Gujarat BoardEnglish MediumSTD 9ScienceNatural Resources3 Marks
Question
Name the partially decayed organic matter of soil. Mention its functions.
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Answer
Soil organic matter - the product of on-site biological decomposition - affects the chemical and physical properties of the soil and its overall health. Its composition and breakdown rate affect the soil structure and porosity; the water infiltration rate and moisture holding capacity of soils; the diversity and biological activity of soil organisms; and plant nutrient availability. Many common agricultural practices, especially ploughing, disc-tillage and vegetation burning, accelerate the decomposition of soil organic matter and leave the soil susceptible to wind and water erosion. However, there are alternative management practices that enhance soil health and allow sustained agricultural productivity. Conservation agriculture encompasses a range of such good practices through combining no tillage or minimum tillage with a protective crop cover and crop rotations. Function of organic matter in soil: Organic matter contributes to plant growth through its effect on the physical, chemical, and biological properties of the soil. It has a:
nutritional function in that it serves as a source of $N$, P for plant growth.
biological function in that it profoundly affects the activities of microflora and microfaunal organisms.
physical and physico-chemical function in that it promotes good soil structure, thereby improving tilth, aeration and retention of moisture and increasing buffering and exchange capacity of soils.
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