Land Resource Technology
Land Resource Technology normally is not expected to be used as a direct package to boost crop yields. Yet, its importance as a vehicle of transfer of other agrotechnologies is well understood. Agricultural output, in fact, is the resultant of interactions of two broad groups of technologies, such as land and soil based technology and crop based technology. Land and soil based technology actually provides the platform whereupon the crop based technology operates.
Reconnaissance soil survey done by the soil resources development institute (SRDI) was principally aimed to make a rapid appraisal of the country's land resources in terms of their agricultural production potential and limitations. The main objective behind this investigation was to attain food autarchy within a short time through use of modern inputs. The findings provide the necessary guiding tools in locating areas of high, medium, low and very low potential and thereby can effectively assist the Decision Support System at the national, regional and district levels.
The major packages derived from processing, analysis and interpretation of land resources inventory data/information are: (i) land type, (ii) land capability, (iii) crop suitability, and (iv) present landuse.
Land type 'the dominant factor guiding choice of crops and cropping patterns in Bangladesh's characteristic agroecological situations. Selection of crop/ cropping pattern largely depends on the topographic position of land in relation to rainy season inundation depth and its duration. Lands, which are above normal inundation level, can provide a range of opportunities for growing both perennial and year round annual dryland crops.
Lands undergoing seasonal inundation do not permit one to grow perennial and dryland kharif crops. They are restricted to wetland crops in the kharif season and dryland crops in the rabi season depending upon the depth and duration of monsoon season inundation of the land. The following are some of the examples of crops/cropping patterns in relation to land types: 1(a) Highland with permeable soils: timber and fruit trees; sugarcane, cotton, ginger, turmeric, pineapple, year round vegetables etc; 1(b) Highland with impermeable soils: aus, jute, millet, in the kharif-I season and aman in the kharif-II season; and with irrigation, HYV boro in the rabi season. 2(a) Medium highland with permeable soils: aus, jute, millet in the kharif-I season; and dryland rabi crops in the rabi season; 2(b) Medium highland with impermeable soils: aus in the kharif-I season; aman in the kharif-II season; with irrigation, HYV boro in the rabi season. 3(a) Medium lowland with permeable soils: mixed aus and broadcast aman in the kharif season; and dryland rabi crops in the rabi season; 3(b) medium lowland with impermeable soils: (i) deepwater aman in the kharif season; and with irrigation, boro in the rabi season, (ii) mustard in the early rabi season followed by boro in the late rabi season, (iii) single crop of boro with irrigation. 4(a) Lowland with permeable soils: broadcast aman in the kharif season and mustard, khesari in the rabi season; 4(b) Late draining lowland: single crop of boro with irrigation; 4(c) Very lowland: single crop of local variety of boro in the rabi season.
From the above examples it is evident that trees and other perennial crops which are susceptible to damage due to water stagnancy are confined to the highland situations only. Dryland rabi crops can be grown on seasonally inundated lands provided the inundation water recedes much before sowing time.
Wetland crops, however, can be grown on both non-flooded and flooded land but the cropping pattern will largely depend on the depth of the inundation regime.
Major fields of application: (i) selection of crop species, varieties for an area, (ii) selection of cropping pattern for an area.
Land capability class and subclass' is the package built on the interactions of soil properties and environmental factors with the output, providing an indication of different degrees of potentiality of land for the sustained production of common agricultural crops in a year. According to this technology lands are classified into: (i) very good agricultural land, (ii) good agricultural land, (iii) moderate agricultural land (iv) poor agricultural land (v) very poor or non-agricultural land.
These classes relate to the severity of limitations for agricultural production. Least severity occurs in the case of class I and highest severity in the case of class V.
The land capability package was primarily built on the basis of land levels in relation to seasonal inundation or in other words, whether the land is seasonally inundated or not. Accordingly, they were denoted by 'D' for non-inundated and 'W' for seasonally inundated land. Again, within these categories secondary factors have been integrated for fine-tuning of the package. Consequently, droughtiness, prolonged or perpetual wetness, irregular relief, unfavourable slope gradient with risk of soil erosion/ landslide, salinity, flood hazard, river bank erosion/burial by sandy alluvium etc have been brought under consideration. They are denoted by 'd', 'w', 'ir', 'e', 's', 'z', and 'x' respectively. These secondary limitations are put suffixing the primary limitations, such as- (i) Dd, Dr, De for soils which stay above normal inundation level, (ii) Wd, Ws, Wz, Wx, Ww for soils undergoing seasonal inundation.
Major fields of application: (i) assessment of areas with different levels of agricultural potential. (ii) prioritisation of areas for major thrust for rapid increase in agricultural production using modern inputs. (iii) zoning of lands for agricultural and non-agricultural development possibilities. (iv) zoning of lands according to rainfed and irrigated cropping potentials. (v) identification and assessment of areas feasible for change/ adjustment in the existing cropping pattern. (vi) identification and assessment of areas requiring risk management/ disaster preparedness planning: flood, drought, cyclone, salinity, riverbank erosion, waterlogging. (vii) environmental protection by restricting unplanned housing settlements, urban sprawl, industrial expansion etc through application of land zoning technology. (viii) evaluation, monitoring and adjustment of development plans formulated by other organisations, especially on soil-crop related matters.
