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green revolution

1) developing plant monocultures of selectively bred high-yield varieties of key crops (rice, wheat, corn) 2) producing high yields by using large inputs of fertilizer, pesticides, and water on the crops 3) increasing the number of crops grown per year on a plot of land through multiple cropping

Food production

1st green rev (1920s-60s) = fertilizer, pesticides, gas engine, irrigation 2nd green rev (1970s-present) = GM foods increase nutrition & yield, increased crop yield feeds more people, less malnutrition, yet practices destroy landscape & more people use more resources meat production = vast resources & waste

Glyphosate

A broad-spectrum systemic herbicide used to kill weeds, especially annual broadleaf weeds and grasses known to compete with commercial crops grown around the globe. Discovered to be a herbicide by Monsanto in 1970 and marketed as "Roundup."

Long Line Fishing

A commercial fishing technique that uses a long line, called the main line, with baited hooks attached at intervals by means of branch lines called "snoods". •Used for specific species of fish •Limit on number of hooks to use, aids in the prevention of overfishing (25 hooks) •A lot of by catch

overnutrition

A condition of excessive food intake in which people receive more than their daily caloric needs.

Anemia

A decrease in number of red blood cells (RBCs) or less than the normal quantity of hemoglobin in the blood.

Drift nets

A fishing technique where drift nets, are allowed to float freely at the surface of a sea or lake. •Very cost effective •Can be used by low-powered ships making it fuel effective •A lot of by-catching •Made illegal in certain places because of overfishing •Lost or abandoned nets damge sea environment

Chronic

A human health condition or disease that is persistent or otherwise long-lasting in its effects.

1985 Food Security Act

A n Act to extend and revise agricultural price support and related programs, to provide for agricultural export, resource conservation, farm credit, and agricultural research and related programs, to continue food assistance to low-income persons, to ensure consumers an abundance of food and fiber at reasonable prices, and for other purposes.

Croplands

Land that is suited to or used for growing crops.

Iodine

Micronutrient vital for good thyroid gland hormonal body regulation, which in turn is essential for health. Deficiency during pregnancy and early infancy can result in preventable brain damage and severe motor impairments. Goiter, an enlarged thyroid gland visible between the Adam's apple and the collar bone, is often present.

Glyphosphate Resistant Crops

Monsanto genetically engineered and introduced glyphosate-resistant crops, enabling farmers to kill weeds without killing their crops. Weed resistance to glyphosate is a growing problem

geneticially modified organisms (GMOs)

Living things that have undergone genetic engineering for the purposes of self betterment. Generally done to improve the quality of foods.

Biofuel

Made by a biomass conversion (biomass refers to recently living organisms, most often referring to plants or plant-derived materials). This biomass can be converted to convenient energy containing substances.

Spoil Conservation

Methods used to reduce soil erosion, prevent depletion of soil nutrients, and restore nutrients previously lost by erosion, leaching and excessive crop harvesting.

Compost

Partially decomposed organic plant an animal matter used as a soil conditionaer or fertilizer.

Herbicide

Pesticides used to kill unwanted plants.

Terracing

Planting crops on a long, steep slope that has been converted into a series of broad level steps with short vertical drops from one to another that run along the contour of the land to retain water and reduce soil erosion.

traditional intensive agriculture

Producing enough food for a farm family's survival and perhaps a surplus that can be sold. This type of agriculture uses higher inputs of labor, fertilizer, and water than traditional subsistence agriculture. See traditional subsistence agriculture. Compare industrialized agriculture.

Windbreaks

Rows of trees or hedges planted to partially block wind flow and reduce soil erosion on cultivated land

Groundwater depletion

Source of many conflicts, legal and violent, worldwide -Ogallala Aquifer in the Great Plains has been depleted by farmers in the Midwest

Bioaccumulation

The selective absorption and concentration of molecules by cells

Night Blindness

Vitamin A deficiency. This affliction makes it impossible to see in dim light, and sufferers become completely blind when night falls.

Scurvy

Vitamin C deficiency. Scurvy causes lethargy, skin spots, bleeding gums, loss of teeth, fever, and death.

