Development of a crop coefficient model for sunflower to save water in arid region M. Kiani1, M. Gheysari2, B. Mostafazadeh-Fard3, M. M. Majidi4 1
Graduate Student, Water Engineering Department, College of Agriculture, Isfahan University of Technology, Isfahan, 8415683111, Iran, Email:
[email protected] 2 Assistant Professor, Water Engineering Department, College of Agriculture, Isfahan University of Technology, Isfahan, 8415683111, Iran, PH (+98) 311-391 3367; Email:
[email protected] 3 Professor, Water Engineering Department, College of Agriculture, Isfahan University of Technology, Isfahan, 8415683111, Iran, PH. (+98) 311-3913430; Email
[email protected] 4 Assistant Professor, Agronomy and Plant Breeding Department, College of Agriculture, Isfahan University of Technology, Isfahan, 8415683111, Iran
Abstract Determination of strategic crops water use of irrigated lands of arid regions is important to save water. Development of Irrigation systems need accurate irrigation management in order to apply the required irrigation amount at the correct time. The purpose of this study was to develop a crop coefficient model for sunflower as function of day and growing degree days (GDD) via drip-tape irrigation system in an arid region. For this purpose, the sunflower water use was determined by daily monitoring soil moisture in 4 middle plots of 1000 square meter experimental field at the soil depths of 10, 20, 30, 40 and 60 cm by PR2 (Delta-T Co.). Determination of irrigation time was based on the 50±5 % soil moisture depletion from the root depth. The Irrigation depth was determined based on replacing soil moisture to field capacity. Daily reference evapotranspiration (ET0) was estimated by FAO-penman-monteith (FPM) equation. The crop evapotranspiration (ETC) was measured using volume balance method. The results showed that there is a difference between average of FAO-Kc and measured Kc. The models were developed as function of GDD and day after planting. The 1
results showed that to save water and to increase water use efficiency the dailybase and thermal-time base Kc have to be used for trickle irrigation system management in arid regions. Keywords: crop model, drip irrigation, sunflower
Introduction Water is becoming increasingly scarce especially in arid regions. Limited availability of water recourses requires fundamental changes in agricultural management practices across the globe (Gaiser et al., 2004). Also, irrigation water requirements of the crops are vary substantially during the growing period mainly due to variation in crop canopy and climatic conditions (Doorenbose and Pruitt, 1977). Thus, determination of accurate crop water use is necessary to increase water use efficiency and to save water in arid regions. To save water in agricultural system it is required to determine daily crop coefficient (Kc) based on growth stages of crops, irrigation system and climatic condition. Sunflower is one of the most important oil crops throughout most countries all over the world, and provides a major source of oil in human diet (AbdelMawgoud et al., 2009). The crop coefficient of some crop has reported only for four growth stages by FAO (Allen et al., 1998). These values are commonly used in places where the local data are not available (Majnooni-Heris et al., 2012). However, they are not accurate enough for micro irrigation system with high flexibility in irrigation water application to apply water based on crop water demand. Allen et al. (1998) have mentioned that lysimeteric method under local climate condition is the best method for calculating of the crop coefficient values because the crop coefficients depend on climate conditions, soil properties, the particular crop and its varieties, irrigation methods and irrigation managements (Allen et al., 1998; Majnooni-Heris et al., 2012). Previous researchers have considered affect of irrigation system, climate condition, crop variety, irrigation management on crop coefficient of sunflower. Tyagi et al. (2000) have developed the sunflower crop coefficient as a function of weeks after sowing in an arid region of India. Abdel-Mawgoud et al. (2009) have reported sunflower crop coefficient under flooding and drip irrigation methods during growth stages in an arid region of Egypt. In the last decade scientists have applied crop models to consider affect of irrigation managements on crop production. For monitoring soil water in the models it needs the estimation of crop evapotranspiration (ETc). The crop coefficient is one of the most important inputs for estimating ETc. So development of crop coefficient models as functions of day after planting and growing degree days are very useful to estimate accurate crop coefficient for using in the crop models. Some researchers have developed various crop coefficient 2
