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

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.

摘要
本研究旨在借助高精度蒸渗仪（lysimeters），确定巴西马托格罗索州（MT）唐加拉达塞拉市（Tangará da Serra）的早熟大豆品种的双作物系数。本研究采用FAO第56号公报提出的双作物系数法（dual Kc），该方法由通过微型蒸渗仪测定的土壤蒸发系数（Ke）与通过称重式蒸渗仪测定的基础作物系数（Kcb）两部分构成。参考作物蒸散量（ETo）采用彭曼-蒙特斯方程（Penman-Monteith equation）计算。试验于2015/2016生长季开展大豆播种与收获，种植行距为0.45米。试验生育期内估算的参考作物蒸散量（ETo）为267.06 mm，全生育期作物总蒸散量为323.61 mm。通过蒸渗仪测定的大豆初始、中期及末期生育阶段的基础作物系数（Kcb）分别为0.47、1.15和0.89；对应阶段的土壤蒸发系数（Ke）分别为0.94、0.14和0.44。