A Trend Analysis on Area, Production and Productivity of Kharif/winter Rice in Assam

Rice is the most dominant food grain of India and it feeds nearly 60 per cent of population. It is a means of livelihood for millions of people living mostly in rural areas providing food security. In India rice is grown in 72.06 million ha, the production level is 149.56 million tones and the productivity is about 2076 kg/ha (Agricultural Statistics at a Glance- 2021). It is the world’s second-largest producer after China. Around 90% of the world’s total rice production has been recorded from Asian nations (Ashkra et al., 2023). A consistent increase in the yield of rice was noted for many years. It is mostly grown in Eastern and Southern parts of India as it is a staple food in these areas. It is fundamentally a kharif crop and is mainly grown in rainfed areas that receive heavy annual rainfall. Rice is also grown through irrigation in those areas that receive comparatively less rainfall. In fact, food security of our nation depends upon the production of rice through irrigated system (Nagarajan et al., 2024). West Bengal, Uttar Pradesh and Andhra Pradesh are the leading rice producing states in India and Assam is the leading producer of rice in North Eastern Region. North Eastern Region accounts for 10.48% of country’s total area and 6.46%of the total rice production.             

(Bujarbaruah, 2004). Amongst the North Eastern states, Assam contributes 5.24 percent towards production and 5.26 percent towards productivity (Agricultural Statistics at a glance- 2021). Rice of Assam provides both food and nutritional security to 3 crore population residing in the state. It is grown in sloppy hills to deep water areas all over Assam. 40 % of area in Assam is fragile in nature making farming in these areas organic.
       
Almost all parts of India are suitable for raising rice during the Kharif season provided that water is available. Kharif/Winter rice crop is raised preferably in low-lying areas that remain flooded mainly during the rainy season. The sowing time is June-July and it is harvested in November-December. It is known as winter rice as per the harvesting time.In Assam it is also known as ‘Sali’ (Package of Practices for kharif crops of Assam, 2023).  Among all the different types of rice, winter or Sali rice is the main rice in respect of area and production (Mech, 2017). About 84% of the country’s rice crop is grown in this season and generally medium to long duration varieties are grown. In Assam rice is mainly grown under rainfed condition in Kharif/winter season in the basins of Brahmnaputra river that receives very heavy rainfall.
       
To fulfill the growing demand of rice with increase in population a rapid increase in production is needed. Cost escalation is the most important factor, which makes rice cultivation a relatively less remunerative enterprise and it suggest that mechanization should be followed wherever possible and which will reduce the cost of human labour and cost of production (Mohandas and Thomas, 1997). Increasing land holding and farm size has substantial benefits for efficiency improvement in cultivation of rice and regional factors were also found to be important in influencing technical efficiency (Linh, 1994).The scope to increase the area under paddy is limited, hence more emphasis should be given to increase the production so that increase in productivity can be achieved
       
Keeping in view these factors the objective of the study was to analyse the scenario of Kharif/Winter rice in Assam and to analyse the trend in area, production and productivity as well. In addition to this the study will examine the relative contribution of area and productivity and their interaction effect of production of Kharif/winter rice in Assam. The study will be very useful for understanding the variations at state level over a period of time. Further, this study may be very useful for identifying the different causes for the increase/decrease in area, production and productivity of rice for recommending some suggestions towards decision making and for policy recommendations.

Assam is located in northeastern India, south of the eastern Himalayas. Geographically the state is extending from 22^o19' to 28^o16' North Latitude and 89^o42' to 96^o30' East Longitude between the foot hills of the Eastern Himalayas and the Patkai and Naga Hill Ranges. In Assam rice crop is grown in the basins of Brahmnaputra river. This region receives very heavy rainfall and rice is grown under rainfed condition. Rice crop needs a hot and humid climate. It is best suited to regions which have high humidity, prolonged sunshine and an assured supply of water. The average temperature required throughout the life period of the crop ranges from 21 to 37^oC. 
       
The study was conducted by using secondary data. The secondary data were obtained from various publications of Directorate of Economics and Statistics, Government of Assam (Anonymous, 2014; Anonymous, 2018).The time series data on area, production and productivity of kharif/winter rice were collected for a period of 50 years from 1970-71 to 2019-20. The trends in area, production and productivity were examined for the overall period as well as analysis for two periods, Period-I (1970-71 to1994-95) and Period-II (1994-95 to 2019-20) were done and the compound annual growth rates (CAGR) of area, production and productivity were estimated. For estimating the CAGR we have considered exponential functional form to be fitted to the collected data set for trend analysis of area, production and productivity of kharif/winter rice in Assam.