Rickets

Vitamin D deficiency. Rickets causes muscles and bones to become soft, which can cause permanent deformities in children.

pastureland

a managed field covered with grass or herbage and suitable for grazing by livestock

Hydroponics

a method of growing plants using mineral nutrient solutions , in water, without soil

genetic engineering (gene splicing)

is the alteration of an organism's genetic material, through adding, deleting, or changing segments of its DNA to produce desirable traits or eliminate undesirable ones.

tradition subsistence agriculture

only make enough for themselves and their families

crop rotation

plating a field with different crops from year to year to reduce soil nutrients depletion. rotating corn or cotton, which removes large amounts of nitrogen from the soil with soybeans which then add nitrogen to the soil

agroforestry

system where harvestable trees are grown around crops or on pastureland as means of preserving the productivity of the land

monoculture

the cultivation of a single crop

rangeland

Land that is not intensively managed and is used for grazing livestock

Animal Manure

Material, especially barnyard or stable dung, often with discarded animal bedding, used to fertilize soil.

Community Supported Agriculture, CSA

Members or subscribers pay at the onset of the growing season for a share of the anticipated harvest; once harvesting begins, they receive weekly shares of vegetables and fruit, in a vegetable box scheme.

Iron

Micronutrient that is a part of all cells and does many things in our bodies. For example, (as part of the protein hemoglobin) carries oxygen from our lungs throughout our bodies. Having too little hemoglobin is called anemia. This element also helps our muscles store and use oxygen.

CITES

The Convention on International Trade in Endangered Species of Wild Fauna and Flora. Its aim is to ensure that international trade of wild animals and plants does not threaten the survival of the species in the wild.

Pheromones

a secreted or excreted chemical factor that triggers a social response in member of the same species. They may signal alarm, food trail or act as sex attractants

Goiter

a swelling of the neck or larynx resulting from enlargement of the thyroid gland (thyromegaly), associated with a thyroid gland that is functioning properly or not. Worldwide, over 90.54% cases of goitre are caused by iodine deficiency

Bottom Trawling

a technique where a net is "towed" along the sea floor. •Gets a great deal of fish in less time •Blames for much of the overfishing •Destroys much of the sea life because of overfishing effects

plantation

a tropical agriculture system that is export oriented. the local governenment and foreign/international companies exploit the natural resources of the tropical rain forest for profit, usually short-term economic gain. it involves introduction of economically desirable species of tropical plants at expense of widespread replacment of original native and natural flora. plantation practices include modifications of natural landscape though such artifical practices as the permanent removal of natural vegetation, changes in drainage channels, application of chemicals to the soil, and so on.

green revolution

first one occured between 1950-1970. involved planting monocultures, using high applications of inorganic fertilizers and pesticides, and widespread use of artificial irrigrations systems. before the first one, crop production correlated with increasesin acreage under cultivation. after the first revolution, crop acreage increased about 25%, but crop yield increased 200%. crop yield then reached a plateau since it was easir and more economical to inrease crop production through various agriculture techniques

interplanting

growing two different crops in an area at the same time. to interplant successfully, plants should have similar nutrient and moisture requirements

Benthic

The bottom of a sea or lake

By Catch

The catching of any undesired fish or animals (i.e. in bottom trawling, collecting Cod fish and catch many seaturtles in the process)

C-horizon

The layer of a soil profile immediately below the B horizon and above the bedrock, composed of weathered rock little affected by soil-forming processes

industrial agriculture or corporate farming

system characterized by mechanization, monocultures, and use of synthetic inputs such a chemical fertilizers and pesticides, with an emphasis on maximizing productivity and profitability

sustainable yield

the highest rate at which a renewable resource can be used indefinitely without reducing its available supply

NPK

the key macronutrients rated in every commercially available fertilizer as given as percentages

Multicropping

the practice of growing two or more crops in the same space during a single growing season.

Persistence

the tendency of a pollutant or pesticide to stay in the air, water, soil or body before breaking down into harmless substances

Parent Material

the underlying geological material (generally bedrock or a superficial or drift deposit) in which soil horizons form

Polyaquaculture

these operations raise fish and shrimp along with algae, seaweed and coastal lagoons, ponds and tanks. The waste form the fish feed the aquatic plants

intercropping

to grow more than one crop in the same field, especially in alternating rows or columns

polyculture

uses different crops in the same space in imiation of the diversity of natural ecosystems, and avoids large stands of a single crop. uncludes crop rotation multicropping, intercropping, and alley cropping. requires more labor, several advantages over monoculture. the diversity of crops avoids susceptibility of monoculture to disease. the greater variety of crps provides habitat for more species, increasing local biodiversity

industrialized (high input) agriculture

uses heavy equipment and large amounts of financial capital, fossil fuel, water, commercial fertilizers, and pesticides to produce single crops, or monocultures.

