GIS Based Model for Agro-Ecological Zoning: A Case Study of Chitwan District, Nepal
4.4 Creation of moisture regimes database.
The moisture regimes database was obtained from the LANDCAP by grouping and classifying the polygons (land on their mapping units) based on their moisture related characteristics.
4.5 Creation of irrigation regimes database
Irrigation regimes database was created based on information collected from published literature (Shukla et.al. 1993, Krishi 1993, WECS 1985), data collected from various local offices; and through extensive travels across the district, irrigation potentials were determined by identifying canal irrigable, pump irrigable and non-irrigable zones.
4.6 Creation of climatic resources database.
The climatic resources database was generated by integrating temperature regimes layer 'CHITTEMP' moisture regimes layer CHITMOIS and irrigation regimes layer CHITIRIP.
4.7 Creation of and resources database.
The land resources database for the district was created by integrating the soil resources layer 'CHITSOIL' and climatic resources layer 'CHITCLIM'
4.8 Agro climatic zoning
The climatic database was derived from the land resources inventory. By combining pump irrigable and canal irrigable mapping units into a single, zone, viz irrigable zone, and classifying all non-agricultural lands as non-irrigable, the agro-climatic zones were delineated.
4.9 Agro edaphic zoning
The soil resources database was derived from the land resources inventory. Two texture classes viz I) medium texture indicating suitability for all field crops and ii) coarse texture indicating suitability for tuber and root crops were identified. Similarly two soil depth classes, viz i) deep - depth more than 50 cm indicating suitability for agricultural use, and ii) shallow - depth less than 50 cm limiting the soil suitability to forestry and grazing (Carson 1992) were considered. Soils with slope less then 300 and those with more than 300 were also differentiated assuming 300 to be the upper limit for arable agriculture (LRMP, 1986b)
4.10 Agro-ecological zoning
Agro-ecological zones database was created by integrating the agro-cilmating layer "AGROCLIM' and agro-edaphic layer 'AGROSOIL'
5.0 Results and Discussion
5.1 Dominant soils
Altogether eight different soil units, viz. eutric cambisols, haplic phaeozems, dystric cambisols, eutric fluvisols, haplic luvicols, eutric nitosols, cambric aeronosols and eutric regosols were identified as dominant soils. The inventory indicates that the first three soul units occupy almost 85% of the area.
5.2 Dominant soil texture
Soils were mainly medium texture in also 34% of the area. The presence of loamy texture indicates a general suitability for all field corps.
5.3 Dominant soil depth
Four different dominant soil depths:" deep, moderately deep, shallow and extremely shallow, were identified. About 49% of the area had deep soils. This indicates that the soil depth is favourable for cultivation.
