Leaf and canopy optical characteristics as crop‐N‐status indicators for field nitrogen management in corn

Rambo, Lisandro; Ma, Bao–Luo; Xiong, You‐Cai; Silvia, Paulo Regis Ferreira da

doi:10.1002/jpln.200900022

Cited by 66 publications

(46 citation statements)

References 40 publications

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“…The quality of information provided by digital photographs is dependent on the resolution of the images. In the present study, the resolution was approximately 0.048 mm 2 per pixel, which is more accurate than that reported by Ngouajio et al (1998) and Rasmussen et al (2007), which were 1.0 and 0.25 mm 2 per pixel, respectively. However, the main purpose of using digital photographs in our study was not as a means of decision making for a particular weed control method.…”

Section: Resultssupporting

confidence: 71%

“…The conditions for using the GreenSeeker™ tool and for achieving the digital photography were optimized in relation to the weed canopy, the horizontal location of the reading, walking speed, and the number of readings per sample area. These determinations were based on studies using the GreenSeeker TM and WeedSeeker sensors (Sui et al, 2008, Grohs et al, 2009) and digital photography (Gerhards & Christensen, 2003;Rasmussen et al, 2007).…”

Section: Resultsmentioning

confidence: 99%

“…In the soybean experiment, the high weed control obtained since the low herbicide doses used did not provide the variability of weed leaf coverage necessary to obtain this information. The implementation of this methodology is derived from one of the main uses of reflectance sensors related to the prediction of nitrogen fertilization in the top dressing of corn, wheat, and barley (Grohs et al, 2009;Rambo et al, 2010) and for pasture utilization (Trotter et al, 2010). Similarly, the prediction of weed leaf coverage through the NDVI index was conducted on cotton with the WeedSeeker TM equipment, resulting in a linear model with a determination coefficient of 0.69 (Sui et al, 2008).…”

Section: Resultsmentioning

confidence: 99%

“…For example, several parameters related to the positioning of the camera, different filters and imaging settings were studied to quantify the coverage of weeds (Rasmussen et al, 2007). Moreover, images from digital photographs were also used for the detection and spraying of herbicides in real-time instrumentations (Gerhards & Christensen, 2003).…”

Section: Resultsmentioning

confidence: 99%

“…The generated radiation is reflected and measured by a photodiode. The GreenSeeker TM equipment was originally developed for crop canopy quantification and has been validated and used for over the top nitrogen application at variable rates in several crops (Grohs et al, 2009;Rambo et al, 2010). The normalized differential vegetation index (NDVI) is the most commonly used parameter for crop nitrogen prediction, quantification of various plant species and other uses in precision agriculture (Sui et al, 2008;Verhuls et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Reflectance indices as a diagnostic tool for weed control performed by multipurpose equipment in precision agriculture

et al. 2012

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Several tools of precision agriculture have been developed for specific uses. However, this specificity may hinder the implementation of precision agriculture due to an increasing in costs and operational complexity. The use of vegetation index sensors which are traditionally developed for crop fertilization, for site-specific weed management can provide multiple utilizations of these sensors and result in the optimization of precision agriculture. The aim of this study was to evaluate the relationship between reflectance indices of weeds obtained by the GreenSeekerTM sensor and conventional parameters used for weed interference quantification. Two experiments were conducted with soybean and corn by establishing a gradient of weed interference through the use of pre- and post-emergence herbicides. The weed quantification was evaluated by the normalized difference vegetation index (NDVI) and the ratio of red to near infrared (Red/NIR) obtained using the GreenSeekerTM sensor, the visual weed control, the weed dry matter, and digital photographs, which supplied information about the leaf area coverage proportions of weed and straw. The weed leaf coverage obtained using digital photography was highly associated with the NDVI (r = 0.78) and the Red/NIR (r = -0.74). The weed dry matter also positively correlated with the NDVI obtained in 1 m linear (r = 0.66). The results indicated that the GreenSeekerTM sensor originally used for crop fertilization could also be used to obtain reflectance indices in the area between rows of crops to support decision-making programs for weed control.

