Intercepted radiation by apple canopy can be used as a basis for irrigation scheduling
TL;DR: In this paper, the authors assessed crop intercepted radiation as the main factor for decision on irrigation scheduling and found that the ratio between transpiratory radiation use efficiency (TRUE) increased linearly with IPARd (R2=0.81 in 2007 and 0.84 in 2008).
About: This article is published in Agricultural Water Management.The article was published on 2011-03-01. It has received 38 citations till now. The article focuses on the topics: Irrigation scheduling & Irrigation.
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TL;DR: In this article, a functional model of tree transpiration by quantifying an average daily canopy conductance (Gc) based on radiation use efficiency and CO2 assimilation was developed for water allocation purposes and to enhance the precision of water applications under full and deficit irrigation.
68 citations
TL;DR: In this paper, the suitability of FAO's water balance method, locally adjusted by sensors, as the basis for the scheduling algorithm, and an approach for their automated interpretation, for providing feedback to the algorithm, was evaluated in the context of drip-irrigated orchards.
68 citations
TL;DR: The results indicate that the remote sensing-based soil water balance estimated ETc reasonably well over two growing seasons, and the proposed methodology could be considered as a useful tool for scheduling irrigation and driving the estimation of water requirements over large areas for apple orchards.
Abstract: The main goal of this research was to estimate the actual evapotranspiration (ETc) of a drip-irrigated apple orchard located in the semi-arid region of Talca Valley (Chile) using a remote sensing-based soil water balance model. The methodology to estimate ETc is a modified version of the Food and Agriculture Organization of the United Nations (FAO) dual crop coefficient approach, in which the basal crop coefficient (Kcb) was derived from the soil adjusted vegetation index (SAVI) calculated from satellite images and incorporated into a daily soil water balance in the root zone. A linear relationship between the Kcb and SAVI was developed for the apple orchard Kcb = 1.82·SAVI − 0.07 (R2 = 0.95). The methodology was applied during two growing seasons (2010–2011 and 2012–2013), and ETc was evaluated using latent heat fluxes (LE) from an eddy covariance system. The results indicate that the remote sensing-based soil water balance estimated ETc reasonably well over two growing seasons. The root mean square error (RMSE) between the measured and simulated ETc values during 2010–2011 and 2012–2013 were, respectively, 0.78 and 0.74 mm·day−1, which mean a relative error of 25%. The index of agreement (d) values were, respectively, 0.73 and 0.90. In addition, the weekly ETc showed better agreement. The proposed methodology could be considered as a useful tool for scheduling irrigation and driving the estimation of water requirements over large areas for apple orchards.
59 citations
TL;DR: In this article, the A&P approach was applied with remotely sensed fc data for a variety of crops in California using the Satellite Irrigation Management Support (SIMS) framework.
52 citations
TL;DR: Li et al. as discussed by the authors compared the effects of apple trees of different ages by partitioning evapotranspiration into canopy interception (calculated), tree transpiration (thermal-dissipation probes) and soil evaporation (micro-lysimeter) in a semiarid region of northwest China from May to September in 2012, 2013 and 2014.
41 citations
References
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01 Jan 1998
TL;DR: In this paper, an updated procedure for calculating reference and crop evapotranspiration from meteorological data and crop coefficients is presented, based on the FAO Penman-Monteith method.
Abstract: (First edition: 1998, this reprint: 2004). This publication presents an updated procedure for calculating reference and crop evapotranspiration from meteorological data and crop coefficients. The procedure, first presented in FAO Irrigation and Drainage Paper No. 24, Crop water requirements, in 1977, allows estimation of the amount of water used by a crop, taking into account the effect of the climate and the crop characteristics. The publication incorporates advances in research and more accurate procedures for determining crop water use as recommended by a panel of high-level experts organised by FAO in May 1990. The first part of the guidelines includes procedures for determining reference crop evapotranspiration according to the FAO Penman-Monteith method. These are followed by updated procedures for estimating the evapotranspiration of different crops for different growth stages and ecological conditions.
21,958 citations
TL;DR: In this paper, the saturation vapor pressure and temperature for moist air were derived for the meteorologically interesting region of −80 to +50°C. The equations are designed to be easily implemented on a calculator or computer and can be used to convert in either direction.
