Potential for U.S. Average Corn and Soybean Yields

The U.S. average corn yield was record large in 1985, 1986, and 1987 and established new highs five times in the succeeding 26 years. Similarly, the U.S. average soybean yield was record large in 1985 and established new highs eight times in the succeeding 26 years. The most recent record yield was in 2009 for both crops. Average yields were below trend value in each of the past four years.

最近几周，今年对美国平均玉米和大豆产量的期望有所增加。玉米种植的开始缓慢，就像去年一样。即使5月的进展加速，在5月的第三周之后种植了农作物的平均百分比。根据美国农业部的每周作物进度报告，估计在5月20日之后种植了18个主要玉米生产状态的玉米面积的23％，而1986年至2013年的平均15％。在过去七年的五年中，大多数种植大多数种植都在北部和远东玉米生产州中种植的玉米面积的平均部分多于玉米面积的平均部分。在5月的第二周或第三周之后，种植的玉米的产量潜力降低，所有其他条件相等。但是，过去一个月中的天气状况通常有利于玉米的出现和发育，尽管比通常的种植量相当多，但仍会产生高收益的预期。美国农业部在6月11日的WASDE报告中承认这些条件是将2014年收益投影以创纪录的165.3蒲式耳保持的原因。

The USDA's weekly ratings of corn conditions have also supported high yield expectations. As of June 8 (23rd week of the year), 75 percent of the crop in the 18 major corn producing states was rated in either good or excellent condition. In the previous 28 years (excluding 1995 when ratings were not yet available due to extremely late planting) an average of 66 percent of the crop was rated in good or excellent condition at the end of the 23rd week. The portion of the crop rated in good or excellent condition was higher than this year in only five previous years. Crop condition ratings tend to decline as the growing season progresses and early season ratings are not a good indicator of either final ratings or the U.S. average yield. Still, the current high ratings along with a mostly favorable weather outlook are keeping yield expectations high. The major concerns in the near term center on deteriorating conditions in areas that have received excessive rainfall in recent weeks. The effect of flooding and ponding may begin to be revealed in the crop condition ratings to be released today. Those concerns are legitimate, but are likely outweighed by the beneficial impact of favorable weather in most areas.

Soybean planting also started slowly this year, but a larger than average portion of the crop was planted before the end of May. For the week ended June 8, 74 percent of the crop in the 18 major soybean producing states was rated in either good or excellent condition. Soybean condition ratings were reported for the 23rd week of the year in 17 of the 28 years from 1986 through 2013. On average, only 62 percent of the crop was rated in good or excellent condition for that week. The previous record high rating was 73 percent in 2010. Soybean crop condition ratings tend to decline even more than for corn as the growing season progresses and early season ratings are not always a good indicator of the final U.S. average yield. Recent and upcoming heavy rainfall in some areas will likely begin to be reflected in deteriorating ratings, but yield expectations remain high.

玉米和大豆生长季节的关键部分仍将到来。2004年和2009年的创纪录产量是夏季降雨充足的结果，比夏季平均温度凉爽。今年的这些条件的重复可能导致平均玉米收益率高于美国农业部预期的创纪录率。例如，2009年的平均收率比2004年平均水平高四蒲式耳。从2009年到2014年的类似跳跃将导致平均168.7蒲式耳。根据目前收获的土地的预测，这种产量将产生比美国农业部目前预期的2.86亿蒲式耳的蒲式耳。对于大豆而言，2009年创纪录的收益率比2005年的蒲式耳蒲式耳0.9蒲式耳。从2009年到2014年的类似涨幅将导致平均收益率为44.9蒲式耳，实际上比当前的USDA预测低0.3蒲式耳。基于目前收获的土地的预测，这种产量将产生比美国农业部预测的农作物低约2400万蒲式耳。

虽然对美国玉米和大豆产量的潜力充满信心还为时过早，但市场清楚地期待着很大的农作物，尤其是玉米。只要条件继续指向趋势价值高于趋势价值的平均收益率，价格可能会保持压力。

Darrel Good发行
Department of Agricultural and Consumer Economics
伊利诺伊大学

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