Page 40 - Nutrient Management Planning Guide

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Soil Nutrient Cycling

There are sixteen mineral and non-mineral •

nutrients essential for plant growth. The non-mineral nutrients—carbon, hydrogen and oxygen—are taken up from air and water. The mineral nutrients are taken up from the soil and are classified as macro- or micronutrients: nitrogen, phosphorus, potassium, sulphur, calcium, magnesium (macronutrients), chlorine, iron, manganese, zinc, boron, copper and molybdenum (micronutrients). The law of the minimum states that crop •

productivity will be limited by the nutrient that is in shortest supply relative to its requirement.

Plants absorb ions from the soil through •

root interception, mass flow, and diffusion. Of these processes, mass flow is responsible for the majority of nutrient uptake. Nutrients exist in several pools. The crop •

available and exchangeable pools are most critical for meeting short-term crop needs. In most nutrient cycles the basic •

processes occurring are mineralization, immobilization, sorption, precipitation, weathering and losses.

summary