Madras Agric. J., 98 (10-12): 356-361, December 2011

Technical Efficiency of Paddy Under Different Irrigation Scenarios in Tamil Nadu K. Govindarajan* and K.R. Karunakaran Directorate of Weed Science Research-Coimbatore Center, Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore - 641 003. Tamil Nadu Rice Research Institute, Tamil Nadu Agricultural University, Aduthurai

Improving the use efficiency of the resources, that are available at the disposal of the farmer is of great concern in enhancing the productivity of paddy. Irrigation is a critical input in paddy cultivation. Under this context, the present study had made an attempt to estimate the farm specific technical efficiency and trace the factors responsible for the technical inefficiency in paddy production under different irrigation systems in Tamil Nadu. The farm specific technical efficiency of paddy farms under different irrigation systems was estimated through Stochastic Frontier Production Function Model. The capital investment pattern had revealed that the expenditure on irrigation structure for lifting groundwater was the highest capital investment made in the paddy farms. The frontier co-efficient had indicated the negative response of nitrogenous and potassic fertilizer in paddy production due to the excessive use of these fertilizers. The Stochastic frontier production function analysis further revealed that the mean technical efficiency (MTE) of paddy production in Tamil Nadu was 73.50 per cent. There lies scope for increasing the productivity further. The conjunctive system of irrigation had the highest MTE as compared to other irrigation systems, since farmers had more flexibility over their irrigation management than surface irrigation system. Hence the canal irrigated farms of the state should be targeted for technological excellence and motivating the farmers in adoption of modern technologies like System of Rice Intensification so as to achieve frontier yields. Key Words: Technical efficiency, Allocative efficiency, Economic efficiency, Stochastic Production, Frontier Function.

Rice is one of the important cereal crops in the world, During 2008-2009, about 22 per cent of world rice production was from India (www.agricoop.nic.in). It has the largest area under rice but it is the second largest producer next to China. India has achieved self sufficiency through the green revolution. As a result, the paddy production had increased manifold from 53.49 million tonnes (mt) during 1961-62 to 99.18mt in 2008-09. Tamil Nadu has contributed 5.23 percent of total paddy production in India during 2008-09. During 2008-09 Tamil Nadu has 29.31 lakh ha of net irrigated area of which 7.65 lakh ha (26.11 per cent) has been served by canal irrigation and 5.40 lakh ha (18.43 per cent) was supported by tank irrigation and 16.25 lakh ha (55.45 per cent) has used ground water for the crop cultivation. The canal irrigation was constituted by the major river basins viz., Cauvery, Vaigai, Thamirabarani, Amaravathi and Bhavani in which mono culture of paddy is largely practiced by the farmers. It was reported that the increasing trend of paddy productivity was stagnant or declined in Cauvery Delta Zone (Govindarajan, et al., 2004). Though, Tamil Nadu was one among the high paddy productivity state in India, it was largely noticed that *Corresponding author email: [email protected]

there exist huge variation in the rice productivity among different paddy production districts (Govindarajan et al., 2004). Tamil Nadu achieved the top position of paddy production which could be attributed to its large area and not due to the efficiency in production. The increase in production was made possible only through improvement in productivity. Productivity can be increased through one or more combination of its determinants namely the technology, the quality and types of resources used and the efficiency with which the resources are used. Among these factors, improving the use efficiency of the resources, which are available at the disposal of the farmer, is of great concern. Irrigation is a critical input in agriculture from the viewpoint of food security in India. The sustainability and adoption in the method of irrigation is greatly influenced by the quantity as well as duration of water availability under different water resource regimes. In this context, the study of technical inefficiency in paddy production under different irrigation systems helps to improve the production efficiency of the respective system. Thus the identification of technical inefficiency would help to formulate policy

357 measures to increase the productivity and production for the respective production system. Under this situation, the present study had made an attempt to estimate the farm specific technical efficiency and trace the factor responsible for the technical inefficiency in paddy production under different irrigation systems of Tamil Nadu. Conceptual framework

