Improvement in Food Resources | Part 2
Fertilizers
Fertilizers are the sources of plant nutrients, manufactured commercially from chemicals. Fertilizers supply Nitrogen, Phosphorus and Potassium (NPK). Basically they are used for good vegetative growth (i.e., growth of leave, branches and flowers), giving rise to healthy plants. Fertilizers are one of the major components for obtaining higher yields specially in high cost farming practices.
1. Nitrogenous Fertilizers
2. Phosphatic Fertilizers
3. Potassic Fertilizers
4. Complex Fertilizes
(iii) Irrigation
Water is a key input for crop production. The process of supplying water to crop plants of the crop fields by means of canals, reservoirs, wells, etc., is known as irrigation.
Crop plants are irrigated with freshwater to supply two essential elements to them, hydrogen and oxygen. Both of these elements are present in water molecules and are necessary for growth and development of crop plants.
Irrigation System
Our country is awarded with large water and land resources with varied climatic conditions. Under such circumstances, various types of irrigation system have been adopted to supply water to the agriculture lands. Some most commonly used irrigation systems are the following :
1. Canal system.
In canal system the human-made canals receive water from one or two reservoirs or from rivers. This is usually an elaborate and extensive irrigation system. Thus, main canal is distributed into branch canals and branch canals further have distributaries or field channels.
2. Tanks.
Tanks are small storage reservoirs, which catch and store the runoff of smaller catchment areas. Small dams are built below the higher elevations of the catchment areas. In the tanks, outflows are controlled according to the availability of water. Otherwise it causes an uneven distribution of water.
3. Wells.
Wells are constructed whenever exploitable ground water is present. Wells are of two types :
(i) Dug wells. In the dug wells, the water is collected from water bearing strata. These dug wells have their bottom below the ground water table. The water from the shallow strata slowly accumulates in the pit. From these wells, water is lifted by mechanical means, e.g., bullock operated devices.
(ii) Tube wells. A tube well can tap water from the deeper strata. From these wells, water is lifted by diesel or electricity run pumps. Deep bore tube well can supply water continuously for many years.
(iii) River valley system. Certain parts of the country such as Karnataka and Kerala which lie along the western Ghats use the water that is discharged into the steep and narrow riverine valleys during the raining season. In these parts of India, the rainfall is heavy but concentrated in four or five month period of the year. This is followed by drying upto during the rabi season.
(iv) Farming is an agricultural process of harnessing solar energy in the form of economic produce of plants and animals.
(iv) Cropping Patterns
Different ways of growing crops can be used to give maximum benefit.
Mixed cropping
Mixed cropping is growing two or more crops simultaneously on the same piece of land, for example, wheat + mustard, or groundnut + sunflower. This reduces risk and gives some insurance against failure of one of the crops.
Inter-cropping
Inter-cropping is growing two or more crops simultaneously one the same filed in a definite pattern. A few rows of one crop alternate with a few rows of a second crop, for example, soyabean + maize, or finger millet (bajra) + cowpea (lobia). The crops are selected such that their nutrients requirements are different. This ensures maximum utilization of the nutrients supplied, and also prevents pests and diseases from spreading to all the plants belongings to one crop in a field. This way, both crops can give better returns.
Crop-rotation
The growing of different crops on a piece of land in a pre-planned succession is known as crop rotation. Depending upon the duration,. Crop rotation is done for different crop combinations. The availability of moisture and irrigation facilities decide the choice of the crop to be cultivated after one harvest. If crop rotation is done properly then two or three crops can be grown in a year with good harvests.
2. Crop Improvement for Higher Yield Through Genetic Manipulation
The art of recognizing valuable traits and incorporating them into future generation is very important in plant breeding. Breeders search for individual plants that exhibit desirable traits. The two most desirable qualities of food plants are high yield and natural resistance to disease. Such traits occasionally arise spontaneously through a process called mutation.
(i) Plant Breeding for High Yielding Crops
The plant breeding means production of new varieties or strains by a programme of artificial selection spanning several generations of the organism concerned. Plant breeding is a science as well as art of improving genetic make up of plant in relation to their economic use. Variuos approaches which are used for genetic improvement of crop plants are referred to as plant breeding methods or techniques. Genetic improvement of various crop plants has been done by adopting the following three steps : Introduction, Selection and Hybridization.
(ii) Hybridization
The crossing between genetically dissimilar plants to produce a new kind (hybrid) is called hybridization. Crossingmay be between two different varieties (intervarietal cross-breeding), between two different species of the same genus (interspecific cross-breeding) and between different genera (intergeneric cross-breeding) and between different genra (intergeneric cross-breeding). This method incroporates the desired (good) characteristics of both parents in one variety.
(iii) Crop Variety Improvement
Practices of cultivation and yield of crop are directly related to agronomic conditions. These conditions are based on weather, soil quality and water resource availability. Since weather conditions are unpredictable such as drought and flooding situations, therefore, crop varieties have been developed that can be grown in diverse climatic conditions. Likewise, some varieties have been developed which are tolerant to high salinity conditions of the soil.
· Higher yield : To increase the productivity of the crop per acre.
· Improved quality : Quality considerations of crop products vary from crop to crop. Baking quality is important in wheat, protein quality is important in wheat, protein quality in pulses, oil quality in oilseeds and preserving quality in fruits and vegetables.
· Biotic and abiotic resistance : Crops production can go down due to biotic (diseases, insects and nematodes) and abiotic (drought, salinity, water logging, heat, cold and frost) stresses under different situations. Varieties resistant to these stresses can improve crops production.
· Change in maturity duration : The shorter the duration of the crop from sowing to harvesting, the more economical is the variety. Such short durations allows farmers to grow multiple rounds of crops in a year. Short duration also reduces the cost of crop production. Uniform maturity makes the harvesting process easy and reduces losses during harvesting.
· Wider adaptability : Developing varieties for wider adaptability will help in stabilizing the crop production under different environmental conditions. One variety can then be grown under different climatic conditions in different areas.
· Desirable agronomic characteristics : Tallness and profuse branching are desirable characters for fodder crops. Dwarfness is desired in cereals, so that less nutrients are consumed by these crops. Thus developing varieties of desired agronomic characters help give higher productivity.
3. Crop Protection Management
Field crops as well as storage (where food grain are stored) are infested with a variety of pests. A pest I any destructive organism which causes great economic loss by destroying crop plants or products obtained from them. Pests of crop plants include weeds, insects, mite, nematodes, rodents, fungi, bacteria and viruses. Field crops are infested by a large number of insect pests and diseases. If these pests are not controlled at appropriate time they can damage the crops to the extent of 50 to 70 percent.
There are various methods by which insects and diseases can be controlled. One of insecticides (for killing the insects), weedicides (for killing the weeds) and fungicides (for killing the fungi). Thus, chemical (poisons) used to kill pests, e.g., weeds, insects, mite, rodents and fungi are called pesticides. These chemicals (i.g., pesticides) are sprayed on crop plants or used for treating seeds and soil. However one should try to avoid the would be far better if we adopt the preventive measures rather than allowing the crops to be infested by pests and then control them by pesticides.