Excerpt from Agricultural Economics Research, Vol. 1: July 1949 A Kansas study of the cost of using machinery takes farmers' estimates of years of life as the basis for calculating depreciation. The authors observe that these estimates include elements of wear and obsolescence. Although amount of annual use is not shown, data for tractors, combines and mowers are grouped according to number of cultivated acres per farm, and it is observed that As farm size in cultivated acres increases, the estimated service life of tractors tends to decrease The estimated life of combines and mowers, however, does not appear to be affected by the size of the farm. 9 For tractors, estimated average life ranges from years on farms with from 50 to 99 acres of cultivated land to years on farms with 600 to 649 acres cultivated. 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.