The term "resource use efficiency" in agriculture may broadly include the concepts of technical efficiency, allocative efficiency and economic efficiency. An efficient farmer allocates his land, labour, water and other production resources in an optimal manner, so as to maximize his income, at least cost and on a sustainable basis. But, as resources and managerial efficiency of different farms vary widely, the net return per unit of input used also vary significantly from farm to farm. There are two common approaches in the literatures for estimating technical efficiency. One approach is based on non-parametric, nonstochastic linear programming technique (data envelopment analysis). This approach suffers from the criticism that it doesn't consider the error on account of the possible influence of measurement and other noise in the data. The estimation of Stochastic Production Frontier Function made it possible to find out whether the deviation in technical efficiency from the frontier output is due to farm specific factor or due to external random factors. A large number of studies were available on the use of stochastic production frontier for the measurement of technical efficiency in production (Kalirajan, 1990; Battese, 1992; Battese and Corra, 1977; Hazarika and Subramanian, 1999; Goyal et al., 2006). The present study has used the Cobb-Douglas form of the stochastic frontier function approach which is first developed by Aigner et al., (1977) in estimating farm specific technical efficiency of paddy production n the different irrigation system. Model

The SFPF assumes an error term with two additive components-an asymmetric component that accounts for pure random vector (vi) and a oneside component which captures the effects of inefficiency relative to the stochastic frontier (ui). The random factor (v) is independently and identically distributed with N (0,σ 2 v) while the technical inefficiency effect, (u), often assumed to have a half normal distribution |N (0, σu2 )| in the data set. The model is expressed as;

….(1,2)

where, xij is the vector of independent variables for the selected ith farm. The β is unknown parameter to be estimated together with the variance parameters which are expressed as

The parameter γ has a value between zero and one such that the value of zero is associated with the traditional response function, for which the non negative random variable, ui, is absent from the model. If the parameter γ values close to one indicating that the random component of the inefficiency effects makes a significant contribution to the analysis of the production system. The parameter, β σ,σu can be estimated by the weighted C-D frontier form using maximum likelihood estimation method, with the help of the Limdep 7, computer programme. The vector of xi includes;

Hl j

use of total labour hours used for paddy by the ith farm

Mli

use of total machine hours used for paddy by the ith farm

Ni

consumption of nitrogenous fertilizer for paddy by the ith farm in kg/ha

Pi

consumption of phosphotic fertilizer for paddy by the ith farm in kg/ha

Ki

consumption of potassic for the paddy by the ith farm in kg/ha

PPvi

Value of plant protection chemical used for the ith farm (Rs); and

Yi

Dependent variable: yield of ith farm in kg/ ha

The crop specific consumption of major nutrients N, P and K for each farm was calculated using the data from Cost of Cultivation of Principal Crops (CCPC) Scheme. The farm specific technical efficiency of production of each crop was estimated using the equation (2) and the Mean technical efficiency is estimated using following formula x 100

…… (3) …….. (4)

where, MTE is Mean Technical Efficiency, σu one side error term; and Π Pie (22/7) Data Set

The study has used both primary and secondary data sources. The primary data were collected from the data bank of the Scheme on Estimation of Cost of Cultivation of Principal Crops. In CCPC, the sample farms were selected based on the multi-

358 productivity. In order to study the production performance of the crops, the area, production and productivity of paddy during last two decades were analyzed and the results are presented in Table.1 along with their annual compound growth rates. It could be inferred from Table 1 that paddy area had marginally decreased from 2.3 million ha (mha) in triennium ending (TE) 1984-85 to 1.88 mha in 199495 and increased to 2.04 mha in TE 2008-09. In the first period, though the area under paddy had recorded a negative growth rate (-1.48 per cent), the production and the productivity recorded a positive growth of 3.69 and 5.28 per cent respectively. However in the second period (1993-94 to 200506), area, production and yield showed negative

stage random sampling technique and clustering sampling technique at ultimate farm selection. The present study has used the primary data set available in the scheme from 2005 to 2007 comprising three years data from paddy growing sample farmers in Tamil Nadu. The secondary data has been collected from the various issues of Season and Crop Report published by Directorate of Economics and Statistics, Tamil Nadu. Results and Discussion Performance of paddy production

The production pattern of crops reflects the overall performance of the crops under study that could be studied by its trend in area, production and

Table 1. Temporal Variation in Area, Production and Productivity of Paddy in Tamil Nadu Particulars

TE 1984-85 to 1993-94

TE 1994-95 to 2008-09

All Period

Area

Prodn.

Yield

Area

Prodn.

Yield

Area

Prodn.

