Cause Of Soil Erosion
>> Monday, July 20, 2009
Soil erosion is the wearing away, detachment and removal of soil from one place and its deposition at another place through the action of natural agents such as water, blowing winds, strong waves, snow and gravity etc.
Kinds of soil erosion: Soil erosion can be divided broadly into two categories-
1. Normal / Natural / Geologic erosion
2. Accelerated soil erosion
1. Normal soil erosion:
When the top soils are gradually removed under normal, physical, biotic and hydrological equilibrium in nature, it is known as normal erosion. It is a slow process in which complete equilibrium is maintained between soil removing and soil forming process. The normal erosion tends to produce wavy or undulating land surfaces with alternating ridges and depressions.
2. Accelerated soil erosion:
When the normal soil erosion does not keep harmony with the soil formation due to the disturbed by man’s exploits and by natural calamities that cause the loss of its (soil) resisting power and eroding agencies become more active and cause accelerated erosion. Actually accelerated erosion is soil erosion.
Agents of soil erosion: Two agents are responsible for soil erosion-
1. Biotic agent
2. Climatic agent / Abiotic agents
1. Biotic agent:
Excessive grazing, deforestation, undesirable forest biota and mechanical practices by man are important factors which cause soil erosion.
2. Climatic agents: These are water and wind.
A. Wind:
i. Saltation: Major part of wind carried soil (1-1.5 mm dia) is moved in a series of bounces called saltation.
ii. Suspension: Small soil particles (<>
iii. Surface creep: Large soil particles (5-10mm dia) creep on surface soil due to wind velocity and move from one place to another.
Wind erosion is not a serious problem in Bangladesh. In places where land is usually sandy and not thoroughly covered with vegetation, strong wind speed causes soil erosion.
B. Water Erosion:
Water erosion is a serious problem in Bangladesh. Water is an important factor in soil erosion where soil is directly affected by heavy rainfall, rapidly running water and by wave action.
Water erosion may be classified into following categories-
i. Splash or raindrop erosion:
The falling raindrop at an approximate speed of 30 ft/sec is capable of creating a force of almost 14 times of its own weight. With this falling force, the raindrops beat up the bare soil surface and causes erosion. Splash erosion is the forerunner of other types of water erosion.
ii. Sheet erosion:
It is the removal of a thin uniform layer of soil from large area is called sheet erosion. It is affected by run-off effect of rain water.
iii. Rill erosion:
In this type of soil erosion heavy rainfall and rapidly running water produce finger-shaped groove or rills over the entire field. It is an intermediary stage between sheet erosion and gully erosion.
iv. Gully erosion:
Gullies may be ‘V’ or ‘U’ shaped. Gullies cut the fields into small fragment and make them uncultivable.
v. Land slide or slip erosion:
This type soil erosion is caused by heavy rainfall and it occurs in sloppy lands such as mountains and hills. In this type when the running water percolates through the crevices of rocks, great masses of soils and loose rocks lying on the steep slip downward.
vi. Stream bank erosion:
On the banks of swollen rivers it is most active. During the rainy season, when fast running water streams take turn in some other directions, they cut the soil and make caves in the bank. As a result, soils become detached and deposited in other places.
vii. Sea shore erosion:
This is caused by the striking action of strong waves which combine eroding effects of both wind and water.
Mainly erosion in Bangladesh is water erosion.
Factors affecting soil erosion:
There are several factors which affects the erosion at a particular area. These are given below-
1. Topography of the land (Land form):
Land form with special difference to nature degree and length of slope influence the soil erosion.
0% Level Land
5%
10%
15%
a) Slope steepness (S)
b) Slope length (L)
The velocity of water movement increases exponentially as the slope steepness of land increases and thereby causes soil erosion.
2. Climate:
Climate, specially distribution, nature and amount of precipitation (rainfall) and wind velocity influence soil erosion. Rainfall is the most important factor which directly influences the soil erosion through the following ways-
a) Intensity of rain (cm/hr)
b) Drop size of rain (mm)
c) Terminal velocity of raindrop (m/sec)
d) Duration of rainfall.