equations for different crops (Elliott et al., 1988; Gheysari et al., 2006; MajnooniHeris et al., 2012). In Iran because of water shortage, drip tape irrigation system is become as a common irrigation system for most of the crops. Therefore, it is necessary to predict crop irrigation water demand under drip tape irrigation system. The objective of this study was to develop of models to estimate crop coefficient of sunflower as function of DAP and GDD for two common varieties of sunflower in an arid region of Iran. Materials and methods This study was conducted in 2011 on the experimental farm of the Agriculture Faculty of the Isfahan University of Technology, Iran (32 º, 32´ N, 51 º, 23´ E, and 1630 m above mean sea level). The soil texture of the research field was clayloam (Table 1). Table 1. Physical and chemical properties of the soil at the experimental field Bulk Field Organic Electric Soil depth Clay Sand density capacity matter conductivity (cm) (%) (%) (Mg m-3) (%) (%) (dS/m) 0-20 27.9 31.9 1.39 24.3 0.93 1.13 20-40 27.6 31.9 1.50 31.0 0.89 0.77 40-60 24.7 30.9 1.55 32.7 0.44 0.85 60-80 26.3 29.6 1.54 32.2 0.33 1.02 80-100 29.3 26.9 1.55 30.9 0.22 1.03
pH 8.1 7.9 7.8 7.8 7.7
The Isfahan has an arid climate with an average annual rainfall of 150.9 mm, which falls during the winter months. There was no rainfall during the 95 days of growing season of this trial. The average daily minimum and maximum temperatures were 20.42˚C and 36.33˚C, respectively and the mean daily minimum and maximum relative humidity were 12.32% and 27.97%, respectively during the growing season (Figure 1). Two common hybrids of sunflower in Iran (Euroflor and Sirna) were planted on June 3, 2011. The drip tape irrigation system was used to supply irrigation water. The experimental plots irrigated under no water stress and no nitrogen stress during growing season. The plots were irrigated based on soil moisture depletion from the root zone with MAD (management allowed depletion) equal 50% (Allen et al., 1998; Martin et al., 1991). Irrigation water was controlled by a flow meter which was located on manifold pipe of irrigation system. To monitor soil moisture contents, a PR2 (Profile Probe, Delta-T Co.) was used. Daily volumetric soil water contents were measured in middle of experimental plot at soil depth of 10, 20, 30, 40, 60, and 100 cm in the morning during the growing period. Irrigation amount was determined based on replacing soil moisture to field capacity. 3
The growing degree days (GDD) was estimated as follow (Morrison et al., 1989): GDD =
[
− T ]k
(1)
Where Tmax and Tmin are the daily maximum and minimum air temperatures (°C), respectively, n is the number of days, and Tb is the base temperature for development which is equal to 6˚C for sunflower (Kiniry et al., 1992).
Figure 1. Minimum and maximum of air temperature and relative humidity during the growing season
Crop coefficient was defined as the ratio of the crop ET to the reference crop evapotranspiration (ET0) (Allen et al., 1998): =
ET ET
(2)
The daily weather data were collected from nearby meteorological station. The Daily ET0 was calculated from these data by using FAO-Penman-Monteith (FPM) equation (Allen et al., 1998). Actual crop evapotranspiration was calculated using soil water balance method in the soil profile. The crop evapotranspiration was calculated by the following equation (Jensen et al., 1990): =
+
−
+∑ ∆
−
∆
(3)
4
