Integrated Nitrogen Management on Nutrient Contents, Uptake and Use Efficiency of BRRI Dhan29

A field experiment was performed with BRRI Dhan 29 at Field Laboratory of Soil Science, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh. The effects of organic (cowdung) and inorganic (urea) amended N fertilizers were evaluated for NPKS contents and uptakes in grain and straw, and also for observing N use efficiency. Randomized complete block design was set for seven treatments based on recommended dose of N (RDN) @ 150 kg ha-1 using cowdung and/or urea alone or their combinations. The NPK contents as well as their uptake in grain and straw were significantly affected due to different treatments while S content was insignificant. The application of recommended dose of N from urea (T1) showed highest N content in grain (1.11%) and straw (0.71%) which was closely followed by the treatment T6 (20% RDN from cowdung + 80% RDN from urea). The maximum P content was found from the grain and straw of T6 treatment whereas a significant increase in the P, K and S contents were noted due to combined application of N from cowdung and urea. The NPKS uptake of grain and straw as well as total uptake (107.60 kg ha-1 N, 27.84 kg ha-1 P, 71.36 kg ha-1 K and 25.63 kg ha-1 S) were recorded maximum in T1, followed by T6. The treatment T1 yielded maximum apparent N recovery efficiency (45.06%) and agronomic N use efficiency (19.60 kg kg-1) while the maximum physiological N use efficiency (43.55 kg kg-1) was found in T6. Results also suggested that the application of lower doses of urea N with higher doses of cowdung N were not useful for the N recovery due to low N supplying potentiality of manures in a single cropping season. However, the incremental rates of urea N upto 80% along with 20% cowdung N effectively increased the recovery of N in all the parameters of N use efficiency and should be applicable to optimize the need for N requirement and build up a good soil health.