Rainfall erosivity (R):
The ability of rainfall to cause erosion in a particular soil under a given climatic condition is called rainfall erosivity and expressed by ‘R’.
Ek=210.3+89 log10I
Ek=Kinetic of energy (metric ton/ha/cm or rain)
I=Rainfall intensity (cm/hr)
3. Physical and chemical characters of soil:
Soils with light textured with low organic matter content are more susceptible to erosion than soil with heavy textured, well structured, high organic matter content and clay content.
Soil erodibility (K):
Under a given slope, rainfall, vegetative cover, susceptibility to erosion depends on mainly soil type. This characteristic of soil to erosion is known as soil erodibility and expressed by ‘K’.
4. Vegetational cover, its nature and extent of coverage:
Bare soil is more susceptible to erosion than the soils covered with vegetation. Crop canopy (reducing wind velocity) and root system (anchoring soil) also reduces erosion and thereby tree crops are recommended in hilly area.
5. Land use practices and soil management.
6. Natural phenomena such as earthquake, landslides and upheavals.
As functional equation soil erosion can be expressed as follows-
Erosion = f (cl,v,t,s,h)
F = Function of the dependent
cl = climate
v = Vegetation
s = soil
h = Human factors
Different Agro-ecological Zone (AEZ): Bangladesh
There are 30 AEZ in Bangladesh. Emphasis is given to soil properties in relation to land use and agricultural development.
I. Physiography (land forms and soil parent materials)
II. Depth and duration of seasonal flooding
III. Climate-
b) Rainfall duration
c) Occurrence of temperature etc.
Ecological / Environmental hazard: Ecological factors which influence crop production are-
I. Climatic factors (related to aerial environment)
III. Physiographic factors (topographical factor)
IV. Biotic factor
These ecological factors are interrelated and intricately mixed. They work through one another acting and reacting together may bring about a change in local climate and in turn may affect the soil and competition impress.
Differences between physiographic units and soil types:
1. Emphasis is given on the process of soil formation.
2. This is the non-technical grouping of soils.
3. A total of 21 general soil types have been recognized in Bangladesh.
4. It is not necessary to maintain the order.
1. Emphasis is given to soil properties in relation to land use and agricultural development. 1. Emphasis is given on the process of soil formation.
2. This is the technical grouping of soils. 2. This is the non-technical grouping of soils.
3. A total of 23 physiographic units have been recognized in Bangladesh. 3. A total of 21 general soil types have been recognized in Bangladesh.
4. In writing physiographic units order must be maintained. 4. It is not necessary to maintain the order.
General soil types
1. Emphasis is given on the process of soil formation.
2. This is the non-technical grouping of soils.
3. A total of 21 general soil types have been recognized in Bangladesh.
4. It is not necessary to maintain the order.
Written By:
Md. Harun- AR Rashid
Regional Agricultural Officer
Mbrara, Uganda.
email: universityjournal@gmail.com
Read more...Diferent Type of Soils in Bangladesh
Physiographic units:
There are 23 physiographic units under 3 geomorphologic (geo-earth; morphi-form; logos-knowledge) division of Bangladesh soil-
B. Terrace Areas (80% of the country)
C. Hill Areas (12% of the country)
1) Old Himalayan Piedmont Plain
2) Teesta Flood Plain
3) Karatoya-Bangali Flood Plain
4) Lower Atrai Flood Plain
5) Lower Purnabhaba Flood Plain
6) Young Brahmaputra Flood Plain
7) Old Brahmaputra Flood Plain
8) Ganges River Flood Plain
9) Ganges Tidal Flood Plain
10) Gopalganj-Khulna Beels
11) Arial Beels
12) Middle Meghna Flood Plain
13) Lower Meghna River Flood Plain
14) Young Meghna Estuarine Flood Plain
15) Old Meghna Estuarine Flood Plain
16) Surma-Kushiyara Flood Plain
17) Sylet Basin
18) Northern and Eastern Piedmont Plains
19) Chittagong Coastal Plain
20) St.Martin’s Island
21) Madhupur Tract
22) Barind Tract
23) Northern and Eastern Hills
General soil type: Types emphasis on the process of silt formation. A general soil type comprises a group of soils which have formed in the same way and which have a broadly similar appearance. A total of 21 general soil types have been recognized in Bangladesh. This classification is a non-technical grouping of soil.
