Crop nitrogen (N) status is known to affect crop water status and crop water use. To investigate further the N effects on soil water changes and on canopy temperature, three water levels × four N levels were imposed on two growing seasons of maize in west central Nebraska, USA. Soil water changes were measured using a neutron probe, whereas canopy temperature was measured using infrared thermometers on a ground-based mobile platform. At all water levels, soil water losses over month-long intervals were generally greater as N levels increased. Given equal water levels, early afternoon canopy temperatures were usually lower with higher N levels, but no trend or even the opposite trend was occasionally observed. Jointly considering canopy reflectance and soil water depletion shows potential to explain much of the variation in estimated instantaneous water use among plots. However, determining the relative contributions of the canopy and soil factors on a particular day may require season-to-date knowledge of the crop. Further research on assimilating such sensor data for a combined stress coefficient would improve crop modeling and irrigation scheduling when variable water sufficiency and variable N sufficiency are simultaneously significant.

中文翻译：

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玉米不同水×氮充足度下土壤水分变化和冠层温度的差异

已知作物氮 (N) 状况会影响作物水分状况和作物水分利用。为了进一步研究氮对土壤水分变化和冠层温度的影响，在美国内布拉斯加州中西部玉米的两个生长季节施加了三个水位 × 四个 N 水平。使用中子探测器测量土壤水分变化，而使用地面移动平台上的红外温度计测量冠层温度。在所有水位，随着 N 水平的增加，在一个月的时间间隔内土壤水分流失通常更大。给定相同的水位，下午早些时候的树冠温度通常较低，氮含量较高，但偶尔没有观察到趋势甚至相反的趋势。联合考虑冠层反射率和土壤水分耗竭显示出解释地块之间估计瞬时用水量的大部分变化的潜力。然而，确定特定日期冠层和土壤因素的相对贡献可能需要对作物的季节性了解。当可变水充足量和可变氮充足量同时显着时，进一步研究将此类传感器数据同化为组合压力系数将改进作物建模和灌溉调度。