Unit 4, some of 2 and 5 for APES: soil formation, succession, agriculture)

rock cycle

• no matter which rock you’re at, you can generate the other two

• fossil fuels at/core from sedimentary

• sedimentary, metamorphic, igneous 

Sedimentary rock

• form from the accumulation and compaction of sediments or organic materials

Metamorphic rock

• form when existing rocks are transformed by heat, pressure, or chemical processes

Igneous rock

• form from the cooling and solidification of molten rock

soil formation

• primary succession

• where we develop ecosystems over time, soil isn’t present so starting with bare rock and it gets weathered

Physical weathering

• wind, waves, rain, streams, friction from other rocks, freezing and thawing (temp.)

Chemical weathering

• acid rain (pH changes)

soil horizons

• C forms first

• then O

• then A

• then B which is mix of C and A

• Then E is last and is not always there unless it rains a lot

O horizon

• primarily composed of decomposing and partially decomposed organic matter

A horizon

• commonly known as topsoil, is the surface layer of mineral soil, located just below the organic O horizon

E horizon

• eluviation horizon, is a light-colored, leached soil layer found beneath the O and A horizons in some profiles, particularly in forested areas

• It consists primarily of sand and silt particles, with most clay, iron oxides, and organic matter removed (eluviated) and washed into the B horizon below

B horizon

• subsoil or illuvial horizon

• is a subsurface layer of soil that is primarily a zone of accumulation, where materials leached from the upper horizons are deposited

• less nurtients

• located below A horizon or the topsoil

C horizon

• the parent material or regolith, is the deepest layer of soil

• is located above the unweathered bedrock (R horizon) and below the subsoil (B horizon)

• is primarily made of slightly altered and weathered rock and minerals

permeability

• soil property

• physical test

• measure of the soil’s ability to move water through it

• rate: amount of water per unit of time

• percolate

soil texture triangle and jar

soil composition/texture

• the mixture of its four primary components: mineral matter (sand, silt, and clay), organic matter, water, and airgravel:biggest

  • sand 

  • silt: small

  • clay: very small, stick together

• 25% air

• 25% water

• 45% mineral

• 5% OM

• largest to smallest

pH

• chemical test

• pH of most soils ranges from 4-8 

• it affects the solubility of certain plaint nutrients

• the optimum pH is 6-7 (plant nutrients are most available)

• soil amendments (ex.~ lime) can be used to achieve this pH

too acidic soil

• low pH

• an abundance of heavy metals are leached from the soil

  • heavy metals are dissolved by water and carried down through the soil, often to contaminate groundwater

• cation exchange capacity happens too quickly

• cations are exchanged for H+ ions obtained from carbonic acid or from the  plant itself

• net nutrient loss

too basic soil

• nutrients cannot dissolve in water

• don’t release many nutrients at all

cation exchange capacity (as it relates to nutrient holding)

• chemical test

• increased exchange= losing nutrients

• ability of soils to absorb and exchange cations (ion with + charge) 

• contribute the most to the chemical properties of soil

• agricultural soils require some level of clay to hold nutrients 

  • more than 20% holds too much water

primary succession

• the ecological process where a life-less environment, like bare rock exposed by a volcanic eruption or retreating glacier, is gradually colonized by organisms, leading to the development of soil and a complex ecosystem

• ex.~ volcanic eruption: new land formed by cooling lava flows can be colonized

secondary succession

• the ecological process of regrowth and reorganization in an area that has been disturbed, but where soil and some life remain, don’t start from bare rock

• ex.~ wildfires: destroys the trees but the soil remains fertile for new growth

commercial farming practices

• tilling

• monoculture

• desertification

tilling

• is the mechanical agitation of soil

• is typically done with tools like hoes, plows, rototillers, or large machinery like tractors

• advantages: Weed Control, Incorporates Organic Matter

• disadvantages: soil erosion, loss of soil structure, increased carbon release

• solution: no-till farming 

  • shortcomings: requires herbicides like glyphosphate which can harm the environment

monocultures

• is the agricultural practice of growing a single crop species over a large area of land, year after year

  • It’s common in industrial agriculture — for example, vast fields of just corn, wheat, or soybeans

• advantages: high efficiency, predicted yields, easier management

• disadvantages: soil degradation, high chemical input, biodiveristy loss

• solutions: intercropping, IPM

  • shortcomings: complex to manage, requires more labor and monitoring

Desertification

• is the process where fertile land becomes degraded and turns into desert-like conditions, losing its ability to support life

• caused by overgrazing, deforestation, etc.