A. Flood Plain Soils:-
2. Calcareous Alluvium Similar to non-calcareous alluvium but calcareous throughout or within 125 cm from surface.
3. Acid Sulphate soils Poorly or very poorly drained, grey or dark grey soils on tidal flood plains which are actually or potentially extremely acid (pH < 3.5) within 125 cm from surface.
4. Peat soil Very poorly drained soils in which organic matters (peat or muck) comprises all or more than half of the upper 80 cm.
5. Non-calcareous Grey Flood Plain soils Seasonally flooded soils developed to below 25 cm, dominantly grey in sub-soils, not very strongly acidic throughout the upper 50 cm and not calcareous within 125 cm from surface.
6. Calcareous Grey Flood Plain soils Similar to non-calcareous grey flood plain but calcareous throughout or within 125 cm from surface.
7. Non-calcareous Dark Grey Flood Plain soils Seasonally flooded soils developed to below 25 cm; not very strongly acidic throughout the upper 50 cm and not calcareous within 125 cm from surface.
8. Calcareous Dark Grey Flood Plain soils Similar to non-calcareous dark grey flood plain soils, but calcareous throughout or within 125 cm from surface.
9. Grey Piedmont Soil Imperfectly to poorly drained soils in piedmont alluvium developed to below 25 cm. Similar to non-calcareous grey flood plain soils but usually more prominently mottled and medium it strong acid in sub-soil.
10. Acid Basin Clays Poorly or very poorly drained heavy clay developed to below 25 cm. Very strongly or extremely acid to below 50 cm but not sulphuric or sulphidic.
11. Non-calcareous Brown Flood Plain Soils Similar to calcareous brown flood plain soils, but not calcareous within 125 cm from surface.
12. Calcareous Brown Flood Plain Soils Moderately well to poorly drained flood plain soils developed to below 25 cm, prominently brown in sub-soil, calcareous throughout or within 125 cm from surface.
13. Black Terri Soils Imperfectly to poorly drained soils in Himalayan piedmont alluvium with a very dark brown to black top soils >25 cm thick.
14. Brown Hill Soil Excessively to well drained hill soils, developed to below 25 cm; yellow brown to reddish brown sub-soil; usually very strongly acid throughout 125 cm from surface.
15. Shallow Red Brown Terrace Soils Moderately well to imperfectly drained olive-yellow to strong brown soils over lying grey, Madhupur clay at 25-60 cm.
16. Deed Red Brown Terrace Soils Well drained to moderately well drained red to yellow-brown soils, overlying a strongly red-mottled substratum.
17. Brown Mottled Terrace Soils Imperfectly drained soils with a strongly mottled brown and red sub-soil, overlying a strongly red mottled substratum.
18.Shallow Grey Terrace Soils Poorly drained, grey, silty soils overlying grey Madhuput clay at 20-30 cm.
19. Deep Grey Terrace Soils Poorly drained, mainly silty soils with a grey mottled brown or red sub-soil, overlying a strongly red-mottled substratum.
20. Grey Valley Soils Poorly drained, deep, grey, mainly silty soils occurring in terrace valleys.
Made Land:
21. Made Land Soils on raised cultivation platforms; similar in color and texture to adjoining natural soils, but better drained and often darker and browner.
Crop Productivity Constraints in Bangladesh:
>> Sunday, July 19, 2009
Crop production constraints influence production in various ways. Some of them are fixed and cannot be changed easily but they influence production and require adjustment. Some of the important constraints are briefly described below-
Climate, land and soil are the primary requisites on which agricultural production is dependent upon. Without proper climate, land and soil no crop can be grown.
The farmer’s intelligence, technique and sustained ability for growing crops are another important requisite for agricultural production. In spite of having ideal climate land and soil if the farmers are not efficient, agricultural production is bound to be low.
