EVALUATION OF IRRIGATION APPLICATION METHODS FOR RICE PRODUCTION

Transcription

1 Sarhad J. Agric. Vol. 26, No. 4, ABSTRACT EVALUATION OF IRRIGATION APPLICATION METHODS FOR RICE PRODUCTION JAWAID MOHYUDDIN and MUHAMMAD TARIQUE LIM Project, WAPDA, Latifabad, Hyderabad, This clay soil study was carried out in Dodai and Dhandi minors command area of Larkana and Tando Muhammad Khan districts in Sindh, during -. The study consisted of the following treatments: (a) Traditional irrigation method also called pancho in local language, (b) Irrigation as required i.e. application of water after an interval of ten days, (c) Irrigation at an interval of seven days with the main focus to compare pancho irrigation with scheduled irrigation systems for growing rice crop. These treatments were replicated thrice in a Randomized Complete Block design. During the study impact of different treatments on electrical conductivity, sodium adsorption ratio, soil infiltration rate, water table depth, groundwater quality and crop yield was monitored. Soil samples from 0-15, 15-30, and cm depth were collected for determining the physico-chemical properties. Soil infiltration rate was measured with the standard ring method. One observation well was installed at the experimental site to monitor water table depth and groundwater quality. Crop yield estimation was carried out on whole plot basis. Soil analysis shows that with the passage of time salinity build up occurred at watercourse 4R, Dodai minor and 16L, Dhandi minor whereas at watercourse 17- CR it showed a slight decrease. The increase might be due to a rise of saline groundwater at watercourses 4R and 16L. The SAR showed depth-wise increase as compared to initial values. Soil infiltration rate decreased the time period at watercourse 17-CR whereas it has increased at watercourse 16L. The water table data shows that the variation trend the time period was prominent and it ranged between 0.63 to 0.84 meters and 0.51 to 1.74 meters at watercourse 17-CR and 16L, respectively. The EC of groundwater ranged between 1700 to 1800 ppm and 1400 to 3400 ppm, which is considered from good to hazardous at watercourse 17-CR and 16L respectively, whereas the SAR remained within safe limits and ranged between 1.3 to 1.6 and 3.3 to 14.4 at watercourse 17-CR and 16L, respectively. The crop yield data revealed that the higher rice yield was obtained in T 1 followed by T 3 at all the watercourses. Key Words: Irrigation practices, Water management, Rice production and Optimum crop yield. Citation: INTRODUCTION Mohyuddin, J. and M. Tarique Evaluation of irrigation application methods for rice production. Sarhad J. Agric. 26(4): In addition to other crops, Pakistan s present and future food security/requirements and foreign exchange earnings depend largely on the irrigated rice production system, however, the water use efficiency of rice is low and growing of rice requires a large amount of water. Until recently, the amount of water allocated for rice production has been taken for granted, but now the recent water crisis threatened the sustainability of irrigated rice cultivation. The recent prolonged drought has seriously aggravated the already most severe water crisis in the history of Pakistan. Kahlown et al. (2000) listed rice as the second major food crop which is cultivated in nearly all the provinces of Pakistan. Sixty percent of the rice grown in Pakistan is grown in Punjab, 30 percent in Sindh, and the remaining 10 percent is grown in the province of KP and Balochistan. Akram et al. (1997) reported that rice is grown on about 10 of the country s cropped area. As reported by Khan and Akhter (2001), Pakistan is the fifth largest rice exporting country in the world after Thailand, Vietnam, United States and India. Twenty-five to 50 percent of irrigation water is lost while traveling through Alluvial Indus Plain due to seepage and leakages from unlined earthen irrigating channels (Shahid et al. 1996). Raja () stated that about 35 water gets absorbed in the soil in the course of water flow in the canals. By the time water travels from the canals to the fields, another 24 of the irrigation water is lost in one way or another or gets absorbed in the soil. Due to defective irrigation methods, as much as 25 of the remaining water does not reach the plant roots. Thus, most of the water between the water resource and the fields goes to waste. Zafar () has reported that world s agricultural land is in a very poor state, one-third of which has been converted to produce food. Three-fourths of this is also not in good condition. Forty percent of this agricultural land has lost its fertility. The United Nations report has made a stunning revelation that during the last century, half of the world s natural water resources have already been utilized. Twenty percent of the fertile land is turning into plains/deserts, and the underground water table is being lowered or polluted. In summary this UN report states that this changing environment of our earth is causing great alarm for the very existence of mankind. According

