The Study on Development and Management of Land and Water Resources for Sustainable Agriculture in Mizoram in the Republic of India Final Report Chapter 4 Agriculture and Rural Setting in Mizoram 4.1 Natural and Social Conditions 4.1.1 Agro-ecology India is divided into 24 agro-climatic zones using Thornthwaite indices. The Planning Commission of GOI divided the country into 15 broad agro-climatic zones based on physiography and climate during the appraisal of the 7th Five-year Plan (1985-1990). Emphasis was given on the development of resources and their optimum utilisation in a suitable manner within the framework of resources constraints and potentials of each region. Mizoram is classified as "Eastern Himalayan Region" together with six other northeastern states, characterised by high rainfall, high forest cover, heavy soil erosion and floods. Mizoram State is further divided into three sub-agro-climatic zones, namely: Humid Mild Tropical Hill Zone situated in the western side of the state; Humid Subtropical Hill Zone in the central part of the state; and Humid Temperate Subalpine Zone in the eastern side. Table 4.1.1 gives the geographic features and characteristics of the respective agro-climatic zones and Figure 4.1.1 shows the demarcation of the three agro-climatic zones. Table 4.1.1 Geographic and Characteristic Features of Agro-climatic Zones in Mizoram Annual Mean Altitude Agro-climatic Average Temperature Major Farming Range Administrative District Zone Rainfall (Max~Min) System (AMSL, m) (mm/year) (°C) Humid Mild 200 ~ 800 2,000 ~ 3,000 30 ~ 12 - Kolasib (North) Irrigated paddy and - Mamit (West) various horticulture Tropical Hill - Lunglei (West) crops taking Zone - Laungtlai (West and Centre) advantage of - Saiha (West) moderate slope and water Humid 1,000 ~ 1,500 2,500 ~ 3,000 30 ~ 12 - Kolasib (South) Mixed cropping of - Mamit (East) upland rice with Subtropical Hill - Aizawl (except Southeast) vegetables Zone - Serchip (West and Centre) predominantly in - Lunglei (Center) jhum culture for - Lawngtlai (East) self-sufficiency - Saiha (Centre) Humid 1,500 ~ 2,000 ~ 3,000 11 ~ 20 - Aizawl (Southeast) Self-sufficient - Champai agriculture relying Temperate - Serchip (East) on jhum, cropping Sub-alpine - Lunglei (East edge) upland rice and Zone - Lawngtlai (East edge) horticulture crops on - Saiha (East) steep slope Source: Agriculture Department (CH), JICA Study Team 4.1.2 Topography The state's topography is, by and large, mountainous with steep slopes forming deep gorges culminating into several streams and rivers. Almost all the hill ranges traverse in the north-south direction. The eastern part of Mizoram is at a higher elevation compared with the western part. The highest peak is 2,165 m above mean sea level (AMSL) at the top of Blue Mountain, called Phawngpul, and the average height of hill ranges is about 920 m AMSL. There are 15 major rivers in the state, of which seven rivers, namely: Tulvawi, Tuvai, Tuirini, Tlawng, Tut and Teirei, flow northward and ultimately confluence with the Barak River in Assam Valley. The five other rivers, namely: Mat, Tuichang, Khawchhaktuipui, Tiau and Chhimtuipui (Kolodyne) flow southwards. The remaining three rivers, namely: Tuichawng, De and Khawthlangtuipui, flow to the west. In the south of Mizoram, the Kamaphull River flows in the northward direction and then enters Bangladesh. The Kolodyne River in southern Mizoram flows southwards and enters Myanmar. Both the Kolodyne and Krnaphuli rivers are large and navigable to a great extent, leading to the ports of Akyab in Myanmar and Chittagong in Bangladesh, respectively. 4-1 The Study on Development and Management of Land and Water Resources for Sustainable Agriculture in Mizoram in the Republic of India Final Report Both Table 4.1.2 and Table 4.1.3 below show the numerical characteristics of Mizoram's topography. The first indicates the slope range-wise area distribution of the respective districts and the whole of Mizoram, and the second shows the altitude range-wise area distribution. Interpreting the figures in the above two tables, the general features of Mizoram's topography are briefly explained below: The average land slope of Mizoram is estimated to be about 35% or 20°, and the majority of its land (80%) are on steep slopes ranging between 15% and 65% or between 10° and 30°; The higher altitude with steep slope topography is prevailing in the central