College students should base their choice of a field of study on the availability of jobs in that field.Write a response in which you discuss the extent to which you agree or disagree with the claim. In developing and supporting your position, be sure to

1. Introduction: The good earth in cultivator’s fields is tired, worn out, and almost lifeless as potter’s clay. But the soil is not lonesome. Cultivators still love it and try to care for it, but the soil is too weak to return the affection by producing higher yields. To make the land produce luxuriant crops requires continuous affection. But human affection alone is not enough for a soil that is hungry and almost lifeless. What the soil need is tons of fresh organic matter to put life into it and the right kind of commercial fertilizer to feed it, so that the soil may adequately feed the plants. Well-fed plants on fertile and well-watered soil will then supply adequate food and feed for man and his animals. In this way man’ affection and proper management of the soil will return to him at least tenfold in greater production.
The production of food and fodder crops requires soil, water, plants, and people. The soil must be physically, chemically, and biologically satisfactory for plant growth. Water must be available to the plant every hour of its growth. Plants must have the potential to produce the right kind of food, and in adequate amounts, and finally, man must so manage the soil, water, and plants, as to produce efficiently food and fodder crops in adequate amounts for Bangladesh’s needs.
Soils are important primarily because food and fodder plants grow in them. Plants are the pipelines through which essential minerals, proteins, and vitamins, flow from the soil to man and his animals. Stunted plants on unproductive soils are like sludge in the pipeline and man and his animals immediately suffer. Healthy plants on productive soils mean large and fast-flowing pipelines, productive livestock, and vigorous people.
The soil is a natural medium for plant growth. In a sense, soil includes all of the productive “out-of-doors”. Soil includes not only the land that is ploughed but also the waters which support green algae and the rocks on which mosses grow.
Man and his plants and animals all live in the world together. Both man and his animals depend upon food and fodder crops. These food and fodder crops depend upon the soil for water and plant nutrients. Plants also depend upon sunshine to supply light for the energy needed to manufacture food in the leaves. If it were not for the soil, water, and sunshine, plants would not grow and man and his animals would starve.
Soil is the most important natural resource. This is true because there is no proper substitute for soil as a medium for the growth of food and fodder plants. Understanding the soil is necessary before the soil can be used efficiently for production.( Arakeri et al., 1967).
Concerns over environmental impacts, resource depletion, safety of conventionally produced food, the vigor of rural society, and the expanse of government farm programs all underlie calls for new approaches to agriculture. “Sustainable agriculture” is an umbrella term encompassing the kinds of new approaches to farming being called for; farming in ways that protect the environment, conserve natural resources, reduce the use of potentially toxic chemicals, and increase financial independence.(Hatfield et al, 1994 )
One reason for the sharply falling share of the food pound is modern farming’s increased dependence on purchased inputs and technologies. External inputs of pesticides, inorganic fertilizer, animal feedstuffs, energy, tractors and other machinery have become the main means to increase food production. These external input, though, have substituted for free natural-control processes and resources, rendering them more vulnerable. Pesticides have replaced biological, cultural, and mechanical methods of controlling pests, weeds, and diseases. Inorganic fertilizers have substituted for livestock manures, composts, nitrogen-fixing crops and fertile soils. What were once valued local resources have all too often become waste products. These changes would represent a major problem if alternatives did not exist. Now they do. Sustainable agriculture technologies do two important things. They conserve existing on-farm resources, such as nutrients, predators, water-harvesting structures or new predator. These then substitute for some or all of the external inputs. (Pretty, 2007)

2.Soil management : Soil Management is the sum total of all tillage operations, cropping systems, fertilizer application, liming and other treatments applied to soil for improving soil condition of crop production. Due to lack of proper management practices, yield level of the soils of Bangladesh is generally decreasing. Moreover, poor management of soil creates undesirable environmental conditions. The truth lies behind this imperfect management is the excessive population pressure. In 1991 the area of arable land available on per capita basis was only 0.08 ha. This immense pressure on arable lands also affects the other socioeconomic aspects of soil management. The soil management in Bangladesh is classified into fertility management, management of soil physical properties and management of problem soils. (http://www.banglapedia.org/HT/S_0463.HTM)

2.1.Tillage Operation: Tillage refers to the different physical (mechanical) manipulations of the SOIL that change its structure, strength or position in order to improve or provide the necessary soil conditions favorable to the growth of CROPs. It is one of the oldest arts associated with farming. Minimum tillage systems, often entailing herbicide use, avoid erosion and maintain soil structure. Tillage improves the productiveness of soil because it causes a breaking down of the large soil clods into smaller ones, which increases the surface area from which plant roots obtain their food. However, some plants do not require ploughing or tillage for their growth. In Bangladesh both mechanical and manual tillers are being used. Sugarcane farmers are mainly using tractors. Rich farmers are also using tractors and other power tillers for cultivation. However, unmechanised tillage is a common practice here. (http://www.banglapedia.org /HT/T_0167.HTM.)
