COMPARISON OF FERTILIZER RATES AND SOIL TEST LEVELS
Research Progress Report 52
March 1963
R. K. Stivers, Agronomy Department and D. R. Griffith, Pinney Purdue Farm
Summary
The primary purpose of this research is to study fertilizer rates for corn and soybeans in relation to soil tests on important soil types in Indiana. One soil being studied is Runnymede loam on the Pinney Purdue Farm in northern Indiana. Purdue tests showed that the soil had an average pH of 6.2, was medium to high in phosphate and low to medium in potash.
Four rates of nitrogen, four rates of potash and a mixture of micronutrients vs no micronutrieats were studied on corn. The only response in 1962 was a 15 bushel per acre yield increase and a significant increase in ear size for the first 60 pounds of nitrogen added. However, yields may have been limited by severe lodging just before the corn tasseled. There was no significant response to the four rates of potash on soybeans.
Experimental Procedure
Previous crops on the soil studied were oats, alfalfa, corn and corn in 1958, 1959, 1960 and 1961 respectively. In those 4 years, a total of 70 pounds of nitrogen,
283 pounds of P2O5 and 210 pounds of K2O were applied per acre. The field was covered with manure twice in the previous 12 year period.
Results of soil tests taken in the spring of 1962 are reported in Table 1. Samples were a composite of 16 to 18 borings from each 1/60 acre plot. The variation in potash
tests was greater than expected since potash applications in the area had been uniform during the previous 12 year period. Variation of phosphate tests may be related to previous band applications of this nutrient.
All experiments were in randomized block design and replicated 3 times. For corn, P2O5 and K2O were applied at 120 pounds per acre each on all plots in the nitrogen experiment. Nitrogen and P2O5 were applied at 180 and 120 pounds per acre respectively to all plots in the potash experiment. On the minor element plots, nitrogen, P2O5 and K2O were applied at 180, 120 and 120 pounds per acre respectively. On all plots which received phosphate, 30 pounds per acre were applied in the row and the remainder was broadcast prior to plowing.
Where potash was varied on soybeans, all plots received 40 pounds per acre of plow down P2O5.
All broadcast fertilizers were plowed under in the spring. After one discing and one harrowing, Cargill S412 seed corn was planted on May 23 and Lindarin soybeans were planted on May 29. Both were in 40 inch rows. Corn seed was treated with dieldrin and young corn plants were sprayed with toxaphene for army worm control.
Corn ears were hand harvested from the center 2 rows, 44.5 feet long, in each 4 row plot. Percent moisture in the kernels and weight of ears were used to calculate
PURDUE UNIVERSITY • Agricultural Experiment Station • Lafayette, Indiana