Seeds are the basic inputs of agricultural production and fertilizer furnishes the requirement of there is any deficiency of nutrient. So quality seeds and timely availability and application of fertilizer are very important for crop production.
It is well recognized that pest and diseases cause great loss to crop production at various stages. Action should be taken to control them and minimize losses.
There is needed to take stock of various indigenous tolls as well as improved machineries which are in use on the countries and in the region.
6. Extension programme:
Proper propagation and dissemination of knowledge of production need to be transmitted to the masses at a great speed through appropriate extension programme.
7. Credit:
Credit is need for production purposes. They should be provided to the farmers as and when necessary.
8. Organization:
Organizations like research, extension, educations, information etc do play important roles in respective spheres of agricultural development for increased production. Read more...
Environmental Change: Artificial Plantation Of Mangrove Plant Species In Sundarban
>> Saturday, July 18, 2009
The world largest single tract mangrove forest, the Sundarbans of Bangladesh is very important ecologically, biologically and economically. The sustainability of this forest has been jeopardized due to change in the ecological conditions.
The Mangrove Silviculture Division of the Bangladesh Forest Research Institute has been conducting research on the silvicultural aspects in the natural mangrove forests (Sundarbans) of the country since 1977. By this time, some technologies have been generated with an objective to afforest some vacant areas (poorly regenerated areas, char lands, canal and river banks) of the Sundarbans by mangrove plant species. The use of these technologies will help protect the embankments, stabilize the newly accreted char lands, increase the productivity and conserve the biodiversity of the Sundarbans. The nursery and plantation techniques of some mangrove plant species of the Sundarbans are as follows:¬
1. Nursery and Plantation Technique of Golpata (Nypa fruticans)
Objectives:-
This technology can be applied for the protection of the river banks.
Rehabilitation of the newly accreted char lands of the Sundarbans.
To meet up the demand of the widely used thatching materials of the people of south-western part of the country.
To increase the plantation area of Bangladesh
Seed collection and Preservation:-
Mature (dark brown) and viable seeds should be collected by cutting the fruit bunches from at least 5 years old plants during the month of February to April. The bunches should be stored in a moist place for 3-4 days, and subsequently the seeds should be detached from the stalk by gentle pressure.
Methods of raising seedlings:
There are two methods have for golpata plantation. They are:
a) Nursery bed method
The nursery site should be selected in a place where inundation by brackish water occurs only by spring high tides. The seeds should be dibbled in the bed at a spacing of 5 cm. The nursery area should be protected by fencing from damage by wild and domestic animals. Regular weeding is necessary. Watering is also necessary if there is no tidal inundation.
b) Ditch method:-
The site should be selected near a canal side in a ditch. Seeds in the nursery bed should be spread in such a way that one does not overlap another. The nursery site should be protected by fencing to protect the buoyant seeds from washing out by tidal water.
Planting and Silvicultural treatment
The site with gentle slopes along the banks of the rivers or in the newly accreted char lands which are inundated by all tides in the less saline and moderately saline zones should be selected. Two to three months old seedlings attaining heights of 25-30 cm should be planted at a spacing of 2 m × 2 m during July to August when there is minimum salinity. Weeding should be done 4 times in the 1st year, 3 times in the 2nd year and 2 times in the subsequent years. In the 3rd year, pruning and thinning is necessary to keep the seedlings 400 to 500 per hectare with removal of rhizomes of the thinned plants.
Bismark Bangali
BSC in Agrotechnology
Khulna University, Khulna, Bangladesh.
bismark_kubangali@yahoo.com
Biofertilizer : The Life Of Soil
Why we use this fertilizer ?
Its needed to present 3-5% of total biofertilizer in the soil. But in our country (Bangladesh) it is present bellow than 2% for this reason crop production decreased day by day.
Biofertilizer helps to increase soil fertility. All elements necessary for plant growth and development, present in biofertilizer and plants easily recover the deficiency of nutrients / element for its optimum growth.