Yield

Mean

2.10

5.60

2.67

2.04

6.04

2.98

2.05

6.04

2.85

Area

2.30

4.65

2.01

1.88

5.66

2.97

2.04

5.89

2.85

CV (%)

8.35

12.12

17.27

10.60

18.77

10.40

9.87

16.70

14.16

CGR (%)

-1.48

3.69

5.28

-1.70

-2.52

-0.86

-0.76

0.16

0.89

Note : Area in million ha; Production in million tones and Yield in ton/ha Source : Estimated from the various issues of Season and crop report, Directorate of Economics and Statistics, Tamil Nadu

growth rates at -1.70, -2.52 and -0.86 percent respectively. The above analyses for the last two decades have indicated the declining trend in the area (-0.76 per cent). The analysis revealed that the declining trend in both area and productivity, cautioned the planners to formulate optimal crop sets for sustaining the paddy production, besides tracing the level of technical efficiency in the current paddy production system, so as to improve the productivity further under different irrigation systems. Since, majority of the paddy cultivation is under irrigated condition through various sources such as canal, tank, well and tube well system or conjunctive use surface and sub-surface system in Tamil Nadu, the details on the performance of these irrigation sources would help us to know the constraint of irrigation sources on paddy cultivation. Thus, the variation in irrigated area under different sources were estimated for the last two decades viz., 1984-1985 to 1993-1994 and 1994-1995 to 2008-2009 along with their annual compound growth rates and the results are presented in Table 2. The results had revealed that the gross tank irrigated area had declined from 6.51 lakh ha in to 5.26 lakh ha during TE 2008-2009. However, the net well irrigated area had increased from 8.46 lakh ha during TE 1984-85 to 12.01 lakh ha at the end of second period (TE 2008-2009). The net and gross irrigated area for the all source had showed a increasing trend at the end of the second period (TE 2008-09) which might be due to

the successful monsoon during the last two years from 2002. This has resulted in the increase of the irrigated area in agriculture. However, the gross irrigated area has showed an decreasing growth Table 2. Temporal variation in different sources of Net irrigated area in Tamil Nadu (in lakh ha.) Particulars

TE 1984-85

TE 1993-94

TE 2008-09

Canal

8.40

8.36

7.67

Tank

6.51

6.25

5.26

Well

8.46

10.47

12.01

Tube well

1.17

1.76

3.90

Supplementary Wells

0.83

1.10

0.11

NIA

24.74

27.01

28.95

GIA CGR (%)

31.42

33.95

33.18

1984-85 to 1993-94

1994-95 to 2008-09

All Period

Canal

-0.21

-1.09

-0.59

Tank

-1.63

-1.97

-0.71

Well

1.72

-0.17

1.17

Tube well

7.22

6.01

5.48

Supplementary Wells

3.27

-20.70

-9.66

NIA

0.51

-0.21

0.58

GIA

0.00

-0.7

0.1

NIA-Net irrigated area and GIA-Gross irrigated area. Source : Estimated from the various issues of Season and crop report, Directorate of Economics and Statistics, Tamil Nadu

rate of 0.70 per cent and -1.84 per cent per annum second period and 0.01 per cent during the overall period. This analysis has revealed that the declining trend of net irrigated area of canal and tank sources has applied the brakes on the expansion of irrigated paddy area which has forced the researchers to

359 identify the next alternative so as to increase the productivity and the need for a shift in the production technology.

which might be due to the diversification of farming operation for sustaining the farm income.

The foregone analysis from the secondary information confirmed that there exists little scope to further increase the area under paddy. The annual compound growth rate of paddy production and productivity had already turned negative which were coupled with declining trend in the canal and tank sources of gross irrigated areas which are the major sources of irrigation for paddy cultivation.

Out of 1800 paddy farms selected for the study, 649 were under surface irrigation followed by 584 and 567 farms under subsurface and conjunctive irrigation systems respectively. The adoption of modern machineries by the different sources of irrigated paddy farms are presented in Table 4. The results had indicated that in the surface irrigation system, about 67 per cent of farmers used tractors and 21 of the farmers have used power tillers for ploughing and other operation. Besides that, about 44 per cent farmers had used the power thresher for threshing and only 3.85 per cent farmers used combined harvester in paddy harvesting and threshing. Table 4. Adoption of modern Machineries in paddy cultivation under different irrigation system

