Response of lettuce cultivars to sludge‐amended soils and bed types

Abstract

A 2‐year nutrition experiment was conducted to determine the effects of sludge, bed, and genotype on lettuce growth and leaf elemental concentration levels. Three leaf lettuce cultivars (Lactuca sativa cvs. Grand Rapids, Ruby, Salad Bowl) were grown in field plots of silt loam amended with 90 MT/ha/year of industrial or municipal sludge and a control with no sludge application. The 3 bed types used were a level or flat bed, a 15‐cm raised bed, and a 15‐cm raised bed of unamended topsoil over prepared flat bed (overcover bed). Sludge and bed type did influence yield and leaf elemental concentrations for all 3 cultivars. When significant differences occurred, the highest yields were with municipal sludge and raised beds and the highest leaf nutrient concentrations with the industrial sludge. Bed effects on leaf elemental concentrations were variable. ‘Grand Rapids’ had significantly lower leaf concentration levels for all elements (except P in 1982) when compared to either ‘Grand Rapids’ or ‘Salad Bowl’.

Key words:

• Lactuca sativa L. var. crispa
• leaf elemental concentrations