Crop Production and Management: CBSE Class 8 Science

What are Agricultural Practices?

To grow crops and get a good harvest, farmers can't just throw seeds on the ground and hope for the best. They follow a series of well-planned activities over a period of time. These activities are called agricultural practices. Think of it like a recipe for growing food! Each step is crucial for the healthy growth of the crop. For example, if the soil is not prepared well, the seeds won't be able to grow strong roots. If the crop is not protected from weeds, the weeds will steal all the nutrients, water, and sunlight! The main agricultural practices, in order, are:

1. Preparation of Soil
2. Sowing
3. Adding Manure and Fertilisers
4. Irrigation
5. Protecting from Weeds
6. Harvesting
7. Storage

We will explore each of these steps in detail to understand how science helps farmers produce more and better food for all of us.

The First Steps: Preparing Soil and Sowing Seeds

1. Step 1: Preparation of Soil — This is the very first and most important step. It involves loosening and turning the soil. This process is called tilling or ploughing. Why is it so important? - Deeper Roots: Loose soil allows the roots of the crop to breathe easily and penetrate deeper. - Helpful Microbes: It helps in the growth of earthworms and microbes present in the soil, which are the farmer's friends! They further turn and loosen the soil and add humus to it. - Nutrient Richness: Tilling brings the nutrient-rich soil to the top for the plants to use. - Tools used: Plough (traditional, made of wood or iron), Hoe (for removing weeds and loosening soil), and Cultivator (modern, tractor-driven, saves time and labour).
2. Step 2: Sowing — Sowing is the process of putting seeds in the soil. Before sowing, farmers must select clean, healthy, and high-quality seeds. A good seed means a good crop! - How to select good seeds? A simple test is to put seeds in a bucket of water. Damaged seeds are hollow and lighter, so they float on top, while healthy seeds sink. - Sowing Methods: Traditionally, seeds were sown by hand (broadcasting) or using a funnel-shaped tool. The modern method uses a seed drill. A seed drill, attached to a tractor, sows the seeds uniformly at a correct distance and depth. This prevents overcrowding and ensures seeds get enough sunlight, nutrients, and water from the soil.

Manure vs. Fertilisers: What's the Difference?

Exam Tip: Don't Confuse Weeds, Weeding, and Weedicides!

Many students get confused between these similar-sounding terms. Let's make it clear!

• Weeds: These are the unwanted plants that grow naturally along with the crop (e.g., wild oat, grass). They are harmful because they compete with the main crop for water, nutrients, space, and light.
• Weeding: This is the process of removing the weeds. It can be done manually by pulling them out or using a tool called a khurpi.
• Weedicides: These are the chemicals that are used to kill weeds, like 2,4-D. They are sprayed in the fields but do not damage the main crop. Remember, a weedicide is a type of chemical, while weeding is a physical action.

Practice Questions with Solutions

• Q: What is the difference between Kharif and Rabi crops? Give two examples of each. A: Step 1: Define Kharif crops. These are the crops sown in the rainy season, which is generally from June to September in India. Step 2: Give examples of Kharif crops. Examples include Paddy (rice), Maize, Soyabean, and Cotton. Step 3: Define Rabi crops. These are the crops sown in the winter season, which is generally from October to March. Step 4: Give examples of Rabi crops. Examples include Wheat, Gram, Pea, and Mustard. Final answer: Kharif crops are grown in the rainy season (June-Sept) like Paddy and Maize, while Rabi crops are grown in the winter season (Oct-March) like Wheat and Gram.
• Q: A farmer wants to sow seeds in his field. Why would you recommend he use a seed drill over the traditional method of broadcasting (sowing by hand)? A: Step 1: Identify the advantages of a seed drill. A seed drill has several benefits over broadcasting. Step 2: Explain the first advantage - uniform sowing. The seed drill sows seeds at equal distances and proper depths. This prevents overcrowding and ensures each plant gets adequate sunlight and nutrients. Step 3: Explain the second advantage - protection. The seed drill covers the seeds with soil after sowing. This protects the seeds from being eaten by birds. Step 4: Explain the third advantage - efficiency. Using a seed drill saves time and labour as it is attached to a tractor. Final answer: I would recommend a seed drill because it sows seeds uniformly at a correct distance and depth, protects them from birds by covering them with soil, and saves time and labour.
• Q: Why is it necessary to store harvested grains properly? A: Step 1: Identify the threats to stored grains. Harvested grains, if not stored correctly, can be damaged by moisture, insects, rats, and microorganisms. Step 2: Explain the effect of moisture. If fresh grains are stored without drying, they have more moisture. This moisture promotes the growth of fungi and moulds, which spoil the grains and make them unfit for consumption or for use as seeds. Step 3: Explain the effect of pests. Pests like rats and insects can eat the grains, leading to a huge loss in quantity and quality. Step 4: Conclude the importance of proper storage. Therefore, grains must be properly dried in the sun to reduce moisture and then stored in sealed containers like jute bags or metallic bins (silos) to protect them from pests. Final answer: Proper storage is necessary to protect harvested grains from damage by moisture, which encourages fungal growth, and from pests like rats and insects, which eat the grains. This ensures the food supply remains safe and available for future use.
• Q: Manure is considered better than fertilisers in the long run. Explain why. A: Step 1: Recall the properties of manure. Manure is an organic substance that provides humus to the soil. Step 2: Explain the benefits of manure for soil health. Manure enhances the water-holding capacity of the soil. It makes the soil porous, which allows for easy exchange of gases for the roots. It also improves soil texture. Step 3: Mention the role of microbes. Manure increases the number of friendly microbes in the soil, which are essential for soil fertility. Step 4: Contrast with fertilisers. While fertilisers provide specific nutrients, their long-term use can degrade soil structure, reduce fertility, and cause water pollution. Manure, on the other hand, improves the overall health of the soil sustainably. Final answer: Manure is considered better than fertilisers in the long run because it improves soil health by adding humus, increasing water-retention, making the soil porous for root respiration, and encouraging the growth of beneficial microbes, all without causing pollution.

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