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Section: Resultssupporting

confidence: 71%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Reflectance indices as a diagnostic tool for weed control performed by multipurpose equipment in precision agriculture

et al. 2012

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On‐farm comparison of variable rates of nitrogen with uniform application to maize on canopy reflectance, soil nitrate, and grain yield

Shang

2013

Z. Pflanzenernähr. Bodenk.

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Recent development in canopy optical-sensing technology provides the opportunity to apply fertilizer variably at the field scale according to spatial variation in plant growth. A field experiment was conducted in Ottawa, Canada, for two consecutive years to determine the effect of fertilizer nitrogen (N) input at variable-vs. uniform-application strategies at the V6-V8 growth stage, on soil mineral N, canopy reflectance, and grain yield of maize (Zea mays L.). The variable N rates were calculated using an algorithm derived from readings of average normalized difference vegetation index (NDVI) of about 0.8 m × 4.6 m, and N fertilizer was then applied to individual patches of the same size of NDVI readings (0.8 m × 4.6 m) within a plot (2184 m 2 ). Canopy reflectance, expressed as NDVI, was monitored with a hand-held spectrometer, twice weekly before tasseling and once a week thereafter until physiological maturity. Soil mineral N (0-30 cm depth) was analyzed at the V6 and VT growth stages. Our data show that both variable and uniform-application strategies for N side-dressings based on canopy-reflectance mapping data required less amount of N fertilizer (with an average rate of 80 kg N ha -1 as side-dressing in addition to 30 kg N ha -1 applied at planting), and produced grain yields similar to and higher nitrogen-use efficiency (NUE) than the preplant fully fertilized (180 kg N ha -1 ) treatment. No difference was observed in either grain yield or NUE between the variable-and uniform-application strategies. Compared to unfertilized or fully fertilized treatments, the enhancements in grain yield and NUE of the variable-rate strategy originated from the later N input as side-dressing rather than the variation in N rates. The variable-rate strategy resulted in less spatial variations in soil mineral N at the VT growth stage and greater spatial variations in grain yield at harvest than the uniform-rate strategy. Both variable-and uniform-application strategies reduced spatial variations in soil mineral N at the VT stage and grain yield compared to the unfertilized treatment. The variable-rate strategy resulted in more sampling points with high soil mineral N than the uniform-rate strategy at the VT stage.

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Nitrogen use efficiency of microalgae application in wheat compared to mineral fertilizer

Mückschel,

Ollo,

Glaeser

et al. 2023

J. Plant Nutr. Soil Sci.

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BackgroundWastewater from sewage treatment plants contains high levels of nutrients, which can be used for plant nutrition. Classical wastewater treatment plants use complex microbial consortia of autotrophic and heterotrophic microorganisms for biological wastewater treatment. Certain autotrophic microalgae (e.g., species of the genera Chlorella, Scenedesmus, and Pediastrum) accumulate nutrients from wastewater very effectively.AimsWe investigated the potential of microalgae biomass obtained from a prototype wastewater treatment plant as a source of nutrients for crops, focusing on nitrogen.MethodsWe provided wheat plants with different levels of algae biomass equivalent to 60, 120, and 180 kg N per hectare or with mineral fertilizer (N, P, and K) equivalent to the amounts contained in the algal biomass. Physiological and phenotypic traits were measured during growth, including vegetation indices, photosynthetic performance, growth, and nitrogen use efficiency (NUE). In addition, the adundances of Bacteria, Archaea and fungi and genes of ammonium oxidizing Bacteria and Archaea were determined in the rhizosphere of differently fertilized plants.ResultsMicroalgal application at fertilizer levels of 120 and 180 kg N ha–1 showed significantly improved physiological performance, growth, yield and nutrient uptake compared to the unfertilized control. Nevertheless, their yields and NUE were lower than with the application of equal amounts of mineral fertilization, while the adundance of rhizosphere microbes and ammonia‐oxidizing microorganisms were not significantly affected.ConclusionsMicroalgae from wastewater treatments form a suitable source of organic fertilizer for wheat plants with only moderate reductions in N use efficiency compared to mineral fertilizer.

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Leaf and canopy optical characteristics as crop‐N‐status indicators for field nitrogen management in corn

Cited by 66 publications

References 40 publications

Reflectance indices as a diagnostic tool for weed control performed by multipurpose equipment in precision agriculture

Reflectance indices as a diagnostic tool for weed control performed by multipurpose equipment in precision agriculture

On‐farm comparison of variable rates of nitrogen with uniform application to maize on canopy reflectance, soil nitrate, and grain yield

Nitrogen use efficiency of microalgae application in wheat compared to mineral fertilizer

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