Deviation Between Net Sown Area and Irrigated Area in the Nagar Kulik Interfluve, Uttar Dinajpur, West Bengal: An Assessment

The Net Sown Area (NSA) represents the total cultivated area during the reference year without considering the number of times it has been cultivated in a year (Agricultural Census Division). Area sown more than once in the same year is counted only once. Irrigation is a basic facility for the crop production. Normally there is a deviation between Net Sown Area and Irrigated area that means any area having higher net sown area may be deficit by the irrigation facility. The regional disparity in distribution of net sown area as well as the irrigation facility is a common phenomenon though the relation normally positively proportional. The magnitude of relation varies over the time and space. In the study area the disparity has been found both in the NSA and irrigation facility among the 126 villages. Quantitative analysis has been applied to analyse the disparity in the two variables separately and jointly too. Firstly, univariate analysis has been done to analyse the individual deviation and then to understand the joint effect of the considered variable, bivariate analysis has been conducted. Fourth quadrant plotting of Z-score of NSA and Irrigated Area may be helpful to detect the villages which are lagging behind by the distribution of NSA or by irrigation facility. Quadrant analysis is also beneficial to detect the regional disparity raised by the considered two variables which in term adjuvant to draw planning proposal at village level. To reduce the regional disparities proper planning proposals are required. Identification of villages lagged behind by getting irrigation facility are required first to be facilitated by irrigation facility. Next to find out the villages having sufficient net sown area but the potentiality to expand the net sown area is required to identify. The present methodology may help to find out both types of villages which are needed attention for irrigation and net sown area to reduce the small scale i.e. village level regional disparity. The Present study is confined on Nagar-Kulik Interfluve of Uttar Dinajpur District. Therefore, this paper has taken as an attempt to identify the problems of the NSA of the Interfluve and also to give some suggestions. Current Agriculture Research Journal www.agriculturejournal.org ISSN: 2347-4688, Vol. 8, No.(2) 2020, pg. 77-88 CONTACT Biswajit Das biswa.geo.das@gmail.com Dept. of Geography, Raiganj University, West Bengal, India. © 2020 The Author(s). Published by Enviro Research Publishers. This is an Open Access article licensed under a Creative Commons license: Attribution 4.0 International (CC-BY). Doi: http://dx.doi.org/10.12944/CARJ.8.2.02 Article History Received: 19 April 2020 Accepted: 07 July 2020


Introduction
People of Uttar Dinajpur are primarily dependent on agriculture as the land is very much fertile. 3 The Nager-Kulik interfluve is an important agriculture productive land of the Raiganj C.D Block as well as Utter Dinajpur district. Besides the kharif crops, rabi crops like winter rice, maize, wheat, mustered are cultivated in most of the villages. According to the census 2011 the interfluve having net sown area about 79% (24733.23 ha.) out of which 42% area is getting the irrigation facility. A good number of main workers about 75.22% engage in agricultural practices as cultivator and agricultural laborer as 31% and 43%, respectively. Therefore, it indicates that the dependency on the net sown area is quite high in the interfluve. The interfluve experiences humid tropical climate with monsoon rainfall (temp. in June 35°C, and in December 7°C; 140 cm/year). Kharif crops are largely dependent on the vagaries of monsoon and rabi crops on irrigation water. There is a significant unequal distribution of irrigation facility is found at village level. In the Interfluve, the irrigation planning is required to reduce the disparity. Therefore, it is the first and important work to find out the villages which are lagging behind by irrigation facility and required irrigation water for the rabi crops mainly. Normally there is a deviation between Net Sown Area and Irrigated area that means any area having higher net sown area maybe deficit by the irrigation facility. To identify the villages for planning of net sown area and irrigation facility z score analysis has been taken into consideration.

Study Area
The area selected for the present study is the lower part of the Nagar-Kulik interfluve (comes under country of India) which extending from 25°32′9.84′′N to 25°50′9.84′′N latitudes and 88°1′27.1′′E to 88°14′7.74′′E longitudes cover an area of 315.671 sq. km. (Raiganj P.S -313.4636 sq. km and Itahar P.S-2.2074 sq. km) of the Uttar Dinajpur district in the state of West Bengal, India ( Figure 1). The interfluve comprises 137 villages of the Uttar Dinajpur district. The interfluve is bounded by the rivers of Nagar in the West and Kulik in the east and south. The length of the river Nagar and Kulik is 165 km and 131 km respectively. The political boundary between India and Bangladesh serves the northern limit of the study area. The maximum north-south extent is about 31 km and the maximum east-west width is about 18 km. The confluence of the Nagar and Kulik rivers indicates the southern limit of the study area, which is situated at Gorahar mouza in Itahar P.S. of the study area. 7 The regional topography is generally flat with a gentle slope in south-west direction. The elevation of the study area ranges from almost 43 m. to 29 m. from mean sea level. The study area is characterized by inactive and active flood plain, piedmont or fan, back swamp, marsh land, oxbow lakes, paleochannels etc. Numerous large water bodies that are remnants of back swamps or abandoned streams locally known as 'Bills. ' 4 Geologically the region is filled up by the fan deposits and riverine sediments during the Holocene and Pleistocene periods. The study area comprises with alternating sand, silt and clay and also observed predominantly course to fine sand alternating with silty sand. The study area is the part of Shaugaon, Malda and Baikunthapur formation. Besides these along the river channel present day deposit is common. 4 Soil of the study area is very fertile and rich with older alluvial disposition. The older alluvium is estimated to be Pleistocene age. Alternating sand, silt and clay are found in soil horizon. Confluence of Nagar and Kulik e.g. the southeast edge of the study area active alluvium deposition and active land building process are currently underway. Basically, black prairie soil, entisol and inceptisol types of soil are found in the study area. 4