Biofertilizer helps in increasing the developing the texture and structure of the soil. It also increases the water holding capacity of sandy soil and helps it to convert into loamy soil day by day with increasing the percentage of this biofertilizer.
Plants uptake organic elements longtime from the soil. The effect of biofertilizer present 6-18 months in the soil, after applying it and crop can uptake this fertilizer season after season.
After applying biofertilizer, the activity of useful micro organism is increased. It also helps in the reproduction of micro organism.
Biofertilizer helps in plant growth. Different helpful insects like earth warm, ant, termite etc. are increase very much in the soil with the application in the soil. This insect makes holes in the soil, thus the root gets extra oxygen profusely. It increases the aeration capacity of the soil.
It increases the erosion of soil by air and water.
In the summer it reduces the soil temperature and in the winter it increases the soil temperature. For this reason the growth of root system not hampered in any season.
In increase the water holding capacity of the soil, so plants get available water in any season. For this reason, the utilization of irrigation water is maximized.
It decreased the toxicity of insecticides & chemical fertilizer. On the other hand it has no toxic effect on soil.
It increases the quality and quantity of crop production.
Bismark Bangali
BSC in Agrotechnology
Khulna University.
FISH CULTIVATION IN NATURAL LAKES AND RESERVOIRS
In China the lakes are categorized as large, medium and small on the basis of surface area. Large lakes are those that exceed 100 000 mu in area; medium lakes are from 10 000 mu to 100 000 mu; while small lakes are from 1 000 mu to 10 000 mu. Bodies of water less than 1 000 mu in area are considered as ponds. The study group visited one reservoir, two large natural lakes, one medium and one small lake. These lakes were of relatively shallow depth, the maximum depth averaging 4 m, while the shallowest ones were of 2 m average depth.
All the lakes, including the largest one, Taihu, were used for fish culture and were under careful management. The smallest one, Tanghu, was managed more like a large fish pond, except that it is not drained or fertilized.
For example, in Paitan Lake, fish are cultivated in deep water, lotus in shallow water, rice around the edge of the lake and mulberry trees on the dikes. The income from the lake has been appreciably increased by this. The income from sideline occupations is over 20 percent of the total income of Yuan 262 000 from the lake.
In the small and medium-sized lakes (Paitan and Tanghu) fishing is done only by the state farms which manage them, while in the larger lakes fishing is open to the members of the communes that control the lake. In all cases, fishing is done by the same group of people who are responsible for stocking and management of the lakes. Such collective ownership and management ensures a highly responsible approach to the utilization of resources.
In large lakes such as Taihu, closed seasons (March to May) are observed to protect brood stocks during their breeding season and to ensure enhanced recruitment to fish populations. For those species which attach their eggs to grasses or vegetation, clumps of floating grass are anchored over large portions of Taihu, to provide favourable breeding sites and thereby increase the chances of successful spawning.
Fishing gear has been improved to facilitate harvesting lakes. Special methods have been developed to concentrate fish in portions of the lake for easy harvesting. Harmful fishing methods such as the use of poisons and explosives are forbidden. Mesh-size regulation is enforced to ensure that fish below 1 jin in weight escape capture.
In Taihu there is a provincial-level Lake Management Committee, which includes representatives of the communes and fishing brigades around the lake, and technical personnel from universities and other institutions. The task of the Committee is to review available information on the lake, including the results of culture and capture, and to use it as a basis for the management of its fisheries. In general, stocked fish under 1 jin are not allowed to be caught. In at least some areas there is now a tendency to reclaim shallow portions of lakes into large ponds for intensive fish farming.
The Hubei Hydrobiological Research Institute carries out research on the limnology and fish production in Tanghu. This work, which includes studies of ichthyomass, primary production and carrying capacity of the lake, has indicated that the lake has a potential production of 2 million jin per year, whereas the actual production in 1977 was 1.3 million jin. It has also been found that the stocking of large-sized fingerlings increases the recapture rate of stocked fish from 1 to 20 percent. In 1977, 95.5 percent of all the fish caught in Tanghu were stocked fish, only 4.5 percent belonging to natural stocks in the lake. Thus the value of culture operations has been clearly demonstrated.