2 Jawaid Mohyuddin and Muhammad Tarique. Evaluation of irrigation application methods 578 to Hassan (), Sindh has entered a phase of water insecurity. Due to defective irrigation practices such as flood irrigation, absence of properly organized management distribution and lack of drainage facilities, more than 50 percent of the area in Sindh is severely affected by waterlogging and salinity (Hassan, ). Bhatti and Qureshi (1977) revealed that farmers in Sindh practice continuous irrigation of rice fields where water is always available. In other places, particularly at the tail of water channels, fields are irrigated whenever the water is available. The general practice which is observed by some of the farmers in rice growing areas is that irrigation water standing in the fields is drained out and replaced with fresh water after a span of 3 to 5 days. The water drained from the rice field is called pancho water. The water requirement for a rice crop of growth duration of 100 days (typical of modern high yielding varieties) varies from 675 to 4450 mm, depending on the season and soil characteristics with mm as a typical value in many low land areas (IRRN, 2001). Submergence depletes free and combined oxygen from the sub-soil and accumulates various organic acids which retard root development, inhibit nutrient absorption and normal aerobic respiration, causing root rot (Yamada, 1965). Surajit and De Datta (1981) observed that organic acids such as acetic and butyric, gasses such as carbon dioxide, methane and hydrogen sulphide are produced. All these substances except methane retard root development, inhibit nutrient absorption and cause root rot when present in large amounts. Grist (1975) reported one of the main disadvantages of stagnant water is a rise in water table to the soil surface, thus causing waterlogging, bringing toxic salts to the surface, and having a deleterious effect on early stage paddy growth. De Datta et al. 1973(b) reported that rotational irrigation is often recommended to irrigate areas with a limited water supply. An experiment conducted in the Philippines showed that grain yield did not vary much with 4-8 day intervals between irrigation. However, grain yield dropped 1 ton per hectare or more when the irrigation interval was increased to 10 days. Based upon the above cited research studies and considering a limited water resources available in the country, proper water management must include the control of the water period for optimum crop yield and the best use of limited supply of water. To this end, the LIM Project carried out a research study in order to compare Pancho with other irrigation systems and to evaluate the best suited irrigation method for growing rice. Broad objectives include: i) To evaluate the need for pancho irrigation in Sindh, ii) To determine the best system of irrigation for rice fields and iii) To control the water table through the new technology (Irrigation application). MATERIALS AND METHODS The experiment was initiated in on a farmer s field at watercourse No. 4R in Deh Dodai about 3 kilometers from Larkana on Miro Khan road. After the study was shifted to the Dhandi minor command area of Gaja branch which off takes from Akram Wah at about 27 km from Tando Muhammad Khan City. Soil samples were collected from 0-15, 15-30, and cm soil depths before sowing and after the harvesting of each crop for ECe and SAR determination. Initial soil infiltration rate was measured with the standard ring method in - before sowing and after the harvest of each crop. Crop yield estimation was carried out on a whole plot basis. One observation well was installed at watercourse # 17-CR and 16L to monitor the groundwater level and collect groundwater samples for quality analysis. Recommended cultural practices carried out during the study period are shown in Table I. Table-I Cultural Operations Cultural operations carried out for rice crop W/C 16-L Land and seedbed preparation No. of ploughings No. of plankings No. of levelings Crop Sowing Seed rate (kg ha -1 ) Date of transplanting 2 nd week of July 2 nd week of July Last week of June Fertilizer application (kg ha -1 ) Nitrogen (Urea) Di-Ammonium phosphate (DAP) Weeding Plant protection measures (weedicides) As per requirement As per requirement As per requirement Harvesting date 2 nd week of November 3 rd week of October 1 st week of October

