{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T13:41:55Z","timestamp":1782826915982,"version":"3.54.5"},"reference-count":52,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2020,4,12]],"date-time":"2020-04-12T00:00:00Z","timestamp":1586649600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100004952","name":"Minnesota Department of Agriculture","doi-asserted-by":"publisher","award":["153761 PO 3000031069"],"award-info":[{"award-number":["153761 PO 3000031069"]}],"id":[{"id":"10.13039\/100004952","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100016705","name":"Minnesota Soybean Research and Promotion Council","doi-asserted-by":"publisher","award":["00071830"],"award-info":[{"award-number":["00071830"]}],"id":[{"id":"10.13039\/100016705","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100016705","name":"Minnesota Soybean Research and Promotion Council","doi-asserted-by":"publisher","award":["00079668"],"award-info":[{"award-number":["00079668"]}],"id":[{"id":"10.13039\/100016705","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The ability to predict spatially explicit nitrogen uptake (NUP) in maize (Zea mays L.) during the early development stages provides clear value for making in-season nitrogen fertilizer applications that can improve NUP efficiency and reduce the risk of nitrogen loss to the environment. Aerial hyperspectral imaging is an attractive agronomic research tool for its ability to capture spectral data over relatively large areas, enabling its use for predicting NUP at the field scale. The overarching goal of this work was to use supervised learning regression algorithms\u2014Lasso, support vector regression (SVR), random forest, and partial least squares regression (PLSR)\u2014to predict early season (i.e., V6\u2013V14) maize NUP at three experimental sites in Minnesota using high-resolution hyperspectral imagery. In addition to the spectral features offered by hyperspectral imaging, the 10th percentile Modified Chlorophyll Absorption Ratio Index Improved (MCARI2) was made available to the learning models as an auxiliary feature to assess its ability to improve NUP prediction accuracy. The trained models demonstrated robustness by maintaining satisfactory prediction accuracy across locations, pixel sizes, development stages, and a broad range of NUP values (4.8 to 182 kg ha\u22121). Using the four most informative spectral features in addition to the auxiliary feature, the mean absolute error (MAE) of Lasso, SVR, and PLSR models (9.4, 9.7, and 9.5 kg ha\u22121, respectively) was lower than that of random forest (11.2 kg ha\u22121). The relative MAE for the Lasso, SVR, PLSR, and random forest models was 16.5%, 17.0%, 16.6%, and 19.6%, respectively. The inclusion of the auxiliary feature not only improved overall prediction accuracy by 1.6 kg ha\u22121 (14%) across all models, but it also reduced the number of input features required to reach optimal performance. The variance of predicted NUP increased as the measured NUP increased (MAE of the Lasso model increased from 4.0 to 12.1 kg ha\u22121 for measured NUP less than 25 kg ha\u22121 and greater than 100 kg ha\u22121, respectively). The most influential spectral features were oftentimes adjacent to each other (i.e., within approximately 6 nm), indicating the importance of both spectral precision and derivative spectra around key wavelengths for explaining NUP. Finally, several challenges and opportunities are discussed regarding the use of these results in the context of improving nitrogen fertilizer management.<\/jats:p>","DOI":"10.3390\/rs12081234","type":"journal-article","created":{"date-parts":[[2020,4,13]],"date-time":"2020-04-13T10:41:52Z","timestamp":1586774512000},"page":"1234","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":39,"title":["Prediction of Early Season Nitrogen Uptake in Maize Using High-Resolution Aerial Hyperspectral Imagery"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8266-7372","authenticated-orcid":false,"given":"Tyler","family":"Nigon","sequence":"first","affiliation":[{"name":"Department of Soil, Water and Climate, University of Minnesota, Saint Paul, MN 55108, USA"},{"name":"Department of Bioproducts and Biosystems Engineering, University of Minnesota, Saint Paul, MN 55108, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1079-118X","authenticated-orcid":false,"given":"Ce","family":"Yang","sequence":"additional","affiliation":[{"name":"Department of Bioproducts and Biosystems Engineering, University of Minnesota, Saint Paul, MN 55108, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8562-4506","authenticated-orcid":false,"given":"Gabriel","family":"Dias Paiao","sequence":"additional","affiliation":[{"name":"Department of Soil, Water and Climate, University of Minnesota, Saint Paul, MN 55108, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7040-5888","authenticated-orcid":false,"given":"David","family":"Mulla","sequence":"additional","affiliation":[{"name":"Department of Soil, Water and Climate, University of Minnesota, Saint Paul, MN 55108, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joseph","family":"Knight","sequence":"additional","affiliation":[{"name":"Department of Forest Resources, University of Minnesota, Saint Paul, MN 55108, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9539-0050","authenticated-orcid":false,"given":"Fabi\u00e1n","family":"Fern\u00e1ndez","sequence":"additional","affiliation":[{"name":"Department of Soil, Water and Climate, University of Minnesota, Saint Paul, MN 55108, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,4,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"074002","DOI":"10.1088\/1748-9326\/9\/7\/074002","article-title":"Land-use change and costs to rural households: A case study in groundwater nitrate contamination","volume":"9","author":"Keeler","year":"2014","journal-title":"Environ. 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