Among the problems encountered in the management of small- and medium-sized lakes is the control of predatory fish such as Siniperca chautsi, Erythroculter mongolicus, and Elopicthys bambusa. Some of these predators appear in schools during the spawning season and advantage is taken of this known habit to capture them by intensive seining. Destruction of spawning grounds is another measure widely adopted for the control of predators.
Fish production per unit area from the Chinese lakes varies with the size of the lake as in other countries. This is clear from Table 6 which summarizes some of the available data on stocking and annual yields of the four lakes visited by the study group. The smallest lake, Paitan, has the highest yield of 250 kg/ha, while the largest, Taihu, has the lowest, 53 kg/ha. Fish culture is admittedly the main source of increased fish production from lakes and reservoirs in the country.
The management of freshwater reservoirs is similar to that of small-sized lakes, except that feeding, manuring and stocking rates approach the standards adopted in fish ponds, if the reservoir is small.
Only one reservoir, the Mei-chuan Reservoir, was visited by the study group. It has an area of 2 500 ha or 37 500 mu, with minimum arid maximum depths of 7.5 m and 19.5 m, respectively. The annual yield was 100 t in 1977, which gives an average yield of only 40 kg/ha. This rain-fed reservoir, although built for irrigation, also provides water for 70 mu of fish ponds and generates power for local use. Fry are reared in the fish ponds and from these 12 million fry are stocked in the reservoir annually. About 1.2 million jin of grass and pig manure are applied as fish feed and fertilizer in the reservoir and associated ponds. The main problem faced in fish production in this reservoir is the low survival of stocked fish (5-7 percent). The fingerlings stocked are only 9-12 cm and fall easy prey to predatory fish.
INTEGRATED FARMING OF FISH, CROP AND LIVESTOCK
The most impressive aspect of Chinese aquaculture that the study group observed was the integration of fish farming with livestock production and farming of agricultural crops, including vegetable farming. Integrated farming is a traditional. Chinese practice and, as mentioned earlier, has in recent years been further supported by the concept of an all-round 'development of agriculture, animal husbandry, fisheries and other sideline occupations. Although integrated farming is economically and environmentally sound, the motivation for integration would appear to be the national policy of diversification of production.
Nature of integration
The fish cultivated and the general farming practices are amenable to easy integration, The grass carp feeds on grass and other vegetable matter which can be grown on the dikes and adjacent agricultural land. They also feed on aquatic plants which can be raised in canals and other adjacent water bodies. Aquatic plants such as Pistia stratiotes, Eichhornia crassipes, Alternanthera phyloxorides and duck weeds, are grown for feeding fish or pigs and poultry on land. Sugar cane, corn and bananas are some of the other crops grown in association with fish farms. Ipomea aquatica, Lolium perenne, sorghum, maize and mulberry are also grown in many areas. The leaves, stalks or other waste products are chopped or crushed and fed directly to the fish or composted to be used as fertilizer. Silver carp and big head feed on plankton which can be grown by the application of organic manures provided by pigs, cattle, and chicken raised by the side of fish farms. As mentioned, pigsties are often built on pond dikes, facilitating the application of manure, either directly or after fermentation. Duck farming in association with fish, is also reported to be practised in a few places. In areas where silk production is prevalent, mulberries are planted on the pond dikes. The silkworm pupae and other wastes are used to feed the fish. Fish pond silt is an excellent fertilizer for land crops and is commonly used by farmers. In areas without adequate irrigation, pond water may also be used for irrigating crops, when necessary. The commune or production brigade members can also be considered as an element in this type of integration and recycling, as they eat fish and other farm products and human wastes are used to fertilize ponds and crop land.
In Lin Fu State Fish Farm in Hengyang, farming is closely associated with a winery. Waste water from the winery goes to the fish ponds for fertilizing and feeding fish and the solid wastes are fed to the pigs. The fish and wine, of course, go to feed man! In many places fish farms are also used for the rearing of the freshwater mussels, Anodonta and Hyriopsis, for the production of pearls. The methods adopted are described in FAO Fisheries Technical Paper, No. 168.