3 Sarhad J. Agric. Vol. 26, No. 4, RESULTS AND DISCUSSION Soil Salinity (EC e ) The data regarding electrical conductivity of soil in four depths viz. 0-15, 15-30, and cm of each treatment is given in Table II. Table-II Effect of different treatments on EC e of soil Treatments Depth (cm) Pancho Irrigation (Control) (T 1 ) Irrigation as and when required (T 2 ) Irrigation with nterval of seven days (T 3 ) W/C 16L Inc/dec (ds m -1 ) Comparison of initial salinity before sowing and post harvest of crop shows a slight salinity build up at watercourse 4R Dodai minor and watercourse 16L Dhandi minor compared to watercourse 17-CR. This might be due to the rise of brackish groundwater during rice cultivation in the area and its subsequent evaporation from soil surface and the transfer of salts from upper to lower soil depths with cultural operation at watercourse 4R Dodai minor and 16L Dhandi minor. Soil Sodicity (SAR) Changes in sodium adsorption ratio of soil at different soil sampling depths are shown in Table III. Table-III Effect of different treatments on SAR of soil Treatments Dept h (cm) Pancho Irrigation (Control) (T 1 ) Irrigation as and when required (T 2 ) Irrigation with interval of seven days(t 3 ) W/C 16L increase (mmol L -1 ) 1/ Depth wise data of SAR shows an increase at lower soil depths due to the leaching of salts from the upper soil layers and subsequent deposition at lower depths. Overall the SAR remained within safe limits. Soil Infiltration Rate The data was recorded before the start of the experiment at the time of demarcation of the layout plan and after harvest of each crop by standard ring method. The data (Table IV) show that the soil infiltration rate

4 Jawaid Mohyuddin and Muhammad Tarique. Evaluation of irrigation application methods 580 slightly decreased at watercourse 17-CR compared to 16L. This might be due to the fine texture and medium texture class of the experimental plot at watercourses 17-CR and 16L, respectively. Table-IV Treatments Soil infiltration rate as affected by different treatments Decrease W/C 16L Increase Over (cm/6 hours) Pancho Irrigation (Control) (T 1) Irrigation as and when required (T 2) Irrigation with interval of seven days (T 3) * Post soil infiltration rate could not be measured due to shifting of site to Dhandi minor area. Rainfall Data Data pertaining to rainfall of the experimental sites during the study period are given in Table V. Table-V Rainfall data collected at Meteorological Observatory, Larkana () and Badin ( to 2009) Year Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec (mm) Trace Trace Trace NIL NIL 3.0 NIL NIL NIL NIL 4.3 NIL NIL NIL NIL NIL Trace 12.3 Trace NIL NIL Trace NIL NIL Trace 2009 NIL NIL Trace (Source: Pakistan Metrological Department) Water table Depth One observation well was installed at watercourse 17-CR and 16L to monitor the depth to groundwater. The monthly data (Fig. 1) show that the water table varies time and space. The water table ranged between 0.63 to 0.84 meters and 0.51 to 1.74 meters at watercourse 17-CR and 16L, respectively. The rise in the water table is due to recharge to the groundwater caused by supply of irrigation water and rainfall. Conversely, declination in water table occurred due to paucity of rain and irrigation water CR L Fig. 1 Changes in water table depth

