Samacheer Class 8 Science - Crop Production and Management

Ploughing, also known as tilling, is an essential agricultural process that involves loosening and turning the soil upward and downward. This mechanical process breaks up compacted soil, making it more friable and workable for crop cultivation. The primary purpose of ploughing is to facilitate the availability and accessibility of nutrients in the root zone of the cultivating crop, allowing plant roots to easily penetrate the soil and absorb essential minerals and water. Ploughing also helps to bury weeds, crop residues, and organic matter into the soil, where they decompose and enrich the soil with nutrients. The process improves soil aeration by increasing pore spaces, which allows better water infiltration and root development. By turning the soil, ploughing brings nutrient-rich lower layers to the surface while burying less fertile upper layers, promoting overall soil fertility. This preparation of the soil through ploughing is a fundamental step in crop production that directly influences crop growth and yield.

Foliar spray is a technique of feeding plants by applying liquid fertilizer directly to their leaves. This method takes advantage of the fact that plants are able to absorb essential elements and nutrients through the stomata, which are tiny pores present in their leaves. When fertilizers are sprayed on the foliage, the nutrients can be rapidly absorbed through these stomata and transported throughout the plant, providing quick nutrient supplementation. Foliar spraying is particularly useful for providing micronutrients and for rapid nutrient uptake when plants show signs of nutrient deficiency. This method is more efficient than soil application in certain situations because the nutrients bypass the soil and are directly available to the plant tissues. Foliar spray can be applied during the growing season to boost plant growth and improve crop yield.

Krishi Vigyon Kendra, which translates to Agricultural Science Centre, is a farm science centre established to bridge the gap between agricultural research and farming practices. This centre serves as the ultimate link between the Indian Council of Agricultural Research (ICAR) and farmers, facilitating the transfer of scientific knowledge and modern agricultural technologies to farming communities. Krishi Vigyon Kendras operate small demonstration farms where new agricultural technologies, crop varieties, and farming techniques are tested under local conditions before being recommended to farmers. These centres provide practical training and education to farmers about improved farming methods and sustainable agricultural practices. They also provide valuable advisory services to farmers regarding weather forecasts and meteorological information, helping farmers make informed decisions about planting and harvesting times. Additionally, these centres offer guidance on crop pricing and market information, helping farmers understand market trends and make better economic decisions. By combining research, demonstration, training, and advisory services, Krishi Vigyon Kendras play a crucial role in improving agricultural productivity and farmer income.

A bio-indicator, also known as a biological indicator, is any species or group of species whose function, presence, or status reveals the qualitative condition and health of the environment. Bio-indicators are organisms that are sensitive to environmental changes and can reflect the overall ecological status of an area. Different organisms serve as bio-indicators for different types of environmental conditions. For example, certain aquatic organisms indicate water quality, lichens indicate air quality, and specific plant species indicate soil conditions. Bio-indicators help human beings in several important ways. They are used to document and understand changes in Earth's living systems, especially changes caused by the activities of an expanding human population such as pollution, habitat destruction, and climate change. By monitoring bio-indicator species, scientists and environmental managers can assess the impact of human activities on ecosystems without conducting expensive and time-consuming chemical analyses. Bio-indicators provide early warning signs of environmental degradation, allowing for timely intervention and conservation efforts. They help in monitoring the effectiveness of environmental protection measures and pollution control strategies. Bio-indicators also aid in identifying areas of environmental concern and in making informed decisions about environmental management and policy. The presence or absence of specific bio-indicator species can indicate the level of pollution, the health of ecosystems, and the overall environmental quality of a region.

Green manure is a technique in which certain plants such as sun hemp or guar are grown in the field prior to the sowing of the main crop seeds. These plants are then ploughed back into the soil where they gradually decompose and turn into organic matter that enriches the soil. This decomposed plant material acts as green manure and helps in enriching the soil with essential nutrients, particularly nitrogen and phosphorus, which are vital for plant growth. The application of green manure always enhances the growth, development, and yield of the subsequent crops grown in that field. This practice is an environmentally friendly way to maintain soil fertility without relying heavily on chemical fertilizers.

