{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,28]],"date-time":"2026-01-28T06:00:57Z","timestamp":1769580057889,"version":"3.49.0"},"reference-count":29,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2015,3,6]],"date-time":"2015-03-06T00:00:00Z","timestamp":1425600000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Regardless of the crop production system, nutrients inputs must be controlled at or below a certain economic threshold to achieve an acceptable level of profitability. The use of management zones and variable-rate fertilizer applications is gaining popularity in precision agriculture. Many researchers have evaluated the application of final yield maps and geo-referenced geophysical measurements (e.g., apparent soil electrical conductivity-ECa) as a method of establishing relatively homogeneous management zones within the same plot. Yield estimation models based on crop conditions at certain growth stages, soil nutrient statuses, agronomic factors, moisture statuses, and weed\/pest pressures are a primary goal in precision agriculture. This study attempted to achieve the following objectives: (1) to investigate the potential for predicting winter wheat yields using vegetation measurements (the Normalized Difference Vegetation Index\u2014NDVI) at the beginning of the season, thereby allowing for a yield response to nitrogen (N) fertilizer; and (2) evaluate the feasibility of using inexpensive optical sensor measurements in a Mediterranean environment. A field experiment was conducted in two commercial wheat fields near Seville, in southwestern Spain. Yield data were collected at harvest using a yield monitoring system (RDS Ceres II-volumetric meter) installed on a combine. Wheat yield and NDVI values of 3498 \u00b1 481 kg ha\u22121 and 0.67 \u00b1 0.04 nm nm\u22121 (field 1) and  3221 \u00b1 531 kg ha\u22121 and 0.68 \u00b1 0.05 nm nm\u22121 (field 2) were obtained. In both fields, the yield and NDVI exhibited a strong Pearson correlation, with rxy = 0.64 and p &lt; 10\u22124 in field 1 and rxy = 0.78 and p &lt; 10\u22124 in field 2. The preliminary results indicate that hand-held crop sensor-based N management can be applied to wheat production in Spain and has the potential to increase agronomic N-use efficiency on a long-term basis.<\/jats:p>","DOI":"10.3390\/s150305504","type":"journal-article","created":{"date-parts":[[2015,3,6]],"date-time":"2015-03-06T10:38:33Z","timestamp":1425638313000},"page":"5504-5517","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":29,"title":["An Approach to Precise Nitrogen Management Using Hand-Held Crop Sensor Measurements and Winter Wheat Yield Mapping in a Mediterranean Environment"],"prefix":"10.3390","volume":"15","author":[{"given":"Luc\u00eda","family":"Quebrajo","sequence":"first","affiliation":[{"name":"Aerospace Engineering and Fluids Mechanics Department, University of Seville,  Ctra. Sevilla-Utrera km. 1, Seville 41013, Spain"}]},{"given":"Manuel","family":"P\u00e9rez-Ruiz","sequence":"additional","affiliation":[{"name":"Aerospace Engineering and Fluids Mechanics Department, University of Seville,  Ctra. Sevilla-Utrera km. 1, Seville 41013, Spain"}]},{"given":"Antonio","family":"Rodriguez-Lizana","sequence":"additional","affiliation":[{"name":"Aerospace Engineering and Fluids Mechanics Department, University of Seville,  Ctra. Sevilla-Utrera km. 1, Seville 41013, Spain"}]},{"given":"Juan","family":"Ag\u00fcera","sequence":"additional","affiliation":[{"name":"Rural Engineering Department, University of Cordoba, C\u00f3rdoba 14071, Spain"}]}],"member":"1968","published-online":{"date-parts":[[2015,3,6]]},"reference":[{"key":"ref_1","unstructured":"Oksanen, T. (2013, January 28\u201329). Estimating Operational Efficiency of Field Work Based on fields shape. 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