Crop-cut is a widely used and well accepted procedure for estimating rice yield. This yield is then multiplied by the area planted under rice cultivation to determine rice production of the country. In Bangladesh, crop-cut is used to estimate transplanted rice yield. Department of Agricultural Extension (DAE) and Bangladesh Bureau of Statistics (BBS) as the public agencies provide estimate on area and production of rice but they use different methods of crop-cut. The estimates of these two agencies on area and production of rice are different posing a question to the users on the reliability of the estimates. An attempt has been made with the objective to formulate a protocol that provides reliable and unique estimates on rice area and production. It is suggested to make at least three cuts in each plot to minimize the chance of over or under estimation of the whole plot yield and the radius of the circle should be 178.5cm so that the cut area becomes 10 m 2 in order to easy conversion of the crop-cut yield to t ha -1 .

Abstract:2

Impact of climate change on crop yield threatens food security which is detrimental to agricultural sector. Cachar district of Assam is a climate susceptible district due to its unique geographical location and hydrological regime in north-eastern India. So, the present study was carried out to assess impact of climate change on crop yield for sustainability of agriculture. Climatic data viz., rainfall, maximum-minimum temperature and sunshine hours were collected from an observatory of Tea Research Association, Silcoorie, Cachar district for 2007-2012. Statistical and correlation analysis was employed to evaluate potential climate change impact on productivity of twenty three major crops of the study site. The correlation coefficient (r, Pearson's Product Moment) between any climatic parameter and crop yield implied that climate has strong linear correlation with yield of crops resulting in twenty-two strong correlations. Among the climatic parameters rainfall was found to have most significant impact on yield. Noteworthy reduction was observed in yield of Autumn .89%, respectively. The study revealed that climate change has significant impact on crop yield which could be alleviated by adopting rainwater harvesting technology at the top and foot hills of the hilly areas.