＜0.05）.在不施氮肥的情况下，添加秸秆可降低土壤铵态氮浓度，且铵态氮浓度随秸秆添加量的增加而降低，不同添加量处理间差异显著（P＜0.05）；在施入氮肥的情况下，1 g·kg^-1玉米和水稻秸秆处理提高了土壤铵态氮浓度，而4 g·kg^-1玉米和水稻秸秆处理降低了土壤铵态氮浓度.无论是否施入氮肥，玉米和水稻秸秆处理的土壤铵态氮浓度差异不显著（P＞0.05）.

Effects of maize and rice straw amendment on the pH, CO2, and exchangeable NH4+ of submerged soil.

A greenhouse incubation test was conducted to study the effects of amendment with different amounts of maize and rice straws on the soil pH, CO2, and exchangeable NH4+ under continuous flooded condition. The results showed that in a near-neutral soil, straw amendment could decrease soil pH, with a significant difference (P < 0.05) between the treatments of 4 g straws x kg(-1) and control (CK), but no significant difference (P > 0.05) between the treatments of 1 g straws x kg(-1) and CK. The CO2 content in soil solution increased with increasing rate of straw amendment, with the peak value being 35.9% and 31.9% (v/v) in the treatments of 1 g maize straw x kg(-1) and 1 g rice straw x kg(-1), respectively. These two treatments had significantly higher CO2 contents (P < 0.05) than CK, but no obvious difference between themselves (P > 0.05). In treatments 4 g maize straw x kg(-1) and 4 g rice straw x kg(-1), the peak value of CO2 content was 54.2% and 41.8% (v/v), respectively, being significantly higher than that of CK (P < 0.01), and significantly different between themselves (P < 0.05). Under non-N fertilization, soil NH4+-N concentration decreased after straw amendment, and the increase of the amendment rate caused a further decrease of soil NH4+-N concentration, with a significant difference (P < 0.05) between the doses of 1 and 4 g straw x kg(-1). Under N fertilization, soil NH4+-N concentration increased after 1 g straw x kg(-1) amendment, but decreased after amendment with 4 g straw x kg(-1). No significant differences were observed between maize straw and rice straw amendment regardless with or without N fertilization (P > 0.05).