Masters Theses

Date of Award

12-1965

Degree Type

Thesis

Degree Name

Master of Science

Major

Agricultural Extension

Major Professor

Lewis H. Dickson

Committee Members

O.H. Long, S.A. Griffin

Abstract

Soybeans have become a valuable cash crop in Tennessee. In 1964 the acreage had grown to 586,000 acres for an income of over thirty five million dollars (22). By comparison in 1955 only 250,000 acres were produced (21). The acreage in soybeans now exceeds that in cotton by over 100,000 acres.

Soybeans are grown across the state, but more than 90 percent of the state's total acreage is found in West Tennessee.

Research work conducted in Georgia in 1960, 1961 and 1962 indicated that molybdenum, a micronutrient, is very important in increasing the yield of soybeans on acid soils. Among the micronutrients molybdenum is unique in that as the soil pH increases the availability molybdenum increases. All the other micronutrients are more available under more acid conditions (pH values between 5.0 and 6.0).

A summary of 1964 soil test results from a total of 9270 samples submitted by West Tennessee farmers to the State Soil Testing Laboratory in Nashville reveals that 7 percent of the samples were in the pH of 5.0 or below for soybeans where four tons of limestone per acre is recommended; 29 percent were in the pH range of 5.1 to 5.5 where three tons of limestone is recommended; and 24 percent were in the pH range of 5.6 to 6.0 where two tons of limestone is recommended. This means that an application of from two to four tons of limestone would have been recommended for 60 percent of these fields had the farmer indicated he was planning to grow soybeans.

Assuming that these were average West Tennessee soils, it might be expected that a yield response from application of molybdenum on soybeans could be forthcoming on 60 percent of the soils. It also is assumed that these same soils that would respond to limestone might respond to molybdenum application.

The Tennessee soybean producer plants his most productive fields to cotton and corn. The remainder of his cultivated land may be planted largely to soybeans. The soybean land is usually lower in fertility and unlimed. In many cases the land is rented and the renter feels that he cannot afford to build up the fertility or invest in limestone under a year-to-year rental agreement.

When these conditions exist, the farmer may treat the soybean land with molybdenum at a cost of 35 cents to 75 cents per acre compared to a cost of $10 to $20 per acre for limestone.

The purpose of this study, then, was to determine soybean response to molybdenum on various soil types and under different soil conditions.

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