ESS Agriculture/Soils

Describe some methods for raising soil pH to a neutral level

Add organic matter or cover crop Reduce tillage Rotate crops--reduce pests, incr nitrogen Manage N,P,K, salts (irrigation, fertilizers...) pH: Add "lime" which ↑pH, (lime=Ca,Mg) Add earthworms

What are monocultures are why are they problematic?

Monoculture is the agricultural practice of producing or growing a single crop, plant, or livestock species, variety, or breed in a field or farming system at a time lead to the quicker buildup of pests and diseases, depletes soil of necessary nutrients

What form of nitrogen do plants use?

Nitrate

Briefly what happens in each horizon? Where is the greatest organic matter found? Where does leaching occur and where are leached minerals deposited?

O=Organic matter, A=Surface Soil, B=Subsoil, C=Weathered Parent Rock, R=Bedrock. A=leaching, B=accumulation B= greatest organic material

Describe the events that lead to the formation of soil. What breaks down to form soil?

Parent Material, Climate, Biota, Time, Topography

How do we determine soil texture?

Particle size analysis breaks a soil into texture classes - sand, silt or clay. Soil texture influences nutrient retention, water storage and drainage. The soil textural triangle is used to determine soil type based on sand, silt and clay percentages.

What is soil permeability? Porosity? What is important about them?

Soil permeability is the property of the soil to transmit water and air. "Soil porosity" refers to the amount of pore, or open space between soil particles. Pore spaces may be formed due to the movement of roots, worms, and insects; expanding gases trapped within these spaces by groundwater; and/or the dissolution of the soil parent material.

What are the positive and negative results of the Green Revolution?

Green Revolution had negative effects on the environment and society. positive effects on food productivity, prices and quantity.

How do sand, silt and clay differ in their porosity and permeability and ability to hold nutrients?

loam best, clay, sand

What is the Green revolution and when did it begin?

1940-70 -people began using fertilizers and pesticides. Heavy irrigation, high yield crops. Food production was able to keep up with population growth. Selective breeding of crops and intensive farming.

What is nitrogen fixation and where does it occur?

Biological nitrogen fixation (BNF) occurs when atmospheric nitrogen is converted to ammonia by an enzyme called a nitrogenase. these bacteria are either free-living or form symbiotic associations with plants or other organisms (e.g. termites, protozoa)

What are the cause(es) and solution(s) for soil salinization?

Competition for fresh water: Domestic, Industrial, Ag uses Fresh 1%, Brackish 1%, Sea water 98% Spread of salinization: (esp in arid, LEDC) Irrigation can concentrate dissolved salts in the soil Forest clearance ; increase evap, draw salts to surface Seal-level Rise: encroachment of salt water into water tables. Currently 4 million km2 of salinized land (UNFAO) Solutions: Flood with fresh water: unavailable, low efficacy Halophytes: can thrive in varying levels of salinity Ex: oil-seed halophyte can compete w Sunflowers Biotechnology (GMO?) has so far not develop salt resistant forms of standard crops (rice, wheat, etc) Potential: Domestication and selective breeding of current halophytes.

How does adding organic material like compost beneficial to the soil? What does it provide?

Compost contains macro and micronutrients often absent in synthetic fertilizers. Compost releases nutrients slowly—over months or years, unlike synthetic fertilizers Compost enriched soil retains fertilizers better. Less fertilizer runs off to pollute waterways. Compost buffers the soil, neutralizing both acid & alkaline soils, bringing pH levels to the optimum range for nutrient availability to plants. Compost helps sandy soil retain water and nutrients. Compost loosens tightly bound particles in clay or silt soil so roots can spread, water drain & air penetrate. Compost alters soil structure, making it less likely to erode, and prevents soil spattering on plants—spreading disease. Compost can hold nutrients tight enough to prevent them from washing out, but loosely enough so plants can take them up as needed. Compost makes any soil easier to work.

What are rhiziobacteria and what is their relationship to Legumes (beans, alfalfa, soybeans, peanuts ...). Why are legumes considered an important crop for soil conditioning?

Enhance the N-supplying power of soils Increase the soil reserves of organic matter Stimulate soil biological activity Improve soil structure Reduce soil erosion by wind and water Increase soil aeration Improve soil water-holding capacity Make the soil easier to till

What is Eutrophication, what causes it to happen and where does it occur? Does it happen in marine ecosystems?

Eutrophication is the excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen. This can occur in ponds or lakes that get excessive fertilizer runoff, which feeds algae or other similar plants, allowing it to overbloom.

What is happening in the Gulf of Mexico?

Human activity in the Midwestern United States impacts not only the surrounding land but also the water in rivers and streams, which run all the way into the Gulf of Mexico. Scientists have identified several human actions, both historical and ongoing, that have contributed to major changes in the Gulf's waters and ecosystems. Each of these man made environmental changes has resulted in unnaturally high levels of specific nutrients, particularly nitrogen and phosphorus. This excess of nutrients in a body of water as a result of runoff is called eutrophication, and can often lead to hypoxia—the subsequent depletion of dissolved oxygen in the water.

