EVALUATION OF AMMONIUM AND SOLUBLE SALTS ON GRASS SOD PRODUCTION IN COMPOST .2. DELAYING SEEDING AFTER COMPOST APPLICATION

In some composts, seed germination and plant growth have been inhibite d by high concentrations of ammonium or soluble salts. Ammonium and sa lt concentrations in media decrease with time after application to lan d or placement in containers for growth of plants. This study was cond ucted to determine if ammonium or soluble salt problems could be avoid ed by delaying seeding after compost application. Turfgrass (Lolium pe renne 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 o n the day of compost application and after 1, 3, 7, and 14 days from a pplication. Flats of composts were watered daily after seeding but wer e not watered before seeding. Ammonium-nitrogen (N) and nitrate-N conc entrations, electrical conductivity, and pH of the compost were measur ed on each day of seeding. Ammonium-N, electrical conductivity, and pH for the compost declined, whereas the nitrate-N concentration increas ed with time. Delaying seeding for 14 days after compost application i ncreased germination and clipping weights. By delaying seeding, ammoni um and salt problems were minimized, apparently by the dis- sipation o f the inhibitory factors by ammonia volatilization.