Abstract: Equations are presented which relate saturation vapor pressure to temperature for moist air. The equations are designed to be easily implemented on a calculator or computer and can be used to convert in either direction. They are more accurate than the commonly used Goff-Gratch equations for the meteorologically interesting region of −80 to +50°C. Equations also are given for the enhancement factor.
1,310 citations
TL;DR: In this paper, the relative sensitivity of plant and soil-based measures of water availability were compared for prune trees subjected to a range of irrigation regimes under field conditions, and the results indicated that a 50% reduction in leaf and canopy level water loss characteristics was associated with relatively small reductions (0.5 to 0.6 MPa) in stem ψ.
Abstract: Additional index words. evapotranspiration, leaf-water potential, soil water, stomatal conductance Abstract. The relative sensitivity of plant- and soil-based measures of water availability were compared for prune trees subjected to a range of irrigation regimes under field conditions. Over the growing season, leaf- and stem-water potentials (ψ) measured at midday exhibited clear differences between frequently irrigated trees and unirrigated trees that were growing on stored soil moisture. Stem ψ was less variable than leaf ψ, ψ, and the daily variability in stem ψ ψ was closely related to daily variability in evaporative demands, as measured by vapor pressure deficit (VPD). As a result of lower variability, stem ψ reflected the small stress effect of a moderate, 50% soil moisture depletion irrigation interval, whereas leaf ψ did not. The relation between soil water content and estimated orchard evapo- transpiration (ET) was influenced by local differences in soil texture within the experimental plot. The relation between stem ψ and ET, however, was not influenced by soil texture and, in addition, was very similar to the relation between stem ψ and leaf stomatal conductance. Both relationships indicated that a 50% reduction in leaf and canopy level water loss characteristics was associated with relatively small reductions (0.5 to 0.6 MPa) in stem ψ. ψ. Stem ψ appears to be a sensitive and reliable plant-based measure of water stress in prune and maybe a useful tool for experimental work and irrigation scheduling. Plant water stress under dry soil conditions is associated with various physiological responses, such as growth reductions and stomatal closure, which can reduce plant water use and can also limit overall plant productivity (Bradford and Hsiao, 1982). Ir- rigation to avoid plant water stress is a common practice, and the need for irrigation is often based on a soil-water balance approach, using estimates of environmental water demand (e.g., reference crop evapotranspiration (ET 0), Burman. 1980) and/or measures of soil-water status (Campbell and Campbell, 1982). The value of both of these measures, however, is limited, be- cause they are not directly related to the occurrence of plant water stress and hence may not be directly related to the symp- toms that ultimately reduce plant productivity. For instance, Denmead and Shaw (1962) found that under high ET0 conditions (6 to 7 mm·day -1 ), a relatively wet soil (soil matric potential greater than - 0.03 MPa) was required to support maximum plant transpiration. Under lower ET0 conditions, however (1.4
530 citations
TL;DR: In this article, the FAO-56 procedure for estimating the crop coefficient K� c as a function of fraction of ground cover and crop height has been formalized in this study using a density coefficient K petertodd d.
Abstract: The FAO-56 procedure for estimating the crop coefficient K
c as a function of fraction of ground cover and crop height has been formalized in this study using a density coefficient K
d. The density coefficient is multiplied by a basal K
c representing full cover conditions, K
cb full, to produce a basal crop coefficient that represents actual conditions of ET and vegetation coverage when the soil surface is dry. K
cb full is estimated primarily as a function of crop height. K
cb full can be adjusted for tree crops by multiplying by a reduction factor (F
r) estimated using a mean leaf stomatal resistance term. The estimate for basal crop coefficient, K
cb, is further modified for tree crops if some type of ground-cover exists understory or between trees. The single (mean) crop coefficient is similarly estimated and is adjusted using a K
soil coefficient that represents background evaporation from wet soil. The K
c estimation procedure was applied to the development periods for seven vegetable crops grown in California. The average root mean square error between estimated and measured K
c was 0.13. The K
c estimation procedure was also used to estimate K
c during midseason periods of horticultural crops (trees and vines) reported in the literature. Values for mean leaf stomatal resistance and the F
r reduction factor were derived that explain the literature K
c values and that provide a consistent means to estimate K
c over a broad range of fraction of ground cover.
327 citations