Analysis of crop water requirements and irrigation demands for rice: Implications for increasing effective rainfall

According to Kunming 1980-2010 monthly weather data and CROPWAT software and the corresponding crop data, crop water requirements and irrigation water use are calculated. By frequency analysis, irrigation water requirement was get for different guaranteed rate. The results show that: corn, potatoes, tobacco, and soybeans average crop water requirements were 390.7mm, 447.9mm, 361.8mm and 328.4mm, crop water dispersion coefficient is small, period effective rainfall during crop growth in most of the year can meet the crop water requirements, so irrigation water demand is small. While the multi-year average crop water requirements were 400.8mm, 353.5mm, 394.3mm for small spring crops of wheat, beans, rape. Because the effective rainfall for these crops during growth period is relative less, crop irrigation water requirements for small spring crop is much. Vegetables and flowers are plant around the year, so the crop water and irrigation water requirements are the largest.

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Crop Water Requirements and Irrigation Schedules for Some Major Crops in Southern Iraq

Water ◽

10.3390/w11040756 ◽

2019 ◽

Vol 11 (4) ◽

pp. 756 ◽

Cited By ~ 22

Author(s):

Ewaid ◽

Abed ◽

Al-Ansari

Keyword(s):

Water Resources ◽

The United States ◽

Simulation Software ◽

United States Department ◽

Effective Rainfall ◽

Crop Water ◽

Water Requirements ◽

Crop Water Requirements ◽

Study Results ◽

Southern Iraq

The climate of Iraq is of the subtropical semi-dry type; however, the country was rich in water resources until a few decades ago. Climate change and the construction of many dams on the Tigris and Euphrates rivers in the neighboring countries have caused water shortages and poor water quality. Now, there is a need to decrease consumption, improve management of water resources, and determine the water requirements of the major crops because agriculture is the first consumer of water in Iraq. The Food and Agriculture Organization (FAO) CROPWAT 8.0 simulation software and the CLIMWAT 2.0 tool attached to it have been used in this research for Dhi-Qar Province in southern Iraq to find the crop water requirements (CWRs) and irrigation schedules for some major crops. The CROPWAT Penman–Monteith method was used to calculate the reference crop evapotranspiration (ET0) and the United States Department of Agriculture (USDA) soil conservation (S.C.) method was used to estimate the effective rainfall. The study results showed that ET0 varied from 2.18 to 10.5 mm/day and the effective rainfall varied from 0.0 to 23.1 mm. The irrigation requirements were 1142, 203.2, 844.8, and 1180 mm/dec for wheat, barley, white corn, and tomatoes, respectively. There is a higher water demand for crops during the dry seasons (summer and autumn) and a lower demand during the wet seasons (winter and spring). The total gross irrigation and the total net irrigation were 343.8 mm and 240.7 mm for wheat, 175.2 mm and 122.6 mm for barley, 343.8 mm and 240.7 mm for white corn, and 203.3 mm and 142.3 mm for tomatoes. This study proved that the CROPWAT model is useful for calculating the crop irrigation needs for the proper management of water resources.

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