Can Frequent Measurement of Normalized Difference Vegetative Index and Soil Nitrate Guide Nitrogen Fertilization of Kentucky Bluegrass Sod?

Abstract

Objective approaches to guide N fertilization of turfgrass sod crops are lacking. This study was conducted to determine the relationships among normalized difference vegetative index (NDVI), frequently‐measured soil NO3–N concentrations, and peak‐shear force of predominately Kentucky bluegrass (Poa pratensis L.) sod, and to evaluate if those relationships could help guide N fertilization. Ramp calibration strips (RCS) with varying N rates were established within production sod fields in Rhode Island across three consecutive years. At 2‐wk intervals during each growing season, soil NO3–N concentrations and NDVI readings were recorded and correlated. Biweekly relative NDVI readings plateaued when soil NO3–N concentrations ranged between 5 and 12 mg kg–1. Mean relative NDVI plateaued at 196 kg N ha–1 yr–1. Relative sod peak‐shear force was negatively correlated to soil NO3–N concentrations and the total amount of N applied per year. Relative peak‐shear force was maximized when mean relative NDVI readings ranged from 0.969 to 0.982, but declined as mean relative NDVI increased towards 1.0. The results suggest that frequently measured NDVI and soil NO3–N concentrations show promise as guides for N fertilization of predominately Kentucky bluegrass sod. Further research will be required to validate these approaches on larger‐scale sod fields.

Comparing a chromameter and a hand held NDVI meter to predict nitrogen and water content of turfgrass

“…However, the use of multiple color parameters (L*C*h°) gave higher R 2 values (0.69) in the current study. On the other hand, in studies using hand-held NDVI devices, different results have been reported for the prediction of nitrogen content depending on the type of turfgrass and NDVI devices (R 2 =0.19-0.85) (Frank, 2008;Moss and Bell, 2010;Caturegli et al, 2016;Guillard et al, 2016;Inguagiato and Guillard, 2016). In the present study, similar coefficient of determination (R 2 ) value between NDVI and N content was determined (0.73) ( Table 4).…”

Evaluating Decision Support Tools for Precision Nitrogen Management on Creeping Bentgrass Putting Greens

“…Spectral reflectance is measured with given wavelengths of light, and studies (Trenholm et al, 1999 ; Bell et al, 2002 ; Fitz–Rodríguez and Choi, 2002 ; Keskin et al, 2008 ) have shown that spectral reflectance could be well correlated with visual quality for turfgrass species maintained under different management practices. Spectral reflectance is sensitive to N fertilization of turfgrasses (Caturegli et al, 2016 ; Guillard et al, 2016 ) and therefore has the potential to serve as an objective measurement of turfgrass performance. For example, spectral reflectance has been used to detect chlorophyll concentration and has also been shown to have a good correlation with plant N status (Horler et al, 1983 ; Steven and Clark, 2013 ).…”

Guiding fall fertilization of cool‐season turfgrass lawns with NDVI sufficiency index

“…In addition to turfgrass lawns, using spectral reflectance to guide N fertilization is applicable to other turf uses such as athletic fields, golf (Baldwin & Brede, 2011; Inguagiato & Guillard, 2016; Kruse, Christians, & Chaplin, 2006; López‐Bellido et al., 2012; Zhu, Schlossberg, Bryant, & Schmidt, 2012), or sod production (Guillard et al., 2016; Li, Fang, & Han, 2011). Because fertilization is more frequent in these systems than lawns, the frequency of reflectance readings will need to be increased to match the fertilizer applications.…”

“…A commonly used spectral measurement in turfgrass research to determine treatment differences is the normalized difference vegetative index (NDVI). There are numerous citations in the turfgrass literature reporting significant relationships between NDVI or other spectral‐reflectance signals with N fertilization (reviewed in Bell, Kruse, & Krum, 2013; Catureglia et al., 2015, 2016; Caturegli et al., 2020; Geng, Guillard, Mangiafico, & Morris, 2014; Geng, Guillard, & Morris, 2014; Guillard, Fitzpatrick, & Burdett, 2016; Inguagiato & Guillard, 2016; Moore et al., 2019; Moore, Guillard, Morris, & Brinton, 2019; Obear, Kreuser, Hubbard, DeBels, & Soldat, 2017). However, relationships between reflectance signals and the response of turfgrass to N fertilization have not been analyzed with the objective to create site‐specific fertilizer recommendations.…”