What is Integrated Pest Management (IPM)? What is the Pesticide Treadmill?

IPM is an ecosystem-based strategy that focuses on long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, and use of resistant varieties. The pesticide treadmill is a term indicating a situation in which it becomes necessary for a farmer to continue using pesticides regularly because they have become an indispensable part of an agricultural cycle.

What agricultural practices characterize the Green Revolution?

Intensive farming

Why is it beneficial to leave crop residue on fields.

It is then converted to organic material that can be decomposed and used as nutrients in the soil.

Describe how soil leaching is related to aluminum mining in tropical regions.

Leaching usually refers to the movement of dissolved substances with water percolating through soil. Sometimes, leaching may also refer to the movement of soluble chemicals out of biological tissues, as when rainfall causes potassium and other ions to be lost by foliage. Aluminum poses no danger of environmental toxicity when soil pH remains at or above 5.0, however acid rain lowers the pH of soil and forces aluminum into solution. This causes it to leach into the water supply where it can damage root systems and create acidified lakes.

What kind of soil is the best for agriculture? Why?

Loam soil is considered as the best soil for agricultural purpose. The reason that loam soil is suitable for growing plants is because its texture has a combination of soil particles. The soil particles are sandy loams, silty loams, loamy sand and clay loams.

Will organic material make the soil more acidic or less acidic? Does that mean the pH went up or down?

More acidic, pH goes down

What are the benefits of no- or minimum-till practices? Cover crops? Adding biomass?

No till- allows soils to have larger pores. Cover crops- retain nutrients when crops are not in season. Biomass- decompose plant and animal residues and soil organic matter to release carbon dioxide and plant available nutrients

What does the term "Hypoxia" mean in a water ecosystem?

Oxygen deficiency in a biotic environment.

Describe the benefits and drawbacks of GMOs, based on facts and not perceptions

Pros Higher yielding crops Better quality crops Feed more people Can provide significant vitamins Prevent pests from disturbing them, reducing pesticides Cons Can maybe hurt other plants around them

What is golden rice and why is it controversial?

Rice with added Vitamin A for people in areas where it is missing in their diets. Helps save thousands of people from going blind, vastly improving their quality of life. People are afraid that it is putting bad/dangerous genes into rice, making it dangerous to eat.

What are soil horizons?

Soil Layers

What technological advances enabled the Green Revolution?

This trend resulted from the introduction of hybrid strains of wheat, rice, and corn (maize) and the adoption of modern agricultural technologies, including irrigation and heavy doses of chemical fertilizer.

What is the role of the USDA, FDA, EPA? What are those acronyms? Explain why all three are involved in the regulation of GMOs.

US Department of Agriculture (USDA) The Environmental Protection Agency (EPA) Food and Drug Administration (FDA) -approved by food administration for health concerns -EPA impact on environment -impact on agriculture

Beyond organic matter and soil texture, what other physical and chemical factors contribute to soil quality? (For ex: pH, aggregates, etc.). List them and describe why they are important.

Water- is a soil component that introduces the moisture and nutrients required to sustain living organisms, the chemicals that affect soil composition and the erosion factors that modify or even wash away the soil. Human and animal interaction -affect quality in shockingly brief periods of time. Chemicals and substances- introduced to the soil are a recursive factor. As water is the major transport medium for adding chemical components to large tracts of fertile soil, anything that washes down to change the composition of the water comes back to change the composition of the soil that when the same water is re-applied to it. (Fertilizers and waste) Overuse of land and over harvesting.

What are the primary Soil MACRONUTRIENTS? What are the main components of chemical fertilizers?

a)nitrogen, phosphorus, potassium,calcium, magnesium, and sulfur b) Nitrogen, phosphorus, potassium

What is the diversity in soil microbes?

bacteria, fungi, viruses

How would the soil in a tropical rainforest differ from the soil in the floodplain of a fertile valley (the Ganges river in India is a great example). How would the soil of a deciduous forest in Colorado compare? Which would be the best for growing crops?

floodplain= deep fertile soils Tropical rainforest= shallow low nutrient soils mountainside= easily depleted soil

What is the importance of soil microbes? Describe some specific functions they provide?

make nutrients available to plants, cycle N,P,K between organic matter and environment, support food webs for invertebrates, regulate soil borne diseases of plants and animals, provide balance to soil composition by purifying chemicals, affect carbon content in soils

Where are the largest reservoirs (aka: storages or sinks) for Nitrogen? Carbon? Phosphorus? Which cycles have gas phases?

nitrogen- atmosphere carbon-surface of the earth phosphorus- sedimentary rock Gas phases: Carbon, Nitrogen

What practices cause a decline in soil microbes?

over tillage, over use of land, monoculture