Studies on the characteristics of paddy farm in three different production environments such as surface, subsurface (both wells and tube wells) and conjunctive irrigation systems for paddy cultivation would be helpful in formulating strategy for improving the technical efficiency and their by enhancing the paddy productivity. Thus, the investment pattern in paddy farms, use of modern machineries like tractor and power tiller for ploughing, power thresher and combined harvester for paddy harvesting and other input use such as human labour, animal labour, use of FYM, N, P, K and agrochemicals, under three different production systems were studied and the results are discussed in the following section. The capital investment pattern by the paddy farms under different irrigation systems have been presented in Table 3. It had revealed that the expenditure on irrigation structure for lifting ground water was the highest capital investment made in the paddy farms which has ranged from Rs 20 to Rs 33 thousands per farm. Among different irrigation systems, sub-surface and conjunctive irrigation Table 3. Capital investments in paddy farm under different irrigation systems in Tamil Nadu

Inventories Implements

(Rs./ farm) Irrigation system Surface Sub Conjunctive State Surface 770 1225 2182 1362 (9.32) (2.10) (4.68) (3.71)

Machineries

1772 (21.44)

7333 (12.54)

13050 (27.99)

7129 (19.43)

Irrigation structures

2916 (35.28)

32935 (56.34)

21206 (45.48)

18470 (50.34)

Livestock

1390 (16.82)

6182 (10.58)

4013 (8.61)

3771 (10.28)

Value of buildings

1417 (17.14)

10780 (18.44)

6177 (13.25)

5955 (16.23)

8265 (100)

58455 (100)

46628 (100)

36687 (100)

Total

Estimated from the sample data

systems had the highest capital investment for construction on irrigation structures, compared to surface irrigation system which might be due to the additional investments on pipes and fittings, pump sets or submergible motor for lift irrigation structures. Besides, that farmer in subsurface irrigation system had invested Rs.7333 and Rs.6182 per farm in other machineries and livestock, respectively,

Adoption of modern machineries

Adoption of Machinery

Surface (649) No.

%

Combined Harvester

25

3.85

Tractors

Sub-surface (584) No.

%

227 38.87

Conjunctive (567) No. 99

%

State (1800) No.

%

17.46 351 19.50

438 67.49 419 71.75

436 76.90 1293 71.83

Power Thresher 288 44.38 117 20.03

214 37.74 619 34.39

Power Tiller

117 20.63 319 17.72

137 21.11

65 11.13

The least adoption of combined harvester was found in the surface irrigation system which may be due to the fact that the availability of the combined harvester, field moisture condition and the availability of human labour at the time of harvest. However, the use of combined harvester was 38.87 and 17.46 per cent for the subsurface and conjunctive irrigation systems, respectively, which might be due to the fact that the farmers had more control over the irrigation systems that enabled them to prepare the field for harvesting through combined harvester. Similarly, the use of tractor for preparatory cultivation was also comparatively higher in subsurface and conjunctive irrigation systems. The higher use of machine power in subsurface and conjunctive irrigation systems was supported with the higher capital investment in the production systems and the farmers' progressiveness in adopting the modern technologies for cultivation. The actual use of resources in paddy cultivation is presented in Table 5. It could be inferred from the table that the family labour employment is more in subsurface and conjunctive irrigation systems where as the casual labour employment is more in surface irrigation system. As discussed elsewhere, the use of machine power was significantly higher in subsurface and conjunctive irrigation systems. In general, paddy cultivation required, 246 hours of machine power, 877 hours of human labour for all operations. The use pattern of organic manure viz, farm yard manure (FYM) was highly varied among the irrigation

360 Table 5. Input use pattern for paddy in different irrigation system in Tamil Nadu* Inputs

Unit

Irrigation system Surface

Seeds Family labour Casual labour Animal power Machine power FYM Nitrogen Phosphorus Potash PP Chemicals

Kgs Hrs Hrs Hrs Hrs Kgs Kgs Kgs Kgs Rs.