How does bottom trawling affect benthic organisms?

•Ruins their environment (coral reefs) •Takes away the organisms that "cleaned" the a habitat (unbalancing the ecosystem)

high-input agriculture

includes the use of mechanized equipment, chemical fertilizers, and pesticides

Marginal Land

land that is found on the edge of cultivated areas and is often difficult to grow crops on

alley cropping

method of planting craps in strips with rows of trees or shrubs on each side. it increases biodiversity, reduces surface water runoff and erosion, improves utililization of nutriens, reduces wind erosion, modifies microclimate for improved crop production, improves wildlife habitat, and enchances the aesthetics of the area

low-till, no-till, or conservation-till agriculture

soil is distrurbed little or not at all to reduce soil erosion. has lower labor costs, reduces the need for fertilizer, and saves energy

malnutrition

deficiencies of proteins and other key nutrients

low input

depends on hand tools and natural fertilizers; lacks large-scale irrigation

Humus

Slightly soluble residue of undigested or partially decomposed organic material in topsoil. This material helps retain water and water soluble nutrients, which can be taken up by plant roots.

Soil conservation

Soil conservation techniques include terracing, contour farming, strip cropping, cover crops, agroforestry, and windbreaks

Soil erosion

Soil erosion causes include tilling before winter and fertilizers which reduce water holding capacity of soil

O-Horizon

Soil layers with a high percentage of organic matter. Typically within a woodland area there are three distinct organic layers: one of leaves, pine needles and twigs (Oi); underlain by a partially decomposed layer (Oe);and then a very dark layer of well decomposed humus (Oa).

B-horizon

That layer of soil in a well-developed soil lying immediately below the A-horizon, and which contains deposits of organic matter leached from surface soils.

Waterlogging

Too much water underground, lowering plant productivity and eventually killing plants with prolonged exposure

Exclusive Economic Zone

Under the law of the sea, a seazone over which a state has special rights over the exploration and use of marine resources (i.e production of energy from water and wind) It stretches from the seaward edge of the state's territorial sea out to 200 nautical miles from its coast.

Beriberi

Vitamin B1 (thiamine) deficiency. Beriberi is a disease whose symptoms include weight loss, body weakness and pain, brain damage, irregular heart rate, heart failure, and death if left untreated.

Hypocobalaminemia

Vitamin B12 deficiency. It causes gradual deterioration of the spinal cord and very gradual brain deterioration, resulting in sensory or motor deficiencies. Mental disorders from the gradual brain damage begin as fatigue, irritability, depression, or bad memory. As the disease progresses over several years, psychosis and mania can appear. This damage is irreversible and is caused by a deficiency in vitamin B12.

Ariboflavinosis

Vitamin B2 (riboflavin) deficiency. This condition is present mostly in people who suffer from malnutrition and in alcoholics. It causes distinctive bright pink tongues, although other symptoms are cracked lips, throat swelling, bloodshot eyes, and low red blood cell count. Ultimately it can cause comas and death.

Pellagra

Vitamin B3 (niacin) deficiency. Symptoms included diarrhea, dermatitis, dementia, and finally death.

Paraesthesia

Vitamin B5 (Pantothenic acid) deficiency. A deficiency in vitamin B5 causes chronic paraesthesia. Paraesthesia is most familiar to us as the numbing sensation we feel as 'pins and needles' or a limb 'falling asleep'.

plantation agriculture

raising a large amount of a "cash crop" for local sale or export

aguaculture

raising and harvesting fish and marine life in ponds or other bodies of water

Fungicide

Chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores.

fish farming

Form of aquaculture in which fish are cultivated in a controlled pond or other environment and harvested when they reach the desired size.

Meatrix

Agribusiness practices include antibiotics, pesticides, space constraints, mistreatment, conglomerate ($, GMO), algae, insects, test tube meat, soylent green (?), wall e https://www.youtube.com/watch?v=rEkc70ztOrc

sustainable (low input) agriculture (AKA organic farming)

Agriculture that has a minimal/no impact on the land. It is often thought that these foods are healthier or safer in some way.

