BARLEY WATER AND NITROGEN REQUIREMENT TO INCREASE ITS SUSTAINABLE PRODUCTION IN SEMI-ARID REGION

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1 BARLEY WATER AND NITROGEN REQUIREMENT TO INCREASE ITS SUSTAINABLE PRODUCTION IN SEMI-ARID REGION Mojtaba Naghdyzadegan, Fatemeh Razzaghi and Shahrokh Zand-Parsa ABSTRACT Barley (Hordeum vulgare L.) is one of the important cereals grown in the arid and semi-arid regions. Two-year field experiments were conducted to study the effects of different levels of water and nitrogen on grain yield (GY) and water productivity (WPGY for grain) of barley (cv. Reyhaneh -) in - and -5. Four levels of irrigation regimes (, 5, 75, and % of irrigation requirement (IR)) as main plot and nitrogen fertilizer (, 7, and kg N ha - ) as subplots were tried out with replications in spilt plot design. All treatments received mm of water as initial water for germination. Main effects of irrigation treatments showed that GY and WPGY increased significantly with increasing in irrigation levels from rain-fed to 75% IR, whereas no significant difference was observed between 75 and % IR. Grain yield and WPGY also increased by increasing nitrogen fertilizer rate. According to the result, maximum grain yield and WPGY achieved at 75%IR with kg N ha - and can be used as appropriate managements for winter barley in the study region in later. Further, because of soil initial nitrogen, the relation between applied water and nitrogen and grain yield showed that water played the main role for grain yield production under low level of applied water in comparison with nitrogen. Keywords: Barley, Water, Nitrogen, Yield, Water productivity. INTRODUCTION Water and nitrogen (N) are the most limiting factors in agricultural production in most parts of the world, especially in arid and semi-arid zones (Cassman, ). More than 55% of the increase in crop production, comes from the use of chemical fertilizers, with N fertilizers being dominant (Li et al., 9). In this situations, water scarcity is driving for the maximization of water and N use in agriculture.the aim of this study is to find out the suitable amount of water and nitrogen fertilizer to increase barley (cv. Reyhaneh -) production under semi-arid condition.. METHODS. Experimental site The two-year field experiments (- and -5) were conducted at the experimental research station of Shiraz Agricultural College, which is located in Badjgah (south of Iran-near Shiraz). Longitude, latitude and altitude were 5º E, 9º N, 8 m amsl, respectively. This Experiment was conducted to investigate the effects of different levels of irrigation and nitrogen on growth and yield of barley (cultivar Reyhaneh -). Barley was sown at the rate 5 kg ha - in.5 m plots MSc. Student, Water Engineering Department, Agriculture College, Shiraz University, Iran, (PO:758); naghdyzadegan@gmail.com Assistant Professor, Water Engineering Department, Agriculture College, Shiraz University, Iran, (PO:758); razzaghi@shirazu.ac.ir Associate Professor, Water Engineering Department, Agriculture College, Shiraz University, Iran, (PO:758); zandparsa@yahoo.com

2 (.5 m ) with rows at the depth of cm with row spacing of cm on Nov. and 7 Oct.. Phosphorus in the form of triple superphosphate was applied at the rate of 5 kg P ha - before planting.. Treatments The experiments were performed in spilt plot with completely randomized block design with irrigation treatments (% - 5% -75% - % irrigation requirement (ETc), I, I, I and I) as main plot and nitrogen treatments ( 7 kg N ha -, N, N, N and N) as subplot with three replications for each treatment. All plots were irrigated with mm of water as initial irrigation after sowing. The crop water requirement (ETc) of each treatment was calculated using the following equation: ETc=ET Kc () Where ETc is crop evapotranspiration, ET is reference crop evapotranspiration and Kc is single crop coefficient. Reference crop evapotranspiration was calculated using FAO-penman-montieth equation modified by Razzaghi and Sepaskhah () and the Kc values for different crop growth stage were obtained from the study of Hashemi-tameh (). The values of Kc for initial, mid and end of growth stage were determined as.,. and., respectively and the period for initial, development, mid and end stages was 99, 8, 7 and days, respectively. The irrigation application efficiency was % and irrigation interval was days. Total amount of Itreatment in first and second year was and 5 mm, respectively. Nitrogen treatments ( 7 kg N ha - ) were performed by adding different levels of Urea (% N) on March ( days after sowing (DAS)) and March 5 (7 DAS), when the slow growth level of barley was ended.average and minimum daily air temperature and average daily air relative humidity during the two growing seasons are shown in Fig.. Total amount of rainfall was 59 mm in first year and mm in second year during the growing season (Fig. and ).

