Importance of pan evaporation for irrigation scheduling and proper use of crop-pan coefficient (Kcp), crop coefficient (Kc) and pan coefficient (Kp)

2011 ◽  
Vol 6 (32) ◽  
Author(s):  
Ahmet ERTEK
Keyword(s):  
Crop Coefficient ◽  
Irrigation Scheduling ◽  
Pan Evaporation ◽  
Pan Coefficient

scholarly journals Evaluation of Several Reference Evapotranspiration Models and Determination of Crop Water Requirement for Tomato in a Solar Greenhouse

HortScience ◽  
2020 ◽  
Vol 55 (2) ◽  
pp. 244-250 ◽  
Author(s):  
Xuewen Gong ◽  
Shunsheng Wang ◽  
Cundong Xu ◽  
Hao Zhang ◽  
Jiankun Ge
Keyword(s):  
Reference Evapotranspiration ◽  
Crop Coefficient ◽  
Growth Period ◽  
Northern China ◽  
Irrigation Scheduling ◽  
Pan Evaporation ◽  
Evaporation Coefficient ◽  
First Choice ◽  
Solar Greenhouse ◽  
Coefficient Method

Studies on dual crop coefficient method in a greenhouse require accurate values of reference evapotranspiration (ETo). This study was conducted in a solar greenhouse at the experimental station of the Chinese Academy of Agricultural Sciences during 2015 and 2016. An automatic weather station was installed in the center of the same greenhouse to record weather parameters at 30-minute intervals. Five ETo models (Penman-Monteith, Penman, radiation, pan evaporation, and Priestley-Taylor) were employed, and their performance was evaluated using the dual crop coefficient method. The basal crop coefficient Kcb and soil evaporation coefficient Ke were adjusted according to the surrounding climate inside the greenhouse. Crop evapotranspiration (ETc) was continuously measured using sap flow system combined with microlysimeter in 2015 and weighing lysimeters in 2016. Daily ETo was simulated from the five models and compared with the measurements. Results show that the adjusted Kcb values were 0.15, 0.94, and 0.65 in 2015 and 0.15, 1.02, and 0.70 in 2016 at initial, midseason, and late-season, respectively. The Ke varies between 0.10 and 0.45 during the whole growth period. The ETc was ≈345 mm for drip-irrigated tomato in solar greenhouse at the whole growth stage. The radiation and pan evaporation models tend to overestimate ETo values. Results of the Penman-Monteith, Penman, and Priestley-Taylor models show comparatively good performance in estimating ETo. Considering the robustness and simplicity, the Priestley-Taylor was recommended as the first choice to estimate ETo of tomato grown in a solar greenhouse. This work can help farmers to optimize the irrigation scheduling based on an ETo model for solar greenhouse vegetables in northern China.

scholarly journals Estimation of crop coefficient for Marigold (Tagetes erecta (L.)) under drip irrigated greenhouse

2020 ◽  
Vol 12 (2) ◽  
pp. 128-132
Author(s):  
E. Sujitha ◽  
K. Shanmugasundaram ◽  
G. Thiyagarajan
Keyword(s):  
Growth Stage ◽  
Crop Coefficient ◽  
Irrigation Scheduling ◽  
Cultivated Plants ◽  
Tagetes Erecta ◽  
Growth Stages ◽  
Crop Water ◽  
Large Area ◽  
Pan Coefficient ◽  
Tagetes Erecta L

Crop water consumption (ETc) varies from region to region depending on crop type, growth stages, soil, and climate conditions. In order to obtain full yield and avoid unnecessary water usage, the water demand of the cultivated plants should be accurately calculated, and irrigation water should be applied in accordance with plant needs. In this, the study was carried out in field No.C3 of Central farm at Agricultural Engineering College and Research Institute, Kumulur, Trichy district to determine the growth stage-specific crop coefficient (Kc) and pan coefficient (Kp) for the greenhouse grown marigold (Tagetes erecta (L.). Since, a large area was occupied by a ClassA pan, the reduced-size evaporative pans (20 and 60 cm compared with Class A pan) was used and pan coefficient was determined as 0.93 and 0.96 respectively. A pan coefficient (Kp) was used to convert pan evaporation (Epan) to grass reference evapotranspiration (ETo). Based on the tensiometer readings, the depleted moisture content was taken to reckon the crop coefficient for different growth stage. The results revealed that crop coefficient (Kc) for marigold was observed as 0.37 during the initial stage (Kcin), 0.8 during mid-stage (Kcmid) and 0.47 (Kcfin) during the final stage. These results would be helpful for crop water requirement and irrigation scheduling for similar condition.

