GSEB Solutions for Class 7 Science and Technology – Fertility of the Soil (English Medium)
Soil is an important resource as we obtain everything directly or indirectly from it. E.g. food, shelter, clothing, etc. Soil helps in proper methods of irrigation of agricultural land. It also helps in construction purposes.
Soil-testing is a process in which purity of the soil, nutrient content and other characteristics are kept in check by removing some elements like magnesium, sulphur, manganese, magnesium and copper.
- By calculating the soil pH.
- By checking the availability of potassium content.
- The relative amounts of sand, silt, and clay are estimated by the feel of the soil in moist condition.
Soil tests should be taken before planting and at regular intervals once plants are established. For example, we can test sandy-textured soils every 2 to 3 years and clay soils every 3 to 4 years.
- The nutrients that are lacking, or are excessive in the soil can be identified.
- Fertilizer costs are reduced.
- It maintains an accurate balance of plant nutrients.
- It adjusts soil pH.
Ploughing is the process of breaking, loosening and turning the soil over for uprooting weeds and aerating the soil.
- Brings fresh nutrients to the surface.
- Loosens soil so that roots can penetrate easily.
- Promotes aerobic microorganisms to increase fertility of the soil.
Plough, Hoe and Cultivator are the equipments used for ploughing.
The process of scattering seeds in the soil for growing crop plants is called sowing.
- Seeds should be sown at the right depth in the soil suitable for germination.
- Seeds should be sown at right intervals or spacing in the field.
- Seeds should not be sown in dry soil.
Claw-wheels and Seed drills are used during sowing.
Wild and undesirable plants which grow in crop fields and compete with crops for space, soil, nutrients, water and sunlight are called weeds.
- Compete with crops for available resources.
- Can be responsible for spreading diseases.
- Provide hideouts for rats and snakes.
- Weeds can be removed by pulling them with hands.
- They can be removed by digging or cutting them with harrow and hoe.
- Weeds can also be removed by spraying weedicides such as 2, 4 – D.
Crop rotation is the practice of growing different crops in each season in a particular field. It is required because –
- It allows soil to recover its lost nutrients.
- It helps to control pests, weeds and diseases.
- It improves the fertility of the soil.
Crops of Maize, Cabbage, Beans and Tomato can be rotated.
Alternative crops may also be defined as rarely used varieties or breeds of common crops due to potential high sale value or specialized benefit to the farming system.
- Improves soil condition.
- Reduces disease or insect problems.
- Enhances environmental sustainability.
Barley, Moong beans, Peanuts, Sesame and Soybeans are alternative crops.
- Increase the water holding capacity of the soil.
- Improve the soil texture.
- Increase the number of useful microbes in the soil.
- Provide quick replenishment of plant nutrients in the soil.
Manures, Compost and Green manure can be used as fertilizers in agricultural fields
Organic fertilizers like cottonseed meal, molasses, compost tea, manure and bone meal can also be used as fertilizers.
- They are more expensive than natural fertilizers.
- They may be toxic to human beings and animals.
- They can cause imbalance in the soil texture.
- They may decrease the fertility of the soil.
- Stimulate plant growth.
- Contain balanced quantity of nitrogen and potassium that are needed for optimum plant growth.
- Protect from insects, bugs and diseases.
- Practising crop rotation.
- Proper use of manures and fertilizers.
- Removing weeds in regular intervals.
- Increased use of organic farming.
Crop protection is the practice of managing pests, plant diseases, weeds that damage agricultural crops and forestry. The approach can be
- Biological pest control.
- Use of herbicides, insecticides and fungicides.
- Biotechnological applications like plant breeding.
Natural fertilizers are produced from nitrogen, phosphates and potassium.
We can also make natural fertilizers ourselves by using compost and manure tea.
Compost can be made at home out of leftover food items and other detritus and is virtually cost free. Composting, or even compost tea, may be all one needs for a successful crop.
In order to keep our house and classroom free of dust and harmful microorganisms, we clean them daily.
While cleaning the floor, we see dust particles, sand, various wastes from kitchen and other rooms.
The soil and the dust particles come from the outside air and soil.
Due to the closed surface area of the tray, the soil particles become wet and strong.
No, the soil particles remain together.
Due to the sloping surface, the water along with soil particles flows downwards.
Normal water was poured on the cardboard.
Water mixed with soil accumulated in the pan.
The water in the pan becomes turbid due to removal of soil particles.
Due to flow of water with the sand particles, sand came into the pan.
- Clean water is collected in the beaker with grass.
- Turbid water is collected in the beaker with steps.
- Clean water is collected in the beaker having only soil.
The third beaker has the cleanest water.
The first beaker has the most turbid water.
The soil filled with grass shows least soil erosion.
The soil flowing directly downwards in the first beaker shows most soil-erosion.
- The trees and plants block the soil from becoming soft and hold the soil in place.
- The roots of the trees drink water from the soil; so that, there is less chance of flooding in the area.
- The tree roots act like netting and protect the soil from erosion.
- Planting more trees.
- Applying fertilizers to the soil which will assist the soil to soak in water slowly and will lessen the impact of rainfall.
- Increasing vegetation and intercropping.
- Control of grazing and by providing proper drainage system in the fields.