Water requirements and single and dual crop coefficients of sugarcane grown in a tropical region, Brazil

Abstract

A field experiment was conducted throughout 2009/2010 in a sugarcane field of a commercial distillery located on the coastal area of Paraiba state, Brazil. The objectives were to determine sugarcane water requirements and to test the single and dual crop coefficients by comparing the calculated values of <i>ET</i> with measured ones. Crop evapotranspiration was determined by field water balance, reference evapotranspiration (<i>ET<sub>o</sub></i>) by the Penman-Monteith approach, while single and dual crop coefficients were computed through the standard FAO-56 methodology. The experimental area was cultivated with irrigation applied weekly by a centre pivot system in addition to rainfall and the irrigation scheduling was based on 100% <i>ET<sub>o</sub></i>. Three statistical tests, mean bias difference (<i>MBD</i>), normalized root mean square difference (<i>NRMSD</i>) and regression analysis, were used to evaluate the performance of single and dual crop coefficients. Results showed that there was a notable symmetry between <i>ET</i> measured and <i>ET</i> calculated by <i>K<sub>c</sub></i> dual. The <i>ET</i> values, calculated from <i>K<sub>c</sub></i> single, underestimated those obtained from soil water balance measurements by 36%

­Actual Evapotranspiration for Sugarcane Based on Bowen Ratio-Energy Balance and Soil Water Balance Models with Optimized Crop Coefficients.

“…There were only two upper (Kc > 1.15) and lower (Kc < 0.93) outliers based on the analyzed sample size. However, these values are within the Kc range observed in several studies (Inman-Bamber and McGlinchey 2003;Marin et al 2008Marin et al , 2016Marin et al , 2020Silva et al 2012;da Silva et al 2013). The Kc_mid in the ThM model retrieved from optimization was equal to 1.05 (only 3% less than the Kc obtained experimentally), whereas the adjusted Kc FAO56…”

“…Parameters like Kc and Kcb are available in FAO-56 for several crops or groups of crops for each growth stage, as well as an equation to adjust these parameters to local climate conditions. However, some authors have found different Kc values from those obtained by the adjusting equations, leading to inaccurate ETa estimates (Silva et al 2012;Bastidas-Obando et al 2017;Marin et al 2020). Thereby, in some cases, these values need to be determined experimentally to attain more accurate estimates.…”

Estimation of Crop Coefficients and Water Productivity of Mustard (<i>Brassica juncea</i>) under Semi-Arid Conditions

“…Figures 11 and 12). Similar trend of K cb and its correlation with LAI were also reported for other crops 3,[22][23][24] . Such relationship would facilitate extrapolation of the results pertaining to the estimation of K cb from LAI for other regions having similar climatic conditions.…”

Implementing Standardized Reference Evapotranspiration and Dual Crop Coefficient Approach in the DSSAT Cropping System Model

“…2 and 3). While these evaporative spikes for ET o -K cb are small during this growth stage, they have been verified through studies using water balance methods (da Silva et al, 2012), lysimetry (López-Urrea et al, 2012), energy balance (Anderson et al, 2017), and isotope tracing (Nay-Htoon, 2016); thus, they should be properly simulated by cropping system models. The new ET o -K cb method is very responsive to frequent irrigations, with both the evaporation and resulting ET being highly dynamic (figs.…”