1985 Food Security Act

An Act to extend and revise agricultural price support and related programs, to provide for agricultural export, resource conservation, farm credit, and agricultural research and related programs, to continue food assistance to low-income persons, to ensure consumers an abundance of food and fiber at reasonable prices, and for other purposes.

Rachel Carson

An American marine biologist and conservationist whose book Silent Spring and other writings are credited with advancing the global environmental movement by alerting the nation to environmental problems such as DDT.

Marine Mammal Protection Act

An act which prohibits (with certain exceptions) the taking marine mammals in U.S. waters and the import, export and sale of any marine mammal along with any marine mammal part or product within the United States, with the goal of managing and conserving the marine ecosystem.

Cash Crop

An agricultural crop which is grown for sale to return a profit.

Biomagnification

An increase in concentration of certain stable chemicals in successively higher trophic levels of a food chain. Ex. : A little fish eats plankton that has tiny amounts of mercury in it, the mercury eventually accumulating in its body. If the mercury makes the little fish stay very small, the bigger fish has to eat more little fish to stay alive. More little fish, more mercury.

agrofrestry (alley cropping)

An integrated approach of using the interactive benefits from combining trees and shrubs with crops and/or livestock. It combines agricultural and forestry technologies to create more diverse, productive, profitable, healthy, and sustainable land-use systems.

Omnivore

An organism that eats both plants and animals

Herbivore

An organism that eats only plants

Cover Crop

Easy to plant species that require only basic care to thrive, these crops suppress weeds, build productive soil, and help control pests and diseases.

Acute

Experienced to a severe or intense degree.

fish ranching

Form of aquaculture in which members of a fish species such as salmon are held in captivity for the first few years of their lives, released, and then harvested as adults when they return from the ocean to their freshwater birthplace to spawn.

Soil Erosion Act of 1935

Franklin Roosevelt signed this into law with the express purpose of encouraging the use of soil resources in such a manner as to preserve and improve fertility, promote economic use, and diminish the exploitation and unprofitable use of the national soil resources

Green Manure

Freshly cut or still-growing green vegetation that I plowed into the soil to increase the organic matter and humus available to support crop growth.

Agrobiodiversity

Includes all forms of life directly relevant to agriculture: rare seed varieties and animal breeds (farm biodiversity), but also many other organisms such as soil fauna, weeds, pests, predators, and all of the native plants and animals (wild biodiversity) existing on and flowing through the farm. However, most attention in this field is given to crop varieties and to crop wild relatives.

Aquaculture

Includes the production of seafood from hatchery fish and shellfish which are grown to market size in ponds, tanks, cages, or raceways.

Commercial Inorganic Fertilizer

Industrially prepared mixture of nitrate, phosphates and potassium applied to the soil to restore fertility and increase crop yields.

Genetic Engineering

Insertion of an alien gene into an organism to give it a beneficial genetic trait.

IPM

Integrated pest management is a multi-pronged way to kill crop pests Biological pest control: using ladybugs to eat aphids Using cats to eat rodents Modern organophosphate/chlorinated hydrocarbons-pesticides in moderation crop rotation-allow nutrients to replenish Hormones that disrupt mating of insects Genetically engineered crops can withstand pests/pesticides

Strip Cropping

Planting regular crops and close-growing plants, such as hay or nitrogen-fixing legumes, in alternating rows or bands to help reduce depletion of soil nutrients.

Contour Planting

Plowing and planting across the changing slope of land, rather than in straight lines, to help retain water and reduce soil erosion.

Green Revolution

Popular term for the introduction of scientifically bred or selected varieties of grain (rice, wheat or corn) that with adequate inputs of fertilizer and water , can greatly increase crop yields

Top Predator

Predators that have no predators of their own, residing at the top of their food chain

Traditional Subsistence Agriculture

Production of enough crops or livestock for a family's survival and, in good years, a surplus to sell or put aside for hard times.

Traditional Intensive Agriculture

Production of enough food for a farm family's survival and perhaps a surplus that can be sold.