Where I, P, and D are irrigation, precipitation and deep percolation (mm), respectively, n is the number of layers, ΔSi is the soil layer depth (mm), θ1 and θ2 are the soil water content (%) that was measured by using the PR2, and Δt is the time interval. It was assumed that there was no drainage from root zone. The soil moisture content in the soil profile was showed that deep percolation from the root zone was negligible, because of applying water using drip tape irrigation and well irrigation management during growing season. Result and discussion The maximum ETc was 14.0 and 13.8 mm per day for Euroflor and Sirna hybrids, respectively during the growing season in the arid climate of Isfahan. Our results agree with previous study that has reported maximum sunflower evapotranspiration equal to 14.11 mm per day in a semi-arid climate of India (Tyagi at el., 2000). Majnooni-Heris et al. (2011) mentioned that the rate of evapotranspiration is high because of the advection phenomena in the semiarid and arid regions of Iran. Using water balance method the accumulated ETc was calculated for two sunflower hybrids and the measured ETc was 649 mm for Euroflor and 622 mm for Sirna hybrids with 95 days length of growing season under drip tape irrigation system. The seasonal estimated ETc (using FPM equation and FAO-Kc, (Allen et al., 1998)) for sunflower was 589 mm. The seasonal measured ETc was 60 mm higher as compare to estimated ETc for Euroflor hybrid and was 33 mm higher than estimated ETc for Sirna hybrid (Figure 2). The differences among measured ETc and estimated ETc may be expected from variation in crop canopy and climatic conditions substantially during the growing period (Allen et al., 1998). Also, it can be because of using drip tape irrigation system. The results showed that it is necessary to measure the Kc value for sunflower in an arid regain of Isfahan. The ratio of the measured seasonal crop ET to the estimated seasonal reference ET was 0.79 and 0.76 for Euroflor and Sirna, respectively. Crop coefficient values for two hybrids of sunflower were determined by dividing the actual crop evapotranspiration of well watered sunflower to the reference ET calculated by FPM method. The Kc values were obtained 0.75 and 0.72 for developing stage, 1.18 and 1.15 for middle stage, and 0.9 and 0.84 for late stage for Euroflor and Sirna hybrids, respectively. For initial stage, Kc was 0.49 that calculated using FAO equations (Allen et al., 1998). The FAO have reported crop coefficient of sunflower 0.35, 0.75, 1.15, and 0.75 for initial, development, middle, and late stages, respectively. The results showed that there was a difference between FAO-Kc and actual Kc because of different in environmental conditions, irrigation system, and crop varieties (Table 2). The results are in agreed with previous studies that have reported there is a difference 5
between FAO-Kc and measured Kc due to climate variety (Ko at el., 2009; Mjnooni-Heris at el., 2012; Allen et al., 1998). Correlation of crop coefficients to accumulated growing degree days (GDD) have been used in previous studies to reduce the effects of yearly climate variations on crop growth and water use (Wright, 1982; Gheysari, et al., 2006). In this study the measured crop coefficient was developed as functions of DAP and GDD for two hybrids of sunflower. The results showed that the values of Kc for Euroflor and Sirna hybrids increased after planting to their maximum values at 1661 °C-days and then decreased to their minimum values at harvest time at 2126 °C-days in an arid region of Iran.
Figure 2. Actual ETc under drip tape irrigation system, FAO56 base ETc and ET0 for two hybrids of sunflower during the growing season in an arid region
Table 2. Measured and estimated crop coefficient of Euroflor and Sirna hybrids of sunflower for four stages Crop growth stages Length of growing stages Measured Kc of Euroflor Measured Kc of Sirna FAO56 Kc
Initial 30 0.49 0.49 0.35
Developing 25 0.75 0.72 0.75
Middle 25 1.18 1.15 1.15
Late 15 0.9 0.84 0.75
The third-order polynomial equations (Sepaskhah and Andam, 2001; Ko at el., 2009) were developed to model Kc as function of GDD and DAP as fallow: For Sirna hybrid: = −9.7382 × 10 DAP + 12.065 × 10 DAP −0.0192 DAP − 0.0356 = 0.98 < 0.001
6
(4)
= −0.0011 × 10 GDD + 0.0366 × 10 GDD −0.0027 GDD + 0.7736 = 0.98 < 0.001
(5)
For Euroflor hybrid: = −6.4403 × 10 DAP + 6.0089 × 10 DAP −0.0137 DAP − 0.4821 = 0.97 < 0.001
(6)
= −0.0008 × 10 GDD + 0.0228 × 10 GDD −0.0009 GDD + 0.1633 = 0.97 < 0.001
(7)
