Crop coefficient, water requirements, yield and water use efficiency of
sugarcane growth in Brazil
A correct evaluation of water losses as evapotranspiration (ET) by crops is important for allocating
irrigation water and improving water use efficiency. Field experiments were conducted throughout
2009/2010 (second ratoon) and 2010/2011 (third ratoon) in a sugarcane field of a commercial distillery
located on the coastal area of Paraiba state, Brazil. The main objective of this study was to determine
crop coefficient, water requirements and water use efficiency (WUE) of sugarcane grown in a tropical
climate. The experimental design was by randomized block design with four irrigation treatments and
three replications using two center pivots. Crop evapotranspiration (ET) was determined by field soil
water balance and reference evapotranspiration (ETo) was obtained based on Penman–Monteith method
(FAO/56), using data of air temperature, relative humidity, wind speed and solar radiation from Data
Collection Platform, located next to the experimental site. The experimental area was cultivated with
irrigation applied weekly by a center pivot system in addition to rainfall. The irrigation scheduling was
based on four irrigation levels (T1 = 25%, T2 = 50%, T3 = 75% and T4 = 100% of ETo). Results showed that ET
and WUE are strongly influenced by soil water availability. When averaged across two years, productivity
increased according to increases in water level. Sugarcane ET ranged from 2.7 (rain-fed condition) to
4.2 mm day−1 (100% ETo irrigation treatment)