Response of no‐tillage and conventional‐tillage cotton to starter fertilization on loess soils

Abstract

Starter fertilizers have been utilized to improve cotton (Gossypium hirsutum L.) yields, but yield increases have differed with soil type, application method, application rates, and tillage. Starter fertilizer tests were conducted from 1991 through 1993 on a Gigger silt loam (Typic Fragiudalf) in Louisiana and on a Loring silt loam soil (Typic Fragiudalf) in Tennessee to evaluate methods and application rates of 11–37–0 liquid fertilizer for cotton. Treatments were evaluated under conventional‐tillage (CT) and no‐tillage (NT) production systems. Application methods included in‐furrow application at planting (IF), spraying a 4‐inch wide surface band behind the planter (SB), and banding fertilizer two inches to the side and two inches below the seed at planting (2×2). The IF treatments were applied at 1.5, 3.0, and 4.5 gal/A. The SB and 2×2 treatments were applied at 7.5 gal/A. Starter fertilizer treatments were supplemented with broadcast granular fertilizers to achieve a total fertilization rate of 80–40–60 (N‐P2O5‐K2O lb/acre). Starter fertilizer treatments were compared to broadcasting 80–40–60 and 80–0–60. Soil test levels for phosphorus (P) were high on both soil types. In‐furrow applications of 3.0 and 4.5 gal/acre usually reduced plant population for both tillage systems on both soil types. The 1.5 gal/acre IF treatment was less detrimental to stand establishment than the higher IF rates. The effect of starters on plant height varied from year to year. Starter fertilizers usually did not affect early‐season plant height relative to broadcast treatments. In several experiments starter fertilization increased plant height compared to one, but not both, of the broadcast fertilization treatments. High IF rates (3.0 and 4.5 gal/acre) reduced plant height in one experiment. The 2×2 starter fertilizer treatment increased leaf area per plant relative to the broadcast fertilization treatments in two of six experiments on the Gigger soil. Responses for NT and CT studies were similar. In one CT experiment on the Loring soil, the 1.5 gal/acre IF treatment increased leaf area relative to the broadcast treatments. Lint yield responses to starter fertilization were inconsistent. Starter fertilization increased lint yield in one of six experiments on the Gigger soil and in two of six experiments on the Loring soil. Increased yields from starters varied with year and application method, however, the 2×2 and SB treatments tended to provide better responses than IF treatments. Starter fertilizer responses for NT and CT tests were generally similar.