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Trend Analysis of Climate Variables (air Temperature and Rainfall) and Its Influences on Rice Yield: a Case Study from Mymensingh District of Bangladesh

S K Kuri*
Department of Agricultural Extension Education, Bangladesh Agricultural University, Mymensingh, Bangladesh

M J Hossain
Department of Agricultural Statistics, Bangladesh Agricultural University, Mymensingh, Bangladesh

M Saha
Department of Agricultural Chemistry, Sylhet Agricultural University, Sylhet-3100, Bangladesh

Abstract/ Executive Summary:

The objectives of the study was to find out the changing trend of major climatic variable (temperature and rainfall) over the period and forecast for succeeding five years (up to 2017) as well as to explore its influences on rice yield in Mymensingh district of Bangladesh. The study was carried out on gathering data from Weather Yard, Bangladesh Agricultural University (BAU) and 8 annual issues of Bangladesh Bureau of Statistics (BBS) from 1975 to 2012. Different statistical methods were employed to attain the results by gathered data. Firstly, from the descriptive statistics it was found that climate variables and rice yield is changing over period and from trend analysis it was found that trend of average annual maximum temperature and average annual rainfall are decreasing. Whereas, average minimum temperature and average mean temperature trend are increasing overtime. From the forecasted value its rate of change was also calculated. It was found from the linear regression analysis that average annual maximum temperature and average annual rainfall had significant negative influences on rice yield while, average annual mean temperature had significant positive influence on rice yield of the study area. The changing trend of climatic variables was highly fluctuating and not favorable for better crop production as well as shows some indication of desertification for the study area.

Keywords: Trend analysis, Climate variables, Rice, Yield

Location: Mymensingh district of Bangladesh

Start Date: 00-00-1975

End Date: 00-00-2012

Program Area: Socio-economic and Policy

Non-commodity: Temperature, Rainfall

Objectives:

To find out the changing trend of air temperature and rainfall over the period and forecast for succeeding five years (up to 2017).
To explore the influences of air temperature and rainfall on rice yield.

Methodology:

Three statistical methods are employed to examine the variability of climate and its influence of rice yield. First, descriptive statistics such as mean, standard deviation (SD), range and coefficient of variation (CV) are used. CV is calculated by using the following formula: CV= (SD ÷ mean) × 100. Second, a simple trend model is used to examine the time trend of variability. In measuring growth rate of a variable, a simple linear trend model is usually employed which takes the following form (Gujrati, 2004) Here, yt = Climate variable which is regressed on time t βo = Constant β1 = Slope coefficient t = Trend variable (time) ut = Error term As well as for forecasting purpose, the above fitted trend equation is used and forecast accuracy was measured in terms of different criteria such as mean absolute deviation (MAD), mean absolute percent error (MAPE) and mean square deviation (MSD). Third, a technique of analysis, linear regression, is used to observe the influence of climate variables on rice yield. The linear regression model has the following form: y = β o + β1 x1 + β2 x2+ β3 x3+ β4 x4+ e

Where, y = y ˆ + e = Influence of climate variables on rice yield β o = Intercept x1= Average annual maximum temperature x2= Average annual minimum temperature x3= Average annual mean temperature X4= Average annual rainfall e = Error term The researchers have collected data from Weather Yard, BAU, Mymensingh to find out changing trend of major climate variables of the study area. Different issues of BBS were used to gather the data on rice yield. Using this approach and applying it to Mymensingh time series data for the 1975 to 2012, due to greater availability of data.

Source of Information: J. Sylhet Agril. Univ. 1(1):15-21, 2014 ISSN: 2308-1597

Article Link (Online Journal):

Funding Source:

1.

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Climatic variables and rice yield of Mymensingh district are unstable and changing significantly. The trend of maximum air temperature and average annual rainfall were decreasing whereas, trend of minimum annual temperature and mean annual temperature were increasing. The calculated rate of change of the forecasted values supported the results. The influence of major climatic variables like annual maximum temperature, annual mean temperature and annual rainfall influences on the rice yield had a significant effect. From the above results it was found that average annual maximum temperature and average annual rainfall negatively influenced rice yield significantly whereas average mean temperature positively influences rice yield. So, these climatic variables significantly affected rice yield and yield might be reduced due to extreme fluctuations of climate variables in coming future. So, necessary measures should be formulated to mitigate this phenomenon and adapt new strategies to minimize the adverse impact of climate change on rice yield.

Knowledge Management: Journal