CHICAGO, April 21 (Xinhua) -- Chicago Board of Trade (CBOT) agricultural commodities closed lower over the trading week which ended April 20, mostly on improved weather forecast and investors' technical selling.

The most active corn contract for July delivery fell 9.75 cents weekly, or 2.52 percent, to 3.765 dollars per bushel. July wheat delivery dropped 9.25 cents, or 1.96 percent, to 4.6325 dollars per bushel. July soybeans went down 14 cents, or 1.33 percent, to 10.5425 dollars per bushel over the week.

CBOT corn futures fell nearly 10 cents amid improved central U.S. weather. Analysts suggest that on a nationwide basis, planting dates correlate poorly with yield potential. National Oceanic and Atmospheric Administration's climate update this week also suggests normal weather is most likely continuing into July.

However, the structure of world feed grain markets has changed enough to keep breaks shallow and short lived. Ethanol margins remain elevated, barley and feed wheat prices rest at multi-year highs.

Wheat futures fell as U.S. Plains sees a moderate boost in soil moisture this weekend. U.S. export demand is disappointing, and on rallies the United States' position in the world market only worsens.

This weekend' s rainfall won' t materially affect hard red wheat production after 5 months of dire drought. And assuming trend yields, major exporter stocks fall noticeably in 2018 while world wheat trade is expected to grow amid improved emerging market economic growth and a lack of new Northern Hemisphere wheat acreage expansion.

Russia may produce another big crop, but between now and July a heavier burden is being placed on mother nature relative to recent years. Longer term price trends are turning more bullish of wheat and sales are only advised on supply driven rallies.

Soybean traded lower through the week on large U.S. cash market supplies and a weak Brazilian real. Chinese demand is largely focused on Brazil, and U.S. sales and shipments remain seasonally slow.

However, domestic crush demand remains exceptionally robust, and National Oilseed Processors Association reported a record large March crush rate. Similarly strong margins have held through April, while weekly soybean meal exports remain strong.

Slow export demand, strong domestic demand, and delayed corn and spring wheat planting is expected to keep soybean futures in a wide range.