■ TYPES OF NUTRIENT CYCLES
◇ Based on the replacement period, a nutrient cycle is referred to as the Perfect or Imperfect cycle.
◇ A perfect nutrient cycle is one in which nutrients are replaced as fast as they are utilized.
◇ Most gaseous cycles are generally considered perfect cycles.
◇ In contrast, sedimentary cycles are considered relatively imperfect, as some nutrients are lost from the cycle and get locked into sediments, and so become unavailable for immediate cycling.
◇ Based on the nature of the reservoir, a nutrient cycle is referred to as the Gaseous or Sedimentary cycle.
◇ Gaseous Cycle: the reservoir is the atmosphere or the hydrosphere — water cycle, carbon cycle, nitrogen cycle, methane (compound) cycle, etc. and
◇ Sedimentary Cycle: the reservoir is the earth’s crust (soluble elements mostly found in earth’s crust) — phospho rous cycle, sulphur cycle, calcium cycle, magnesium cycle etc.
