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Bulgarian Journal of Agricultural Science, 16 (No 4) 2010, 482-492 Agricultural Academy
DETERMINING WATER-YIELD RELATIONSHIP, WATER USE EFFICIENCY, SEASONAL CROP AND PAN COEFFICIENTS FOR ALFALFA IN A SEMIARID REGION WITH HIGH ALTITUDE Y. KUSLU*, U. SAHIN, T. TUNC and F. M. KIZILOGLU Ataturk University, Faculty of Agriculture, Department of Agricultural Structures and Irrigation, 25240 Erzurum, Turkey
Abstract KUSLU, Y., U. SAHIN, T. TUNC and F. M. KIZILOGLU, 2010. Determining water-yield relationship, water use efficiency, seasonal crop and pan coefficients for alfalfa in a semiarid region with high altitude. Bulg. J. Agric. Sci., 16: 482-492 A field study was conducted to determine effects of seasonal deficit irrigation on plant dry forage yield and water use efficiency of alfalfa for a 2-year period in the semiarid region with high altitude. In addition, the seasonal crop and pan coefficients kc and kp of alfalfa was determined in full irrigation conditions. Irrigations were applied when approximately 50% of the usable soil moisture was consumed in the effective rooting depth at the full irrigation treatment. In deficit irrigation treatments, irrigations were applied at the rates of 80, 60, 40, 20 and 0% of full irrigation treatment on the same day. Irrigation water was applied by hose-drawn traveler with a line of sprinklers. Seasonal actual evapotranspiration, total dry forage yield and water use efficiency was the highest in full irrigation conditions and the lowest in continuous stress conditions. The linear relationship between seasonal actual evapotranspiration and total dry forage yield was obtained. According to the averaged values of 2 years, yield response factor (ky) was 1.33. Both seasonal kp and kc were determined as 0.86 for alfalfa, when combined values of 2 years.
Key words: Alfalfa; crop coefficient; pan coefficient; water deficit; yield response factor Abbreviations: ETo - reference evapotranspirasyon (mm); ky - seasonal yield response factor kc - seasonal crop coefficient; kp - seasonal pan coefficient; ETa - actual evapotranspiration, mm; I - the amount of irrigation water applied (mm); P – precipitation, mm; Cr - capillary rise (mm); Dw - amount of drainage water (mm); Rf - amount of runoff (mm); Δ S - change in the soil moisture content (mm); Ya - actual harvested yield; Ym - maximum harvested yield, ETm - maximum evapotranspiration, mm; Yd - relative yield reduction; ETd relative evapotranspiration reduction, mm; Epan - evaporation of Class A pan, mm; Rn - net radiation at the crop surface, MJ m-2 day-1; G - soil heat flux density, MJ m-2 day-1; T - mean daily air temperature at 2 m height, °C; u2 - wind speed at 2 m height, m s-1; es - saturation vapour pressure, kPa; ea - actual vapour pressure, kPa; es ea - saturation vapour pressure deficit, kPa; Δ - slope of the saturation vapour pressure curve, kPa/°C; γ psychrometric constant, kPa/°C; WUE - water use efficiency, kg ha-1 mm-1 E-mail:
[email protected] or
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Determining Water-yield Relationship, Water Use Efficiency, Seasonal Crop and Pan Coefficients...
Introduction Alfalfa has a high water requirement compared to other crops. Evapotranspiration is between 800 and 1600 mm growing period depending on climate and length of growing period (FAO, 2002a). Seasonal evapotranspiration of alfalfa reported by Sahin and Hanay (1996) was approximately 700 mm in the Erzurum region. In addition, Evren and Sevim (1998) determined evapotranspiration of alfalfa as 678 mm in Erzurum plain conditions. In Erzurum region with semiarid climate, summers are short, hot and dry. Water is the main factor limiting yield production in the hot and dry summer period of semiarid regions. The great challenge for coming decades in arid and semiarid regions will be focusing on increase food production by using less water (FAO, 2002b). Therefore, studies are needed to increase the efficiency of the water use that is available. One approach is the development of new irrigation scheduling techniques such as deficit irrigation (Bekele and Tilahun, 2007). Deficit irrigation has potential benefits such as increasing irrigation efficiency, decreasing the cost of irrigation and water opportunity cost (English and Raja, 1996). The lack of water in plant and resulting water stress has an important effect on water consumption and yield. Alfalfa is very responsive to water stress (Guitjens, 1993; Orloff et al., 2004; Frate and Roberts, 2006). Various researchers (Smeal et al., 1991; Grimes et al., 1992; Saeed and El-Nadi, 1997; Bai and Li, 2003) recognized a positive linear relationship between alfalfa yield and evapotranspiration. Doorenbos and Kassam (1979) developed a relation between water applied and yield that can measure yield per applied water unit which can largely be practiced with a certain mistake level and can be performed in the conditions of sufficient and deficit water resource. On the other hand, an understanding of water use efficiency was essential for evaluating the field crops in semiarid regions where irrigation water was a limiting factor (Johnson and Henderson, 2002). Several alfalfa water use efficiency studies have been reported.
