APES Chapter 9

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soil is formed from a parent material, weathered & transported & deposition to a new location ** soil needs to be protected from wind and water erosion and soil filters & cleans water by protecting water qualityhow is soil formednitrogen, potassium, phosphorus, water are important for survival of the soilgood balance of nutrients for soilprovides nutrients & helps with structure with water retentionwhat does organic matter do for soil?(nitrates & ammonia) and phos enable plant growthwhat does nutrients such as nitrogen do for the soil?influence root penetration & growthwhat does soil structure/texture do?soil profileAll the vertical layers or horizons that make up a soil in a particular placeO horizon( organic layer) A Horizon(topsoil) E Horizon B Horizon (subsoil) C Horizon( Weathered parent material) R Horizonsoil profile in orderO horizonleaf litter, twigs, dead stuff, on top* start of real soil * topsoil * humus is important soil; mature compostHumusRich, dark organic material formed by decay of vegetable matter, essential to soil's fertility ** mature compost, * solves soil problems ** acidic-> put down more of this; can change the PH ** microorganism live in this layer * prevent nurtients from leaching out(liquid moving) of the soil through water runoff * prevents water evaporationhold mosisture well, good plant productivityhigh humus=leachingremoval of dissolved materials from soil by water moving downwards (runoff) * when it raoins, water inflitrates the soil, dissolves some of its componentstopsoil*crucial horizon * consists of mostly inorganic mineral components, with organic matter & humus from above mixed in * portion of the soil that is must nutritive for plantsC: look at PH, N, P, K P: look at texture, porosity, perameability, bulk densiry (dark brown, black=good soil) B: looking to see if you have a lot of microorganismsChemical soil tests vs physical vs biological- look at concetrations of clay, silt, sand -clay: smallest particle, silt, sandphysical test: clay,silt, sandLoameven mixture of clay, silt, sand **best type of soilbig particles=porous=water pass quuickly=crops planted in sandy soils require frequent irrigationSoil with large particles are _______ & allow water to pass through ______ = effect?small particles=small pore spaces=makes it difficult for water & air to pass through Ex: clay soils, water inflitarte slowly & less oxygen is abaliableSoil with small particles=______=effect?medium sized (loamy soils)best sized pore particles?** Amazon rainforest is less productive than soils in Iowa or Kansas = enormous amount of rain leaches minerals & nutrients out of the topsoil & E horizon - warm temps speed decomposyion & uptake nutrients by plants=small amounts of humus remain in the thin topsoil layer(varies with soil type) too much water can get waterlogged & brutes of plants can actually rot too little water= nutrients will leach, not enough nutrients **need to look at porse spaceswater capacity (too much water vs not enough)porsoity *clay & sand=least porosity *silt & loam=most porositylooking at the pore sizes, amount of open spaces to the amount of water soil can hold ** clay & sand= *silt & loam=permeabilityhow well water is able to drain through & move through the soil = water is slow, sits there=will rot the roots =water is too fast, your plants will not take it up(nutrients)slash and burn agricultureAnother name for shifting cultivation, so named because fields are cleared by slashing the vegetation and burning the debris. - rainforests - bad long term*humans use 70% of freshwater for irrigation1) furrow 2) water-logging 3) drip 4) conventionalTypes of irrgiationfurrow irrigationcut furrows between crops & rows, flood it with water - cheaper - leaving water exposed= lose 1/3 of water to evaporation or runoffFlood irrigationwater is poured through canals and waterways so that it flows through fields (bigger piece of land) *similar to furrow * 20% of water is lost to evaporation =waterloggingwaterloggingover irrgation saturates the soil & causes the water table to rise to the point that water drowns plant roots, depriving them of access to oxygen and suffocating themirrigationA way of supplying water to an area of land -articifical way of producing water (not rainfall) - large plants like rice, cotton need _____* water may be evaporated before it can inflitarte the soil=crops may need