Exponential function:

Where,

Y = The area/production/productivity.
X = Time variable in years.
a = Intercept.
b = Slope coefficient.
       
The compound annual growth rate (CAGR) is estimated using the following exponential function as explained below:

 
Taking the logarithm on both the sides it takes the linear form:

  
which can be written as:

 
Where,

b₁ = Regression coefficient of the linear regression equation  (i).

The compound annual growth rate (CAGR) is calculated as:

 
Instability analysis in the area, production and productivity of kharif/winter rice in Assam were done by using Cuddy-Della Valle index of instability. John Cuddy and Della Valle developed this index for measuring the instability in time series data (Cuddy and Della Valle, 1978). Although Coefficient of Variation (C.V) is the simplest measure of instability, there are some limitations in its use in time series data. It over-estimates the level of instability in time-series data which exhibits any trend. Cuddy-Della Valle index is considered as a better measure to evaluate instability in time series data. A low value of this index indicates low instability and vice-versa. The Cuddy-Della Valle index is given by

 
The range of Cuddy - Della Valle Instability Index (Sihmar, 2014) are as stated below:
 
Low instability = 0 < CDVI< 15
 
Medium instability = 15<CDVI<30
 
High instability = CDVI>30
 
 The coefficient of variation (CV) is obtained by dividing standard deviation by the mean and expressed in percentage as:

 

 
In this study we have observed that year wise more area has been allotted for kharif/winter rice for the period starting from 1970-71 to 2019-20. It has been increased from 1404.68 thousand hectares in 1970-71 to 1863.90 thousand hectares in 2019-20. Likewise production also increased from 1525.84 thousand tones to 3960.55 thousand tones and also productivity from 1103kg/ha to 2157 kg/ha. An attempt was also made to study the relative contribution of area, productivity and their interaction in increased production of kharif/winter rice in the state. The relative contribution of area, productivity and their interaction in increased production of kharif/winter rice was estimated with the help of the following measures (Sharma, 2015; Angeles and Sundar, 2012; Dhakre and Bhattacharya, 2013; Agarwal  et al. 2016; Sood et al., 2020).
 
∆P = Y₀∆A + A₀∆Y + ∆A∆Y
 
Where,

∆A = A_n - A₀
 
∆Y = Y_n - Y₀
 
∆P = P_n - P₀
 
A₀, P₀  and  Y₀ = Area, production and productivity in the  base year.  
                            
A_n, P_n and Y_n = Corresponding area, production and productivity   in the n^th  year.
       
The first term, Y₀∆A, the second term A₀∆Y and the third term ∆A∆Y in the above equation (ii) represents area effect, the productivity effect and the interaction effect respectively. The total change in production can thus be decomposed into three effects viz. productivity effect, area effect and the interaction effect due to the changes in productivity and area.

From the graph (Fig 1) of trend analysis of area for overall period (19710-71 to 2019-20), it was observed that there was a increasing trend in area in case of kharif/winter rice showing lowest value of 1405 thousand ha in 1970-71 and highest of 1889 thousand hac in 2014-15. There was variation in production during the study period. The trend of production was increasing having the lowest production of 1526 thousand tones in 1970-71 and highest production of 4083 thousand tones was observed in 2017-18. The increasing trend in production may be due to good climatic conditions and availability of inputs including good seeds, fertilizers and irrigation facility etc. The productivity for the said period follows the similar trend. Likewise for period I (19710-71 to 1994-95) and Period II (1995-96 to 2019-20) similar kind of trend in area, production and productivity were observed (Fig 2 and Fig 3).






       
This study considered exponential functional form and the coefficients of determination (R²) was computed for this functional form and are presented in the Table 1.


       
 It was observed from the Table 1 that the R² value of exponential function of area, production and productivity of kharif/winter rice in Assam were high during the entire period (1970-71 to 2019-20) as well as in both the periods Period-I (1970-71 to 1994-95) and Period-II (1994-95 to 2019-20). The lowest value of R² was observed in case of area under Period-II.
       
