Assessing nitrogen supply potential and influence on growth of lettuce and Amaranthus of different aged composts

This study assessed the potential of different composts at different maturity stages to supply n and their effect on the vegetative growth of lettuce and amaranthus. five composts aged 1,3,6,9,and 12 months,were mixed with soil @ 5%,10% and 15% then seeded with lettuce and amaranthus. results showed that 1,3 and 6 month aged composts had a negative effect on plant height of lettuce and amaranthus as 1-15.78% and 4.78 to 29.45% decrease in plant height over control was recorded respectively. on the other hand 9 and 12 month aged composts had a significant positive effect on plant height of lettuce and amaranthus where 43.48% and 34.8% increase over control was recorded with the application of 15% of 12 month aged compost respectively. a similar effect was observed on fresh biomass of both lettuce and amaranthus where a 386% and 59.43% increase over control was recorded with the application of 15% of 12 month aged compost respectively. one and three month aged composts revealed a negative effect on n absorption by lettuce whereas 1,3,6 and 9 month aged composts had a negative effect on n absorption by amaranthus. 30.39% and 21.48% increases over control in n absorption by lettuce and amaranthus respectively were recorded with the application of 15% of 12 month aged compost.