FURTHER ARGENTINE COARSE GRAIN LOSSES FEARED Argentine grain producers adjusted their yield estimates for the 1986/87 coarse grain crop downward in the week to yesterday after the heavy rains at the end of March and beginning of April, trade sources said. They said sunflower, maize and sorghum production estimates had been reduced despite some later warm, dry weather, which has allowed a return to harvesting in some areas. However, as showers fell intermittently after last weekend, producers feared another spell of prolonged and intense rain could cause more damage to crops already badly hit this season. Rains in the middle of last week reached an average of 27 millimetres in parts of Buenos Aires province, 83 mm in Cordoba, 41 in Santa Fe, 50 in Entre Rios and Misiones, 95 in Corrientes, eight in Chaco and 35 in Formosa. There was no rainfall in the same period in La Pampa. Producers feared continued damp conditions could produce rotting and lead to still lower yield estimates for all the crops, including soybean. However, as the lands began drying later in the week harvesting advanced considerably, reaching between 36 and 40 pct of the area sown in the case of sunflower. Deterioration of the sunflower crop evident in harvested material in Cordoba, La Pampa and Buenos Aires forced yield estimates per hectare to be adjusted down again. The season's sunflowerseed production is now forecast at 2.1 mln to 2.3 mln tonnes, against 2.2 mln to 2.4 mln forecast last week and down 43.9 to 48.8 pct on the 1985/86 record of 4.1 mln. Area sown to sunflowers was two to 2.2 mln hectares, 29.9 to 36.3 pct below the record 3.14 mln hectares last season. Maize harvesting has also reached 36 to 40 pct of the area sown. It is near completion in Cordoba and Santa Fe and will begin in La Pampa and southern Buenos Aires later in April. Production estimates for maize were down from last week at 9.5 mln to 9.8 mln tonnes, against 9.6 mln to 9.9 mln estimated previously. This is 22.2 to 23.4 pct below the 12.4 mln to 12.6 mln tonnes estimated by private sources for the 1985/86 crop and 21.9 to 25.8 pct down on the official figure of 12.8 mln tonnes. Maize was sown on 3.58 mln to 3.78 mln hectares, two to seven pct down on last season's 3.85 mln. Sorghum was harvested on 23 to 25 pct of the area sown in Cordoba, Santa Fe and Chaco. Harvest will start in La Pampa and Buenos Aires in mid-April. The total area sown was 1.23 mln to 1.30 mln hectares, 10.3 to 15.2 pct down on the 1.45 mln sown last season. The new forecast for the sorghum crop is 2.9 mln to 3.2 mln tonnes compared with three mln to 3.3 mln forecast last week, and is 23.8 to 29.3 pct down on last season's 4.1 mln to 4.2 mln tonne crop. The soybean crop for this season was not adjusted, remaining at a record 7.5 mln to 7.7 mln tonnes, up 4.2 to 5.5 pct on the 7.2 mln to 7.3 mln estimated by private sources for 1985/86 and 5.6 to 8.5 pct higher than the official figure of 7.1 mln. The area sown to soybeans this season was a record 3.7 mln to 3.8 mln hectares, 10.8 to 13.8 pct up on the record 3.34 mln sown in 1985/86. The soybean crop is showing excessive moisture in some areas and producers fear they may discover more damage. Some experimental harvesting was carried out in Santa Fe on areas making up only about one pct of the total crop but details on this were not available. Preparation of the fields for the 1987/88 wheat crop, which will be sown between May and August or September, has so far not been as intense as in previous years.