3 a Daily average temperature ( o C) T ave - T ave -5 - b Daily minimum temperature ( o C) c Average daily relative humidity (%) DAY Figure. Average (a) and minimum (b) daily air temperature and average daily air relative humidity (c) during the - and -5 growing season (DAY: days after October 7)

4 Rainfall (mm) Rainfall (mm) 5 I 5 I I Cumulative irrigation (mm) I Rain fall 5 5 DAS Figure. Rainfall and applied cumulative irrigation during the - growing season (DAS: days after sowing) 5 5 Rainfall (mm) I I I I Cumulative irrigation (mm) 5 5 DAS Figure. Rainfall and applied cumulative irrigation during the -5 growing season (DAS: days after sowing)

5 Grain or straw yield were estimated as a function of applied water and nitrogen as follows: Y(I + R, N + Nr) = a + a (I + R) + a (I + R) + a (N + N r ) + a (N + N r ) + a 5 (I + R) (N + N r ) + a (I + R) (N + N r ) + a 7 (I + R) (N + N r ) + a 8 (I + R) (N + N r ) () where Y(I+R, N+Nr) is grain (or straw) yield (Mg ha - ), I is applied water (m),r is the amount of rainfall (m),n is applied nitrogen (kg N ha - ),N r the is residual nitrogen before sowing (kg N ha - ) and a to a 8 are constant coefficients.. Plant measurement and calculations Grain yield was determined at the end of growth period by harvesting the crop from m at the centre of each plot to avoid border effects. Grain yield was dried in oven at 8 C until constant weight reached. Water productivity of grain yield (WP GY, kg m - ) was calculated as follows: WP GY = GY W () where GY is grain yield (kg ha - ) and W is the total applied irrigation (m ha - ).. RESULTS AND DISCUSSIONS. Prediction of grain and straw yield Nonlinear regression equation between grain and straw yield against applied water and rainfall (I+R) and also nitrogen and residual nitrogen (N+N r) were fitted by using data from the first year of experiment, and the values of their constant coefficients are shown in Table.According to the values of R (.9 and.9 for grain and straw yield, respectively), Normalized Root Mean Square Error (NRMSE,.7 and. for grain and straw yield, respectively) the predictions of grain and straw yields were good enough. Table : The coefficients of Eq. for prediction of grain and straw yields in -. Yield a a a a a a5 a a7 a8 Grain Straw Figure shows barley grain and total dry mater contour line that it was drawn based on different irrigation and nitrogen treatments in first year of this study. Under minimum amount of applied water, because of residual nitrogen (8 kg N ha - ), applied water play main rule for grain yield production. This situation continue till Mg ha - production and after that due to interaction of water and nitrogen, applying nitrogen became effective. In this situation, farmers can produce special amount of grain yield by different amount of applied water and nitrogen fertilizer. 5

6 a 5 N+N r (kg ha - ) b Irrigation 8 water (m) 8 N+N r (kg ha - ) Irrigation water + Rainfall (m) Fig.. Contour line of grain yield (a) and total dry matter (b) (Mg ha - ) as a function of applied water plus rainfall (I+R) and applied plusresidual soil mineral nitrogen (N+N r), (number on contour lines are in Mg ha - ) in -. According to Fig. a and based on the results of this e x periment, farmers could harvest Mg ha - grain yield by different scenarios of applied water and nitrogen fertilizer, such as using.7 m and kg N ha - or.58 m and kg N ha - or.58 m and kg N ha -.. According to Fig.b, Mg ha - total dry mater achieved by different amount of applied water and nitrogen fertilizer such as or.7 m and 79 kg N ha - or.7 m and kg N ha - or. m and kg N ha -.Selecting the best scenario under this condition is depended on the agricultural economics, available resource of water and nitrogen and environmental problem.