Some common tillage practices are described below:
2.1.1. Conventional tillage: Conventional tillage, the primary form of tillage since invention of the moldboard plow, involves two stages. First, primary tillage breaks up the soil buries crop residues. Primary tillage is often accomplished with an inverting implement, like the plow or lister plow, that inverts or tips over the top few inches of soil. Secondary tillage produces a fine seedbed by a series of operations that break up the soil into smaller and smaller chunks. Secondary tillage involves mixing implements like harrows.
2.1.2. Conservation Tillage: Conservation tillage is a program of crop residue management aimed at reducing erosion. Rather than plowing under crop residues, some or all of the residues is left on the soil surface. Conservation tillage reduces water and wind erosion by at least 40 to 50 percent. In areas where moisture can be limiting, conservation tillage increases soil moisture by improving infiltration and reducing runoff, reducing evaporation, fewer pesticides and nutrients leave the field. Conservation tillage also improves organic matter content near the soil surface. Conservation tillage, therefore, is a most important best management practice, or BMP, for soil water conservation. Because of soil conservation and economic benefits of conservation tillage, its use has spread rapidly in recent decades. The Conservation Technology Information Center reported that in 1993 about 35 percent of United States cropland was under conservation tillage, while 39 percent was under clean tillage. As technology improves, conservation-tillage use is expected to grow.
2.2. Cropping System: Growers employ a number of cropping systems; several are described here. A grower’s choice depends on climate, economics and market demand, government programs, and grower’s preference. Each system requires different soil management techniques has different effect on the soil.
2.2.1. Continuous Cropping: In continuous cropping, a farmer grows the same crop each year. Continuous is favored by many farmers because they can grow the most profitable crop. This method also allows the growers to specialize in the crop best suited to local soil or at the same time, expenses for fertilizers, herbicides, and pesticides tend to rise compared with expenses for a crop rotation system.
2.2.2. Crop Rotation: Crop rotation means that a series of different crops is planted on the same piece of ground in a repeating system. Many farmers do not rotate because it means planting some less profitable crops. Often a farmer has no use for certain crops in common rotations. For instance, a farmer who feeds no animals has little use for hay unless a buyer can be found for it. However, crop rotation has important benefits for those who practice it. Crop rotation aids the control of diseases and insects that rely on one plant host, reducing a grower’s pesticide bill. One rotation, double cropping soybeans and wheat, has reduced soybean cyst nematode damage by 90 percent. Some researchers suggest that yield declines that often accompany continuous cropping are caused by a buildup of soil pathogens.
It also supplies nitrogen if certain legumes like alfalfa are in the rotation; improves soil organic matter and tilth; and reduces erosion compared with continuous row crops, as long as the rotation includes small grains or hay.
Generally, crop rotation involves some combination of three kinds of crops: row crops, small grains, and forages. The specific crops and crop sequence vary from place to place.
