1 Interfering with Natural Cycle Section 1:10 pp. 32-33

1

Interfering with Natural Cycle

Section 1:10

pp. 32-33

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Define Fertilizers

Fertilizers are materials that restore or add nutrients to soil. They are used to increase production from the land and may be natural (manure) or synthetic (chemical).

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Fertilizer Use

Plants contain valuable nitrogen. When we harvest and eat plants, this valuable nitrogen often does not get returned to the ecosystem and thus there is a break in the nitrogen cycle.

The greatest human-driven increases in global nitrogen is for food production.

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Fertilizer Use

Humanity requires intensive agriculture to support a growing population.

The highest rates of application are now found in some developing countries with the highest rates of population growth.

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Effects on the Carbon Cycle...

Thanks to the fertilizer effects of nitrogen in stimulating plant growth, global carbon cycle may be indirectly altered.

Human activity has substantially increased the deposition of nitrogen.

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Effects on the Carbon Cycle...

Fossil fuel burning and deforestation has resulted in excessive amounts of carbon dioxide.

Could this help explain the imbalance in the carbon cycle that has come to be known as the ‘missing sink.’

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What is pH?

pH is a measure of how acidic or basic a substance is.

Acidic and basic are two extremes that describe chemicals, just like hot and cold are two extremes that describe temperature.

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What is pH?

Mixing acids and bases can cancel out their extreme effects, much like mixing hot and cold water can even out the water temperature. A substance that is neither acidic nor basic is neutral

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pH Scale

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pH Scale

The pH scale measures how acidic or basic a substance is. It ranges from 0 to 14.

A pH of 7 is neutral. A pH less than 7 is acidic, and a pH greater than 7 is basic.

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Pure Water

Pure water is neutral, with a pH of 7.0.

When mixed with water, the mixture can become either acidic or basic.

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Examples of Chemicals

Vinegar and lemon juice are acidic substances.

Laundry detergents and ammonia are basic.

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Dangerous Acids and Bases

Chemicals that are very basic or very acidic are called "reactive."

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Examples

Automobile battery acid is reactive. Automobile batteries contain a stronger form of some of the same acid that is in acid rain.

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Examples

Household drain cleaners often contain lye, a very alkaline chemical that is reactive.

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Changing the pH of Soil

In soil, bacteria change the nitrogen found in fertilizers into nitrates which are then used by plants. If there are large amounts of nitrates, this may result in large amounts of nitric acid.

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Large amounts of nitric acid in the soil results in a decrease in the pH of the soil. Changes in the acid content of the soil affects all living organisms such as worms and bacteria which require a certain pH in which to live.

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As fertilizers are applied to soils over the years, the pH of the soil will change drastically.

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For example, most grassland soils in Canada's prairies have a pH of 7 and if the pH were to drop to 6, then certain plants such as barley would not grow as well.

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Environmental Problems.....Algal Blooms

The accumulation of nitrogen and phosphate fertilizers can result in algal blooms in lakes and ponds during spring runoff.

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As spring runoff carries rotting plant material and fertilizer rich soil into streams and lakes, the nutrients provide an abundance of food for algae living in the water.

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If temperatures are warm, this results in a large growth in algae known as an algal bloom. When the algae die, bacteria use oxygen from the water to decompose them which results in less oxygen for fish and other animals.

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As a result, the population of fish and other animals will begin to decrease. Dying fish and other animals will then result in even less oxygen as bacteria use up this oxygen breaking down their dead bodies.

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Human Health and the Nitrate problem....

Nitrates are a wide spread contaminant of ground and surface waters worldwide Nitrate is a potential human health threat especially to infants, causing the condition called "blue baby syndrome".

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Chronic consumption of high levels of nitrate may also cause other health problems such as cancer.

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In addition, high nitrate levels in water and feed lead to reduced vitality and increased stillbirth, low birth weight, and slow weight gain in livestock .

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Organic Farming

As people become more aware of the connection between their food choices and their health as well as the health of the environment, organic food has become one of the fastest growing trends in the food industry.

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Organic vs. Inorganic fertilizers

There has been much controversy over organic versus inorganic fertilizers. Plants do not recognize the difference between organic and inorganic fertilizers. Their tiny root hairs can absorb only nutrients that have been broken down into inorganic, water-soluble forms.

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Organic Fertilizer (Advantages)

Include such things as cow, sheep, poultry and horse manure.

Less danger of over-fertilization Organic material improves soil

structure or "workability" immensely and improves the water-holding capacities of sandy soils.

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Organic Fertilizer (Disadvantages)

Organic fertilizer cannot supply immediate need for nutrients.

Organic fertilizer such as manure is not readily available to the home gardener.

Possible nitrogen depletion is another drawback of organic fertilizers.

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Inorganic Commercial Fertilizer

Advantages The primary advantage is that

nutrients are immediately available to the plants.

As well, the exact amounts of a given element can be calculated and given to plants.

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Inorganic Commercial Fertilizer

Disadvantages Easily washed below the level of the

plant's root system.May cause "burning“ if to close to

roots.Toxic concentrations of salts in the

soil if to much used.

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1 Interfering with Natural Cycle Section 1:10 pp. 32-33