State

SubConjunctive surface

163.65 195.87 673.37 34.74 80.38 1877 90.79 53.81 46.06 535.00

151.88 320.14 557.52 67.19 345.08 2524 96.64 52.92 51.97 501.00

173.67 219.12 663.26 33.53 286.33 1623 97.91 52.71 47.83 430.00

165.06 240.05 637.47 42.95 246.07 1935 95.63 52.73 48.67 478.00

tons and 1.8 tons per hectares in the conjunctive and surface irrigation systems farms, respectively. However, the inorganic chemical fertilizer and agrochemical use showed little variation among the irrigation systems and applied up to 70-75 per cent of the blanket recommendation. Stochastic Frontier Production Function for Paddy

The Cobb-Douglas form of Stochastic Frontier Production Function (SFPF) for paddy under different irrigation system was estimated and the results are presented in Table.6 along with 't' statistics. The production elasticity of potassic fertilizer and machine labour were negative for all the irrigation systems. But, the elasticities of phosphatic fertilizer, human systems and is at the very low level of application labour and seeds for all, surface and subsurface than the recommended level (one fifth of the irrigation systems were negative. However, the recommended level of FYM). It could be noted from variables included in the model have not sufficiently table 4, that the farms in the subsurface irrigation explained the variation which is inferred from the system have used 2.5 ton of FYM compared to 1.6 low adjusted R2, the elasticities were significant Table 6. Estimates of Frontier Stochastic production function for different irrigation system in Tamil Nadu Surface

Variables Constant Seed N P K Human labour hrs Machine power Animal power PP value σ2v σ2v Lambda (γ) Sigma (σ) LL ratio Discrepancy parameters (γ) No. of samples

Coeff. 3.4180 -0.0633 0.2056 -0.0122 -0.0091 0.0282 -0.0245 0.0049 0.0055 0.1735 0.0296 2.4251 0.4506 -131.40 0.39 649

Sub-Surface t 7.90 -0.95 6.66 -1.09 -1.77 0.53 -2.28 1.45 2.20

8.35 22.34

Coeff. 4.5445 -0.1197 0.0728 -0.0098 -0.0065 -0.0427 -0.0079 -0.0057 0.0031 0.0829 0.0457 1.3428 0.3579 -72.23 0.23 584

only for N use in surface and subsurface irrigation systems, P use in subsurface and conjunctive irrigation systems. The implicit assumption in our analysis is that there exists Hick's neutral technical change, which means that the intercept in MLE results should be higher than that in computed by OLS, while the slopes should be more or less equal in both OLS and MLE results. The results shown in table 6 clearly support this assumption. The results revealed that the use of seed, potassium and machine labour had negative response to the production in all the irrigation systems, which indicated the over use of these inputs. Similarly, the phosphatic fertilizer was over used in the paddy farms in the surface irrigation system. The machine labour and animal power use were exceeds the optimal level which was inferred from the negative value of the SFPF coefficients. The results also confirmed that increase in application nitrogenous fertilizer would increase the

t 13.02 -2.09 2.55 -1.46 -1.64 -1.19 -0.49 -1.70 1.36

5.91 17.15

Conjunctive Coeff. 3.7559 0.0376 -0.0367 0.0325 -0.0148 0.0317 -0.0142 -0.0051 0.0003 0.0543 0.0306 1.3620 0.2958 40.89 0.19 567

t 10.93 0.75 -3.67 6.67 -4.51 0.86 -1.69 -1.99 0.15

7.58 22.82

State Coeff. 4.3960 -0.0762 0.0260 0.0042 -0.0102 -0.0015 -0.0274 -0.0007 0.0048 0.1236 0.0345 1.7999 0.3933 -250.93 0.30

t 20.37 -2.26 4.28 1.15 -4.49 -0.07 -6.59 -0.38 3.75

13.38 36.23

1800

paddy yield by 2-3 per cent for the Tamil Nadu as whole. The proportion of yield increase would be still higher in the surface irrigated farms to the tune of 20 per cent. Farm Specific Technical Efficiency

The farm specific technical efficiency of each paddy farms under different irrigation systems was estimated and the results are given in table 7 along with their Mean Technical Efficiencies (MTE). The mean technical efficiency was about 74 per cent, which means that the rice productivity could be further increased by 26 per cent, without any additional resources through efficient use of existing inputs and technology. In the state, about 74 per cent of farms were 70-90 per cent efficient category while only 3.45 per cent farms were under the efficiency category of below 50 per cent where ample scope exists to improve upon the resource use pattern for achieving the higher paddy productivity.

