Why do plants require nutrients and how do humans supply those nutrients?
Plants require nutrients for its growth and developement, which are absorbed through the soil. The nutrient supplying sources are manure and fertilisers.
Manure is a product obtained after decomposition of organic matter like dung from barns and stables. These when added to the soil contribute to the fertility of the soil by adding humus and nutrients, such as nitrogen, that are trapped by bacteria in the soil.
Fertilisers are materials of natural or synthetic origin that is applied to soil to supply plant nutrients essential to the growth of plants. They mainly provide :-
Macronutrients: nitrogen, potassium and phosphorous.
Secondary macronutrients : calcium, magnesium, sulphur.
Micronutrients: copper, iron, manganese, molybdenum, zinc, boron,
silicon, cobalt, vanadium.
Manures and fertilisers improve soil structure so that the soil holds more nutrients and water and becomes fertile. They also enhance the effectiveness of the soil by modifying its water retention and aeration.
Manures increase soil microbial activity which promotes the soil trace mineral supply, improving plant nutrition assist plant growth.
Green manure are crops grown for the express purpose of plowing them in, thus increasing fertility through the incorporation of nutrients and organic matter into the soil.