The values of b1 in the fitted exponential trend for area, production and productivity of kharif/winter rice in Assam were also found positive for the overall period and the periods taken individually as Period I and Period II (Table 1). It revealed a positive growth in terms of area, production and productivity which implies that along with self sufficiency the farmers are getting benefit by selling their produce. That may be because of growing some new recommended varieties, use of fertilizers, pesticides etc and adoption of new technologies and good marketability. Similar kind of findings was observed in case of area, production and productivity of rice in Assam for a period from 1972 to 2014 (Mech, 2017). From another study it was observed that over the period from 1980-81 to 2014-15, there was positive growth rate in area, production and productivity of rice in India and across states position of Assam in growth rate was 5^th in area and production and 6^th in productivity with positive growth rates (Laitonjam et al., 2018).
       
With the help of this fitted exponential trend the Compound Annual Growth Rates (CAGR) were calculated for area, production and productivity of kharif/winter rice for the overall period (1970-71 to 2019-20) and period I (1971-72 to 1994-95) and Period II (1994-95 to 2019-20) respectively as given in Table 2.


       
Table 2 depicts the increase CAGR in case of area of kharif/winter rice in Assam for the overall period (1970-71 to 2019-20) with a value of 1% and for period I and Period II also the CAGR values were higher i.e 2.09% and 1.16% respectively. Likewise area, the production and productivity of kharif/winter rice was also shown an upward trend as a whole and for both the periods separately with highest in production of 5.68% in case of period II.
       
The instability indices for area, production and productivity were low according to CDVI for overall period as shown in Table 2. For period I and period II also lower value of CDVI were noticed. As a whole only in case of production, instability indices were highest. This indicates that growing of kharif/winter rice is less risky in Assam. This is an indicative of the fact that in case of kharif/winter rice in Assam there is positive growth and less instability. (Dhakre and Sharma, 2009)
       
Another way the increase in production of rice has been noticed from 1525.84 thousand tones to 3960.55 thousand tones over the entire period of study. The relative contribution of area and productivity on this production of Kharif/winter rice from 1970-71 to 2019-20 were obtained as given below:
 
 ∆P = Y₀∆A + A₀∆Y + ∆A∆Y                                                      
 
= 1.103×459.21+1404.68×1.054+459.21×1.054
 
= 506.51+480.533+484.007
 
= 2471.058 thousand tones

Here, the area effect and productivity effect is more than that of interaction effect. The productivity effect is found greater than area effect on production of kharif/winter ice in the state during 50 years period.
       
Again, we have analysed the area effect, productivity effect and interaction effect for period I (1970-71 to 1994-95) and period II (1994-95 to 2019-20). For period I (1970-71 to 1994-95) we have observed the equations as mentioned below.
 
∆P = Y₀∆A + A₀∆Y + ∆A∆Y
 
=1.103×355.16+1404.68×0.410+355.16´0.410
 
=391.7415+575.919+145.616

=1113.2765 thousand tones
 
For period II (1995-96 to 2019-20) the equations are
 
∆P = Y₀∆A + A₀∆Y + ∆A∆Y
 
=1.471×127.62+1736.28´0.686+127.62×0.686
 
=187.729+1191.089+87.54
 
=1466.365 thousand tones
 
For both the periods, period I and Period II, the area effect and productivity effect were  higher than that of interaction effect. The productivity effect was found greater than area effect on production of kharif/winter rice in the state from the study of both periods.

The above discussion has revealed that the growth rate for area, production and productivity of kharif/winter rice is positive in our state for the last 50 years (1970-71 to 2019-20). The Compound Annual Growth Rate (CAGR) for production is highest with a value of 4.5% and CAGR for area and productivity is 1% and 3.5% respectively. The highest growth rate was observed in case of production for both the periods Period-I and Period-II. In case of instability studies, only production instability indices were highest indicating less risk involvement in growing of kharif/winter rice in Assam. The area effect and productivity effect was having higher contribution in increased production of kharif/winter rice in the state. Amongst area and productivity effect, the productivity effect has more contribution towards the growth. Also, productivity effect has been found higher for both the periods. The analysis overall indicates that the production is increasing positively and that may be because of farmers adaption of new developed varieties as well as adoption of new scientific technologies, fertilizers, pesticides etc. So, as kharif/winter rice is very important in terms of food and employment generation in our state Government can take the issue in concern and can formulate various policies appropriate to make our state self sufficient.

All authors declared that there is no conflict of interest.