to eastern parts along the border of Myanmar, covering the four districts of Aizawl, Champhai, Serchhip and Saiha, while four other districts have rather gentle topographies; and Mechanised farming would not be possible on more than half of the land where the Source: Source: Agriculture Department (CH), JICA Study Team slope is steeper than 15°. Figure 4.1.1 Agroclimatic Zones of Mizoram Table 4.1.2 Slope Range-wise Area Distribution Mizoram Slope-wise Slope Range Districts' Slope Range-wise Area Distribution (%) Area Distribution in % in degree Mamit Kolasib Aizawl Champhai Serchhip Lunglei Lawngtlai Saiha Km2 % Accum. % Less 15% Less 10° 17% 17% 7% 7% 9% 12% 16% 6% 2,412 11% 11% 15% -40% 10°- 20° 47% 51% 40% 41% 42% 44% 46% 36% 9,154 43% 55% 40% -65% 20°- 30° 26% 25% 38% 37% 36% 32% 28% 40% 6,899 33% 88% 65%-90% 30°- 40° 8% 6% 13% 11% 11% 9% 8% 14% 2,109 10% 98% 90% more 40°more 2% 1% 3% 3% 3% 2% 2% 3% 512 2% 100% Total 21,087 100% Source: Mizoram Remote Sensing Application Centre (MIRSAC) and JICA Study Team Table 4.1.3 Altitude Range-wise Area Distribution Altitude Range-wise Altitude Range Districts' Altitude Range-wise Area Distribution (%) Area Distribution (AMSL in meter) Mamit Kolasib Aizawl Champhai Serchhip Lunglei Lawngtlai Saiha Km2 % Accum. % Less 100 m 9% 17% 1% 0% 0% 8% 7% 1% 1,110 5.3% 5.3% 100 - 200 m 23% 29% 4% 0% 0% 11% 25% 5% 2,471 11.7% 17.0% 200 - 300 m 16% 15% 7% 0% 0% 10% 18% 7% 1,937 9.2% 26.2% 300 - 400 m 13% 12% 10% 0% 2% 11% 12% 9% 1,853 8.8% 35.0% 400 - 500 m 11% 10% 13% 1% 7% 13% 9% 9% 1,931 9.2% 44.1% 500 - 600 m 9% 7% 13% 4% 10% 12% 7% 8% 1,912 9.1% 53.2% 600 - 800 m 13% 8% 23% 16% 28% 19% 10% 15% 3,519 16.7% 69.9% 800 - 1,000 m 5% 3% 16% 24% 26% 10% 7% 15% 2,695 12.8% 82.6% 1,000 - 1,200 m 1% 1% 8% 24% 15% 4% 4% 12% 1,785 8.5% 91.1% 1,200 - 1,400 m 0% 0% 3% 17% 9% 2% 2% 9% 1,101 5.2% 96.3% 1,400 - 1,600 m 0% 0% 1% 10% 3% 0% 1% 6% 547 2.6% 98.9% 1,600 - 1,800 m 0% 0% 0% 4% 1% 0% 0% 2% 193 0.9% 99.8% 1,800 - 2,000 m 0% 0% 0% 1% 0% 0% 0% 0% 30 0.1% 100.0% 2,000 m more 0% 0% 0% 0% 0% 0% 0% 0% 2 0.0% 100.0% (Max. 2,165 m) Total 21,087 100% Source: Mizoram Remote Sensing Application Centre (MIRSAC) and JICA Study Team 4-2 The Study on Development and Management of Land and Water Resources for Sustainable Agriculture in Mizoram in the Republic of India Final Report 4.1.3 Soil and Soil Erosion (1) General Features of Soils The geography of Mizoram is broadly divided into hills and valleys. Hills consist of (a) high hills above 1,300 m AMSL, (b) medium hills between 500 m and 1,300 m, and (c) low hills below 500 m. The hills run in a north to south direction parallel to each other with valleys in between them. Flat valley bottoms are found in the Tiau Valley and Champhai in the eastern part of Mizoram. Dissected hills and hill-rocks are predominantly found in most of the river valleys in the western part of the state. The soils of different geographic units are of homogeneous nature, and they are mainly derived from sandstones, shales and siltstones. The hill slopes and valleys have soil orders of Ultisols and Entisols, respectively. They are further classified into Udults and Orthents at sub-order level, while Inceptisols are commonly found in the hills and valleys. The surface soils of the hilly terrain are dark, highly leached and poor in bases, rich in iron and highly acidic with pH values from 4.5 to 5.5. These are well drained, deep to very deep, rich in organic carbon, low in available phosphate content and high in available potash. The textures of surface soils are loam to clay loam with clay content increasing with depth. The ratio of clay, silt and sand within the 50 cm of top soil in most cases is 20-30%, 35-45% and 25-45%, respectively. The pH and organic carbon content decrease and clay content increases with depth. The base saturation above a lithic or paralithic is mostly below 35%. These soils are capable of providing substantial oxygen supply for plant growth and have the capability to retain moisture and maintain its supply throughout the growing seasons of most crops. Soils of the flat valley bottoms are brown to dark brown, poor in bases, moderately acidic with pH ranging from 5.5 to 6.0, medium to high in organic carbon content, low in available phosphate and medium to high in available potash. They are deep to very deep but moderate to poorly drained. The texture of the soils is mostly sandy loam to sandy clay loam.