Fertilizer placement studies on Hillsdale sandy loam soil

A study was made of the effect on crop yields of applying 2-12-6 fertilizer by different methods to corn and wheat in a rotation of corn, barley, wheat, and clover grown on Hillsdale sandy loam soil. Some treatments also included manure, heavy applications of fertilizer plowed under for corn, and 0-12-6 fertilizer. Each crop was grown every year. The increases in yield resulting from fertilization are probably greater than they would have been had the experiment been placed on a different field each year as the soil of the untreated or check plots became somewhat less productive as the years passed. In an effort to explain the response of corn to different soil treatments, observations and records were made of the effects of seasonal conditions and of a combination of fertilizer treatment and seasonal conditions on crop growth and yield. Counts were made of the number of corn suckers produced per plot for a number of years and of the number of good and poor ears. Average weights of ears were determined and a relationship worked out between soil treatments, weather conditions, yields, size of ears, and percentage of ear-bearing stalks. Although no fertilizer was applied directly for barley and clover these crops showed noticeable responses to the residues of fertilizer applied to other crops in the rotation. Residues from manure applications produced the greatest increases in clover. Barley yields were materially increased by residues of manure and of heavy application of commercial fertilizer. Seasonal conditions also greatly influence the growth of clover and barley. Manure plowed under resulted in the largest yields of wheat, followed by commercial fertilizer drilled with the seed supplemented with a spring topdressing of manure. Commercial fertilizer drilled with the wheat seed gave better results than that applied broadcast and worked into the soil or that plowed under. Superphosphate used as a reinforcement to manure gave some, but not outstanding, increase in wheat yields. There was a very close relationship between yields of grain and straw in the case of wheat and barley, but no such relationship existed between yields of corn grain and stover. The largest increases in stover yields resulted from applications of manure and from heavy applications of commercial fertilizer, especially fertilizer containing excessive amounts of nitrogen. Moderate applications of fertilizer produced larger yield increases of stover when placed in or near the row than when broadcast or plowed under. The proportion of grain to stover was greatest in corn grown on plots receiving broadcast applications of fertilizer and on plots well fertilized for wheat but receiving no fertilizer for corn. The largest average yield of corn grain was obtained from the plot receiving, 300 pounds of 2-12-6 fertilizer for wheat and a spring top-dressing of 5 tons of manure, with no fertilizer applied for corn. In favorable seasons all fertilizer treatments resulted in increased corn yields, but in unfavorable seasons fertilizer applications were of little and frequently of negative value. Considering the average increases for the 11-year period, the results show little benefit from fertilizer applied directly for corn. Considering the rotation as a whole, there was a net financial gain from all fertilizer treatments. The frequent failure of corn to respond satisfactorily to fertilizer materially reduced the returns for the rotation. The tendency for fertilizer to increase the early growth of corn and to stimulate the production of suckers resulted, in dry years, in smaller ears and a higher percentage of barren stalks. These effects appear to account for the lower yields of grain and higher stover yields on the fertilized plots than on those receiving no fertilizer in unfavorable seasons. From the results it appears that the best way to increase corn yields on this soil type is to fertilize other crops in the rotation rather heavily, making use of green manures or animal manure, and to let the corn draw on the stored fertility. A direct correlation was found between yield in bushels, on the one hand, and size of ear and percentage of ear-bearing plants, or a combination of these two factors, on the other.