Where Kc is the sunflower crop coefficient, DAP is the days after planting, and GDD is the growing degree days (˚C-days) with the base temperature of 6˚C. The equations are valid in period of 30DAP to 95DAP. These equations can be used as reference data for irrigation scheduling and developing crop modeling of sunflower in an arid region of Iran under drip tape irrigation system. Conclusion In this study the seasonal measured ETc values of Euroflor and Sirna hybrids were 649 and 622 mm, respectively, under drip tape irrigation system in an arid region of Iran. The results showed that there was a difference between of FAO-Kc and measured Kc for initial, development, middle, and late stage. The third-order polynomial equations were developed as function of GDD and DAP with high correlation coefficient, that can be used for water consumption and increasing water use efficiency in an arid region of Iran. Also, these equations can be used in crop modeling for well irrigation managements. The results can be used as reference data for irrigation planning and efficient management of irrigation of sunflower for the region of similar condition. References Abdel-Mawgoud, A. S. A., Gameh, M. A., Elaziz, S. H., and El-Sayed, M. M. (2009). Sunflower water relation at various irrigation regimes with modern irrigation systems under climatic conditions of assiut governorate, upper Egypt, Thirteenth international Water Technology Conference, IWTC. Allen, R. G., Pereira, L. S., Raes, D., and Smith, M. (1998). Crop evapotranspiration-guidelines for computing crop water requirements, Irrigation and Drainage Paper 56, Rome, Italy. 300 p. 7
Doorenbose, J., and Pruitt, W. O. (1977). Guideline for predicting crop water requirements, FAO Irrigation. Report, Central Soil and Water Conservation Research Institute, Dehar Dun, pp. 100. Elliott, R. L., Harp, S. L., Grosz, G. D., and Kizer, M. A., (1988), Crop coefficients for peanut evapotranspiration, Agricultural Water Management, 15(2), 155-164. Gaiser, T., De Barros, I., Lange, F. M., and Williams, J. R. (2004). Water use efficiency of a maize/cowpea intercrop on a highly acidic tropical soil as affected by liming and fertilizer application, Plant and Soil, 263, 165-171. Gheysari, M., Mirlatfi, S. M., Homaee, M., and Asadi, M. E. (2006). Determination of crop water use and crop coefficient of corn silage based on crop growth stages, Iranian Journal of Agricultural Engineeing Research, 7(26), 125-142 Jensen, M. E., Burman, R. D., and Allen, R. G. (1990). Evapotranspiration and irrigation water requirements. ASCE Manuals and Reports on Engineering Practice, 70. Kiniry, J. R., Blanchet, R., Williams, J. R., Texier, V., Jones, C. A., and Cabelguenne, M. (1992). Sunflower simulation using EPIC and ALMANAC models. Field Crops Research, 30, 403-423. Ko, J., Piccinni, G., Marek, T., and Howell, T. (2009). Determination of growthstage-specific crop coefficients (Kc) of cotton and wheat, Agricultural Water Management, 96, 1691-1697. Majnooni-Heris, A., Zand-Parsa, Sh., Sepaskhah, A. S., Kamgar-Haghighi, A. A., and Yasrebi, J. (2011). Modification and validation of maize simulation model (MSM) at different applied water and nitrogen levels under furrow irrigation, Arch of Agronomy and Soil Science, 57(4), 401-420. Majnooni-Heris, A., Sadraddini, A. A., Nazemi, A. H., Shakiba, M. R., Neyshaburi, M. R., and Tuzel, I. H. (2012). Determination of single and dual crop coefficients and ratio of transpiration to evapotranspiration for canola, Annals of Biological Research, 3 (4), 1885-1894. Martin, D. L., Gilley, J. R., and Skaggs, R. W. (1991). Soil water balance and management.19 p. 199-235. In R.F. Follet et al. (ed.) Managing Nitrogen for Groundwater Quality 20 and Farm Profitability. ASA, SSSA, Madison, WI. Morrison, M. J., McVetty, P. B. E., and Shaykewich, C. F. (1989). Determination and verification of a baseline temperature for the growth of Westar summer rape Canadian J of Plant Sci, 69, 455-464. Sepaskhah, A. R., and Andam, M. (2001). Crop coefficient of sesame in a semiarid region of I.R. Iran. Agric Water Manage, 49, 51-63. Tyagi, N. K., Shamara, D. K., and Luthra, S. K. (2000). Determination of evapotranspriation and crop coefficients of rice and sunflower with lysimeter, Agricultural Water Management, 45, 41-54. Wright, J. L. (1982). New evapotranspiration crop coefficient. Journal of the Irrigationand Drainage . Division. ASCE. 108, 57-74. 8
