CLASS: VIII NCERT (CBSE)
Biology
Crop Production and Management
SUMMARY
Agriculture
The term crop is used to describe plants of the same kind that are grown and cultivated at one place in significant quantities. Plants that are planted during the rainy season are called kharif crops. Crops that grow during the winter season are called rabi crops.
Many activities are performed before cultivating a crop, which are termed as agricultural practices. Soil preparation means loosening the soil or turning it.Earthworms decompose plant and animal waste, and thereby benefit the soil by increasing the humus and nutrient level in it. Ploughs have been in use since ancient times for tilling soil, adding manure and fertilisers, and for scraping of soil. Depending upon the animals available on a farm, ploughing is done using horses and camels to pull ploughs. A plank is used to break the crumbs into fine soil. The next step is to levelthe soil with the help of a leveller.
Ploughs were made from wood. Nowadays, iron ploughs have become more popular. Earlier, a hoe was used for tilling, but these days we use it only to remove weeds. When the cultivator is pulled by a tractor, the teeth assist in breaking the soil.Healthy seeds contain more nutrients.Damaged seeds are hollow, discoloured and contain fewer nutrients.Seed selection is done by soaking the seeds in a beaker containing water.
Modern seed drills sow seeds at a proper depth and distance, and cover them with a layer of soil, keeping them well out of a bird’s reach. The traditional seed drill contains a funnel-shaped container, from where the seeds pass and get placed into the soil. Bananas are first sown in anursery and the saplings are planted in the field.
Crop Protection
Agriculture is cultivating on large areas.Manureprovides soil with nutrients. The crop has beenharvested last week and is left fallow to recovernutrients. Decomposition occurs in pits dumped withorganic waste with the help of earthworms and bacteria.
Fertilisers are chemicals used to add minerals likepotassium, phosphorus and nitrates to the soil. The supply of water to crop is irrigation. The frequency of irrigation varies from season to season. Manure increases the water retention capacity of soil, making it porous.
Plants contain nearly 90% water, and need water for proper development of flowers, fruits and seeds. In dry conditions, seeds do not germinate. Water protects plants from frostbite and hot air currents. Water protects crops from hot air by evaporation, and trapscold breeze. Traditional methods of irrigation include moat, chain pump, dhekli and rahat, and need animal and human labour to draw water.
Wells, tube wells, ponds, lakes, rivers, dams andcanals are sources of water. Sprinklers and dripsystems are used when the soil is sandy or uneven.Pumps lift water and run on biogas or solar energy. During summer, it is difficult for farmers to water crops.Weeds are removed manually before they produceflowers and seeds.
Weeds are controlled by chemicalssuch as 2, 4-D, a systemic weedicide that kills weeds. Weedicides are poisonous to humans. Drip irrigation waters fruit plants and suits regions that have scarcityof water. Khurpi is used to remove weeds. Farmers use weedicides in diluted form and they handle weedicidescarefully by covering their nose and mouth whilespraying. This stops their propagation in the field. Tillingthe soil uproots the weeds.
Harvest and Storage
Cutting the crop after it has ripened and gathering the grains is known as harvesting. We can use the word crop ripened rather than using the word crop mature. A sickle has a sharp serrate-edged metal blade attached to a wooden handle. A sickle is used for cutting the crop. A harvester is a machine that helps to cut the ripened crop from the fields. Threshing is the process of separating the grains from the straw and chaff.
A thresher is used for threshing. A combine is a combination of a thresher and a harvester. Winnowing is a process in which we allow natural wind to blow through the grains, so the lighter substances fly away, whereas the heavier grains fall to the ground.
The fan in a winnowing machine blows away the chaff.Protection of crops against microorganisms, rodents,pests and moisture is done by drying in sun and exposing to fumes. Silos are huge, air-tight cylindrical structures used to store grains. Granaries are large rooms built above ground level to prevent rodents and pests from getting near the grains.
In cold storage, vegetables and fruits are stored at low temperatures.Animal husbandry means rearing and breeding livestock on a large scale. Poultry farming meansrearing hens, ducks and turkey for meat and eggs.