Industrialized Argiculture

Production of large quantities of crops and livestock for domestic and foreign sale, involves use of energy from fossil fuels, water, fertilizers and pesticides

undergrazing

Reduction of the net primary productivity of grassland vegetation and grass cover from absence of grazing for long periods (at least 5 years).

Blue Revolution

Refers to the management of water resources that can steer humanity to achieve drinking water and crop irrigation security.

Micronutrients

Required by humans and other organisms throughout life in small quantities to orchestrate a range of physiological functions.

Salinization

Result of flood irrigation Irrigation canals' water evaporates, leaving behind salt Prevention: drip irrigation Remediation: flooding land with fresh water

Waterlogging

Saturation of soil with irrigation water or excessive precipitation so that the water table rises close to the surface enveloping roots in salt water.

Dust Bowl

A period of severe dust storms that greatly damaged the ecology and agriculture of the US and Canadian prairies during the 1930s; severe drought and a failure to apply dryland farming methods to prevent wind erosion (the Aeolian processes) caused the phenomenon.[

Purse Seine Fishing

A technique where a rope passes through all the rings of a net and when pulled, draws the rings close to one another catches the fish. •Avoids the seabed, preserving the interior of the area •Takes out large amounts of fish from a wide area at one time

Tragedy of the Commons

A theory that when a common renewable resource is shared, people tend to exploit the resource since they feel that if they do not use it, someone else will.

Golden Rice

A variety of rice produced through genetic engineering to biosynthesize beta-carotene, a precursor of vitamin A, in the edible parts of rice.

second green revolution

began during the 1970s and is still going. it involves growing gentically engineered crops that produce the most yields per acre. its in contrast with past agricultural practices in which farmers planted a variety of locally adapted strains. for ex: all wheat grown in the US, 50% comes from 9 different genotypes

Salinization

Accumulation of salts in soil that can eventually make the soil unable to support plant growth.

Pelagic

Any water in a sea or lake that is not close to the bottom or near to the shore

Biotin deficiency

Biotin deficiency is caused by a lack of vitamin B7 (biotin). It causes rashes, hair loss, anaemia, and mental conditions including hallucinations, drowsiness, and depression.

Macronutrients

Classes of chemical compounds humans consume in the largest quantities and which provide bulk energy. These are protein, fat, and carbohydrate. For plants the primary elements required are nitrogen, phosphorus and potassium.

polyculture

Complex form of intercropping in which a large number of different plants maturing at different times are planted together.

Soil

Complex mixture of inorganic minerals and decaying organic matter, water air and living organisms.

Fishery

Concentration of particular aquatic species suitable for commercial harvesting in a given ocean area or inland body of water.

fisheries

Concentrations of particular aquatic species suitable for commercial harvesting in a given ocean area or inland body of water.

Chronic Undernutrition

Condition suffered by people unable to grow or buy enough food to met their basic energy needs. They are likely to suffer from mental retardation and stunted growth and die from infectious diseases.

Food Security

Condition under which every person in a given area has daily access to enough nutritious food to have an active and healthy life.

Food Insecurity

Condition under which people live with chronic hunger and malnutrition that threatens their ability to lead healthy and productive lives.

Feedlot

Confined outdoor or indoor space used to raise hundreds to thousands of domesticated livestock.

Conservation Tillage Farming

Crop cultivation in which the soil is disturbed little or not at all in an effort to reduce soil erosion, lower labor costs and save energy.

Alley Cropping

Crop strips alternate with rows of closely spaced tree or hedge species. Normally, the trees are pruned before planting the crop. The cut leafy material is spread over the crop area to provide nutrients for the crop. In addition to nutrients, the hedges serve as windbreaks and eliminate soil erosion.

Chronic Malnutrition

Deficiencies of protein or other key nutrients which weakens the individual making them more susceptible to diseases and hinders normal physical and mental development.

commercial extinction

Depletion of the population of a wild species used as a resource to a level at which it is no longer profitable to harvest the species.

overgrazing

Destruction of vegetation caused by too many grazing animals consuming the plants in a particular area so they cannot recover

Industrial fishing

Global fish production starting to decrease Overfishing (using renewable resource beyond sustainable yield Bottom-trawling-dragging massive metal net across bottom of ocean; indiscriminate Bycatch-non-target species Purse seine & drift net (not towed) & long ling Sonar-uses sound waves & reflections to locate schools

Malnutrition

Goiter=iodine deficiency Marasmus=calorie deficiency Kwashiorkor=protein deficiency Rickets=vitamin D deficiency Scurvy=vitamin C deficiency Anemia=iron deficiency Beri Beri=vitamin B deficiency Pellagra=vitamin B deficiency

intercropping

Growing two or more different crops at the same time on a plot. For example, a carbohydrate-rich grain that depletes soil nitrogen and a protein-rich legume that adds nitrogen to the soil may be intercropped.

