Background: Selection of a suitable planting time is one of the key factors for obtaining a desirable rice grain yield. This study focuses on the effect of planting date on the key agronomic traits and provides useful information on optimal planting window to maximize grain yield of Bangabandhu dhan100 in the cold-prone Rangpur region, Bangladesh. 
 
Methods: The study was conducted at the Rangpur regional station farm of the Bangladesh Rice Research Institute from October 2021 to June 2022. The selected cultivar was seeded on eight different dates at a 15-day interval, starting on October 16. Time series data on agronomic parameters including seedling biomass, leaf number of seedlings and tiller number per plant were collected at a 15-day interval.&nbsp; 
 
Result: A good relationship was found between accumulated GDD (growing degree days) and the associated leaf number per plant and the highest leaf number was observed with early seeding. Similarly, seedling biomass yield depended on accumulated GDD and it was found to be higher at early seeding than late seeding. The tillering pattern of Bangabandhu dhan100 was influenced by planting dates and reached its peak at 60 days after planting for all seeding dates. The highest tiller number (368/plants) was found when the cultivar was seeded on December 1. Total biomass showed an increasing trend after planting and reached its maximum of 13.9 t/ha with December 1 seeding. Planting time significantly influenced the grain yields and the highest yields were observed during seeding between 1 and 16 December; yields gradually decreased with the advancement of seeding dates. This finding provided a good idea for the selection of an optimal planting time for Bangabandhu dhan100 to maximize grain in the Rangpur region, Bangladesh.

Response of Yield and Agronomic Output of Bangabandhu dhan100 under Varying Sowing Window in Cold Prone Rangpur Region

<div>Background: A laboratory incubation study was carried out to study the influence of long term manuring and fertilization on soil organic matter (SOM) quality by means of C mineralization in terrace soil of Bangladesh. 
 
Methods: Soil samples were collected in 2016 from a highly weathered terrace soil with rice-wheat cropping pattern at Bangabandhu Sheikh Mujibur Rahman Agricultural University experimental farm having five OM (control, cow dung, green manure, rice straw and compost) treatments combined with three mineral N fertilizer (control, 155 kg ha-1, 220 kg ha-1) levels. A model was used to explain detected C mineralization in soil known as parallel-first and zero order kinetic model. 
 
Result: Long term (28 years) application of mineral fertilizers and manure resulted that all the estimated parameters were not significantly influenced by either manure application or N fertilization except C mineralization rate was constant for resistant carbon pool (ks). The ks value was significantly influenced by manure application. Cumulative annual C mineralization evolved from SOM under field conditions were estimated between 6.21 to 9.31% of total soil organic carbon. The annual carbon mineralization was found to be significantly influenced by different exogenous organic matter application but not with N fertilization. There was a significant difference in annual C mineralization between green manure, cow dung and compost. However, the annual C mineralization was statistically similar between control and green manure treated soil. This result indicates that more stable organic matter was formed in compost treated soil which is less prone to decomposition if present crop management has been changed.</div>

Response of Yield and Agronomic Output of Bangabandhu dhan100 under Varying Sowing Window in Cold Prone Rangpur Region

Effect of Long Term Manuring and Fertilization on Carbon Sequestration in Terrace Soil