Objectives
• to find out the changes in the net sown area • to find out the problems of net sown area • to find out the relation between net sown area and irrigated area • to give planning proposals at village level

Sources of Information
Both primary and secondary types of data are used for this work. Data are collected from P.S. Maps, Toposheet (78 C/2, G45Q2, NG 45-11), Census Reports, District Statistical Hand Book and District Gazetteer, Landsat Satellite Image 2019. Soil related information is collected from various reports and books related from different offices.

Methodology
The main objective of this work is to find out the relation between cultivated area and irrigated area by applying Z-score for village level landuse planning. 9 After selecting the objectives, the agricultural problems of the study area have been identified. Secondly, the data have been collected from Census Handbooks (1991 & 2011), Police Station Map, Topographical sheets and Landsat satellite image 2019 etc. to find out the land use change pattern and to prepare base map. Thirdly, the data has been computed and compiled and prepared thematic maps. Finally, data and present scenario have been analysed for village level planning.

Review of Literature
A good deal of works has been done on changes of cultivated area and irrigation area. 2.5.6.8.9.10.11 Though, a considerable work has been done on landuse change and net sown area or cultivated area change but at village level no such work is done still on the relation between cultivated area and irrigated area.
In the previous works numerous techniques are used to calculate the changes. Application of Z-score is an attempt to understand the relation between cultivated area and irrigated area to assess the agricultural landuse in the Nagar-Kulik interfluve.

Result Analysis
To explore the village-wise parity and disparity between the distributions of net sown area and irrigated area, standard deviation (S.D.) and Z-score have been calculated. 8,9,12  The score value must be positive (+) or negative (-) and greater than 1 or less than one. Less than one value indicates that the area is deviated less than standard deviation and vice-versa.
Positive value indicates that the area has net sown area or irrigation more than "Mean".  (Figure 4). Village wise variation of irrigated area also has been found in the Interfluve.  Table 3).

Changes in Net Sown Area
The irrigation map reveals that there is a notable positive change in irrigation facility. At present 41.73% cultivated land gets irrigation water, whereas it was only 29.88% in 1991. It has improved steadily, which is one of the most important elements of agriculture and future landuse planning. Some important observations are mentioned as follows: • The whole Interfluve shows an increase of irrigation (Table 3). • In 1991 there were only 2.91% of villages get more than 50% irrigation facility (4 mouzas) but at present 23.52% of villages (32 mouzas) has got irrigation water more than 50%. • In 2011, 77.94% of the village is getting irrigation water for less than 50% of cultivated land whereas it was 97.08% in 1991. In 1991, 2.18% of the village was under irrigation water for 50 to 80% cultivated land but has increased to 11.76% in 2011. Only 1 (0.72%) villages get water for more than 80% cultivated land in 1991 whereas it is 16 villages (11.76%) in 2011. • There are 6 villages in 2011 are getting 100% irrigation water for the total cultivated land.

Relation Between Net Sown Area and Irrigated Area
To explore the village-wise parity and disparity between the distributions of net sown area and irrigated area, standard deviation (S.D.) and Z-score have been calculated. Some important observations have come out which are as follows: • S.D. is relatively higher for the net sown area (SD-142.38 ha.) than the irrigated area (SD-71.42 ha.) which means greater variation exists in the available net sown area among the villages than irrigated area. There is huge gap between the mean (M) of net sown area (181.86 ha.) and irrigated area (76.50 ha.) on an average 105.36 ha. Planning is required to reduce the gap. When the whole net area will get irrigation facility then it will become zero. • Positive score indicates that the villages have net area or irrigated area more than mean distribution. Therefore, positive value has been treated here as a good symbol for the village than negative value. Because negative value indicates that the respective villages have lower net area or irrigated area than the mean. • The score with a lower positive value (less than +0.50) indicates more stable condition than the score with lower negative value (less than -0.50). • When the score is positive and more than 1, it reveals that the villages are in better condition than the other villages of the Interfluve. • Negative scores more away from zero are representing more poor condition at regional aspect for both net area and irrigated area.