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

Arthur Carniato Sanches,Débora Pantojo de Souza,Eder Pereira Gomes,Fernando Campos Mendonça,Fernanda Lamede Ferreira de Jesus

doi:10.1590/1678-992x-2017-0386

Arthur Carniato Sanches, Débora Pantojo de Souza + Show 3 more

Open Access

https://doi.org/10.1590/1678-992x-2017-0386

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Abstract

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. Mombaca) 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).

Highlights

Livestock and agriculture have been engaging in a competing claim for land in Brazil
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
This work aimed to obtain Kc for two tropical forage crops (Guinea grass and Bermuda grass) single cropped throughout the year and overseeded with black oat and ryegrass during the fall/winter season

Summary

Introduction

Livestock and agriculture have been engaging in a competing claim for land in Brazil. Cattle ranchers must increase their adoption of technologies to raise soil fertility levels and to use irrigation, with the aim of enhancing both the animal stock rate per area and production efficiency (Barbosa et al, 2015). The pasture forage yield is high during the warm, rainy season and low during drought periods or in the cold, dry season. The reduced forage yield during the dry season is defined as production seasonality (Antoniel et al, 2016; Durante et al, 2017). The main factors that affect tropical forage yield are soil water content, solar radiation, photoperiod and temperature (Barbosa et al, 2015). If the last three factors are not a hindrance, irrigation can overcome the soil water deficit and increase the forage yield (Neal et al, 2011)

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