BROILER AND LAYER POULTRY MANURES AS NITROGEN-SOURCES FOR DOUGLAS STRAWBERRY IN A TUNNEL PRODUCTION SYSTEM

Floor litter from laying hens (1-year old) and from broiler chickens ( 8-week old) were incorporated into soil and compared with ammonium sul fate [(NH4)2SO4] and an unfertilized control treatment as sources of n itrogen (N) for 'Douglas' strawberry grown in a tunnel production syst em. Layer litter had 5.6% moisture, 3.9% N and 1.7% P, while broiler l itter had 7.7% moisture, 4.9% N and 1.6% P; they were applied at a rat e of 12.8 and 10.8 t/ha on wet basis, respectively, in August 1991. Am monium sulfate was applied at 100 kg N/ha in three split applications during the growing season. 'Douglas' strawberry plants were transplant ed on 15 November 1991 and fruits were harvested from 1 April to 10 Ju ne 1992. Nitrate-nitrogen (NO3-N) concentrations at last harvest were comparable in the soil and leaf tissue among all treatments (P>0.05); leaf NO3-N, early in the harvest period, was highest (P<0.05) in the b roiler treatment (8.55%) and lowest in the control (5.15%). Yields wer e increased (P<0.05) by the manure, with the broiler treatment yieldin g the highest and the control yielding the least.