Soil Erosion

Movement of soil components, especially topsoil, from one place to another, usually by wind, flowing water or both. This natural process can be greatly accelerated by human activities that remove vegetation from the soil.

What is the formula to calculate % change?

New value / Old value * 100 = %

Compaction

Occurs when cows trample land Reduces permeability of soil to water and air

interplanting

Simultaneously growing a variety of crops on the same plot.

Beta-Carotene

One of a group of red, orange, and yellow pigments called carotenoids. Beta-carotene and other carotenoids provide approximately 50% of the vitamin A needed in the American diet. Beta-carotene can be found in fruits, vegetables, and whole grains.

Fertilizer Clarification

Organic fertilizers include animal waste, compost, humus Inorganic fertilizers include chemicals, sprays, pellets; release N2O; like steroids, increasing yield but not in long term Effects of intensive agriculture in California include polluted & depleted aquifer, salinization, high cancer rates for workers Organic produce/meat is produced with no hormones, antibiotics, pesticides

Genetically Modified Organisms, GMO's

Organism whose genetic makeup has been altered by genetic engineering.

Carnivore

Organisms that mainly prey upon animals

Circle of Poison (boomerang effect)

Pesticides banned in the United States are being found in apples, tea, potatoes, pineapples and other foods imported into this country because we still export those banned pesticides to other countries from which we buy food.

Selective Agents

Pesticides that are toxic primarily to the target pest (and perhaps a few related species), leaving most other organisms, including natural enemies, unharmed.

Artificial Selection

The process by which humans breed other animals and plants for particular traits. Typically, strains that are selectively bred are domesticated, and the breeding is normally done by a professional breeder. Bred animals are known as breeds, while bred plants are known as varieties, cultigens, or cultivars. The cross of animal's results in what is called a crossbreed, and crossbred plants are called hybrids.

A-horizon

The uppermost, darkest zone that is rich in organic matter. The upper section of the A horizon usually contains humus along with plant and animal matter in varying stages of decay

Broad Spectrum Agents

They kill a variety of organisms, including some that are beneficial, in addition to the target pest.

Vitamin K deficiency

This deficiency affects nearly half of all newborn infants worldwide. In severe cases it causes uncontrolled bleeding and underdeveloped faces and bones. Other than newborns, vitamin K deficiency is found in alcoholics, bulimics, strict dieters, and people with various severe diseases such as cystic fibrosis

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)

To control of pesticide distribution, sale, and use. All pesticides used in the United States must be registered (licensed) by EPA. Registration assures that pesticides will be properly labeled and that, if used in accordance with specifications, they will not cause unreasonable harm to the environment. Use of each registered pesticide must be consistent with use directions contained on the label or labeling.

Famine

Widespread malnutrition and starvation in a particular area because of a shortage of food, usually caused by drought, war, flood or other catastrophic event that disrupts food production and distribution.

Sonar Fishing

a fishing technique where sonar waves are used to detect objects in water and different methods are collecting fish are performed. •Easy to detect anything in the area •Good for navigation •Beneficial in Ice Fishing

subsistence

agriculture carried out for survival-with few or no crops available for sale. its usually organic, simply for lack of money to buy industrial inputs such as fertilizer, pesticides, or gentically modified seeds

overfishing

catching fish at a faster rate than they can reproduce

Pesticide

chemical that kills insects

undernutrition

condition caused by a diet deficient in Calories

tillage

conventional method in which the surface is plowed which then breaks up and exposes the soil. this is then followed by smoothing the surface and planting. this method exposes the land to water and wind erosion

Monocultures

cultivation of a single crop, usually on a large area of land

Perennials

plant that can live for more than two years

polyvarietal cultivation

planting a plot of land with several varieties of the same crop

polyvarietal cultivation

planting a plot with several genetic varieties of the same crop