scholarly journals THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF SUGAR CANE (SACCHARUM OFFICINARUM): A REVIEW

2011 ◽  
Vol 47 (1) ◽  
pp. 1-25 ◽  
Author(s):  
M. K. V. CARR ◽  
J. W. KNOX
Keyword(s):  
Water Stress ◽  
Water Relations ◽  
Sugar Cane ◽  
Root Zone ◽  
Water Productivity ◽  
Crop Coefficient ◽  
Saccharum Officinarum ◽  
Irrigation Scheduling ◽  
Background Information ◽  
Technology Choice

SUMMARYThe results of research on the water relations and irrigation needs of sugar cane are collated and summarized in an attempt to link fundamental studies on crop physiology to irrigation practices. Background information on the centres of production of sugar cane is followed by reviews of (1) crop development, including roots; (2) plant water relations; (3) crop water requirements; (4) water productivity; (5) irrigation systems and (6) irrigation scheduling. The majority of the recent research published in the international literature has been conducted in Australia and southern Africa. Leaf/stem extension is a more sensitive indicator of the onset of water stress than stomatal conductance or photosynthesis. Possible mechanisms by which cultivars differ in their responses to drought have been described. Roots extend in depth at rates of 5–18 mm d−1 reaching maximum depths of > 4 m in ca. 300 d providing there are no physical restrictions. The Penman-Monteith equation and the USWB Class A pan both give good estimates of reference crop evapotranspiration (ETo). The corresponding values for the crop coefficient (Kc) are 0.4 (initial stage), 1.25 (peak season) and 0.75 (drying off phase). On an annual basis, the total water-use (ETc) is in the range 1100–1800 mm, with peak daily rates of 6–15 mm d−1. There is a linear relationship between cane/sucrose yields and actual evapotranspiration (ETc) over the season, with slopes of about 100 (cane) and 13 (sugar) kg (ha mm)−1 (but variable). Water stress during tillering need not result in a loss in yield because of compensatory growth on re-watering. Water can be withheld prior to harvest for periods of time up to the equivalent of twice the depth of available water in the root zone. As alternatives to traditional furrow irrigation, drag-line sprinklers and centre pivots have several advantages, such as allowing the application of small quantities of water at frequent intervals. Drip irrigation should only be contemplated when there are well-organized management systems in place. Methods for scheduling irrigation are summarized and the reasons for their limited uptake considered. In conclusion, the ‘drivers for change’, including the need for improved environmental protection, influencing technology choice if irrigated sugar cane production is to be sustainable are summarized.

Irrigation Scheduling Based on Evaporation and Crop Water Requirement for Summer Peanuts1

1984 ◽  
Vol 11 (1) ◽  
pp. 4-6 ◽  
Author(s):  
D. K. Pahalwan ◽  
R. S. Tripathi
Keyword(s):  
Water Use ◽  
Irrigation Water ◽  
Irrigation Scheduling ◽  
Water Requirement ◽  
Crop Water Requirement ◽  
Pan Evaporation ◽  
Crop Water ◽  
Formation Stage ◽  
Evaporation Ratio ◽  
Pod Development

Abstract Field experiment was conducted during dry season of 1981 and 1982 to determine the optimal irrigation schedule for summer peanuts (Arachis hypogaea L.) in relation to evaporative demand and crop water requirement at different growth stages. It was observed that peanut crop requires a higher irrigation frequency schedule during pegging to pod formation stage followed by pod development to maturity and planting to flowering stages. The higher pod yield and water use efficiency was obtained when irrigations were scheduled at an irrigation water to the cumulative pan evaporation ratio of 0.5 during planting to flowering, 0.9 during pegging to pod formation and 0.7 during pod development to maturity stage. The profile water contribution to total crop water use was higher under less frequent irrigation schedules particularly when the irrigations were scheduled at 0.5 irrigation water to the cumulative pan evaporation ratio up to the pod formation stage.

