CBSE Class 8 Science Chapter 1: Crop Production and Management NCERT Solutions

(a) The same kind of plants grown and cultivated on a large scale at a place is called a crop. A crop refers to a plant species that is cultivated and harvested for food, fiber, or other economic purposes.

(b) The first step before growing crops is the preparation of the soil. This involves loosening and tilling the soil to make it suitable for seed germination and root growth.

(c) Damaged seeds would float on top of water. Healthy seeds are denser and sink, while damaged or hollow seeds are lighter and float.

(d) For growing a crop, sufficient sunlight and water and nutrients from the soil are essential. These are the basic requirements for photosynthesis and overall plant development.

Here is the correct matching of items from Column A to Column B:

• (a) Food for cattle matches with (iv) Organic manure, as agricultural by-products and animal waste are often used as feed or processed into manure.
• (b) Urea and super phosphate matches with (iii) Chemical fertilisers. These are synthetically produced substances that provide essential nutrients to plants.
• (c) Animal excreta, cow dung, urine and plant waste matches with (iv) Organic manure. This combination is the source material for preparing compost and other organic fertilizers.
• (d) Wheat, gram, pea matches with (ii) Rabi crops. These crops are typically sown in the winter season.
• (e) Paddy and maize matches with (i) Kharif crops. These crops are usually cultivated during the rainy season.

Here are two examples for each type of crop:

(a) Kharif crops are those sown in the rainy season (typically June to September). Examples include:

Paddy (Rice)

Maize (Corn)

(b) Rabi crops are those sown in the winter season (typically October to March). Examples include:

Wheat

Gram (Chickpea)

(a) Preparation of soil: Preparing the soil is the very first and a critical step before planting any crop. This process involves turning the soil upside down and loosening it. Loosening the soil is important because it allows the plant roots to breathe easily and penetrate deeper into the ground. This also helps in the multiplication of useful microorganisms and earthworms, which further enrich the soil with humus. The top layer of the soil is usually rich in nutrients, and by turning the soil, these nutrients are brought to the surface, making them available for the plants to absorb.

(b) Sowing: Sowing is a fundamental part of crop production where seeds are planted into the prepared soil. Before sowing, it is essential to select good quality seeds that are clean, healthy, and of a superior variety to ensure a good yield. Seeds can be sown manually by scattering them by hand or using a seed drill, which is a tool that sows seeds at a uniform depth and spacing, ensuring better germination and growth.

(c) Weeding: Weeds are unwanted plants that grow naturally in agricultural fields alongside the main crops. These weeds compete with the crops for essential resources like water, nutrients, sunlight, and space, thereby reducing the crop yield. Weeding is the process of removing these unwanted plants. This can be done manually by pulling out weeds by hand or using tools like a 'khurpi'. Alternatively, chemical substances called weedicides (like 2, 4-D) can be sprayed in the fields to kill the weeds without harming the crops.

(d) Threshing: Threshing is the agricultural process that follows harvesting, where the harvested crop stalks are processed to separate the edible grain kernels from the rest of the plant material, such as the chaff and straw. This separation is crucial for obtaining the usable grain. Traditionally, threshing was done manually by beating the stalks, but now it is commonly performed using machines like a 'combine harvester', which efficiently performs both harvesting and threshing in one operation.