{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Biology Chapter 26 - 26.1 Plant Nutrition and Soil 1 The...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
26.1 Plant Nutrition and Soil 1. The ancient Greeks considered plants "soil-eaters" that converted soil into plant tissue. 2. The 17 th Century Dutchman Jean-Baptiste Van Helmont conducted an experiment. a. He planted a five pound young willow tree in a pot with 200 pounds of soil. b. After five years of watering, the tree weighed 170 pounds but only a few ounces of soil was missing. c. He concluded the increase in tree weight came from water; he was unaware of substances in air. B. Essential Inorganic Nutrients 1. Approximately 95% of a plant's dry weight is carbon, hydrogen, and oxygen. a. Carbon dioxide is the source of carbon for a plant. b. Water is the source of hydrogen. c. Oxygen can come from either atmospheric oxygen, carbon dioxide, or water. 2. A mineral is an organic substance usually containing two or more elements. 3. To be classified as an essential nutrient , the following criteria must be fulfilled. a. It must have an identifiable nutritional role. b. No other element can substitute and fulfill the same role. c. A deficiency of the element causes the plant to die. 4. These elements are divided into macronutrients and micronutrients , according to their relative concentrations in plant tissue. 5. Beneficial nutrients are elements required for or to improve growth of a particular plant. a. Horsetails require silicon as a mineral nutrient. b. Sugar beets show better growth in the presence of sodium. c. Soybeans use nickel when root nodules are present. C. Determination of Essential Nutrients 1. When a plant is burned, most mineral elements (except for nitrogen) remain in the ash. 2. Hydroponics (water culture) is the preferred method for determining plant mineral requirements. a. Hydroponics is cultivation of plants in water. b. Nutrient requirements of plants are determined by omitting a mineral and observing the effects. c. If plant growth suffers, it can be concluded that the omitted mineral is a required nutrient. d. This works for macronutrients but impurities make micronutrient measurement difficult. D. Soil 1. Soil Formation a. Soil formation begins with weathering of rock by freezing, glacier flow, stream flow, and chemicals.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
b. Lichens and mosses grow on barren rock and trap particles and leave decaying tissues. c. Decayed organic matter ( humus ) takes time to accumulate; its acidity leaches minerals from rocks. d. Depending on parent material and weathering, a centimeter of soil may develop within 15 years. 2. The Nutritional Function of Soil a. Soil consists of mineral particles, decaying organic matter, living organisms, air and water. b. The best soil includes particles of different sizes; this provides critical air spaces. c. Mineral Particles i. Mineral particles vary in size. 1. Sand particles are largest: 0.05–2.0 mm in diameter. 2. Sand particles are medium sized: 0.002–0.05 mm in diameter.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}