irrigationclimate is too dry=spray irrigationexpensive and energy-consuming; 75-95% efficient; water is pumped from a well into an apparatus that contains a series of spray nozzles that spray water across the field ** pumping ground water ** more efficent than flood furrow **expensive b/c more tech & energydrip irrigationthe practice of using small pipes that slowly drip water just above ground to conserve water to use for crops - expensive - only losing 5% of water to evapconvential methodinefficent, water is lose to evaporation Ex: flood-furrow vs. dripsalinizationthe buildup of salts in surface soil layers; when salts in groundwater remain in soil and becomes toxic to plants * too much salt=toxic soil --> need to add in water* drip irrgation * planty crops that need less water * water sensors so you know when it needs water * use humus to keep in mositure, and not lose it to evaporation *how to fix salinization - flush the soil w/ freshwater -plant crops like barely that likes salts (tolerate salty soil)how to prevent salinizationNitrogen: helpful for leafy greens Phos: helps for root developemt Pottasim: flowering3 substances in fertilieersInorganic: -synthetic, manmade - excess amount of nitrogen & phos=runoff= eutrophication - can also soak into ground & groundwater=drinking contaminated groundwater -air pollution: nitrogen becomes airborne; can ruin trees & change air quality Organic: -green manure -compost -animal manureInorganic v Organic fertilizer1) tilling 2) slash-burn 3)fertilizers3 main agricultural practcies that are most damagingtillingThe turning-over of soil before planting. - plow & turn over soil to prepare it for seeds which leaves it vulnerable to wind & water erosionno-till farmingMethod for reducing soil erosion; plant stalks are left in the field after harvesting and the next year's crop is planted within the stalks without plowing. -leaves crop resudibe behind to cover the soil & protect topsoil & wind/water erosion1)overgrazing livestock->34% 2)deforestation 3) cropland from agriculture** most of the world's soil degration comes from **degragation: decline in the quality of somethingland degrationrefers to general deteriation of the land; diminishes it sproductivity & biodiversity - soil eriosion, nutrient depletion, water scaricty, salinization, waterlogging, chemical pollutionsoil degrationsoils degrate in quality & production - results from forest removal, cropland agriculture, overgrzing livestock** natural process, but removes topsoil 1) over-cultivating fields through poor planning or excessive tilling (plowing) 2) grazing rangeland with more livestock than land can support 3) clearing forests on steep slopes or with large clear-cuts * to minimize erosion: put up barriers, wind barriers, bushes, trees, so that the soil doesn't travel too far - grow vegegation like cover crops when you're not using the land - practice no-till agriculturecauses of erosion ***how to minimize erosionerosion is when water or wind remove soil from an area; deposition is when they deposit that soil somewhere else Ex: Dust Bowl; picked up from Kansas and dumped 100 mi awayerosion vs. depositionDesertificationDegradation of land, especially in semiarid areas, primarily because of human actions like excessive crop planting, animal grazing, and tree cutting. -land is not useful anymore - erosion, dust storms, salinizationSoil Conservation Service Agency -helps educate farmers on how to keep their most valuable source of soil in place if there's a droughtAfter dustbowl U.S puts together...1) crop rotation -rotating crops such as soybeans & corn restore soil nutrients 2) contour farming - reduces erosion on hillsides -reduce erosion on hillside -perpendicular 3) terracing -minimizes erosion in mountainous areas -steps like staircase - helps not lose water to water erosion -Himilayas 4) intercropping -reduces soil loss & maintains soil fertility -integrates various crops in the same area -Animal House/Farm? 5) shelter-belts -protect against wind erosion 6) no-till farming - soybeans grow through stubble remaining from wheat crop, in no till agricultureTypes of erosion prevention1) crop rotations 2) green manure-bring in other nutrients 3) limestone-balance PHhow to improve soil fertilitycover cropscrops planted to hold soil in place between the times that main food crops are growingConservation Reserve Program Wetlands Reserve ProgramU.S. policy in farm bills since 1985 that pays farmers to stop