Ammonia Volatilization from Urea-Application Influenced Germination and Early Seedling Growth of Dry Direct-Seeded Rice

Abstract EN

Poor seed germination and early seedling growth associated with urea-induced soil ammonia volatilization are major constraints in the adoption of dry direct-seeded rice.

To directly examine soil ammonia volatilization and its damage to seed germination and early seedling growth of dry direct-seeded rice when urea is applied at seeding, two Petri-dish incubation experiments and a field experiment were conducted.

Ammonia volatilization due to urea application significantly reduced seed germination and early seedling growth of dry direct-seedling rice.

NBPT significantly reduced ammonia volatilization following urea application.

The application of ammonium sulfate, instead of urea at seeding, may mitigate poor crop establishment of dry direct-seeded rice.

Root growth of dry direct-seeded rice was more seriously inhibited by soil ammonia volatilization than that of shoot.

Results suggest that roots are more sensitive to soil ammonia toxicity than shoots in dry direct-seeded rice system when N is applied as urea at seeding.