By Rajendra Jadhav and Mayank Bhardwaj
MUMBAI/NEW DELHI, July 18 (Reuters) - India's monsoon rains were 20% below average in the week ending on Wednesday, the weather office said, as summer showers turned patchy over the central, western and southern parts of the country, raising concerns over the progress of crop plantings.
Overall, India has received 16% below average rain since the monsoon season began on June 1.
Monsoon rains are crucial for farm output and economic growth in India, where about 55% of all arable land is reliant on rainfall and the farm sector employs nearly half of the country's 1.3 billion people.
India typically receives 75 percent of its annual rain from the June-September monsoon as moisture-laden winds sweep in from the southwest of the peninsula.
In the week to July 17, soybean and cotton areas in the central parts of the country received 68% less than average rainfall, while rubber and tea areas in southern India got 71% lower rains, data from the India Meteorological Department (IMD) showed.
Key sugarcane and groundnut producing areas in western India also received below average rains, the IMD data showed.
The IMD defines average, or normal, rainfall as between 96 percent and 104 percent of a 50-year average of 89 centimetres for the entire four-month season beginning June.
Indian farmers plant rice, cane, corn, cotton, soybean and groundnut -- the main winter oilseeds -- in the rainy months of June and July, with harvests from October.
Patchy rains have led to some anxious sky-watching, even as floods in eastern and northeastern India have displaced and killed people.
At least 5.8 million people have been displaced and some 30 have died in the past two weeks in the tea-growing state of Assam due to the monsoon rains.
Assam and Bihar states have been the worst-affected parts of India, and floods have also hit neighbouring Nepal and Bangladesh.
At least 153 people have been killed in India, Nepal and Bangladesh. Parts of Pakistan have also seen flooding.
Although India is sitting on massive mounds of staples such as rice, wheat and sugar, any drop in oilseed production will push up imports of expensive vegetable oils.
India imports about 60% of its vegetable oil needs at an annual cost of up to $10 billion – its third-biggest import item after crude oil and gold. (Reporting by Rajendra Jadhav and Mayank Bhardwaj; editing by Richard Pullin)
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