Evapotranspiration and crop coefficient for potato in organic farming

Abstract

The aim of this study was to quantify the water consumption and the crop coefficients (Kc) for the potato (Solanum tuberosum L.), in Seropédica, Rio de Janeiro (RJ), Brazil, under organic management, and to simulate the crop evapotranspiration (ETc) using the Kc obtained in the field and the ones recommended by the Food and Agriculture Organization (FAO). The water consumption was obtained through soil water balance, using TDR probes installed at 0.15m and 0.30m deep. At the different stages of development, the Kc was determined by the ratio of ETc and reference evapotranspiration, obtained by Penman-Monteith FAO 56. The crop coefficients obtained were 0.35, 0.45, 1.29 and 0.63. The accumulated ETc obtained in the field was 109.6 mm, while the ETc accumulated from FAO's Kc were 142.2 and 138mm, respectively, considering the classical values and the values adjusted to the local climatic conditions. The simulation of water consumption based on meteorological data of historical series from 1961 to 2007 provided higher value of ETc when compared with the one obtained in the field. From the meteorological data of historical series, it was observed that the use of Kc recommended by FAO may overestimate the amount of irrigation water by 9%, over the same growing season.

Yield, water use efficiency, and yield response factor in carrot crop under different irrigation depths

“…According to CARVALHO et al (2013), the climate in the region is classified as Aw (Köppen classification), with high temperatures and rains in summer, and dry weather with mild temperatures in winter. The rains are concentrated in the period Nov-Mar (annual averages for: rainfall: 1213mm; temperature: 24.5°C).…”

“…Although the water amount applied by irrigation has been enough to raise θ to the field capacity, Dd and ΔSW were also monitored by TDR. The Ep term was determined for each treatment according to the methodology described by CARVALHO et al (2013). It consisted of the fraction of the precipitated depth that contributed to raise the soil moisture to the field capacity in the depth corresponding to the root system.…”

Water requirement and yield of fig trees under different drip irrigation management

“…Sensor calibration was performed based on daily readings of the apparent dielectric constant (ka) and respective determination of soil moisture by the gravimetric model. According to CARVALHO et al (2013), soil samples were collected in calibration bowls built in representative locations of both textural classes, where sensors with 0.15 m length metal rods were horizontally installed at 0.2 and 0.4 m depth. From the volumetric moisture (θ) and kA data, the following adjustment equations were obtained via simple regression analysis: θ 20 = 0.0099 ka + 0.1048 and θ 40 = 0.011 ka + 0.103 (for B1), and θ 20 = 0.0132 ka + 0.0213 and θ 40 = 0.0108 ka + 0.0401 (for B2).…”

Crop coefficient of a popular potato variety in Bangladesh

“…8 and was done by following averaging method (Biswas et al, 2014). Carvalho et al (2013) found the Kc values of 0.35, 0.45, 1.29 and 0.63 for initial, development, mid-season and late season, respectively in Rio de Janeiro (RJ), Brazil. Kashyap and Panda (2001) found the Kc values of potato at initial, crop development, reproductive and maturity were 0.42, 0.85, 1.27 and 0.57, respectively at the experimental farm of the Agricultural and Food Engineering Department, Indian Institute of Technology, Kharagpur, India.…”

“…Tyagi et al (2000) recommended utmost importance for the locally calibrated Kc values for a given climatic condition. Many researchers determined Kc values of potato using different lysimeter under various climatic conditions across the world (Carvalho et al, 2013;Kashyap and Panda, 2001;Allen et al,. 1998;Ferdous et al, 1985;Hane and Pumphre, 1984;Doorenbos and Kassam, 1979;Doorenbos and Pruitt, 1977).…”