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

Abstract

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).

Production and water-use efficiency of Megathyrsus maximus cv. Mombaça “Guinea grass” under nitrogen and boron doses

“…Higher values were found in the fall, spring, and summer seasons, which led to accumulated rainfall of 1569.9 mm. The value of water applied in the fall (irrigation + rainfall) was very similar to the estimated potential consumption (ETc) of Guinea grass found by Sanches et al (2019). It shows that the evapotranspiration methods can correlate better in periods of a mild climate and little rainfall, especially when using lysimetry, in which sensors can suffer a lot from weather conditions (e.g., storms, winds, and thunderstorms).…”

“…The experiment conducted by Sanches, Souza, Jesus, Mendonça and Gomes (2019) in the same site during the experimental period, which evaluated the crop evapotranspiration (ETc) for Guinea grass and the reference evapotranspiration (ETo), was Figure 2. Mombaça "Guinea grass" productivity (Mg ha −1 ) per season in Piracicaba, SP, Brazil (2017/2018).…”

APSIM‐Tropical Pasture model parameterization for simulating Marandu palisade grass growth and soil water in irrigated and rainfed cut‐and‐carry systems

“…In the standard model, the value of U, which represents the maximum accumulated evaporation of the soil at the end of the first stage, is equal to the value of 6 mm (during the summer) as presented in Table 4. In the estimates of this study, in none of the periods, this value was reached (Figure 3), possibly because the evaporation of the soil is lower in crops that fully cover the soil, considered null in some cases (Sanches et al, 2019; Souza, 2017).…”

“…(5) 4. In the estimates of this study, in none of the periods, this value was reached (Figure 3), possibly because the evaporation of the soil is lower in crops that fully cover the soil, considered null in some cases (Sanches et al, 2019;Souza, 2017).…”

The Effect of Best Crop Practices in the Pig and Poultry Production on Water Productivity in a Southern Brazilian Watershed

“…The lowest WPindirect,Feed of safra (fm-safra; rm-safra) and soy (fs-soy; rs-soy) among all crops arrangements, producer regions and the four scenarios analyzed was found for crops produced in RS for both animal feed production (Tables 3 and 4). Considering forage crops like ryegrass, for instance, can present high water consumption throughout their growth cycle [56], another intercropping species with lower water demands (lower single crop coefficient K c ) could be sown in order to improve WP indirect,Feed of crops produced in PR and RS.…”