Describe the role of fertilisers in improving crop yield. Mention one adverse effect of excessive use of fertilizers.
Fertilizers provide three essential nutrients required by plants like nitrogen, phosphorus and potassium. The use of fertilisers has helped farmers to get better yield of crops such as wheat, paddy and maize.
However, in case fertilizer is used in excess, it causes significant issues. One of the main problems of excess fertilizer is water pollution. Nitrogen fertilizers break down into nitrates and travel easily through the soil. Being water-soluble it can remain in groundwater for many years. Groundwater contamination has been linked to gastric cancer, goitre, birth malformations, and stomach cancer.
Explain the various methods of weeding.
Farmers use many ways to remove weeds and control their growth.
Tilling before sowing of crops helps in uprooting and killing weeds, which may then dry up and get mixed with the soil. The best time for the removal of weeds is before they produce flowers and seeds.
The following tools may be installed
i. Khurpi - The Khurpi is used to remove of weeds by uprooting or cutting them from time to time.
ii. Seed Drill - A seed drill is also used to uproot weeds.
iii. Weedicides - Weeds are also controlled by using weedicides.
Describe the role of irrigation in improving crop yield. Mention any one effect of it if it is used in excess.
Irrigation provides water, necessary for the growth of plants and hence increases the crop yield.
If excess of irrigation water is used, then evaporation will deposit excessive salt on the surface of soil and decrease crop yield.
Why do the Governments in some countries impose restrictions on the import of plants? What are the advantages of having these restrictions removed?
The Governments in some countries impose restrictions on the import of plants because:
a. It hinders the research work going on in the country for the development of new, improved varieties of plants.
b. The imported plants may not suit the climate and soil conditions of the country.
c. The imported plants may bring with them some new pests and crop diseases in the country.
If the restrictions on the import of plants are removed, then the agricultural scientists of the country can cross-breed local plants with imported plants and produce new, improved, high yielding varieties of plants which are more suited to the local climate and soil conditions. This will lead to a tremendous increase in the food production in the country.
Is having loose soil good for plants? What will happen if the soil is too loose?
Loose soil is good for the plants since the roots of plants can penetrate easily in it. The loose soil also provides oxygen to the roots of plants through aeration. It also helps to bring the nutrient-rich soil to the top so that plants can use the nutrients.
However, if the soil is too loose then it will not be able to hold the roots of plants firmly enough for support and hence the plants may not stay erect and rooted to the soil. Too loose soil means that the water will drain through the soil and will not be available for the plants.