cultivating highly erodible cropland and instead place it in conservation reserves planted with grasses and trees. -returns wetlands that we've tried to turn into farmland; restore them back into wetlands-Good soil need microorganism, NKP, water, oxygen Fertilizer: Inorganic (synthetic): liquid or powder, more likely to cause issues with runoff(phosphate,nitrate) Organic: manure, green manure(plat scraps), compost (includes more nutrients variety and bacteria) Worms and gophers allow aeration and worms decompose Rotate animals to prevent compaction of soil which can reduce water and oxygen retention Cover crops and tree lines prevent erosion from wind and water Contour farming-on hills you create rings of crops to prevent running down hill of soil and seeds No till farming-leave remnants of crops behind to hold down soil and build nutrients during off seasonSoil (fertility & Conservation)Traditional farming: creating enough product to sustain yourself with a little more to sell at market. Polyculture, no pesticide/herbicide, use organic fertilizers Industrial farming: big machinery, monoculture crops, huge yield with pesticide and fertilizer use Biological Pest management: using predators to control pest population(snail-->ducks, aphids-->ladybugs)Farming Practices (crops, pest management)Irrigation pond to hold water and well to pump from aquifer Aquifer recharge was low with the drought Organic farming prevent chemical contamination to aquifer Water erosion was an issue before crop cover Drought prevented new water from entering pond + duck poop=eutrophication Drip irrigation used on trees to prevent evaporation Sprinkler watering of other crops is useful but will lead to more evaporationWater (quality & conservation)** greater the slope=more likely erosionChemical: acid rain, oxidation, carbonation Physical: wind, sand, rain, freezingm thawing, rootsEx of chemical & mechanical weathering C*Desert lost water quickly due to high permeability. Parent bedrock experiences little chem/phys weathering so C horizon is large and little organic life is present (small a and B) *Rainforest gets high precipitation, but contains lots of organics to replenish nutrients *generates more clay due to high precipitation and weathering. The clay reduces permeability holding in too much water, rotting plants *Prairie gets moderate precipitation in warmer months and has a lot of decomposition to replace lost nutrients.The ditch at the bottom of the clay would flood because the clay hill would allow for the water to run off into the ditch belowThere are 2 fields with equal slope, one sandy and one with more clay. At the bottom of the field is a ditch. If a prolonged downpour occurred, which ditch would be more likely to flood?The area with more clay will allow for an impermeable layer that will hold more water above it and allow the plants to thrive during the drought while the sandy water will offer less support to the plants and will leach more of the nutrients and loose water quicklyThere are 2 fields with equal slope, one sandy and one with more clay. At the bottom of the field is a ditch. Describe water holding capacities of both fields. Which is best suited for crops during a drought? Justify.As the pH of a soil decreases (more acidic) more cation binding sites on the roots are occupied by H+ ions and not the nutrient cations, depleting the plant of needed nutrientsWhen bedrock is weathered there are exchanges of nutrient cations (N, K, P) for H+ ions by plant roots.Solution- Add Humus and fertilizers to add nutrients to the soil. Clay holds the most nutrients as well and can increase ion exchange****Soil Acidity= Nutrient Depletion solution?weatheringThe chemical and physical processes that break down rock at Earth's surface. -Physical (mechanical), chemical and Biological processes that form soilleachingwhen dissolved particles move down through horizonsinflitrationThe movement of water into the soil or ground surfacewarmer climateWhich of these factors or changes would increase the rate of weathering and accumulation of organic matter in soil? 1) less time 2)increased sheltering by hills 3)warmer climate 4)fewer plants and decomposersterracingno-tillPlowing furrows perpendicular to the slope of a hillside would be an example of what soil conservation technique? *wind or rain breaking down parent materialPhysical weathering is characterized by: *

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