耕种方式对稻田甲烷排放的影响

Effects of Soil Tillage and Rice Cultivation Pattern on Methane Emission From Paddy Field

通过田间试验研究了稻田2种土壤耕作强度(深翻耕和浅旋耕)和3种水稻栽培方式(直播、抛秧和插秧)下的CH4排放规律,以探讨稻田土壤耕作强度和水稻栽培方式对CH4排放的影响。结果表明,各水稻栽培方式下,深翻耕和浅旋耕稻田CH4排放季节变化趋势一致。土壤耕作强度对稻田CH4季节排放总量的影响受水稻栽培方式的制约:抛秧方式下,浅旋耕与深翻耕处理相比,稻田CH4排放量减少31.37%(P<0.05);而直播和插秧方式下,2者CH4季节排放总量相当。水稻栽培方式显著影响稻田CH4排放季节变化规律:直播稻田CH4排放大致呈现"双峰型"模式,且水稻生育前期CH4排放水平较低;而移栽稻田(抛秧和插秧)CH4排放大致呈现"三峰型"模式,且水稻生育前期CH4排放水平较高。与深翻耕抛秧相比,深翻耕直播和深翻耕插秧稻田CH4排放分别减少23.31%和42.51%;而浅旋耕方式下,3种水稻栽培处理CH4季节排放总量相当。降低土壤耕作强度,以浅旋耕代替深翻耕,可以减少耕作对土壤的扰动,在一定程度上减少稻田CH4排放。与水稻移栽相比,水稻直播能够显著降低水稻生育前期CH4排放,具有一定的CH4减排潜力,但仍需加强中后期田间水分管理。

A field experiment was carried out to study CH4 emissions from rice field as affected by two levels of soil tillage intensity（digging tillage and rotary tillage） and three rice cultivation patterns（direct seeding,seedling throwing and hand transplanting）.Results show that the same in rice cultivation pattern,the tillage intensity treatments,digging and rotary tillage presented the same trend of seasonal variation in CH4 flux.The effect of tillage intensity on total CH4 emission during the rice-growing period depended on rice cultivation pattern： compared with digging tillage,rotary tillage decreased CH4 emission significantly by 31.37% with seedling throwing adopted;and did not have much effect with direct seeding and hand transplanting adopted.Rice cultivation pattern had significant effects on seasonal variation of CH4 flux.The CH4 flux in direct seeding treatment showed roughly a ＂two-peak＂ seasonal variation curve,being relatively low at the early rice growing stage.The CH4 flux in transplanting treatments（seedling throwing and hand transplanting） displayed ＂three-peak＂ seasonal variation curve,being relatively high at the early rice growing stage and reaching the highest level on D12 after rice transplanting.With digging tillage,the total CH4 emissions,regardless of rice cultivation patterns,all increased,but did in the order of seedling throwing 〉direct seeding〉 hand transplanting.With digging tillage,compared with seedling throwing,direct seeding and hand transplanting decreased CH4 emission by 23.31% and 42.51%,respectively;with rotary tillage,total CH4 emission in the three rice cultivation patterns were almost the same.Reducing soil tillage intensity by using rotary tillage instead of digging tillage could reduce disturbance of soil,thereby decreasing CH4 emission from the rice field to some extent.Compared with rice transplanting,rice direct seeding could significantly decrease CH4 emission at the early rice growing stage,which obviously has some potential in CH4 reduction,but field water management needs to be intensified at the middle and late stages of the rice growing season.