361 The farm specific technical efficiency below 70 per cent was more in surface irrigated farms (26.19 per cent) followed by 11.3 and 3.9 per cent in subsurface and conjunctive irrigation systems, respectively. The results confirmed that further productivity increase with the given resource set and technology was possible in the surface irrigated paddy farms than other sources of irrigated system. The mean technical efficiency in paddy farms under subsurface and conjunctive irrigation systems were 82 and 85 per cent, respectively which were comparatively higher than the surface irrigated farms (73.5 per cent). Thus, SFPF analysis indicated that

there is ample scope to further increase in the productivity of the paddy to 15 -16 per cent with the given resource set by efficient use of resources that too more scope in surface irrigation system. However, the current paddy productivity was low in the surface irrigation system compare to other systems which need to improve by moving to technology shift to attain food security for the increasing population. Conclusion and Policy Implication Paddy is the important food grain of country constituting 40 per cent of the total food grain

Table 7. Farm Specific Technical Efficiency in Different Irrigation System in Tamil Nadu Efficiency category (%) < 50 50-70 70-90 >90 Total farms MTE

Surface No. 57 170 391 31 649 73.50

Sub-Surface % 8.78 26.19 60.25 4.78 100 81.68

No. 4 66 492 223 584 85.17

production. In Tamil Nadu, paddy is being cultivated mostly under irrigated condition and irrigated by canal and tank irrigation systems and largely supported by the ground water sources in some water deficit areas. The declining trend noticed in the area and productivity resulted in decline of the state's rice production which has shrinked the food basket and questioning the food security in the state. This warrants improvement in the production efficiency or shift in the technology. Thus, the estimation of technical efficiency in paddy production under different irrigation system helps to improve the production efficiency of the respective system. The study results has indicated that the farm level capital investment in surface, sub-surface and conjunctive irrigation systems were Rs 8265, Rs 58455 and Rs 46628 respectively. The capital investment on irrigation structure had constituted 56.34 per cent of the capital investment in the subsurface irrigation system. The input use pattern under different irrigation systems indicated that the sub-surface and conjunctive irrigation system used comparatively lesser casual labour than the surface irrigation system indicating higher efficiency of hired labour use. The frontier co-efficient had indicated the negative response of nitrogenous and potassic fertilizer in paddy production. The stochastic frontier production function analysis revealed that the mean technical efficiency (MTE) of paddy production in Tamil Nadu was 73.50 per cent. There lies scope for increasing the productivity further. The conjunctive system of irrigation had the more MTE as compared to other irrigation systems, since farmers had more flexibility over their irrigation requirements than surface irrigation system. More than eight per cent

% 0.68 11.30 84.25 3.74 100 73.50

Conjunctive No. 1 22 459 87 564

% 0.18 3.90 80.50 15.43 100

State No. 62 258 1337 140 1797

% 3.45 14.36 74.40 7.79 100

of the farmers were observed under less than 50 per cent efficiency category in surface irrigation systems. This has revealed that the efficiency of these farms could be improved by better management practices. On the other hand, in the conjunctive irrigation system, 15.43 per cent of the farmers are in the category of more than 90 per cent efficiency level, which had revealed that these farmers could further their productivity only by technological shift. References Aigner, D.J., Lovell, C.A. and Schmidt, P. 1997. Formulation and Estimation of Stochastic Frontier Production Function Models, J. Economet., 6 : 21-37 Battese, G.E., 1992. Frontier Production Function and Technical Efficiency: A Survey of Empirical application in Agricultural Economics, Agri. Econ., 7: 185-208. Battese, G.E. and Corra G.S. 1977. Estimation of Production Frontier Model: with application to Pastoral Zone of Eastern Australia, Australian J. Agri. Econ., 21:169179. Govindarajan, K., Karunakaran. K.R., Shanmugam T.R. and Swaminathan, L.P. 2004. Rice productivity variation in Cauvery delta region of Tamil Nadu: A case of cross section and time series analysis, Asian-African J. Econ. Economet., 4: 85-96. Goyal, S.K., Suhag, K.S. and Pandey, U.K. 2006. An Estimation of Technical Efficiency of Paddy Farmers in Haryana State of India, Indian J. Agri. Econ., 61: 108-122. Hazarika and Subramanian S.R. 1999. Estimation of Technical Efficiency in the Stochastic Production Frontier Function Model -an Application to the Tea Industry in Assam, Indian J. Agri. Econ., 54: 201211. Kalirajan. K.P., 1990. On Measuring Economic Efficiency, J. Economet., 5: 75-85.

Received: March 3, 2011; Accepted: November 15, 2011