基于称重式蒸渗仪的喷灌条件下冬小麦和糯玉米作物系数估算方法

利用位于北京的称重式蒸渗仪，对喷灌条件下的冬小麦和糯玉米需水规律进行了测定，进而计算了两种作物的作物系数。结果表明，冬小麦和糯玉米的作物系数与播种后天数之间的关系均可以用四次多项式来表征。根据FAO-56推荐的作物系数计算方法，计算了两种作物的分段单值作物系数和双作物系数，发现华北平原喷灌条件下冬小麦和糯玉米的作物系数在生育期内的变化可以用FAO-56推荐的模式来描述，但实测值一般大于FAO-56的建议值。为了能利用FAO-56推荐的模式较好地描述喷灌作物系数变化规律，依据实测资料对FAO-56建议的单值作物系数和基础作物系数进行调整后，模拟了两种作物需水量的变化，模拟的作物阶段需水量与实测值吻合良好。

Estimation of crop coefficients for sprinkler-irrigated winter wheat and sweet corn using a weighing lysimeter

Crop water demands for sprinkler-irrigated winter wheat and sweet corn were measured using a weighing lysimeter located in Beijing. Then the coefficients of two crops were calculated. The results showed that the relationships between crop coefficient and days after seeding can be represented by a fourth-order polynomial equation for both crops. Single and dual crop coefficients for winter wheat and sweet corn were computed based on the method recommended by FAO-56 and compared with the observed data. The comparison indicated that the variation of crop coefficients during the growing season for sprinkler-irrigated crops of Northern China Plains could be described by the patterns recomrnended by FAO-56, but the computed crop coefficients were usually smaller than the observed values. The single and basal crop coefficients suggested by FAO-56 were therefore modified based on the observed results and crop water demands for winter wheat and sweet corn were simulated. A good agreement between the simulated and the observed crop water requirements was obtained for different growing periods of the two crops.