Using CROPWAT 8.0 for intermittent irrigation scheduling and yield estimation of paddy rice under rainy season cropping in Pingtung, southern Taiwan

• Main Authors: Kima Etienne, 金馬
• Other Authors: Wang Yu-Min
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/rzjz4u

碩士 === 國立屏東科技大學 === 土壤與水工程國際碩士學位學程 === 105 === This study was carried out to set up rice crop intermittent irrigation scheduling during the rainy season (from July to November, 2016) at the National Pingtung University of Science and Technology (NPUST) experimental farm where irrigation water was scheduled at 7 days intervals. Five irrigation treatments were replicated thrice and four. The first treatment (CW) was the application of the result of CROPWAT 8.0 irrigation scheduling and the remaining four (T2, T3, T5, and T5) stood for an respectively application of 2 cm, 3 cm, 4 cm and 5 cm. To prevent seepage, plots were separated in two blocs. Altogether, there were five treatment combinations replicated thrice and four. The first treatment was designed for intermittent irrigation of 7 days interval using the results of CROPWAT 8.0 scheduling whereas the second treatment was structured for Alternate Wetting and Drying (AWD) method. CROPWAT8.0 simulation was run using 13 years climatic data provided by the NPUST meteorological station. Reference crop evapotranspiration (ETo) was determined using the FAO Penman Monteith method. The results showed reference evapotranspiration (ETo) average value 3.55 and 140.2 mm crop water requirement for rice for the whole cropping period. Results on irrigation scheduling provided a weekly water supply amount which has been applied for practical assessment of grain yield. The amount of irrigation water supplied was estimated at a minimum of 9.4 mm at the development stage to a maximum of 72 mm at the end of mid-season and the late season. The results indicated variable grain yield between treatments under the intermittent irrigation. Average grain yield was obtained as (6.70 t.ha¯¹) while the highest (7.8 t.ha¯¹) and lowest (6.12 t.ha¯¹) were obtained in T2 and CW. The water input was reduced to 35 % for the whole season in the CW treatment and 10%, 12%, 15%, 18% respectively for T2, T3, T4 and T5. The water productivity ranges from 0.29 kg/ m3 for CW treatment to 0.40 kg/m3 for T3 treatment. The yields obtained confirm that, in the rainy season a good schedule and good water delivery, crop yields of more than 6 t ha -1 could be realized. As it could be seen the entire yield is more than 6 t ha-1 is obtained in each treatment. Results showed that CROPWAT 8.0 can be used for intermittent irrigation scheduling, effective and efficient water management and to optimize production of rice during the rainy season. But the most important findings from this research were highlighted by total grain yield, water productivity, irrigation water productivity and rain water productivity in the treatment with less water depth (T2) and height water depth (CW). The variation in water holding during the cropping period was one of the facts that affected the yield obtained. Under rainy season, active drainage system and mid-season drainage is important to strengthen the plant productivity.