5 Sarhad J. Agric. Vol. 26, No. 4, Groundwater Quality The quality of groundwater varies monthly with respect to time and space (Fig. 2 and 3). The EC w (ppm) ranged between 700 to 1800 and 1400 to 3400, SAR 1.3 to 1.6 and 3.3 to 14.4 at watercourse 17-CR and 16L, respectively. Deterioration in water quality might be due to low recharge to the groundwater because of less need of irrigation to crops. However, the SAR remained within safe limits CR L Fig. 2 Changes in groundwater quality (EC w ) CR L Fig. 3 Changes in groundwater quality (SAR) Crop Yields The data regarding crop yield is given in Table VI. The results show that at all the watercourses, treatment with pancho irrigation (T 1 ) gave the highest rice crop yield (6520 kg ha -1, 5740 kg ha -1 and 5977 kg ha -1 ) followed by yields with irrigation intervals of 07days (T 3 ) which gave 5770 kg ha -1, 5220 kg ha -1

6 Jawaid Mohyuddin and Muhammad Tarique. Evaluation of irrigation application methods 582 and 5320 kg ha -1. (T 2 ) irrigation as and when required produced lowest yields of 4770 kg ha -1, 5000 kg ha -1 and 5109 kg ha -1, respectively. High yields obtained from T 1 were due to fresh water application. Furthermore, it is observed that the longer the interval period of irrigation, the lower will be the crop yield. Table-VI Average yield of rice crop Treatment W/C # 4R W/C # 17-CR W/C # 16L Mean (3 seasons) Rep. Kg ha -1 Avg Rep. Kg ha -1 Avg Rep Kg ha -1 Avg T 1 Pancho R R R Irrigation R ,520 R ,740 R ,977 6,079 (Control) R R R T 2 Irrigation R R R as and when R ,770 R ,000 R ,109 4,960 Required R R R T 3 Irrigation R R R with interval R ,770 R ,220 R ,320 5,437 of seven days R R R CONCLUSION AND RECOMMENDATIONS Better rice yields were obtained in order of treatments T 1 - pancho irrigation> T 3 - irrigation with interval of seven days and >T 2 - irrigation as and when required. Pancho irrigation has the potential to produce optimum rice yields. Grain yield did not vary much with seven day interval as compared to Pancho irrigation. Treatment T 2 proved better and more economic in terms of irrigation water application. The longer the interval period of irrigation, the lower the crop yields. Irrigation with an interval of seven days may be recommended to irrigate rice area with a limited canal water supply. Such experiments should be carried out under different soil types with sound recommendations for demonstration of technology (best suited irrigation methods) to the farmers. Efforts may be continued for development of best system irrigation to rice fields. REFERENCES Akram, M., M. Ashraf, and M.A. Sagar, Current status of rice research in Pakistan. Seed Tech. & Dev. 16: Bhatti, I.M. and M.A.H. Qureshi Irrigation and water management of rice production in Sindh. Seminar on Water Mgt. of Agric. Nov Lahore. De Datta, S.K., H.K. Krupp, E.I. Alvarez and S.C. Modgal 1973(b). Water management practices in flooded tropical rice Pages 1-18 in International Rice Res. Instt. Water Mgt. in Philippine Irrig. Systems: Res. and Operation. Los Banos, Philippines. Grist, D.H Rice. 5 th ed. Longman Group Ltd. London. Hassan, A.. State of environment and development. ICUN Pakistan, Sindh Prog. IRRN Internal Rice Research Notes. Int. Rice Res. Instt. IRRN Kahlown, M.A., A. Raoof, and M. Hanif, Rice yield as affected by plant densities. Mona Reclamation Experimental Project, WAPDA, Bhalwal, Pub. No.234. Khan, G.K. and M. Akhtar, rice production technology. The daily Dawn, Karachi, Agric. And Tech. Section. Raja, A.. Pakistan too is now among the countries facing severe water shortage. The daily Nawa-i- Waqt, Saturday, Shahid, B.A., A.B. Shakir and M.A. Bodla Review of Seepage losses from unlined and lined canals inside and outside Pakistan. IWASRI. Pub. No.167. Surajit, K. and De Datta Principles and Practices of rice production. Los Banos, Philippines. Yamada, N Some problems of irrigation and drainage in rice culture. Int l. Rice 14(3), Comm. News letter. Zafar, R.. Half of World s natural water resources have exhausted. The daily Jang Sunday Magazine,

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