Calculating Methods of Forage Crop Water Requirements in Pasture

Zheng, Hexiang; Li, Heping; Ke-zhen, Guo

doi:10.1016/j.proeng.2012.01.753

Cited by 4 publications

(3 citation statements)

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“…With the ETc and estimation of reference evapotranspiration (ETo) (Allen et al, 1998), it is possible to determine values for the crop coefficient (Kc). Given the Kc values and ETo, it is possible to estimate ETc from meteorological data (Zheng et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Crop coefficients of tropical forage crops, single cropped and overseeded with black oat and ryegrass

Sanches

Souza

Jesus

et al. 2019

Sci. agric. (Piracicaba, Braz.)

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Crop coefficient (Kc) is the ratio between crop evapotranspiration (ETc) and reference evapotranspiration (ETo), representing the phenological effects on crop water consumption. Kc is fundamental to estimating ETc by agrometeorological methods. This research study aimed to determine Kc and ETc values for Guinea grass (Megathyrsus maximus cv. Mombaça) and Bermuda grass (Cynodon spp.), both single cropped for one year and overseeded with black oat (Avena strigosa) and ryegrass (Lolium multiflorum) during fall/winter. The experiment in the field comprised four plots, two for each tropical forage, with and without overseeding. At the center of each plot, there was a weighing lysimeter with an automated system for data collection. ETc was measured daily over four seasons following the lysimetric method; ETo was calculated using the Penman-Monteith equation. ETc and ETo values were used to estimate Kc values. The single cropped Guinea grass showed the highest values for ETc, with mean ETc and Kc of 3.99 mm d-1 and 1.07, respectively. The single cropped Bermuda grass showed ETc and Kc values of 3.57 mm d-1 and 0.96, respectively. The results of paired t-testing for Kc showed no significant differences (p = 0.05) between single cropped and intercropped for both Guinea grass and Cynodon spp. During winter, intercropped Guinea grass did not show an ETc significantly higher than single cropped Guinea grass, with mean Kc values 0.98 for intercropped and 1.10 for single cropped. Similarly, Bermuda grass did not show significant differences between mean Kc values for intercropped (1.02) and single cropped (1.00).

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Section: Introductionmentioning

confidence: 99%

Crop coefficients of tropical forage crops, single cropped and overseeded with black oat and ryegrass

Sanches

Souza

Jesus

et al. 2019

Sci. agric. (Piracicaba, Braz.)

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show abstract

“…So, with ETc and the estimation of reference evapotranspiration (ETo), it is possible to calculate the crop coefficient (Kc), as shown by Allen et al (1998). With the Kc values for each phase of the crop phenological cycle, it is possible to estimate ETc with meteorological data (Zheng et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

WATER CONSUMPTION ESTIMATE FOR MOMBAÇA AND Cynodon spp. GRASSES IN EXCLUSIVE CROPPING AND OVERSEEDED WITH WINTER FORAGE

Sanches¹,

Souza²,

Jesus³

et al. 2017

Anais Do IV Inovagri International Meeting - 2017

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ABSTRACT:In order to improve irrigation water management practices, it is essential the precise estimation of evapotranspiration (ET). The crop coefficient (Kc) is the ratio between crop evapotranspiration (ETc) and reference evapotranspiration (ETo), and represents the effect of crop growth on water consumption. This work aimed to determine the Kc and ETc for Panicum maximum cv. Mombaça and Cynodon spp. in exclusive cropping and consorted in overseeding with oat and ryegrass during fall/winter seasons. This work was developed at ESALQ / USP, in Piracicaba (SP), using 4 experimental plots (Two for Mombaça and two for Cynodon spp., both in exclusive and overseeded cropping). At the center of each plot was placed a circular weighing lysimeter with a surface area of 1.17 m² and an automated system for data collection, composed by load cells, wires and a datalogger. During one year (February 2016 to February 2017, daily data of the lysimeter weight variation were collected, in order to calculate the forage water consumption,

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“…Therefore, it is necessary to carry out research on medium‐ and long‐term crop water requirement forecasting. Crop water requirement forecasting methods can be divided into the following categories: (1) direct estimation of crop water requirement from empirical formulas (Shuttleworth & Wallace, 2009; Zheng et al, 2012) and (2) obtaining the crop water requirement on the basis of the reference crop evapotranspiration (ET 0 ) by using the crop coefficient ( K c ) method (Allen et al, 1998). Crop water requirement‐based K c methods are commonly used because the first category is based on a large number of experimental observation data (Abdelhakim et al, 2021; Allen et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Medium‐ to long‐term forecast of reference crop evapotranspiration based on the correction of the principal control factor

Gong

Peng

Zheng

et al. 2022

Irrigation and Drainage

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This study selected the temperature Penman–Monteith (PMT) model to solve the difficulty of reference crop evapotranspiration (ET0) prediction caused by incomplete meteorological data. Then, the principal control factor of the PMT model was determined using several indicators. The results show that the annual average correlation and sensitivity coefficients between Tmax and ET0 are the highest. Hence, among the factors, Tmax is the largest contributor in contribution proportion and amount to ET0 and the principal control factor of the PMT model. The root mean square error (RMSE), relative error (RE) and mean absolute error (MAE) of the forecast ET0 increased by 0.7, 0.2, and 0.6 mm/day, respectively, after the 16th day compared with those on the 15th day. Thus, a remarkable drop in ET0 forecast precision is observed and is hardly accurate for the purpose of water distribution management in an irrigation district. The RMSE, RE, and MAE of the Tmax forecast decrease by 2.0–3.0°C, 0.1–0.2, and 2.0–2.8°C, respectively, and those of the corresponding ET0 forecast decrease by 0.7–0.9, 0.2–0.3, and 0.6–0.7 mm/day, respectively, after Tmax correction. Compared with the decaying‐average method, the improved decaying‐average method can correct Tmax better and improve the ET0 prediction accuracy.

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Calculating Methods of Forage Crop Water Requirements in Pasture

Cited by 4 publications

References 0 publications

Crop coefficients of tropical forage crops, single cropped and overseeded with black oat and ryegrass

Crop coefficients of tropical forage crops, single cropped and overseeded with black oat and ryegrass

WATER CONSUMPTION ESTIMATE FOR MOMBAÇA AND Cynodon spp. GRASSES IN EXCLUSIVE CROPPING AND OVERSEEDED WITH WINTER FORAGE

Medium‐ to long‐term forecast of reference crop evapotranspiration based on the correction of the principal control factor

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