The allocation of land and water for fish, crops and livestock varies. For example, in one state farm, about 60 percent of the land was devoted to fish culture, 14 percent to pigs and cattle, 14 percent to cultivation of fodder and 10 percent to growing rice and wheat.
The experiences gained over several years of integrated farming of this type, when critically analysed and rationalized, could be of considerable value to all developing countries interested in integrated rural development. There are many aspects of such farming that are fascinating subjects for research, which, when carried out, could give a scientific understanding of the processes involved and consequently, lead to better management of the system.
About 20 000-25 000 jin of aquatic plants can be produced in every mu of water area and this will be enough to feed ten pigs. One mulberry tree can produce up to 270 jin of leaves. The production of sugar-cane leaves is estimated to be up to 12 000 jin per mu of land. Over 70 jin of grass or other plant material will be needed to produce 1 jin of grass carp and 200 jin of manure for producing 1 jin of silver carp of big head. Each pig produces 4 000-5 000 jin of manure a year and, based on local experience, about 3-5 pigs are grown for every mu of fish ponds. Similarly, 30 chickens are raised for every mu of fish ponds. It is estimated that a cow can produce 1 t of "manure water" per day and this is used to calculate the number of cattle to be raised. One mu of fish ponds produces 20 000-30 000 jin of silt and silt from 2 mu of fish ponds will fertilize about 1 mu of land. It should be pointed out that the above estimates are rather empirical and remain to be confirmed through critical studies.
Advantages of integration
The advantages of integration are obvious. As far as fish production is concerned, it serves the major purpose of providing cheap feedstuffs and organic manure for the fish ponds, thereby reducing the cost and need for providing compounded fish feeds and chemical fertilizers. By reducing the cost of fertilizers and feedstuffs the overall cost of fish production is reduced and profits increased. The study group was told that the profit from fish culture is often increased 30-40 percent as a result of integration. Secondly, the overall income is increased by adding pig and/or poultry raising, grain and vegetable farming, etc., which supplement the income from fish farming. Thirdly, by producing grain, vegetables, fish and livestock products, the community becomes self-sufficient in regard to food and this contributes to a high degree of self-reliance. Fourthly, the silt from the ponds which is used to fertilize crops, increases the yield of crops at a lower cost and the need to buy chemical fertilizer is greatly reduced. It is estimated that about one third of all the fertilizer required for farming in the country comes from fish ponds. The production of freshwater pearls in fish ponds provides one more additional source of income.
Management of integrated farms
Integrated farming calls for skill in different types of activity such as raising pigs and poultry, crop and vegetable farming, growing grass and aquatic plants and farming of fish. One person can take care of 6-8 ponds of 5-7 mu each; or 30-50 pigs or 500-1 000 chickens, but many of the activities, including harvesting, will need a large number of people. Obviously, if integrated farming has to be done on a large scale, a sufficient number of people with the required skills have to work together. The organization of production brigades and communes appears to be very well suited for the adoption of the practice. A production team may be found to be too small a unit, as was reported in Hengyang, where, with the introduction of integrated farming, the organizational and accounting unit was changed to production-brigade-level.
As pointed out earlier, the main motivation for integrated farming is the accepted national policy of all-round development, where the economic benefits of individual operations do not figure very prominently. The social and political milieu of the country is highly favourable for such development. From the limited experience in some other countries also, it appears that the introduction of integrated farming can play a major role in rural development in developing countries. However, the study group does not believe that the Chinese system can be transplanted as such to other countries. Species of fish, crops and livestock to be raised will have to be selected on the basis of local conditions and requirements. In most other developing countries the objectives of integrated farming will have to be heavily oriented to economic, social and nutritional benefits. Farmer cooperatives or other associations may have to be built up to meet the manpower requirements for economically viable units. Suitable pilot projects will have to be designed and implemented to test the systems and based on the results of such projects, further development will have to be planned.
Written by:
Md. Harun- Ar- Rashid
Regional Agricutural officer
Kampala, BRAC Uganda.
