Abstract
A study was carried out to find out the appropriate source of nitrogen and planting pattern for MV boro rice during 2000 - 2003 at the Bangladesh Agricultural University, Mymensingh. It included four experiments conducted in three consecutive years. One field experiment and one pot experiment were conducted in \(1^{\text{st}}\) year. The other field experiment was conducted in \(2^{\text{nd}}\) year, which was repeated in \(3^{\text{rd}}\) year. Field trial with 12 planting patterns (4 single row and 8 paired row arrangements) revealed that paired row arrangement with higher plant population produced higher grain yield. The highest and the lowest plant population (37.2 and 20 hills m⁻², respectively) reduced grain yield. Planting patterns (35cm + 15cm) × 15cm, (35cm + 15cm) × 12.5cm and 25cm × 12.5cm were found better. In the pot trial, 17 nitrogen sources which comprised of 100% N from each of the prilled urea (PU), urea super granules (USG), vermicompost (VC), blackgram biomass (BGB), grasspea biomass (GPB), farmyard manure (FYM), poultry manure (PM), biogas slurry (BGS), polythene pit compost (PPC) and substitution of 50% N from PU by rest of the nitrogen sources, were tested on BINA dhan6 and BRRI dhan29. Varieties produced identical grain yield. USG out yielded all other N sources. In general, organic manures alone could not produced higher grain yield. However, application of BGB or GPB alone and integration of PU with any of the BGB, GPB and PM yielded similar to 100% N from PU. Field trials with selected 9 N sources and 3 planting patterns in the next two consecutive years showed that USG out yielded all other N sources, replacement of urea N 50% or 25% by PM or GPB produced grain yield comparable to 100 N from PU in the \(1^{\text{st}}\) year. But in the following year, replacement of urea N 50% or 25% by PM and 50% by GPB produced grain yield higher than 100% N from PU but similar to 100% N from USG. Planting pattern (35cm + 15cm) × 15cm was the best. Total dry matter, crop growth rate and leaf area index were influenced considerably due to N source and planting pattern. Nitrogen concentration in grain and straw as well as total N uptake were also higher in N sources replaced 50% or 25% urea N by PM or GPB and 100% N from USG. Soil N balance was better due to application of integrated N sources where FYM performed the best. Soil organic matter, total N, available P, exchangeable K and available S were increased but bulk density decreased considerably due to the application of organic manure alone or in combination with PU. Performance of PM and FYM replaced 50% urea N was better. It was further observed that replacement of urea N 50% by PM was the best sources of nitrogen considering higher yield of boro rice.