Micro-organisms survive under adverse conditions. How?
Differentiate between fertilizers and manure.
What are weeds? How can we control them?
Answers
Answer:
Explanation:
Micro-organisms survive under adverse conditions.
Bacteria, fungi and lower plants survive in adverse conditions through formation of thick walled spores. Algae form resting spore or akinetes which are thick walled spores and store food material. In fungi, thick walled perennating spores called chlamydospores are formed. Bacteria form endospores which is probably the most resistant living thing known. They may remain alive in boiling water for more than 2 hours.
differences between fertilizer and manure are:
1. Fertilizer is an inorganic chemical synthesized artificially while manure is a combination of inorganic and organic substances obtained naturally by decomposing cattle excreta, plant litter, and human wastes.
2. Fertilizer can add only a specific nutrient to the soil whereas manure can provide many useful nutrients.
3. A fertilizer cannot add humus to the soil whereas manure can.
What are weeds? How can we control them?
1.Weeds are unwanted and uncultivated plants that grow with crops and compete with crops for nutrients and can also cause crop toxification. 2.Weeding is removal of weeds and is mostly done before flowering begins in crop plants.
3. It is done using trowel, harrow or weedicides. Trowel is used in manual removal of weeds. Ploughing/tilling of soil, before seed sowing, using plough or cultivar followed by breaking the left over soil crumps using leveller also removes the weeds. Similarly, use of weedicides, the chemicals that control the growth of weeds, is also practised.