Dry Matter, Nodulation and Nutrient Uptake in Chickpea (Cicer arietinum) as Influenced by Irrigation and Phosphorus

1989 ◽  
Vol 25 (3) ◽  
pp. 349-355 ◽  
Author(s):  
S. S. Parihar ◽  
R. S. Tripathi
Keyword(s):  
Grain Yield ◽  
Nutrient Uptake ◽  
Irrigation Water ◽  
Vegetative Growth ◽  
Dry Matter ◽  
Dry Weight ◽  
Irrigation Scheduling ◽  
Dry Matter Accumulation ◽  
Pan Evaporation ◽  
Eastern India

SUMMARYThe response of chickpea to irrigation and phosphorus was studied at Kharagpur in Eastern India. Irrigation scheduling was based on the ratio between irrigation water applied and cumulative pan evaporation (ID/CPE), and had little effect on dry matter accumulation. Increasing the frequency and amount of irrigation reduced the number and dry weight of nodules per plant, which increased to a maximum 70 days after sowing and then declined. Irrigation significantly reduced grain yield as a result of excessive vegetative growth at the expense of pod formation. Application of phosphorus promoted nodulation and increased both nodule dry weight and the concentration of N, P and K in grain and stover. Uptake of N, P and K by the crop was also increased.

scholarly journals Evaluation of a Hybrid Reflectance-Based Crop Coefficient and Energy Balance Evapotranspiration Model for Irrigation Management

2018 ◽  
Vol 61 (2) ◽  
pp. 533-548 ◽  
Author(s):  
J. Burdette Barker ◽  
Christopher M. U. Neale ◽  
Derek M. Heeren ◽  
Andrew E. Suyker
Keyword(s):  
Remote Sensing ◽  
Energy Balance ◽  
Water Balance ◽  
Real Time ◽  
Eddy Covariance ◽  
Irrigation Management ◽  
Crop Coefficient ◽  
Irrigation Scheduling ◽  
Balance Model ◽  
Crop Coefficients

Abstract. Accurate generation of spatial soil water maps is useful for many types of irrigation management. A hybrid remote sensing evapotranspiration (ET) model combining reflectance-based basal crop coefficients (Kcbrf) and a two-source energy balance (TSEB) model was modified and validated for use in real-time irrigation management. We modeled spatial ET for maize and soybean fields in eastern Nebraska for the 2011-2013 growing seasons. We used Landsat 5, 7, and 8 imagery as remote sensing inputs. In the TSEB, we used the Priestly-Taylor (PT) approximation for canopy latent heat flux, as in the original model formulations. We also used the Penman-Monteith (PM) approximation for comparison. We compared energy balance fluxes and computed ET with measurements from three eddy covariance systems within the study area. Net radiation was underestimated by the model when data from a local weather station were used as input, with mean bias error (MBE) of -33.8 to -40.9 W m-2. The measured incident solar radiation appeared to be biased low. The net radiation model performed more satisfactorily when data from the eddy covariance flux towers were input into the model, with MBE of 5.3 to 11.2 W m-2. We removed bias in the daily energy balance ET using a dimensionless multiplier that ranged from 0.89 to 0.99. The bias-corrected TSEB ET, using weather data from a local weather station and with local ground data in thermal infrared imagery corrections, had MBE = 0.09 mm d-1 (RMSE = 1.49 mm d-1) for PM and MBE = 0.04 mm d-1 (RMSE = 1.18 mm d-1) for PT. The hybrid model used statistical interpolation to combine the two ET estimates. We computed weighting factors for statistical interpolation to be 0.37 to 0.50 for the PM method and 0.56 to 0.64 for the PT method. Provisions were added to the model, including a real-time crop coefficient methodology, which allowed seasonal crop coefficients to be computed with relatively few remote sensing images. This methodology performed well when compared to basal crop coefficients computed using a full season of input imagery. Water balance ET compared favorably with the eddy covariance data after incorporating the TSEB ET. For a validation dataset, the magnitude of MBE decreased from -0.86 mm d-1 (RMSE = 1.37 mm d-1) for the Kcbrf alone to -0.45 mm d-1 (RMSE = 0.98 mm d-1) and -0.39 mm d-1 (RMSE = 0.95 mm d-1) with incorporation of the TSEB ET using the PM and PT methods, respectively. However, the magnitudes of MBE and RMSE were increased for a running average of daily computations in the full May-October periods. The hybrid model did not necessarily result in improved model performance. However, the water balance model is adaptable for real-time irrigation scheduling and may be combined with forecasted reference ET, although the low temporal frequency of satellite imagery is expected to be a challenge in real-time irrigation management. Keywords: Center-pivot irrigation, ET estimation methods, Evapotranspiration, Irrigation scheduling, Irrigation water balance, Model validation, Variable-rate irrigation.

