设施菜田土壤呼吸速率日变化特征分析

研究设施菜田土壤呼吸速率日变化特征对于了解CO₂排放对环境和作物生长的影响十分重要。本研究采用CO2红外分析仪 动态箱法在2009年秋冬季和2010年冬春季监测了不同有机肥和氮肥处理下设施菜田土壤呼吸速率的日变化特征。结果表明: 施用有机肥和秸秆明显提高设施菜田土壤呼吸速率, 尤其是在高氮投入下, 鸡粪和小麦秸秆混施土壤呼吸速率明显高于其他处理; 不同季节各处理土壤呼吸速率的日变化特征基本一致, 土壤呼吸速率的最大值出现在14:00-17:00; 随着温度升高, 土壤呼吸速率逐渐增加, 但是过高的温度和CO₂浓度均会抑制土壤呼吸速率; 上午8:00-11:00测定的土壤呼吸速率值与土壤呼吸速率日平均值基本一致, 可采用上午8:00-11:00土壤呼吸速率的观测值评估设施菜田CO₂的排放量; 施肥、温度和温室内近地面CO₂浓度是影响不同季节土壤呼吸速率日变化的主要因素, 合理调控对于实现设施蔬菜的可持续发展具有重要意义。

Analysis of daily dynamics of soil respiration rate in greenhouse vegetable fields

As an important component of ecosystem carbon (C) budget, soil respiration is critical for soil-plant C cycle. As an entirely different cropping system, greenhouse vegetable system is characterized as excessive nutrient input, intensive land use, high temperature and high humidity and airtight environment. All of these factors have considerable influence on soil respiration rate and C cycle. With increasing greenhouse vegetable production in China, CO₂ emission in greenhouse vegetable systems can not be ignored in the whole agricultural production system. In addition to studies of seasonal variations of soil respiration rate in greenhouse vegetable fields, understanding daily variation characteristics of soil respiration rate can enhance the estimation of the effects of CO₂ emission on the environment and crop growth in greenhouse vegetable system. Thus this study investigated the driving factors and characteristics of daily dynamics of soil respiration rate under different organic manure and N (nitrogen) fertilizer inputs in a greenhouse vegetable field. The infrared gas analyzer (IRGA)-closed chamber technique was used to analyze greenhouse vegetable conditions in 2009 2010 in Shouguang City, Shandong Province. Four measurements were taken to determine daily variations in soil respiration rate during the main growth period. The results showed that the application of organic manure and wheat straw significantly improved soil respiration rate, especially in the treatments with high N fertilizer where the soil respiration rates were highest. Although some differences existed in soil respiration rate among different treatments in different seasons, daily dynamics of soil respiration rate were similar for all the treatments. With rising temperature, soil respiration rate increased steadily and the highest soil respiration rate occurred 14:00 17:00, which was later than the highest temperature. Also with rising temperature, CO₂ increased steadily. High temperature and CO₂ concentration inhibited soil respiration rate in greenhouse vegetable fields. Based on the four measurements over the study period, soil respiration rates during 8:00 11:00 a.m. were similar to daily average rates. This suggested that soil respiration rate during 8:00 11:00 a.m. could be used to estimate CO₂ emission in greenhouse fields. Fertilization, temperature and near-ground CO₂ concentration were the main driving factors of the daily dynamics of soil respiration rate. Optimal regulation was critical for reducing CO₂ emission and enhancing sustainable development of greenhouse vegetable production in China.