地膜覆盖对旱作玉米田水热通量传输的影响研究

Effects of Plastic Mulch on Water and Heat Flux Transfer in Rainfed Maize Fields

摘要:

为探明旱作农田生态系统生态水文过程、提升农田水分利用效率，选取黄土高原东部旱作春玉米田为研究对象，设置露地（CK）和地膜覆盖（PM）两种处理，利用涡度相关系统对两种处理条件下玉米田水热通量进行了连续观测，基于观测结果对两种处理下玉米田水热通量的日、季节变化特征和能量分割进行了分析。结果表明：两个处理各能量通量均存在显著的日、季节变化特征。在快速生长期（拔节期），降水后CK和PM处理潜热通量（λET）均明显增大，而显热通量（H）和土壤热通量（G）均减小；但在后期（成熟期），降水对各能量通量变化过程的影响没有快速生长期明显，表明玉米生育期内降水的分布能够显著影响旱作玉米田的能量平衡。玉米生育期内，净辐射（Rn）主要以λET为主，而休闲期Rn主要以H为主。Rn是玉米田λET的最主要影响因子，其次是平均气温和饱和水汽压差，风速和相对湿度对λET的影响相对较小。

Abstract:

Aiming to understand eco-hydrological processes and boost water use efficiency in rainfed agroecosystem, a field experiment was conducted in non-mulched (CK) and mulched (PM) maize fields of eastern Loess Plateau to continuously monitor water and energy flux in the maize fields under CK and PM. Based on the monitoring results, diurnal and seasonal variations of water and energy flux as well as energy partitioning were investigated. The results indicated that energy fluxes presented typical diurnal and seasonal variations during the entire growing seasons. Net radiation (Rn) was dominated by latent heat flux (λET) during maize growing seasons while sensible heat flux (H) was the predominant component of Rn during non-growing seasons. Compared with the energy flux before rainfall, λET was increased significantly while H and soil heat flux (G) was decreased after rainfall in development stage, however, in late stage, the changes in soil water content resulted by rainfall did not increase λET significantly for the both treatments, which indicated seasonal distribution of rainfall had significant influence on energy budget of maize fields. Rn was the primary factor affecting λET, followed by average air temperature and vapor pressure deficit, wind speed and relative humidity had relatively minor influence on λET.