关键词: 华北平原, 冬小麦, 土壤呼吸速率, Q₁₀模型, 秸秆还田

Abstract: Experiments were conducted at the Yucheng Comprehensive Experimental Station of the Chinese Academy of Sciences during 2002～2003 to investigate the respiration of a pulverous sandstone soil under cultivation of winter wheat over a growth season.The effluent CO₂ was collected and analyzed by the static-chamber/gas chromatography(GC)method at a frequency of once a week in spring and autumn,once two weeks in winter,twice a week for straw manure treatment,once a week for no straw manure treatment and nitrogen fertilization treatment in summer.The results indicated that diurnal variation of soil respiration rate showed a single peak in typical winter wheat farmlands in the North China Plain,and reached the highest at about 13 o'clock,and the lowest at about 4 o'clock in the early morning.In winter wheat growth season,the soil respiration rate was 31.23～606.85 mg·m^-2·h^-1 under straw manure,28.99～549.66 mg·m^-2·h^-1 under no straw manure,10.46～590.86 mg·m^-2·h^-1 in N₀,16.11～349.88 mg·m^-2·h^-1 in N₁₀₀,12.25～415.00 mg·m^-2·h^-1 in N ₂₀₀,and 23.01～410.58 mg·m^-2·h^-1 in N₃₀₀,showing a similar seasonal variation tendency with soil temperature.Among all treatments,the straw manure had the most distinct soil respiration,though the soil respiration also increased slightly with increasing nitrogen fertilization.Soil respiration increased exponentially with increasing soil temperature,and the correlation of soil temperature at the depth of 5 cm was the best.This relationship was usually described with the Q₁₀ model,which represented the sensitivity of soil respiration to temperature.Q₁₀ was not a fixed value,which varied with the depth at which the temperature was measured and the depth of the active soil layer and soil temperature.At same time,the Q₁₀ value decreased with increasing soil temperature.Soil water content was another important factor affecting soil respiration rate,but in this region,the relationship between soil respiration and soil moisture was poor,and no distinct rules were shown.The average net photosynthesis rate of winter wheat had a close relation with soil respiration rate.The differences between them showed that the photosynthetic uptake of CO₂ was beyond emission of soil respiration during the period from return green to mature,and the winter wheat farmland was a sink of CO₂.

Key words: North China Plain, Winter wheat, Soil respiration rate, Q₁₀ model, Straw manure