2.2.3. Double cropping: Double cropping is the practice of harvesting two crops from the same piece of ground in one year. A common example is planting soybeans into winter wheat stubble. Sometimes a cover crop is planted in the off-season then killed with herbicides. The cash crop is then planted into this mulch. Double cropping is easiest in warm climates with long growing seasons. The use of double cropping has grown with the use of no- till systems. The second crop can be planted right behind harvest of the first crop, omitting time-consuming seedbed preparations. Multiple cropping keeps the soil covered with vegetation for a larger part of the year. Better erosion control results. Two crops grow more green matter than one, so the practice helps maintain organic matter in the soil. Where one crop is a legume, the nitrogen addition is welcome. Two crops also draw more heavily on soil nutrients and water, so fertilizer and water must be more carefully managed.(Plaster, 1997)
2.3.Fertilizer Application: Fertilizer organic or inorganic material of natural or synthetic origin (other than liming materials) that is added to a soil to supply one or more plant nutrients essential to the growth of plants. Any inorganic salt such as ammonium sulphate, or an organic substance, such as urea, used to promote crop production by supplying plant nutrients is considered to be a 'commercial' fertilizer. Specifically there are three different kinds of fertilizers: (i) chemical fertilizers, (ii) organic fertilizers, and (iii) biofertilizers. Fertilizers are the most important agricultural input throughout the world. Synthetic fertilizers contain nutrients in concentrated form. Naturally occurring inorganic materials are also rich in nutrients. Consequently, relatively lower amounts of fertilizers are needed to meet the crop requirement compared to naturally occurring organic materials. Soil is the principal supplier of plant nutrients. Plants derive 14 essential nutrients out of 17 from the soils. But soils vary considerably in their inherent capacities to supply nutrients which gradually decline over time due to intensive cropping with high yielding varieties, very little or no use of organic materials and improper soil and crop management practices. As a result, crops suffer from inadequate supply of nutrients which is reflected in poor yield and quality. Therefore, there is a need to add nutrients to the soil through fertilizers in order to get desired yields. Materials of plant and animal origin that are applied to the soil for increasing yield of crops are called organic fertilizer or manure. These are generally voluminous substances used in raw or processed condition. A variety of organic fertilizers are applied to the soils in different countries of the world. In the past, organic fertilizers were mainly used for crop production in Bangladesh. With the advent of chemical fertilizers in 1960s the use of organic fertilizers first gradually and then drastically reduced. However, animal manure, compost, green manure and biofertilizers are among the organic fertilizers, which are used in Bangladesh. Fertilizers are indispensable for the crop production systems of modern agriculture. Among the factors that affect crop production, fertilizers play a crucial role in yield increase. In fact, inorganic fertilizers hold the key to the success of the production systems of Bangladesh agriculture, being responsible for about 50% of the total production. However, the contribution of fertilizers to crop yields may vary depending on the crop, cropping intensity, season, soil characteristics and management conditions. Chemical (inorganic) fertilizers were introduced into this country during the early nineteen fifties as a supplemental source of plant nutrients. But their use increased steadily from the mid-sixties in line with the introduction and expansion of modern varieties and the development of irrigation facilities. The increasing trend of fertilizer use, particularly urea-N, still continues. Until 1980, three primary major plant nutrients - nitrogen (N), phosphorus (P) and potassium (K), along with one secondary major nutrient calcium (Ca), were supplied from fertilizer to BANGLADESH SOILs. The importance of sulphur (S) and zinc (Zn) for rice culture in particular was recognized during the early eighties. Gypsum, zinc sulphate, and zinc oxy-sulphate were then introduced to supply these nutrients. Very recently, magnesium (Mg), boron (B), and molybdenum (Mo) deficiencies have been reported for some soils and crops. Appropriate fertilizers to supply these nutrients will be needed in the future. Among the fertilizers, nitrogen occupies pivotal position because of the low nitrogen content of the soils and the quick visual action of nitrogenous fertilizers on crop growth, which drew attention of the farmers. Other fertilizers drew less attention because of their less visual response, although their need cannot be ignored. A variety of organic fertilizers are applied to the soil such as cowdung, urine, poultry manure, farmyard manure, compost, dried blood, bone meal, fish meal, groundnut cake, oil cake, dhaincha, sunhemp, cowpea, blackgram, mungbean, rice and wheat straw, sugarcane leaves, WEEDs, ash etc. Of these however, animal manure, compost, green manure, and oil cake are the most important. The preparations with living or latent specific microbial strains that are associated with the cycling of