长期深窄沟排渍对冷浸田地下水位、土壤化学特性及水稻籽粒品质的影响

Effects of long-term drainage of stony open deep-narrow drainage ditches on groundwater level, soil chemical characteristics and rice grain quality in cold-waterlogged paddy fields

  • 摘要: 以福建省顺昌县持续运行约30年的石砌深窄沟为平台, 连续3年监测长期深窄沟排渍对冷浸田地下水位、土壤化学特性及水稻籽粒品质的影响。结果表明, 距沟75 m(CK)、25 m、15 m、5 m的冷浸田的土壤类型逐渐呈现由深脚烂泥田→浅脚烂泥田→青泥田→青底灰泥田的方向演变。距沟75 m、25 m、15 m、5 m位点的常年平均地下水位分别为5.0 cm、8.3 cm、 5.4 cm、 16.7 cm, 其中距沟5 m位点地下水位常年变幅为 62~13 cm, 变幅最大。距沟越近, 耕层土壤还原性物质则越低, 而碱解氮、速效磷与速效钾则越高, 其中距沟5 m的还原性物质总量较CK平均降低62.6%, 而碱解氮、速效磷和速效钾平均分别增加40.7%、38.8%和184.5%。距沟5 m、15 m与25 m位点的水稻籽粒氨基酸含量均显著高于CK。籽粒氨基酸含量与土壤还原性物质呈显著负相关, 而与土壤碱解氮、速效磷等显著正相关, 籽粒淀粉含量也与土壤活性还原性物质呈显著负相关。长期深窄沟排水改善了土壤理化性状, 提高了籽粒氨基酸品质。石砌深窄沟对15 m以内的土壤脱潜效果明显。

     

    Abstract: Cold-waterlogged paddy fields across Jiangnan rice-growing regions belong to low-yield paddy fields. The main characteristics of these paddy fields include low soil temperature, high reducing agents and bad soil structure. However, the fields have the potential to significantly increase paddy rice yields. A 30-year stony open deep-narrow drainage ditch system in Shunchang County, Fujian Province, was investigated for its effects on groundwater level, soil chemical characteristics and rice grain quality in cold-waterlogged paddy fields using a consecutive 3-year monitoring. The results showed that soil conditions in paddy fields 75 m, 25 m, 15 m and 5 m from the ditches were deep-foot mud, shallow-foot mud, blue mud and blue-bottom mud, respectively. The groundwater levels in paddy fields 75 m, 25 m, 15 m and 5 m from the drainage ditches were 5.0 cm, 8.3 cm, 5.4 cm and 16.7 cm, respectively. The highest variation in groundwater level (from 62 cm to 13 cm) was in paddy field 5 m from the drainage ditches. The closer the distance to the drainage ditches, the lower the reducing agents and the higher the contents of available N, P and K. Compared with the field 75 m from the drainage ditches (CK), soil reducing agents content at the field 5 m from the drainage ditches decreased by 62.6% while available N, P and K contents increased respectively by 40.7%, 38.8% and 184.5%. At closer distances to the drainage ditches (e.g., 5 m, 15 m and 25 m sites), amino acids content of rice grain were significantly higher than that of CK. Amino acids content of rice grain was significantly negatively correlated with soil reducing agents content, but positively correlated with soil available N and P contents. Starch content of rice grain was also significantly negatively correlated with soil reducing agents content. Soil physiochemical properties and rice amino acids content were improved by long-term drainage of stony open deep-narrow drainage ditches. Soil improving effect was obvious in paddy fields within 15 m distance from stony open deep-narrow drainage ditches.

     

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