• advantages: n/a?

• disadvantages: loss of arable land, food insecurity, biodiversity loss

• solutions: education and policy, reforestation,

  • shortcomings: slow process, may lack funding

fertilizers

• Substances added to soil/plants to provide nutrients and boost growth.

  • Synthetic: Made in factories (e.g., urea, NPK, from ammonia, phosphate, potash).

  • Organic: Natural sources (e.g., manure, compost, bone meal).

• Advantages: Fast plant growth, Higher yields, Replenishes poor soil

• Disadvantages: Soil degradation (chemicals), Water pollution (runoff)

• Solutions:Use compost, crop rotation, Soil testing

• Shortcomings of solutions: expensive, slow

Irrigation

• Artificial application of water to soil for growing crops

  • Surface: Water flows over land (furrows, basins

  • Sprinkler: Water sprayed like rain

  • Drip: Water drips near roots (efficient)

  • Subsurface: Underground pipes deliver water

• Advantages:Increases crop yields, Allows farming in dry areas

• Disadvantages: Waterlogging & salinization

• Solutions:Drip & sprinkler systems (efficient), Use rainwater harvesting

• Shortcomings of solutions: high cost, maintenance, rainwater storage is limited in dry years

furrow irrigation

• ditches w/ water

• inexpensive

• 1/3 of water lost to evaporation and runoff

• risk of soil erosion too

• getting water close to crops

flood irrigation

• floods the agricultural field w/ water

• water-logging

• 20% of water lost to evaporation and runoff

• methane

spray irrigation

• more efficient then furrows and flood (<25% water loss)

• more expensive and requires energy

• salinization

drip irrigation

• expensive

• 5% is lost to evaporation

• targeted to release water at the plant

pesticides 

• chemicals used to control pests, weeds, fungi, and rodents

  • synthetic (lab-made chemicals like DDT, glyphosate), natural (plant-based or microbial like neem or Bt)

• Advantages: protects crops, increases yield, fast action, reduces labor, easy to use

• Disadvantages: kills beneficial insects, pest resistance, water and soil pollution, human health risks, bioaccumulation

• Solutions: integrated pest management, bio-pesticides, crop rotation, resistant crop varieties, farmer education

  • Shortcomings: IPM is complex, bio-pesticides act slowly, not always effective, lack of training, pests may still adapt

sustainable practices

• crop rotation, intercropping, no till, countour

• GMOs

• IPM

crop rotation

• the practice of growing different crops in the same area in a planned sequence over seasons or years

  • alternating crop types (e.g. cereals, legumes, root crops) to balance soil nutrients and break pest/disease cycles

• Advantages: improves soil fertility, reduces pests and diseases, lowers need for chemical inputs, controls weeds, increases biodiversity

• Disadvantages: requires planning, crop choice limitations, not always profitable short-term, may need different equipment, knowledge-intensive

• Solutions: farmer training, government support, market access for diverse crops, research on rotation-compatible varieties

• Shortcomings of solutions: training may be unavailable, market demand may favor monocultures, limited access to equipment, resistance to change

intercropping

• growing two or more crops together on the same land at the same time

  • combining crops with different growth habits or needs (e.g. maize + beans, tomato + basil) in rows, strips, or mixed patterns

• Advantages: better use of space, improved soil health, pest and disease control, reduced erosion, higher total yield

• Disadvantages: complex management, competition between crops, difficult harvesting, may reduce individual crop yield, needs more labor

• Solutions: farmer training, research on compatible crops, use of simple tools or machinery, government support

  • Shortcomings: lack of knowledge, not suited for all crops, limited equipment access, more time and effort required

no-till farming

• farming method where soil is not disturbed by plowing before planting

  • seeds are directly planted into residue-covered soil using special equipment like no-till drills

