Date of Award
Master of Science
O. H. Long
W. L. Parks, H. C. Smith
Adequate fertilization of cotton improves yields. More efficient use of soil nutrients is enhanced by avail-able soil moisture. Producers in the Tennessee cotton-producing belt are primarily dependent upon soil moisture storage plus seasonal rainfall for moisture supply. Fre-quently, the growing cotton crop undergoes periods of moisture stress. When the moisture in the surface soil becomes depleted, the plant roots must obtain moisture in the subsoil. Thus, nutrients, if available, must be ob-tained from the subsoil at the same time. In the Southeast, the subsoil is usually deficient in plant nutrients. Since soil water affects fertilizer response, deep placement of fertilizer may create a more favorable condition for efficient use of fertilizers by plants. Results of experiments reported to date on deep ferti-lizer placement indicate that the responses are variable and are dependent on certain physical and chemical properties of the soil as well as the amount and distribution of rainfall. Placement of fertilizers below the three-inch depth has given indications of positive yield results recently in west Tennessee. Field-size plots have also indicated yield responses. There is increasing evidence of the growing use of the "chisel" plow in tillage operations. This implement is be-coming a commonplace tool in west Tennessee. The implement can easily be used for deep fertilizer placement. An interest in obtaining more efficient use of fertilizers in addition to cotton yield increases prompted a fertilizer depth of placement study in field-size plots using an experimental design that would perhaps clarify the value of deep placement of fertilizer in cotton production. Included in the study was a rate of phosphorus and potassium that is commonly applied. A higher rate was included to determine if a yield response could be obtained by addi-tional amounts of phosphorus and potassium.
Connell, John Thomas, "Fertilizer rate and depth of placement experiment on cotton. " Master's Thesis, University of Tennessee, 1967.