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Mean annual values fluctuate between 10 and 23 kg ha-1 mm-1 (Grimes et al., 1992; Saeed and El-Nadi, 1997; Hirth et al., 2001). The reference evapotranspirasyon (ETo) is a measurement of the water use for that reference crop. In the case of ETo, grass is used as the reference; however, other crops may not use the same amount of water as grass due to changes in rooting depth, crop growth stages and plant physiology. The crop coefficient takes into account the crop type and crop development to adjust the ETo for that specific crop. The FAO Penman-Monteith equation is recommended for determining ETo (Allen et al., 1998; Cuiping, 2005). Class A pan data is also used extensively throughout the world to estimate ETo (Grismer et al., 2002; Irmak et al., 2002). However, reliable estimation of ETo using pan evaporation depends on the accurate determination of pan coefficients. Alfalfa is the most important forage crop in Erzurum, in Turkey. Erzurum is accepted as one of the most important animal breeding regions of Turkey. According to last statistics given by Turkish Statistical Institute the alfalfa growing area in the Erzurum region is 37480 ha, and the green, hay and seed production are 188761, 259198 and 143 ton, respectively. However, the studies with water consumption of alfalfa plants in the region are not sufficient. Predicting yield response to water use of alfalfa is important in developing strategies and decision-making for use by farmers and their advisors, and researchers for irrigation management under limited water conditions. In semiarid climatic regions with high altitude, however, little attempt has been made to assess the water–yield relationships and optimum water management programs for alfalfa. The objectives of this research are: (1) to determine the effect of seasonal water deficit treatments on the plant dry forage yield and water use efficiency of alfalfa in the semiarid conditions with high altitude, (2) to determine the seasonal yield response factor (ky) that would contribute to irrigation scheduling programs in deficit irrigation treatments for semiarid climatic zones with high altitude, (3) to determine pan and crop
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Y. Kuslu, U. Sahin, T. Tunc and F. M. Kiziloglu
coefficients kp and kc enabling the estimation of actual evapotranspiration of alfalfa grown under semiarid conditions with high altitude from Class A pan evaporation.
Material and Methods This study was conducted during the growing periods (April-September) of 2005 and 2006, at the Agricultural Research Station of Ataturk University in Erzurum, in Turkey. The coordinates of the experimental area are 39º55' N and 41º16' E. Its altitude is 1835 m from the sea level. The experimental region has a semiarid climate. The climatic variables for growing period of experimental years are given in Table 1. Temperature, humidity, wind speed and sunshine data were taken from
Erzurum meteorological station (39º57' N, 41º11' E, 1757 m a.s.l., 3 km distance than experimental field). Precipitation and evaporation data were measured with a standard pluviometer and a Class A pan, respectively, located in the experimental area. The pan was placed in a fallow area. Pan readings were taken by daily at the morning time. The soil was classified as an Aridisol according to the US Soil Taxonomy (Soil Survey Staff, 1992) with parent materials mostly consisting of volcanic, marine and lacustrine transported materials. Before establishment of the experiment, soil samples were taken with an auger from the soil layers of 0-30, 30-60 and 6090 cm. Some physical and chemical properties of the experimental field soil were determined according to the methods used Klute (1986) and Page et al. (1982) and they were given in Table 2.
