垄沟覆膜栽培冬小麦田的土壤呼吸

Abstract

通过大田试验研究了垄沟覆膜栽培条件下冬小麦生长过程中土壤呼吸规律。结果表明,垄沟覆膜栽培条件下垄脊土壤呼吸速率高于平作栽培,而垄沟部土壤呼吸速率小于平作。冬小麦生育期内垄脊平均呼吸速率为(2.06±0.44) μmol CO₂·m^-2·s^-1,垄沟为(0.75±0.11) μmol CO₂·m^-2·s^-1,而平作栽培为(1.14±0.20) μmol CO₂·m^-2·s^-1。土壤呼吸季节变化显著,越冬期低,夏季高。不同生育期土壤呼吸日变化规律不同,越冬前和返青期土壤呼吸与土壤温度成正相关,随着土壤温度的升高而增加,呈单峰曲线;拔节期后垄脊部的土壤呼吸日变化明显,呈现双峰曲线;而平作和垄沟的土壤呼吸速率平稳,没有明显峰值。5 cm土壤温度与土壤呼吸之间的相关性最好。在一定范围内(<24-31 ℃),土壤呼吸随着温度的增加而增加,温度过高反而会抑制土壤呼吸速率。土壤呼吸<em>f(R)</em>与5 cm土壤温度之间的关系可以用二次函数表示;5 cm土壤温度<em>T</em>和土壤含水量<em>W</em>的交互效应可用函数:<em>f(R)=a(bT²+cT)(1+d</em>ln<em>(2W)/T)+e</em>表示。垄沟覆膜栽培显著改变了冬小麦田的土壤呼吸作用。;The objectives of this experiment were to study the effects of a plastic mulched-ridges and unmulched furrows (PMRF) cropping system on soil respiration. The experiment field was planted to winter wheat. Soil CO₂ emission was determined with an SR1LP chamber (Qubit Inc., Canada) between October 2010 and June 2011. The data suggested that soil CO₂ emission in the plastic film mulched-ridge (RM) was greater than that in an unmulched, smooth field (FC). Furthermore, CO₂ emission rates from the plastic film-mulched ridges were greater than those from the unmulched furrows (FU). The mean soil CO₂ fluxes were (1.14±0.20) μmol CO₂·m^-2·s^-1 from the unmulched, smooth field, (2.06±0.44) μmol CO₂·m^-2·s^-1 from the plastic film-mulched ridge, and (0.75±0.11) μmol CO₂·m^-2·s^-1 from the unmulched furrow. There were significant seasonal variations in soil respiration. Soil respiration was lowest during the winter when the wheat was in the seedling stage and highest during the summer when the wheat was mature. Diurnal CO₂ emissions from plastic film-mulched ridges, unmulched furrows, and unmulched, smooth fields followed similar patterns during the winter and early spring. Specifically, CO₂ emissions increased during the morning, reached a peak around noon, and then decreased in the afternoon. In contrast, there were differences in diurnal CO₂ emissions among the treatments after jointing stage. There was a double peak in soil CO₂ emission from plastic film-mulched ridges. However, CO₂ emissions from unmulched furrows and unmulched, smooth fields remained steady throughout the day. Soil respiration was significantly correlated with soil temperature at the 5 cm depth. Soil respiration increased as the soil temperature increased from 10 to 24-31 ℃. Soil respiration decreased at soil temperatures >31 ℃. The effect of soil temperature on soil CO₂ emission was best described by a quadratic function, whereas the interactive effects of soil temperature <em>(T)</em> and soil moisture <em>(W)</em> on soil CO₂ emission were best described by the following equation:<em> f(R)=a(bT²+cT)(1+d</em>ln<em>(2W)/T)+e</em>. The soil respiration in winter wheat field was changed with the plastic mulched-ridges and unmulched furrows practice.