Effects of Subsurface Drip Irrigation on Chemical Soil Properties and Cotton Yield

Abstract

Subsurface drip irrigation (SDI) has proven to be an economical method of irrigation for agronomic row crops. It is suitable for small irregular shaped fields and has the highest water use efficiency of any other irrigation system available. The objective of this research is to determine the effects on soil chemical properties and cotton yield from fertilizing through a sub-surface drip irrigation system compared to the conventional method of broadcast surface fertilizing cotton. Research was conducted at two locations: Tennessee Valley Research and Extension Center (TVREC) on a Decatur silt loam (fine thermic, Rhodic Paleudults) and Wiregrass Research and Extension Center (WREC) on Dothan sandy loam (fine, loamy siliceous, thermic Plinthic Kandiudults). Fertilization treatments were: (1) conventional, surface broadcast fertilizer over the top with no irrigation, (2) conventional broadcast fertilizer over the top with sub-surface drip irrigation, and (3) fertilizer through the sub-surface drip irrigation system. Data was taken from soil samples using a Giddings soil probe after five years. Phosphorus, K, Mg, Ca, and pH samples were taken at four depths and at four distances from the drip tape emitter. The sub-surface fertilize increased the cotton yields one year when there was not enough rainfall to push the surface fertilize to the plant roots to supply the plant needs. When normal rainfall occurred there were no significant yield differences between the fertilized treatments. The data showed significant soil differences from fertilizing with the subsurface drip irrigation system but these differences were not enough to show an effect on crop production after five years; difference could be more dramatic after a longer period of time.