Soil and Plant Nutrition

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Erosion of soil causes loss of nutrients.

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Contour tillage helps reduce soil erosion

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Erosion can be reduced by:

Planting trees as windbreaks

Terracing hillside crops

Cultivating in a contour pattern

Practicing no-till agriculture.

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Preventing Soil Compaction

Soil compaction from heavy equipment reduces pore space between soil particles.

Soil compaction slows gas exchange and reduces root growth.

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Phytoremediation

Some areas are unfit for agriculture because of contamination of soil or groundwater with toxic pollutants.

Phytoremediation is a biological, nondestructive technology that reclaims contaminated areas.

Plants capable of extracting soil pollutants are grown and are then disposed of safely.

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Concept 37.2: Plants require essential elements to complete their life cycle

Plants derive most of their organic mass from the CO2 of air, but they also depend on soil nutrients such as water and minerals.

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Macronutrients and Micronutrients

A chemical element is considered an essential element if it is required for a plant to complete its life cycle.

Nine of the essential elements are called macronutrients because plants require them in relatively large amounts. The macronutrients are carbon, oxygen, hydrogen, nitrogen, phosphorus, sulfur, potassium, calcium, and magnesium.

Eight of the essential elements are called micronutrients because plants need them in very small amounts. These are chlorine, iron, manganese, boron, zinc, copper, nickel, and molybdenum.

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Hydroponic culture - used by researchers to determine which chemical elements are essential

TECHNIQUE

Control: Solution

containing all minerals

Experimental: Solution

without potassium

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The 17 Essential Elements = Micro- and Macro- Nutrients

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Symptoms of Mineral Deficiency

Symptoms of mineral deficiency depend on the nutrient’s function and mobility within the plant.

Deficiency of a mobile nutrient usually affects older organs more than young ones.

Deficiency of a less mobile nutrient usually affects younger organs more than older ones.