1. Soil preparation: (LoosenIng of top soil)
Ploughing – Process of loosening and turning the soil up and down to facilitate nutrient availability.
levelling – Done with leveller and helps in uniform distribution of water for irrigation
Basal Nianuring – Increase soil fertility by manuring
2. Sowing of seeds:
Hand – Scattering of seeds by hand.
Seed Drill – Sowing seeds by iron drills attached to a tractor.
Dibbling – Placing seed in furrow or pits or hole by hand.
3. Adding manure and fertilisers:
Manure is a substance added to the soil in the form of Nutrients to enhance plant growth.
Organic Sources – Plant and animal waste
Synthetic Sources – Urea, Super phosphate.
4. Irrigation:
Supply of water to crops:
Traditional method – Irrigation done manually.
Modem method – Involve two systems. Sprinkler system Drip system
5. Harvesting of crops:
Manual harvesting – Harvested without tools. Eg – Groundnut crop, green gram, black gram, house gram.
Mechanical method – Harvesting by instruments small sized farms Eg – Sickle.
Machine harvesting – Used for large sized farms.
6. Threshing and Winnowing:
Process of separating the grains from their chaffs or pods.
7. Storage:
Supply of the produce has to be stored properly.
Grains must be free from moisture to avoid growth of microorganism.
Need to be dried in Sun before storing.
Collected in Gunny bags and stored in go downs.

Irrigation:
The supply of water to crops at regular intervals is called irrigation.
Source of irrigation – Wells, tube wells, ponds, lakes, rivers, dams and canal.Traditional Methods:
Irrigation is done manually.
Here, a farmer pulls out water from wells or canals by himself or using cattle and carries to farming fields.
Pumps used for lifting water from various sources.
Diesel, biogas, electricity and solar energy are the sources of energy needed to run these pumps.
Modern Methods:
It helps to overcome the problems exist in the traditional methods.
It also facilitates the even distribution of moisture in the field.
Sprinkler system:
Sprinkles water over the crop and helps in an even distribution of water.
This method is advisable in areas facing water scarcity.
Pump is connected to pipes which generate pressure and water is sprinkled through the fine nozzles of pipes.
Drip System:
Here, water is released drop by drop exactly at root zone using a hose or pipe.
This method is effective one in regions where the availability of water is less.

Weed:
The undesirable plants may grow naturally along with the main crop, and these undesirable plants are called weeds.
Weeding:
The removal of weeds is called weeding. It is an important process because weeds compete with the crop plants for the nutrients, sunlight, water, space and other resources. It results in the undernourishment of crops and it leads to low yield.
Mechanical methods:
Here, weeds are destroyed physically.
Hand pulling or weeding with the help of weeding hole is the oldest and most efficient method for controlling weeds.
Tillage methods:
It is the practical methods of destroying weeds of all categories.
Weeds are buried in the soil and also exposed to Sun heat by deep ploughing.
Crop Rotation:
Proper rotation of crops is followed for controlling crop associated and parasitic weeds.
Summer tillage:
Deep ploughing after harvest of Rabi crop and exposing underground parts of weeds to strong sunlight during summer months is useful for destroying many annual and perennial weeds.
Biological weed control:
Bio agents like insects and pathogens are used to control weeds.
The objectives are not eradication, but reduction and regulation of the weed population.
Chemical methods:
Very effective in certain cases and have great scope in weed control.
The chemicals used for killing the weeds or inhibiting their growth are called herbicides.
Chemicals are mixed with water and sprayed over the crops.
Integrated weed management:
Integrated weed management combines different agronomic practices and herbicides use to manage weeds, so that the reliance on any one weed control technique is reduced.
Mechanical, biological, cultural and chemical methods are included in integrated weed managements.