studies using seeds of wheat ( triticum aestivum l. ) , rye ( secale cereale l. ) , barley ( hordeum vulgare l. ) , and corn ( zea mays l. ) indicated that the adverse effect of urea fertilizer on seed germination in soil is due to ammonia formed through hydrolysis of urea by soil urease and is not due to urea itself , to urea fertilizer impurities such as biuret , or to nitrite formed by nitrification of urea nitrogen .
C0041942
urea
C0005667
biuret