scholarly journals Measurement and Estimation of Annual Variability of Water Loss at Njuwa Lake Using Class ‘A’ Pan Evaporation Method

2020 ◽  
pp. 11-21
Author(s):  
A. A. Sadiq
Keyword(s):  
Water Loss ◽  
Irrigation Scheduling ◽  
Water Volume ◽  
Pan Evaporation ◽  
Morphometric Characteristics ◽  
Average Width ◽  
Evaporation Method ◽  
Class A ◽  
Annual Variability ◽  
Class A Pan

Aim: To measure and estimate the annual variability of water loss at Njuwa Lake using Class ‘A’ Pan Evaporation Method. Place and Duration of Study: Njuwa Lake in Yola South LGA, Adamawa State Nigeria between November, 2019 and May, 2020. Methodology: Direct measurements of morphometric characteristics of the lake were adopted using simple bathymetric method. Evaporation rates data and other related weather variable for the periods of ten (2007-2016) years were obtained from Upper Benue River Basin Development Authority located near the lake where the volume of water in the lake and the annual water loss were estimated using FAO estimate of water requirement procedures. Results: The results revealed that Njuwa Lake has morphometric characteristics of 1, 325 m average length, 180m average width, average depth 3.4 m, 238, 500 m2 of  surface area, 1,445 m shoreline length and 0.834 m shoreline development with an estimated water volume of  810, 900 m3 respectively. Similarly, highest Class ‘A’ Pan evaporation rates were found in the year 2011, 2007 and 2008 with the corresponding total annual values of 2688.06 mm, 2403.64 mm and 2389.63 mm having an estimated values of water lost from the lake of 641, 102.310 m3 (79.07%), 573, 268.140 m3(70.7%) and 569, 926.755 m3 (70.29 %) correspondingly. Conversely, the year 2013,2012 and 2014 were found with the lowest measured Pan evaporation rates (1585.00 mm, 1611.54 mm and 1663.27 mm) with an estimated water lost on the lake of about  378, 022.500 m3 (46.6 %), 384, 352.290 m3 (47.4 %) and 396, 689.895 m3 (48.9 %). Conclusion: The rate of water loss was through evaporation was estimated to be greater than the stored water in the Lake in most of the years under study which led to untimely drying of the lake thereby affecting the irrigation farming in the area. Valuable strategies of water use efficiency and irrigation scheduling for effective utilization of the limited stored water in the lake for sustainable food production should be therefore adopted. The research work, however, need further work to make a comparison between the class ‘A’ Pan method and other empirical models method to revalidate the reliability.

scholarly journals Drip-irrigation Scheduling for Fresh-market Tomato Production

HortScience ◽  
1993 ◽  
Vol 28 (1) ◽  
pp. 35-37 ◽  
Author(s):  
T.K. Hartz
Keyword(s):  
Drip Irrigation ◽  
Crop Coefficient ◽  
Crop Productivity ◽  
Irrigation Scheduling ◽  
Yield Reduction ◽  
Fresh Market ◽  
Marketable Yield ◽  
Tomato Production ◽  
Canopy Development ◽  
Canopy Coverage

Drip-irrigation scheduling techniques for fresh-market tomato (Lycopersicon esculentum Mill.) production were compared in three growing seasons (1989-91). Three regimes were evaluated: EPK [reference evapotranspiration (ETo, corrected Penman) × programmed crop coefficients], ECC (ET0 × a crop coefficient based on estimated percent canopy coverage), and SMD (irrigation at 20% available soil moisture depletion). EPK coefficients ranged from 0.2 (crop establishment) to 1.1 (full canopy development). Percent canopy coverage was estimated from average canopy width ÷ row width. Irrigation in the SMD treatment was initiated at -24 kPa soil matric tension, with recharge limited to 80% of daily ET0. The EPK and ECC regimes gave similar fresh fruit yields and size distributions in all years. With the EPK scheduling technique, there was no difference in crop response between daily irrigation and irrigation three times per week. In all seasons, ECC scheduling resulted in less total water applied than EPK scheduling and averaged 76% of seasonal ET0 vs. 86% for EPK. Irrigating at 20% SMD required an average of only 64% of seasonal ET0; marketable yield was equal to the other scheduling techniques in 1989 and 1991, but showed a modest yield reduction in 1990. Using an SMD regime to schedule early season irrigation and an ECC system to guide application from mid-season to harvest may be the most appropriate approach for maximizing water-use efficiency and crop productivity.

Sign in / Sign up

Export Citation Format

Share Document