Nitrogen availability and uptake as influenced by time of application and N sources in semi-dry rice (Oryza sativa)

295 Semi dry rice refers to rice which is sown on dry seed bed as an upland crop taking advantage of monsoon rains. At fourth or fifth leaf stage, when the rainfall intensifies or sufficient water is released from the tank or irrigation projects, the field is converted to wet land rice. The major barrier in improving the productivity of rice in this system is inefficient use of important plant nutrients especially N. Occurrence of diametrically opposite environment, both upland and lowland condition during the growth cycle of semi-dry rice, requires precise nitrogen management technology which is different from that of upland and lowland systems. Semi-dry rice fits very well during the short growing periods as in the case of delayed monsoon and in pre and post flood periods in the flood prone rice growing areas.