* Monsoon runs four days late than schedule
* Rains continue to display a weak phase-weather official
* Rains may pick up in soybean, rice areas next week (Adds quotes from farm lobby group, details)
By Ratnajyoti Dutta
NEW DELHI, June 19 (Reuters) - The monsoon has covered half of India's landmass four days behind the usual schedule, failing to recover from a late start that has slowed sowing of summer crops in a country where half of the farmland still lacks irrigation.
India's farming sector accounts for about 14 percent of its nearly $2 trillion economy. Inadequate rains can not only hurt farm output but also stoke inflation, a cause of major concern for the new government of Prime Minister Narendra Modi.
The annual rains arrived over the southern Kerala coast five days behind the normal June 1 start and then entered a lull, with poor rains over the interior parts of southern India.
Rainfall was 45 percent below average for the week ended June 18, compared with 48 percent below average the previous week, weather office data showed on Thursday.
"Rainfall has increased in some parts of the central region, but monsoon has continued to be weak," said a weather official who did not want to be named.
Weather officials, however, expect the monsoon to strengthen over the soybean growing areas of central India and rice growing areas of southeastern region in the next week.
P. Chengal Reddy, head of the lobby group Consortium of Indian Farmers Association, said farmers were waiting for the monsoon rains to gather momentum to speed up sowing.
In the initial days of the June-September monsoon season, summer crops are not hugely affected by the quantity of rains. But its distribution in mid-July after the monsoon covers the entire country is important for their growth.
Sowing activities of major summer crops such as rice, corn, soybean, cane and cotton have started in many areas but at a slower pace.
"The northwest belt can withstand delay in sowing up to 10 days, deriving benefits of healthy soil moisture due to good pre-monsoon showers," Farm Commissioner J.S. Sandhu said, adding that farmers could also turn to reservoirs, in which water levels are up around 25 percent this year compared with year-ago levels.
Favourable reservoir levels and plenty of government grain stocks could help mitigate the impact of poor rain this year, according to the Indian Council for Research on International Economic Relations.
Earlier this week the government imposed export curbs on onions and ordered a crackdown on hoarding to check food price rises, after wholesale price inflation hit a five-month high in May.
India's weather office has forecast below average rainfall in 2014 due to fears of El Nino, a weather event marked by the warming of sea surface temperatures in the Pacific Ocean that can lead to droughts in the Asia Pacific region including India.
The Australian Bureau of Meteorology's latest forecast put the chance of El Nino at 70 percent. (Editing by Krishna Das and Jane Baird)