Crop suitability classes 'this technology, unlike land capability classes provides a basis for determining the degree of prospects and limitations of the soil within an area for growing a specific crop species or variety in a specific season.
Key factors related to crop production, such as depth and duration of rainy season, inundation of land, length of period for which the soil can supply optimum quantity of plant available moisture during the dry season, natural fertility status of soil were given special consideration besides climatic and other factors, in the crop suitability assessment. In fact, the crop suitability package is the resultant of the interactions of as many as eleven important soil factors together with the moisture and thermal regimes of the climatic factor.
Five suitability classes of land were recognised, depending upon the yield of the crop grown and they are as follows: (i) very suitable, (ii) suitable, (iii) moderately suitable, (iv) marginally suitable and (v) not suitable.
Major fields of application: can provide necessary guidance to the agricultural development planners, research scientists and extension specialists in chalking out realistic programmes in their respective fields; can efficiently guide the production planners in finding out suitable areas for expansion of existing crops or introduction of new crop species or varieties to formulate long-term national and regional plans and short-term local plans and can help develop crop species/ varieties suited to agroecological diversities and their adaptation/ introduction/ expansion at the farm level.
Present landuse 'present landuse data were aimed to provide a broad appraisal of cropping intensity involving major cropping patterns in the country, putting emphasis on agricultural landuse mainly. Thus landuse practices were classified as triple cropland, double cropland, and single cropland.
Major fields of application 'provides a guideline to identify areas which are under/over utilised compared to their potentialities; provides a logical basis for selection of areas to be further thrusted; provides a guideline to appreciate farmer's future acceptance/ resignation to expansion and/or introduction of new crop species and varieties within an area; provides a guideline in preparing realistic annual and long-term production plans, taking into consideration the rate of annual increase of area for the desired crops cropping pattern to achieve the set target; provides necessary assistance in detecting spatial and temporal changes in agricultural and other landuse patterns and provides necessary clues in identifying the rate of decline of agricultural land due to non-agricultural activities.
Thana Nirdeshika' 'Thana Land and Soil Resources Utilisation Guide', popularly known as 'Thana Nirdeshika' helps in formulating realistic mauza, union and thana level agricultural development planning. This Nirdeshika provides the logical basis in formulating realistic development plans by combining the aspirations and experience of local people with technical expertise, which was missing in the earlier planning processes. The areas where this Thana Nirdeshika data could be most effectively utilised are given below: (i) Preparation of block, mauza, union and thana level short and long term agricultural production programmes and other related development plans. (ii) Preparation of site specific recommendations for fertiliser use and irrigation on the basis of land qualities and crop requirements. (iii) Preparation of site specific recommendations for introduction and/or expansion of new crops or cropping patterns. (iv) Selection of representative sites for conducting crop and fertiliser related basic and applied research, trials and demonstrations as per agroecological diversities and transfer of generated technologies to similar situations. (v) Local level project identification, formulation, implementation, monitoring, evaluation and adjustment in the field of agriculture, forestry, fisheries, livestock, urban settlements and infrastructure development. (vi) Identification of risk-prone areas and development of pre-disaster preparedness and post-disaster rehabilitation plans.
Of all these, Block, Mauza, Union and Thana level Agricultural Production Programmes and site specific recommendations for fertiliser use, on the basis of soil tests and crop response correlation, are the most important areas of application of the Thana Nirdeshika based soil technology.
The following is a step-wise example on the application of the Thana Nirdeshika based soil technology in preparing local level agricultural production plans:
Step-1 Selection of crops/ cropping patterns, which are going to be expanded/ introduced.
Step-2 Selection of site(s) where these crops/ cropping patterns are going to be applied.
Step-3 Preparation of a table including the soil association. Soil series and land types covering the site(s) under consideration.
Step-4 Preparation of a table showing the soils and land types suitable for the crops of interest with the help of the standard crop suitability table prepared earlier.
Step-5 Preparation of a table showing soil association-wise gross suitable area (ha) for the desired crops.
Step-6 Assessment of the area (ha) of the suitable soils and land types in each soil association.
Step-7 (a) Preparation of potential crop suitability maps for individual crops to show spatial distribution of soil with different levels of suitability for a particular crop. (b) Prioritisation of location for the desired crop with the help of relevant crop suitability maps already prepared. (c) Estimation of gross areas (ha) suitable for the desired individual crop. (d) Finalisation of net areas taking consideration of ongoing practices, competing crops and farmer's choice. (e) Recommendation of a number of alternatives for future crops/ cropping patterns based on crop suitability ratings for selection by the users.
Step-8 (a) Assessment of input requirements: seed, fertiliser, pesticides, land preparation and irrigation equipment etc as per accepted area (ha) and crop species/ varieties. (b) Preparation of detailed work-plan (annual, short-term, or long-term) for implementation. [Md Serajul Islam]
Bibliography' Soil Resources Development Institute, Thana Land and Soil Resource Utilisation Guides, SRDI, Dhaka, 1986-1999; BARC, Method of Extrapolation of Farming System Research (FSR) based Agrotechnology, AEZ/GIS Project BGD/95/006 BARC, Dhaka, 1998-1999.