Table 1 Climatic data of the experimental area in the growing periods of 2005 and 2006
Years
2005
2006
Climatic parameters Mean Mean Mean Mean Mean Total Total maximum minimum relative wind daily precipitation, evaporation, temperature, temperature, humidity, speed, sunshine, mm mm ºC ºC % h m s-1
Months
1
April May June July August
14.0 17.2 20.6 28.6 29.3
2.7 4.1 6.2 9.9 10.5
74.8 72.2 67.9 55.0 54.8
2.5 3.4 2.7 2.7 2.6
4.3 7.2 9.1 11.6 10.8
41.3 93.5 92.7 31.3 38.8
20.7 120.6 141.7 217.8 202.5
September2 April1 May June July August
22.4
5.1
61.6
2.9
9.3
11.3
67.4
11.6 18.9 27.2 27.2 31.7
2.0 2.7 6.5 12.4 12.3
76.8 67.3 56.7 62.5 50.9
2.6 2.9 2.7 4.0 2.7
3.7 9.4 11.9 10.3 9.6
64.8 49.8 25.9 29.5 18.5
19.3 134.0 219.4 223.2 246.9
25.8
6.6
57.4
3.0
9.3
2.0
77.7
3
September 1 2 3
Calculated from the data between 20 and 30 April Calculated from the data between 1and 15 September Calculated from the data between 1and 14 September
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Determining Water-yield Relationship, Water Use Efficiency, Seasonal Crop and Pan Coefficients...
Table 2 Some physical and chemical properties of the experimental field soil Properties Texture Clay, % Silt, % Sand, % Field capacity, Pw Wilting point, Pw Bulk density, g cm-3 pH* -1
Electrical conductivity, dS m * Carbonates, % Organic matter, % *: in saturated soil extract
0-30 Loam 20.90 33.20 45.90 17.80 10.20 1.48 8.11 0.49 0.79 0.88
Soil layer, cm 30-60 Clay loam 28.20 36.30 35.50 18.90 11.10 1.41 7.97 0.50 0.81 0.47
Fig. 1. The design of experimental field
60-90 Clay loam 27.60 43.20 29.20 21.90 13.80 1.37 8.10 0.52 0.68 0.25
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The experiment was laid out as six main plots with an area of 1500 m2 (50 x 30 m) representing five treatments and the control (Figure 1). Each treatment and the control have three replicated sub-plots with an area of 500 m2 (50 x 10 m). There was a 5 m space between main plots in order to minimize water movement among treatments. Alfalfa (Medicago sativa L. cv. Prosementi) seeds were sown at a rate of 20 kg ha-1 on 20 April 2005. All plots received at the same amount of P2O5 (120 kg ha-1) and N (50 kg ha-1) fertilizer during the sowing and P2O5 (150 kg ha-1) fertilizer after the third harvest in 2005 year (Serin and Tan, 2001). No pesticides were applied. Soil moisture contents in all plots were increased to the field capacity after the sowing in 2005 and April 20 in 2006. The total usable soil water content within the top 0.9 m of the soil profile was 100 mm. Irrigations were applied when approximately 50% of the usable soil moisture was consumed in the effective rooting depth (0.9 m) at the full irrigation (control) treatment (T-100) in both years (Allen et al., 1998). In deficit irrigation treatments, T-80, T-60, T40, T-20 and T-0 (non-irrigation) irrigations were applied at the rates of 80, 60, 40, 20 and 0% of full irrigation treatments (T-100) on the same day, respectively. Irrigations were started on June 25 in 2005 and May 24 in 2006. Irrigation water was applied by the hose-drawn traveler with a line of sprinklers (Figure 1). The total length of sprinkler line is 50 m. The sprinkler line was mounted to a trolley from the central point. During the irrigation water application, the trolley moves toward the irrigation machine. Total 40 sprinkler heads with a nozzle diameter of 8 mm and equal flow rate have been mounted on the sprinkler line with an interval of 1.25 m. The total flow rate of the system is 73.4 m3 h-1 at the operational pressure of 2 atm. The duration of irrigation water application for each plot has been determined according to the required water amount to be applied to each plot. In this situation, the duration of irrigation water application for T-100, T-80, T-60, T-40 and T-20 plots was 1.02, 0.82, 0.61, 0.41 and 0.20 h, respectively. Surface flow in plots has not been observed during the water application. In order to obtain irrigation unifor-
Y. Kuslu, U. Sahin, T. Tunc and F. M. Kiziloglu
mity, irrigation was performed in hours when no wind or low wind (
