Evapotranspiration of typical agroecosystems in the North China Plain based on single crop coefficient method
-
摘要: 作物系数法可以简单、准确地反映作物不同生育期内实际蒸散量变化规律及特点, 但针对华北平原地区不同类型农业生态系统, 尤其是梨园种植区生育期内作物系数的变化及蒸散规律研究并不充分。本研究针对华北平原典型的冬小麦-夏玉米农田生态系统、棉田生态系统和梨园生态系统, 基于FAO56手册推荐的单作物系数法计算和验证了2016—2017年各农业生态系统初始生长期至生育末期的实际蒸散量, 分析了不同生育阶段蒸散变化规律。不同作物初始生长期、快速发育期、生育中期和生育末期作物系数, 冬小麦分别为0.60、0.88、1.07和0.72, 夏玉米分别为0.46、0.76、1.01和0.80, 棉花分别为0.34、0.71、1.07和0.78, 梨树分别为0.81、0.91、1.02和0.96。冬小麦-夏玉米、棉田和梨园的单作物系数法计算的实际蒸散量分别为694.3 mm、472.2 mm和825.7 mm。3类作物生育期内实际蒸散量计算值比实测值分别低1.0%、低4.9%和高8.1%, 变化趋势一致, 相关系数为0.80~0.91 (P<0.01)。粮、棉和果树生态系统是华北平原农业生态系统的典型代表, 本研究不仅明确了各类作物尤其是研究比较缺乏的梨树的不同生育期内的作物系数, 同时利用涡度相关实测结果进行了同时空尺度的验证, 明确了单作物系数法在华北平原不同农业生态系统的适用性, 为制定合理灌溉计划、实现作物耗水精准管理提供科学依据。Abstract: The crop coefficient method recommended by FAO56 is a method to calculate the actual evapotranspiration of crops, which can simply and accurately reflect the evapotranspiration patterns and characteristics of different agroecosystems during different growth stages. Although the crop coefficient method is widely used, there are still some problems in applying this method in the North China Plain. Research on a single agroecosystem of winter wheat-summer maize has been conducted for a long time. However, there is a lack of systematic and comprehensive research on the evapotranspiration patterns of various typical agroecosystems in the North China Plain through the single crop coefficient method. Therefore, it is difficult to provide quantitative theoretical support for water consumption management and planting structure adjustment. Furthermore, the variation in crop coefficients for the typical pear orchard agroecosystem, the main fruit and the most important economic crop in the North China Plain, is urgently needed. In this study, the crop coefficients and evapotranspiration patterns of different growth stages of irrigated crops in the typical agroecosystems of winter wheat-summer maize farmland, cotton field, and pear orchard in the North China Plain were examined and verified from 2016 to 2017. The entire growth stage was divided into initial, developing, mid, and end stages based on the crop growth stages and physiological characteristics. According to the single crop coefficient method recorded in FAO56 manual, the average crop coefficients of the initial, developing, mid, and end stages of different crops were 0.60, 0.88, 1.07, and 0.72 for winter wheat; 0.46, 0.76, 1.01, and 0.80 for summer maize; 0.34, 0.71, 1.07, and 0.78 for cotton; 0.81, 0.91, 1.02, and 0.96 for pear trees, respectively; while the calculated actual evapotranspiration was 694.3 mm, 472.2 mm, and 825.7 mm for the above three ecosystems, respectively. Evapotranspiration measured by the eddy covariance systems was 701.4 mm, 496.5 mm, and 763.5 mm for winter wheat-summer maize, cotton field, and pear orchard agroecosystems, respectively. Both the calculated and measured actual evapotranspiration values of the four crops showed a single-peak change from the initial to the end stages, with the same trend. The correlation coefficients between the calculated and measured evapotranspiration for all three agroecosystems were greater than 0.8. The calculated actual evapotranspiration values compared to the measured values during the growth stage of winter wheat-summer maize, cotton, and pear orchard agroecosystems were 1.0% lower, 4.9% lower, and 8.1% higher, respectively. This study not only provided the crop coefficients of wheat, maize, and cotton but also filled the gap in the research on crop coefficient of pear trees in this region. It is particularly important that this study used the observed evapotranspiration by the eddy correlation system to verify the calculated evapotranspiration using the single crop coefficient method at the same spatial and temporal scale, which shows the applicability of the calculated crop coefficients in the region. The applicability of the single-crop coefficient method in different agroecosystems in the North China Plain was clarified. This research provides a scientific basis for making reasonable irrigation plans and achieving precise management of crop water consumption.
-
表 1 不同试验站点(农业生态系统)种植作物和土壤性质
Table 1. Detail information of plants and soil property in different experimental sites (agroecosytems)
试验站点
Experiment site地理坐标
Geographical coordinate作物类型
Crop type土壤性质 Soil property 田间持水量
Field capacity
(%)凋萎系数
Wilting point of
soil moisture (%)碱解氮
Available nitrogen (mg∙kg−1)速效磷
Available phosphorus (mg∙kg−1)速效钾
Available potassium (mg∙kg−1)栾城 Luancheng 37°53′N, 114°41′E 冬小麦-夏玉米
Winter wheat-summer maize34 12 60~80 15~20 150~170 深州 Shenzhou 37°47′N, 114°55′E 棉花 Cotton 28 11 80 21 180 赵县 Zhaoxian 37°54′N, 115°42′E 梨树 Pear 35 13 70 19 257 表 2 不同作物生育阶段(月-日)划分
Table 2. Division of growth stages (month-day) of crops of different agroecosystems
作物 Crop 初始生长期 Initial stage 快速发育期 Developing stage 生育中期 Mid stage 生育末期 End stage 冬小麦 Winter wheat 10-06—03-17 03-18—05-02 05-03—05-28 05-29—06-12 夏玉米 Summer maize 06-13—07-19 07-20—08-31 09-01—09-18 09-19—09-27 棉花 Cotton 05-01—06-15 06-16—07-15 07-16—09-30 10-01—10-25 梨树 Pear 03-01—03-31 04-01—06-30 07-01—08-31 09-01—10-31 表 3 不同作物各生育阶段查表所得作物系数(Kc-Tab)取值
Table 3. Crop coefficient (Kc-Tab) values of different growth stages of crops
生育期
Growth stage冬小麦
Winter wheat夏玉米
Summer maize棉花
Cotton梨树
Pear初始生长期 Initial stage 0.60 0.47 0.35 0.80 生育中期 Mid stage 1.07 1.11 1.15 1.20 生育末期 End stage 0.70 0.83 0.60 0.85 表 4 不同农业生态系统作物不同生育阶段及总参考作物蒸散量
Table 4. Reference evapotranspiration (ET0) of different crops at different growth stages and during whole growth stage of different agroecosystems
mm 作物
Crop初始生长期
Initial stage快速发育期
Developing stage生育中期
Mid stage生育末期
End stage总计
Total冬小麦
Winter wheat187.2 140.6 127.8 74.8 530.4 夏玉米
Summer maize190.4 141.5 51.0 26.0 408.6 棉花 Cotton 248.2 158.5 232.2 34.2 673.1 梨树 Pear 78.8 426.5 246.5 128.7 880.5 表 5 不同农业生态系统作物不同生育阶段及总实际蒸散量
Table 5. Actural evapotranspiration of different crops at different growth stages and during whole growth stage of different agroecosystems
mm 作物
Crop初始生长期
Initial stage快速发育期
Developing stage生育中期
Mid stage生育末期
End stage总计
Total<