Science Question Answer (2 Marks)

Each crop needs a specific amount of water during its various stages of its growth. The irrigation requirements depend on the nature of crop. Some crops like need more water whereas other crops require less water. For example, paddy crop requires continuous irrigation whereas wheat crop requires less water.

When plants of the same kind are grown and cultivated at one place on a large scale, it is called a crop.
Examples: Wheat and Maize.

Based on seasons, all crops are classified into two main groups:

1. Kharif crops: The crops which are sown in the rainy season are called kharif crops. Example: paddy, maize.
2. Rabi crops: The crops grown in winter season are called rabi crops. Examples: wheat, gram, etc.

The advantage of storing food grains in gunny bags is that food grains filled in gunny bags can be easily transported and distributed at various parts of country.

The fresh crop has more moisture. So, the food grains obtained by harvesting the crop are dried before storage. If freshly harvested food grains are stored without drying, they may get spoilt or attacked by organisms, losing their germination capacity.

Harvesting is missing from the above list.

Weedicides affects the health of farmer. So, weedicides should be used vary carefully. During spraying of weedicides, the nose and mouth of farmer should be covered with a piece of cloth.

If wheat is sown in the kharif season, it will not grow well as plants cannot tolerate too much water of the rainy season.

Kharif crops: The crops which are sown in the rainy season are called kharif crops. The rainy season in India is generally from June to September. Example: paddy, maize.

The various sources of irrigation in our country are: wells, tubewells, ponds, lakes, rivers, dams and canals.

Plants require nutrients for their proper growth and functioning. If continuous plantation of crops is done in the fields then the soil will become poor in necessary nutrients like nitrogen, phosphorus, potassium, etc. This affect the yield and also affects the quality of soil. So, the nutrients once consumed by crop must be replenished so that soil get all its nutrients back and it will be ready for the next harvest.
Fertilizers help the farmers to get better yield of crops such as wheat, paddy and maize.

The branch of agriculture which deals with feeding, shelter, health and breeding of domestic animals is called animal husbandry.

The correct order is: Ploughing the field; Preparation of soil, Sowing; Manuring; Irrigation; Harvesting; Sending crop to sugar factory.

Top layer of soil supports plant growth. It gets loss due to ploughing because of which it can easily washed away by rain or blown away by wind. So, ploughed soil is levelled by pressing it with a wooden leveller, so that top soil is not blown away by wind or washed away by water.

Pesticide solution are sprayed on the gunny bags in big go downs from time to time to protect the grains from damage.

The various practices necessary for raising animals for food and Other purposes are:

• Proper food of animals.
• Proper shelter of animals.
• Proper care of animals.

Traditional methods of irrigation are chain pump and dhekli.
Modern methods of irrigation are sprinkler and drip system.

The government agency like food corporation of India (FCI) buy food grains from farmers and storing them properly so that they can be supplied throughout the country.

The process of loosening and turning the soil is called ploughing or tilling. The agricultural implements used for tilling (loosening and turning) the soil are plough and hoe.

The process of threshing is done with the help of a machine called combine. It is in fact a combined harvester and thresher.
Combine separates the grains from chaff.

1. Crops wheat and gram can be cultivated by sowing seeds directly into fields.
2. Paddy and tomatoes can be cultivated by transplanting.

The frequency of irrigation of crops is higher in summer season due to the increased rate of evaporation of water from the soil and the leaves.

1. Crop rotation.
2. The nitrogen-fixing bacteria present in root nodules of leguminous plants is rhizobium bacteria. Rotation of crops (leguminous and non-leguminous crops) in the same field replenishes the soil with nitrogen naturally and increases the soil fertility.

Proper watering of crop at right time is called irrigation. Each crop needs a specific amount of water during its various stages of its growth. The irrigation requirements depend on the nature of crop. Some crops like paddy crop (rice crop) need more water whereas other crops like wheat, gram require less water.

In this system, there is a network of narrow pipes with small holes, in the fields. When water flows through these pipes, water falls drop by drop just at the position of the roots. So, it is called drip system. Water is not wasted at all. It is the best technique for watering fruit plants, gardens and trees.Advantages:

1. Drip system is very useful in those regions where availability of water is poor.
2. Drip system provides water to plants drop by drop. So, water is not wasted at all.

Weedicides are special chemicals which are used to control weeds. 2,4-D is an example of weedicide.

The undesirable plants which grow along with a cultivated crop are called weeds. Wild oat is a weed which is found in wheat crop field.

Weed compete with the crop plants for water, nutrients, space and light. Thus, they affect the growth of crops.

The various agricultural practices which they are undertaken by the farmers are:

1. Preparation of soil.
2. Sowing.
3. Adding manure and fertilisers.
4. Irrigation.
5. Protecting from weeds.
6. Harvesting.
7. Storage.

Food grains are stored on a large scale in silos and granaries (gunny bags).

The removal of weeds is called weeding. Weeding is necessary since weeds compete with the crop plants for water, nutrients, space and light. Thus, they affect the growth of the crop. Some weeds interfere even in harvesting and may be poisonous for animals and human beings.

Seeds should be sown at right spacings. They should be neigher sown too close nor too far apart. If seeds are placed too close, then plants formed form them will be also too close and will not get enough sunlight, water and nutrients to grow. On the other hand, if seeds are placed too far, then it will be a wastage of field space. Thus, the seeds should be sown at right spacing to proper growth.

Rabi crops: The crops grown in winter season are called rabi crops. The winter season in India is generally from October to March. Examples: wheat, gram, etc.

The farmers store food grains in jute bags and metal bins at home.

Kharif crops	Rabi crops
Paddy	Wheat
Maize	Gram
Cotton	Mustard
Soyabean	Linseed
Groundnut	Peas

The irrigation requirements of a crop depend on the nature of soil in which the crop is grown. There are two types of soil- sandy soil and clayey soil. Sandy soil is highly porous having highly permeability. So, the water quickly percolates down to the soil and crop plants standing in the sandy soil, are not able to get adequate amount of water. Thus, crop cultivated in sandy soil need more frequent irrigation of water. On the other hand, the clayey soil is much less permeable than sandy soil due to which it can retain water for a much longer time. Thus, crop cultivated in clayey soil can absorb adequate amount of water. Hence, the crop grown in a clayey soil need irrigation less frequently.

Fertilisers are chemical substances which are rich in a particular nutrient. Some examples of fertilizers are urea, potash, NPK (nitrogen, phosphorus, potassium), etc.
Harmful effects caused by the excessive use of fertilizers are:

1. Excessive use of fertilizers makes the soil less fertile.
2. Excessive use of fertilizers causes water pollution.