Estimating nitrogen requirement of grain corn in Manitoba using optical spectral reflectance
| dc.contributor.author | Quilesfogel-Esparza, Claudia | |
| dc.contributor.examiningcommittee | Badreldin, Nasem (Soil Science) | en_US |
| dc.contributor.examiningcommittee | Cordeiro, Marcos (Animal Science) | en_US |
| dc.contributor.supervisor | Tenuta, Mario | |
| dc.contributor.supervisor | Bullock, Paul | |
| dc.date.accessioned | 2023-03-23T14:46:47Z | |
| dc.date.available | 2023-03-23T14:46:47Z | |
| dc.date.copyright | 2023-03-06 | |
| dc.date.issued | 2023-02-27 | |
| dc.date.submitted | 2023-03-06T16:50:28Z | en_US |
| dc.degree.discipline | Soil Science | en_US |
| dc.degree.level | Master of Science (M.Sc.) | en_US |
| dc.description.abstract | Optical sensors can measure optical (visible/near-infrared) reflectance and be used to assess crop canopy conditions. In this study, two hand-held active sensors (GreenSeeker® and CropCircleTM) and a passive aerial sensor (Red-Edge multi-spectral camera) were compared at three growth stages of grain corn (V4, V8 and V12) to predict in-season nitrogen (N) requirement. Active optical sensors have a light source. Passive sensors rely on sunlight; thus, their reflectance measurements are subject to changing sunlight conditions. Here a high reflectance area of canopy non-limited by N was used to standardize for variations in sunlight conditions between measurements days. The Normalized Difference Vegetation Index (NDVI) for all three sensors and the Normalized Difference Red-Edge index (NDRE) using the CropCircleTM and Red-Edge were also compared. Four site-years (2018-2021) of N response trials were combined to capture N response under different meteorological conditions and create a regional response model, adjusted for N fertilizer and corn grain prices to determine the optimum N rate to apply. Measured grain yield significantly increased (adjR2=0.40) with N supply (spring soil nitrate plus N rate). The maximum return to nitrogen (MRTN) using a current high price ratio ($N: $Corn) of 9.15:1 was 177 kg N/ha for 7,986 kg grain/ha. Two methods were used to make N addition recommendations. The first was using a quadratic response model for grain corn yield to N supply. The second was the optical sensor approach compared the difference between a non-limited area and the field estimate using canopy spectral reflectance. The optical sensor approach (187 kg/ha N) was the closest to the determined MRTN of 177 kg N/ha. Standardizing light conditions at V4 provided significant associations of NDVI and NDRE with yield regardless of the sensor. At V8, only Red-Edge NDVI and NDRE were improved by standardization. Standardization had no effect at V12. For determining in-season N addition to grain corn in Manitoba, it is best to determine NDRE using the CropCircle V12 (adjR2 = 0.62). However, it is recommended for Manitoba farmers to standardize reflectance values to an N non-limited crop area as they prefer earlier timing for top or side-dressing corn between the V4 to V8 developmental stages. | en_US |
| dc.description.note | May 2023 | en_US |
| dc.description.sponsorship | Manitoba Corn Growers Association (MCGA), the Grain Farmers of Ontario (GFO), Fertilizer Canada, and Agriculture and Agri-food Canada through the Corn Science Cluster of the Canadian Agricultural Partnership (CAP) as well as WGRF, Fertilizer Canada, and the Natural Sciences and Engineering Research Council (NSERC) through the 4R Nutrient Stewardship Industrial Research Chair | en_US |
| dc.identifier.uri | http://hdl.handle.net/1993/37215 | |
| dc.language.iso | eng | en_US |
| dc.rights | open access | en_US |
| dc.subject | Nitrogen | en_US |
| dc.subject | Ground Based Sensors | en_US |
| dc.subject | UAV | en_US |
| dc.subject | NDVI | en_US |
| dc.subject | NDRE | en_US |
| dc.title | Estimating nitrogen requirement of grain corn in Manitoba using optical spectral reflectance | en_US |
| dc.type | master thesis | en_US |
| local.subject.manitoba | yes | en_US |
| project.funder.identifier | NSERC: https://doi.org/10.13039/501100000038 | en_US |
| project.funder.name | Natural Sciences and Engineering Research Council of Canada | en_US |