nitrogen, phosphorus and carbon assisting the supply of plant nutrients are popularly known as biofertilizers. Blue-Green Algae (BGA), Rhizobium, Azotobacter, Azospirillium, Vesicular Arbuscular Mycorrhizal fungi and Phosphobacterin are the commonly known examples of biofertilisers. The benefits of Rhizobium for pulses and other legumes, and BGA in association with Azolla for rice have been well demonstrated in Bangladesh through many experiments, but their use at the farm level is yet to gain widespread acceptance. Bacteria of the genus Rhizobium and Bradyrhizobium have the unique ability to fix atmospheric nitrogen in association with plants of the legume family. In 1962-63, a total of 20,235 tons of fertilizer nutrients were used in Bangladesh, of them, the amounts of N, P and K were 18,916, 661 and 703 tons, respectively. In the year 1995-96, the total amount of fertilizer nutrient consumption raised to 11, 79,390 tons. In that year, the amounts of consumption of different fertilizer nutrients were nitrogen 9,42,771 tons, phosphorus 68,866 tons, potassium 77, 940 tons, sulphur 89,468 tons and zinc 345 tons. The production of fertilizers in 1997-98 in Bangladesh was 1.873 million tons of urea, 50 thousand tons of triple superphosphate (TSP), 100 thousand tons of single superphosphate and 3 thousand tons of ammonium sulphate. Gypsum, however, is produced as a by-product of TSP industry. (http://www.banglapedia.org/HT/F_0060 .HTM)
In Bangladesh urea is used to meet almost all the N requirements of crops. In addition, ammonium sulphate is used for some crops, especially for tea plantation. Phosphorus is supplied from TSP and diammonium phosphate (DAP). In addition to phosphorus, DAP also provides nitrogen for the crops. Other chemical nutrients applied include Potassium (MURIATE OF POTASH), Gypsum, Zinc Sulphate and Zinc Oxide, Ammonium Molybdate and Solubor and Borax. It has been estimated that about 108 kg nutrient per hectare was used in Bangladesh in 1994 compared to 18 kg nutrient per hectare in 1973. This figure is far below as compared fertilizer nutrient consumption in Republic of Korea (467 kg/ha/yr) and China (309 kg/ha/yr) in 1994, bit higher than that of India (80 kg/ha/yr) and Pakistan (102 kg/ha/yr).
In addition to their capacity to supply plant nutrient fertilizers also exert other effects on soil properties. Organic fertilizers have favorable effects on chemical, physical and biological properties of soil. Constituents released through decomposition exert these diverse effects and the effects are also long lasting on the contrary. The effects of synthetic fertilizers are quick but short lasting. (http://www.banglapedia.org/HT/F_0060.HTM)
Some common methods of fertilizer placement are: a. Preplant: - 1.Broadcast, 2. Subsurface Band, 3. Surface Band, b. At Planting: - 1. Subsurface Band, 2. Seed Band, 3. Surface band, c. After Planting: - 1. Top-dressing, 2.Side-dressing. (Tisdale et al., 1997)

2.4. Liming: Liming process where agricultural lime is added to acidic soil to raise the pH to a level conducive to the growth of acid intolerant CROPs. In strict chemical terms, the liming material is calcium oxide. But for agricultural purposes, it is the material containing carbonates, oxides and/or hydroxides of calcium and/or magnesium used to neutralize soil acidity. The amount to be applied to raise the desired level of pH is known as the lime requirement. In Bangladesh, liming is not a usual practice. Liming is done in tea soils when the pH becomes too low. (http://www.banglapedia .org/HT/L_0104.HTM)
2.5. Organic Matter: The functioning of soils is profoundly influenced by their organic matter content. The abilities of a soil to supply nutrients, Store water, release greenhouse gases, modify pollutants, resist physical degradation and produce crops within a sustainably managed framework are all strongly affected by the quality and quantity of the organic matter that it contains(Rees et al.,2001). One of the important contributions of organic matter to sustainability compared with other soil properties is that it influences many soil functions(Swift and Woomer,1993).Organic matter is that portion of soil that includes animal and plant remains at various stages of decay. Organic matter causes soil particles to clump together to form soil aggregates and gummy substances produced by soil organisms bind the soil clumps. Better aggregation improves soil tilth and permeability. Data used in the Universal Soil Loss Equation indicate that increasing a soil’s organic matter from 1 to 3 percent can reduce erosion by one-third to one-fifth. (Plaster, 1997)
Crops grown for the purpose of restoring or increasing the organic matter in a soil are known as green manure crops. Their use in a cropping system is called green manuring. (Arakeri et al., 1967)

