Dual crop coefficient for the early-cycle soybean cultivar SoyTech 815 RR

Rivanildo Dallacort,Paulo S. L. de Freitas,Guilherme Bariviera,Diego F. Daniel,Joao D. Barbieri

doi:10.1590/1807-1929/agriambi.v24n2p75-81

Abstract

ABSTRACT The objective of this study was to determine the dual crop coefficient of an early-cycle soybean cultivar for the city of Tangará da Serra, MT, Brazil, using high-precision lysimeters. The method used was the dual crop coefficient (dual Kc) of FAO Bulletin 56, constitued by soil evaporation coefficient (Ke), determined by microlysimeters, and by basal crop coefficient (Kcb), determined by weighing lysimeters. Reference evapotranspiration (ETo) was calculated using the Penman-Monteith equation. Soybean sowing and harvesting were performed in the 2015/16 season with spacing of 0.45 m between rows. The reference evapotranspiration (ETo) estimated for the cultivation period was 267.06 mm; the crop evapotranspiration was 323.61 mm throughout its cycle. The Kcb values determined by lysimeters for soybean cultivation were 0.47, 1.15 and 0.89 for the initial, intermediate and final stages, respectively; Ke values at the initial, intermediate and final stages were 0.94, 0.14 and 0.44, respectively.

Highlights

Water is the main limiting factor for soybean to express all its production potential, as it acts on virtually all physiological and biochemical processes of the crop, besides constituting most of the plant’s weight (Farias et al, 2007; Silva et al, 2014).The irrigation system becomes a widely used tool to increase yields, but it is necessary to perform a correct water management and correctly design the system
Evapotranspiration values are used to determine the dual crop coefficient, and FAO Bulletin 56 defined that Kc can be divided into two components, aiming to improve the efficiency of measuring the water consumption of plants under field conditions
This methodology is based on the determination of the soil evaporation coefficient (Ke), as the ratio between soil evaporation and reference evapotranspiration (ETo), and on the determination of the basal crop coefficient (Kcb), as the ratio between plant transpiration and ETo (Allen et al, 1998)

Summary

Introduction

Water is the main limiting factor for soybean to express all its production potential, as it acts on virtually all physiological and biochemical processes of the crop, besides constituting most of the plant’s weight (Farias et al, 2007; Silva et al, 2014).The irrigation system becomes a widely used tool to increase yields, but it is necessary to perform a correct water management and correctly design the system. Evapotranspiration values are used to determine the dual crop coefficient (dual Kc), and FAO Bulletin 56 defined that Kc can be divided into two components, aiming to improve the efficiency of measuring the water consumption of plants under field conditions. This methodology is based on the determination of the soil evaporation coefficient (Ke), as the ratio between soil evaporation and reference evapotranspiration (ETo), and on the determination of the basal crop coefficient (Kcb), as the ratio between plant transpiration and ETo (Allen et al, 1998).

Objectives

Methods

Results

Conclusion