Evaluation of ammonium and soluble salts on grass sod production in compost. II. Delaying seeding after compost application

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Abstract
In some composts, seed germination and plant growth have been inhibited by high concentrations of ammonium or soluble salts. Ammonium and salt concentrations in media decrease with time after application to land or placement in containers for growth of plants. This study was conducted to determine if ammonium or soluble salt problems could be avoided by delaying seeding after compost application. Turfgrass (Lolium perenne L.) was seeded into municipal solid waste (MSW) compost depleted of ammonium during storage and into this compost with 1,150 or 2,300 mg ammonium‐N/kg (dry weight) added from (NH4)2SO4. Seeding occurred on the day of compost application and after 1, 3, 7, and 14 days from application. Flats of composts were watered daily after seeding but were not watered before seeding. Ammonium‐nitrogen (N) and nitrate‐N concentrations, electrical conductivity, and pH of the compost were measured on each day of seeding. Ammonium‐N, electrical conductivity, and pH for the compost declined, whereas the nitrate‐N concentration increased with time. Delaying seeding for 14 days after compost application increased germination and clipping weights. By delaying seeding, ammonium and salt problems were minimized, apparently by the dis‐ sipation of the inhibitory factors by ammonia volatilization.