减少环境影响和提高氮利用率对确保中国的粮食安全至关重要。根区施肥已被认为是提高氮肥利用率（NUE）的有效策略，但在根区施肥条件下，控释尿素（CRU）与普通尿素掺混对夏玉米田的影响仍不清楚。因此，本研究进行了为期3年的田间试验，以不施氮为对照，采用两种施肥模式（FF：人工开沟条施，即农民施肥习惯；HF：人工点播的根区穴施），每公顷施氮量为210 kg hm^-2（控释尿素与普通尿素的混合比例为5：5），同时进行了一年的原位微区试验。研究了不同施肥模式下的玉米产量、氮肥利用率和潜在氮损失。结果表明，与FF相比，HF处理在三年内使平均产量和氮素回收效率分别提高了8.5和22.3%。相比之下，HF具有更大的应用潜力，且显著提高了干物质积累、总氮吸收、SPAD值和LAI。此外，相比于FF，HF使来自肥料的¹⁵N积累提高了17.2%，且¹⁵N的潜在损失减少了43.8%。收获时，HF处理较FF增加了土壤耕层中矿质氮的积累，以便在下一季使用。因此，HF可以满足夏玉米对氮的需求，维持产量，提高NUE，同时减少环境中的氮损失。总的来说，根区穴施条件下控释尿素掺混普通尿素是一种有效且有前景的施肥模式，有助于实现华北平原的环境完整性和粮食安全，值得进一步应用和研究。

The physical and chemical heterogeneities of soils make the soil spectral different and complicated, and it is valuable to increase the accuracy of prediction models for soil organic matter (SOM) based on pre-classification. This experiment was conducted under a controllable environment, and different soil samples from northeast of China were measured using ASD2500 hyperspectral instrument. The results showed that there are different reflectances in different soil types. There are statistically significant correlation between SOM and reflectence at 0.05 and 0.01 levels in 550–850 nm, and all soil types get significant at 0.01 level in 650–750 nm. The results indicated that soil types of the northeast can be divided into three categories: The first category shows relatively flat and low reflectance in the entire band; the second shows that the spectral reflectance curve raises fastest in 460–610 nm band, the sharp increase in the slope, but uneven slope changes; the third category slowly uplifts in the visible band, and its slope in the visible band is obviously higher than the first category. Except for the classification by curve shapes of reflectance, principal component analysis is one more effective method to classify soil types. The first principal component includes 62.13–97.19% of spectral information and it mainly relates to the information in 560–600, 630–690 and 690–760 nm. The second mainly represents spectral information in 1 640–1 740, 2 050–2 120 and 2 200–2 300 nm. The samples with high OM are often in the left, and the others with low OM are in the right of the scatter plot (the first principal component is the horizontal axis and the second is the longitudinal axis). Soil types in northeast of China can be classified effectively by those two principles; it is also a valuable reference to other soil in other areas.