Excerpt from Measuring the Effects of Weather on Agricultural Output: Procedures for Constructing Weather Indexes When we talk about weather in agriculture, we are interested in the net influence of all meteorological and closely associated factors on output. Weather and technol ogy, therefore, are defined in their broadest sense. Weather is those conditions Of the crop-growing environment that are beyond the control of farmers; technology is the sum total Of controllable resources and how they are used. Weather indexes for corn yields and production in Iowa from 1929 to 1960 were constructed using a plot data approach. State indexes were developed by aggregating weather indexes for individual Crop Reporting districts. The weather indexes were used in adjusting for the influence of weather the State and district actual yields per harvested acre and total production of corn. Variation in the adjusted yield series is an estimate of the effect of changes in technology. The series of adjusted corn yields for Iowa, 1929-60, indicates that improved technology increased yields in two steps. Yields from 1929 to 1935 were relatively stable. Beginning around 1935, corn yields increased rapidly until the early l94o's. This was the period marked by the rapid acceptance Of hybrid seed corn. Less than 1 percent of the corn acreage in 1933 was planted with hybrid seed; the percentage increased to nearly 99 by 1942. Corn yields remained at the new level throughout the l94o's and early l95o's. Then about 1954 a second period of yield increase began. This second increase does not appear to be due to any single factor but to a combina tion of improved practices such as increased use of fertilizer and higher planting rates. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.