Nursery And Plantation Techniques Of Some Mangrove Plant Species
The world largest single tract mangrove forest, the Sundarbans of Bangladesh is very important ecologically, biologically and economically. The sustainability of this forest has been jeopardized due to change in the ecological conditions.
The Mangrove Silviculture Division of the Bangladesh Forest Research Institute has been conducting research on the silvicultural aspects in the natural mangrove forests (Sundarbans) of the country since 1977. By this time, some technologies have been generated with an objective to afforest some vacant areas (poorly regenerated areas, char lands, canal and river banks) of the Sundarbans by mangrove plant species. The use of these technologies will help protect the embankments, stabilize the newly accreted char lands, increase the productivity and conserve the biodiversity of the Sundarbans. The nursery and plantation techniques of some mangrove plant species of the Sundarbans are as follows:¬
1. Nursery and Plantation Technique of Golpata (Nypa fruticans)
Objectives:-
This technology can be applied for the protection of the river banks.
Rehabilitation of the newly accreted char lands of the Sundarbans.
To meet up the demand of the widely used thatching materials of the people of south-western part of the country.
To increase the plantation area of Bangladesh.
Seed collection and Preservation:-
Mature (dark brown) and viable seeds should be collected by cutting the fruit bunches from at least 5 years old plants during the month of February to April. The bunches should be stored in a moist place for 3-4 days, and subsequently the seeds should be detached from the stalk by gentle pressure.
Methods of raising seedlings:
a) Nursery bed method
The nursery site should be selected in a place where inundation by brackish water occurs only by spring high tides. The seeds should be dibbled in the bed at a spacing of 5 cm. The nursery area should be protected by fencing from damage by wild and domestic animals. Regular weeding is necessary. Watering is also necessary if there is no tidal inundation.
b) Ditch method:-
Planting and silvicultural treatment
The site with gentle slopes along the banks of the rivers or in the newly accreted char lands which are inundated by all tides in the less saline and moderately saline zones should be selected. Two to three months old seedlings attaining heights of 25-30 cm should be planted at a spacing of 2 m × 2 m during July to August when there is minimum salinity. Weeding should be done 4 times in the 1 st year, 3 times in the 2nd year and 2 times in the subsequent years. In the 3rd year, pruning and thinning is necessary to keep the seedlings 400 to 500 per hectare with removal of rhizomes of the thinned plants.
Written by:
Md. Harun- Ar- Rashid
Regional Agricutural officer
Kampala,Uganda
Read more...Insect pheromones and their use in Integrated Pest Management (IPM)
• Pest monitoring
• Mass trapping
• Lure and kill
• Mating disruption
• Pheromones can be utilized to catch or deter insects. Example: Pheromone “traps”, which contain the pheromone emitted by the female gypsy moth can be set to catch male moths
Definition
Pheromones:
• Aggregation Pheromones: release by ind of one species that attract conspecific ind to the source organisms (e.g. stinkbugs)
• Alarm Pheromones: elicit escape and defensive behavior. (e.g. Ants)
• Sex Pheromones: involve with attraction between sexual partners to increase mating probability. Emitted by one sex, to attract opposote sex (e.g. moths, butterflies)
• Other Pheromones: Trail, maturation, epidiectic (dispersal) Read more...
Insect pheromones and their use in Integrated Pest Management (IPM)
• Pest monitoring
• Mass trapping
• Lure and kill
• Mating disruption
• Pheromones can be utilized to catch or deter insects. Example: Pheromone “traps”, which contain the pheromone emitted by the female gypsy moth can be set to catch male moths
Definition
Pheromones:
• Aggregation Pheromones: release by ind of one species that attract conspecific ind to the source organisms (e.g. stinkbugs)
• Alarm Pheromones: elicit escape and defensive behavior. (e.g. Ants)
• Sex Pheromones: involve with attraction between sexual partners to increase mating probability. Emitted by one sex, to attract opposote sex (e.g. moths, butterflies)
• Other Pheromones: Trail, maturation, epidiectic (dispersal) Read more...
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