• Advantages: reduces soil erosion, improves soil structure, retains moisture, saves fuel and labor, increases organic matter

• Disadvantages: initial cost of equipment, weed control challenges, possible increased herbicide use, slower soil warming in spring

• Solutions: integrated weed management, crop rotation, cover crops, government incentives for equipment purchase

  • Shortcomings: requires farmer training, herbicide reliance can cause resistance, cover crops need extra management, upfront costs remain high

countour farming

• farming along the natural contours of the land to reduce soil erosion

  • planting crops in rows that follow the slope’s curves instead of up and down the hill

• Advantages: reduces water runoff and soil erosion, improves water infiltration, conserves soil moisture, increases crop yields

• Disadvantages: requires planning and skill, may reduce planting area, machinery use can be difficult on slopes, initial setup time and cost

• Solutions: farmer training, use of contour plows, government support and incentives, combining with other soil conservation methods

  • Shortcomings: training may be limited, equipment may not be affordable, not suitable for very steep or irregular terrain, adoption can be slow

GMOs

• genetically modified organisms with altered DNA for desired traits

  • scientists insert genes from other species into plants or animals to enhance traits like pest resistance or drought tolerance

• Advantages: increased crop yields, pest and disease resistance, reduced pesticide use, improved nutritional content, longer shelf life

• Disadvantages: potential environmental risks, gene transfer to wild species, ethical concerns, dependence on seed companies, possible health risks

• Solutions: strict regulation and testing, development of biosafety protocols, public education, promoting transparent labeling

  • Shortcomings: regulatory gaps in some countries, public mistrust, high costs for small farmers, slow policy adaptation, ongoing scientific debate

IPM

• a pest control strategy that uses a combination of biological, cultural, physical, and chemical methods to manage pests sustainably

  • monitoring pest levels, using natural predators, crop rotation, selective pesticide use only when needed, and habitat management

• Advantages: reduces chemical pesticide use, lowers environmental impact, delays pest resistance, cost-effective over time, protects beneficial organisms

• Disadvantages: requires knowledge and training, more labor-intensive, slower results compared to chemical spraying, complex decision-making

• Solutions: farmer education programs, government support, development of easy-to-use monitoring tools, research on biological controls

  • Shortcomings: limited access to training, initial costs and labor demands, resistance to change from traditional methods, uneven government support

CAFOs (concentrated animal feeding opterations)

• large-scale industrial livestock farms where many animals are confined in a small area

  • animals like cows, pigs, or chickens are kept in high densities to maximize production efficiency

• Advantages: high production efficiency, lower costs, year-round meat/dairy supply, better disease control under some conditions

• Disadvantages: environmental pollution (manure runoff, air quality), animal welfare concerns, antibiotic resistance, disease outbreaks risk

• Solutions: improved waste management, stricter regulations, alternative farming methods (free-range), better animal welfare standards

  • Shortcomings: enforcement challenges, higher costs for farmers, resistance from industry, limited scalability of alternatives

commercial fisheries

• large-scale fishing operations that catch fish and seafood for sale and consumption

  • using fishing vessels with nets, trawls, longlines, or traps to harvest large quantities from oceans, rivers, or lakes

• Advantages: provides food and jobs, supports economies, supplies global seafood demand,

• Disadvantages: overfishing, habitat destruction, bycatch (unintended species caught),

• Solutions: fishing quotas, marine protected areas, sustainable fishing certifications, improved gear to reduce bycatch, aquaculture development

  • Shortcomings: enforcement difficulties, illegal fishing, economic pressure on fishermen, limited awareness, aquaculture environmental impacts

aquaculture

• farming of fish, shellfish, and aquatic plants in controlled environments

  • raising aquatic species in ponds, tanks, cages, or raceways, often with feeding and water quality management

• Advantages: supplements wild fish supply, creates jobs, supports food security, can be more efficient than wild fishing

• Disadvantages: water pollution, disease spread, habitat destruction, genetic issues from escaped farmed species, reliance on wild fish for feed

• Solutions: improved farm management, use of sustainable feed, disease control measures, habitat protection, regulations and monitoring

  • Shortcomings: high costs, enforcement challenges, variable farmer knowledge, environmental trade-offs remain