7 . Grain yield and water productivity Considering the main effect of irrigation treatments, GY increased significantly with increasing irrigation levels from rain-fed to.75 IR treatment in both year. Although, there was no significant difference between the GY of I and I treatments. For e x ample GY decreased 8, 5, and 88 percent in I, I and Itreatments compared to I treatment, respectively. Also, increasing the nitrogen application rate from N to N, increased the GY from.8 to.85 and.77 to.9 Mg ha - in first year and second year, respectively. However, there was no significant difference between the grain yield obtained at nitrogen application rate of and kg N ha -. Increasing the nitrogen fertilizer rate enhanced shoot growth rate and eventually grain yield production because of more absorption of nutrients in the soil (Kumbhar et al., 7). Results indicated that among the irrigation levels, ma x imum and minimum ofwpgy (. and.7 kg m - in first and second year, respectively) achieved at I and I treatments, respectively. Further, WPGYof I and I treatments increased and % in the first year and and % in the second year compared to I treatment, respectively. Also WPGY decreased 7 and % in first and second year, respectively, at I compared to Itreatment. Comparison between the nitrogen levels showed that ma x imum WP GY (. and.7 kg m - in first and second year, respectively) achieved at N (Table ). The WP GY at kg N ha - (N) was significantly higher than those obtained at N and N in both years, while it was not significantly different with N. This indicated that increased rate of nitrogen application ( to kg N ha - ) increased WP GY significantly. Increased the amount of applied nitrogen might have resulted in more water uptake from deeper layers of soil under lower water application (Lawlor, 995; Pessarakli, 995) and consequently increased water productivity (Emam and Niknejhad, ). Table. Effects of different irrigation water levels and nitrogen levels on grain yield water productivity (WP GY, kg m - ) of barley Treatments - WPGY (kg m - ) WPGY (kg m - ) Nitrogen application rate Irrigation level (kg ha - ) WPGY (kg m - ) WPGY (kg m - ) rein-fed.58 c**.58 d N. c.5 c.5 IR*. ab.8 b N. b.95 b.75 IR. a.7 a N. a.7 a. IR.9 b.9 c N.7 a. a * IR = Irrigation requirement ** Mean followed by the same letters for each parameter are not significantly different at 5% level of probability. CONCLUSIONS The results of this study showed that under minimum level of irrigation water, nitrogen played non-significant role to produce grain and straw yield. By increasing the amounts of water and nitrogen, interaction of these two become more effective. In addition, the results indicated that farmers could produce special amount of grain yield by different scenarios of applied water and nitrogen fertilizer. In this situation, appropriate farm management have to be considered by specially considering 7

8 economic analysis and situation, environmental pollution and available water resources. Increasing irrigation levels significantly increased grain yield up.75 IR treatment in both years. Increasing the nitrogen application rate from to kg N ha -, increased the GY and WPGY in both years, respectively. However, there was no significant difference between nitrogen application rate of and kg N ha -. Finally, based on this e x periment, it can be suggested that 5%deficit irrigation (.75 IR) with kg N ha - is the appropriate management for winter barley in order to obtain ma x imum amounts of yield and water productivity. REFERENCES Cassman, K.G.. Science research to assure food security. In J. Nosberger, H.H. Geiger, and P.C. Struik (Eds.), Crop Science and Prospects. CABI Publishing. pp.. Emam, Y. and M. Niknejhad.. An introduction to the physiology of crop yield (translation). Unpublished MSc. Thesis, Crop Production Department, Agricultural College, Shiraz University, Shiraz, Iran. Heshemi Tammeh M.. Determination of crop coefficient and potential evapotranspiration for barley by weighting lysimeter in Kooshkak region Fars province. Unpublished MSc. Thesis, Water Engineering Department, Agricultural College, Shiraz University, Shiraz, Iran. Kumbhar A, Buriro U, Oad F, Chachar Q. 7. Yield parameters and N-uptake of wheat under different fertility levels in legume rotation. J Agric Technol.:-. Lawlor, D.W Photosynthesis, productivity and environment. J. E x p. Bot., : 9. Li, S. X., Z.H. Wang, S.S. Malhi, S.Q. Li, Y.J. Gao, and X.H. Tian. 9. Nutrient and water management effects on crop production, and nutrient and water use efficiency in dryland Areas. Adv. Agron.,: 5. Pessarakli, M Handbook of Plant and Crop Physiology. United States of America Publisher. pp. Razzaghi, F. and A.R. Sepaskhah.. Calibration and validation of four common ET estimation equations by lysimeter data in a semi-arid environment. Arch. Agron. Soil Sci., 58: -9. 8