起垄和施肥对冷浸田土壤氧化还原状况的影响

通过起垄和施肥试验, 研究不同措施对冷浸田土壤氧化还原状况的影响, 以期为冷浸田改良提供数据参考。结果表明, 冷浸田土壤氧化还原电位介于 48.5~ 198.0 mV之间, 远低于正常稻田(450~700 mV)。起垄使0~5 cm土层氧化还原电位有升高趋势, 但使>5 cm土层土壤氧化还原电位降低。冷浸田还原性物质总量变化范围为5.7~15.6 cmol·kg^-1(起垄试验)和7.7~16.0 cmol·kg^-1(施肥试验), 起垄在短期内会提高土壤还原性物质总量, 增施钾肥、锌肥和硅肥会降低土壤还原性物质总量, 而磷肥用量对土壤还原性物质基本无影响。0~25 cm和25~50 cm土层土壤Fe2+含量平均为3 388.92 mg·kg^-1和3 356.39 mg·kg^-1; 起垄60 d后, 土壤Fe²⁺含量随着起垄高度增加而逐渐降低; 与不施肥(CK)、氮磷钾(NPK)处理相比, 施钾量增加20%(NPK₂)、增加硅肥(NPK+Si)和增加锌肥(NPK+Zn)可以大幅度降低土壤Fe²⁺含量; 0~25 cm土层土壤Fe²⁺含量高于25~50 cm土层。 起垄和施肥使冷浸田土壤Mn²⁺含量先降低后升高。

Effect of ridging and fertilization on soil redox in cold waterlogged paddy fields

Soil redox was one of the most important chemical process in cool waterlogged paddy fields that occurred in the entire process of soil development. It importantly influenced the migration and transformation of soil materials and determined biological effectiveness of soil nutrients and contaminants. Soil redox research was still largely lacking in cold waterlogged paddy fields. The effects of ridging and fertilization on the state of soil redox in cold waterlogged paddy fields were analyzed in this study to lay relevant references for improving cold waterlogged paddy soils. An experiment of four ridge treatments [control (CK), ridge height of 10 cm (LG₁₀), 15 cm (LG₁₅), and 20 cm (LG₂₀)] and eight fertilization treatments [CK (without fertilization), NPK (N 180 kg?hm^-2, P₂O₅ 90 kg?hm^-2 and K₂O 120 kg?hm^-2), NP₁K (N 180 kg?hm^-2, P₂O₅ 72 kg?hm^-2 and K₂O 120 kg?hm^-2), NP₂K (N 180 kg?hm^-2, P₂O₅ 108 kg?hm^-2 and K₂O 120 kg?hm^-2), NPK+Zn (N 180 kg?hm^-2, P₂O₅ 90 kg?hm^-2, K₂O 120 kg?hm ^-2 and Zn 0.75 kg?hm^-2), NPK₁ (N 180 kg?hm^-2, P₂O₅ 90 kg?hm^-2 and K₂O 96 kg?hm^-2), NPK₂ (N 180 kg?hm^-2, P₂O₅ 72 kg?hm^-2 and K₂O 144 kg?hm^-2), NPK+Si (N 180 kg?hm^-2, P₂O₅ 90 kg?hm^-2, K₂O 120 kg?hm^-2 and SiO₂ 0.75 kg?hm^-2)] was conducted to study soil redox in cold waterlogged paddy fields. Results showed that soil redox potential was 48.5~ 198.0 mV in cold waterlogged paddy fields, which was far lower than that (450~700 mV) in normal paddy fields. Ridging increased soil redox potential in the top (0~5 cm) soil layer while suppressing it in the lower (5~20 cm) soil layer. Total reductions in cold waterlogged paddy soils were 5.7~15.6 cmol?kg 1 under ridge treatments and 7.7~16.0 cmol?kg 1 under fertilizer treatments. Ridging increased total reduction over the short-term. While applications of potassic, zinc- and silicon fertilizer retarded total reduction, application of phosphate had no effects on total reduction. Average soil Fe²⁺ content was 3 388.92 mg?kg 1 in the 0~25 cm soil layer and 3 356.39 mg?kg^-1 in the 25~50 cm soil layer. About 60 days after ridging, soil Fe²⁺ content decreased with increasing ridge height. NPK₂, NPK+Si and NPK+Zn treatments sharply decreased soil Fe²⁺ content compared with CK and NPK. Ridging and fertilization initially decreased soil Mn²⁺ content and then increased it in cold waterlogged paddy fields.