The correct sequence for preparation of green manure is,
b) Green plants are cultivated for preparing manure or crop plant parts are used.
c) Plants are ploughed and mixed into the soil.
a) Green plant decompose in the soil
d) After decomposition it becomes green manure.
Manure is prepared by the decomposition of animal and plant. It helps to enrich the soil with essential nutrients and hence makes the soil fertile and rich in organic matter. It helps to increase the water holding capacity in sandy soils and avoids water logging in clayey soils. Some plants like guar are first grown on the cultivating fields and then mulched by ploughing them into the soil before sowing the crop seeds in order to replenish the soil with essential like nitrogen and phosphorus. This manure is called green manure.