3. Fertility Management: Fertility status of Bangladesh soil is moderate to low. The organic matter content is not high and it is below 2%. In floodplains and terrace soils nitrogen content is low. About 5.6, 7.5 and 8.7 million- ha land of Bangladesh is deficient in phosphorus, potassium and sulphur respectively for upland crops. Zinc deficiency is present in about 1.74 million ha and boron deficiency is now coming to attention. Major cultivable crops of Bangladesh remove huge amount of nutrient elements from soil. HYV rice uptake 108, 18, 120 and 11kg/ha N, P, K and S from soil. Wheat also uptake high amount of N and K from soil. For the present level of production of crops about 1.0 million tons of N, P, K and S are annually removed from soil. Compared to other Asian countries during the past few years, the total fertilizer nutrient use in Bangladesh has remained static. Depending on the existing soil and land types, and varied cropping patterns it has been estimated that Bangladesh need at least 4.0 million tons of fertilizers but currently applied about 2.25 million tons that is 56% of the total demand. This creates continuous stress on the soils of Bangladesh. The major fertilizers are in use in Bangladesh are urea, triple super phosphate (TSP), gypsum and muriate of potash (MP).The total distribution of fertilizers from 1971 to l994 shows that urea occupied 68.7%, TSP 22.2% and MP 5.2% of total fertilizer used. Trends of fertilizer use in Bangladesh show that the application of nitrogen fertilizer is the highest. The use of sulphur and zinc in agriculture started from 1980-81 and from then the use of these two increases gradually. Diammonium phosphate (DAP) as a source of nitrogen and phosphorus is now becoming popular in Bangladesh. The use of DAP will reduce the use of chemicals in agricultural fields. Besides inorganic fertilizers, manures are also important in Bangladesh agriculture. Domestic animals produce a huge amount of excreta (dung and urine) per year. Cow dung is the most important animal manure. But a large portion of it is mainly used as fuel in Bangladesh. These days biogas plant is getting popular in Bangladesh. The remaining decomposed organic matter of biogas plant can be applied directly to soil. The cultivation of Azolla in rice field can be marked as a break through of biofertilisation in this country. The other biofertilisers such as inocula of Rhizobium are also commercially available. (http://www.banglapedia.org/HT/S_0463.HTM)

4. Management of Soil Physical properties: Rice is the main cultivated crop of Bangladesh. It grows on submerged soil. The common practice of land preparation for rice culture is puddling. It is the process of complete destruction of soil structure by repeated plowing by country plow and harrowing in submerged condition. A plough pan (5 to 10 cm depths) is formed due to puddling of soil. This compact layer is favorable for rice cultivation but not for other arable crops. For the cultivation of other crops soils are usually ploughed and harrowed for several times. Recently research on no-till farming has initiated in Bangladesh. This technique is not known to many farmers. Reduction of tillage cost in no-till farming system is promising for Bangladesh agriculture. (http://www.banglapedia.org/HT/S_0463.HTM)

5. Management of Drainage and Irrigation Systems: Drainage means the process of removing water in the soil that is in excess of the needs of crop plants. A soil may need artificial drainage for one of two reasons:
When there is a high water table that should be lowered, or
When excess surface water cannot move downward through the soil or over the surface of the soil fast enough to prevent the plant roots from suffocating.
High water tables are common in most peat and muck soils and in some low-lying sandy soils. More commonly, however, level upland soils need artificial drainage because of excess surface water. Soils that permit only a slow movement of water downward may need artificial drainage. Repeated experiments in areas of high rainfall have shown that low-lying, fine-textured soils such as clays with a massive structure usually need artificial drainage. A permeable soil seldom needs artificial drainage, except where the soil has a high water table. Slowly permeable soils often need artificial drainage, especially when the land surface is level and rainfall is high. Permeable soils that do not require drainage are uniform in color throughout the profile. Land can be drained by surface ditches or by tile drains.
Not all soils can withstand irrigation without deterioration. Before launching any irrigation scheme it is necessary to study the suitability of soils for irrigation. The soil should be examined with a view to seeing whether the water can be conveyed properly and the flow can be controlled easily. If the topography is too undulating it would be very difficult to control the flow of water. Another point that should be considered in planning for irrigations is the physical properties of the soil. The soil should not contain an excessive amount of clay or sand. They should not be shallow over bedrock or hardpan for fear of water-logging the soil. If the soils are very sandy, water will have to be supplied very often. All soils to be irrigated successfully must also be capable of being drained successfully. The soil should also be examined from the chemical point of view. The soil should be sufficiently fertile so that the cost of supplying fertilizers and manures is low. At the same time the soil should not contain a high percentage of soluble salts. If the percentage of soluble salts is high and if the drainage is poor, the soils are likely to develop toxic salinity. In summarizing, it may be stated that soils to be successfully irrigated must be satisfactory in the following respect:
Topography should be fairly level or capable of being leveled.
Texture should be a loam with a crumb structure.
Depth of soil must be at least thee feet to bedrock or a hardpan.
Organic matter content should be high.
Inherent fertility should be high.