Coffee crop coefficient for precision irrigation based on leaf area index

Abstract

<jats:p>Crop coefficient (Kc) for coffee plantations was found to be linearly related to the leaf area index (L) up to 3, i.e., Kc = b L. The basic assumption is that for irrigated trees the water use per unit leaf area (ET LA) is equal to the reference evapotranspiration (ETo) expressed also on a unit leaf area basis of the reference surface (ET LA = ETo/Lo). As recommended by FAO-56 the leaf area index (Lo) for the hypothetical reference surface (grass) is equal to 2.88, then the most likely value is b = Lo-1 = 2.88-1 = 0.347. However, for L &gt; 3 (completely covered ground surface) Kc decreased from a peak value (~1.05) tending to an asymptotic low value around 0.7 for L &gt; 6, but the linear model gives unrealistic Kc estimates; tentatively the empirical function Kc = 1.8 L-0.5 is offered here as an initial guess due to the lack of experimental results for the interval 3.5 &lt;L &lt; 5.5. To become operational under commercial fields it is necessary to estimate the leaf area per coffee tree (LA, m² tree-1), and based on a very limited set of data, LA was estimated as a function of planting density (PD, trees ha-1), i.e., LA = 88.38 - 8.63 Ln (PD). Alternatively, L (&lt; 3.4) can be computed directly as a function of canopy volume (for V &lt; 1.2 m³).</jats:p>

Relationship Between Spatio-Temporal Leaf Area Index and Crop Coefficient When Monitoring Coffee Plots in Brazil Using the Sentine-2

“…The Kc values obtained in this study are consistent with those found in the literature for coffee crops (Doorenbos & Pruitt, 1977;Allen et al, 1998;Villa Nova et al, 2002;Marin et al, 2005;Oliveira et al, 2007;Sato et al, 2007;Pereira et al, 2011;Flumignan et al, 2011).…”

“…The studies published of Kc in irrigated coffee include those of Flumignan et al 2011, Marin et al (2005), Oliveira et al (2007), Pereira et al (2011) and others related with cultural practices or growth of the culture carried out and published by Villa Nova et al 2002and Sato et al (2007).…”

“…The authors indicate that, for perennial crops such as coffee, LAI may vary seasonally due to abiotic factors such as drought, shade, temperatures, and biological factors, such as diseases and overproduction, or even by pruning or fertilization. Brazilian studies that periodically evaluated LAI values using allometric measurements indicated results from 0.27 to 2.98 (Pereira et al, 2011) and from 2.3 to 8.7 (Flumignan et al, 2011). Pereira et al (2011) report that the LAI increases linearly as the coffee grows.…”

“…Brazilian studies that periodically evaluated LAI values using allometric measurements indicated results from 0.27 to 2.98 (Pereira et al, 2011) and from 2.3 to 8.7 (Flumignan et al, 2011). Pereira et al (2011) report that the LAI increases linearly as the coffee grows. On the other hand, Flumignan et al (2011) reported that LAI showed large oscillations throughout the measurements in all treatments evaluated with irrigated, non-irrigated and controlled and that tendency was observed in the present study (Figure 4).…”

Los balances hídricos agrícolas en modelos de simulación agroclimáticos. Una revisión analítica

“…Por su parte la ET c expresa la evapotranspiración de un cultivo que se desarrolla libre de enfermedades, con buena fertilización, que crece en un campo extenso bajo condiciones óptimas de humedad en el suelo y alcanza su producción total bajo ciertas condiciones climáticas (FAO, 2006). El cálculo de la ET c se representa en la ecuación 4 (Casa et al, 2000;Pereira et al, 2011).…”