Soil & Water Management & Conservation Soil Water Dynamics ...
TOPIC 3 Soil Conservation
Transcript of TOPIC 3 Soil Conservation
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Soil conservation
a set of management strategies for
1. prevention of soilbeing erodedfrom theearths surface or becoming chemically
altered by overuse, acidification,salinizationor other chemical soil
contamination. It is a component ofenvironmental soil science
http://en.wikipedia.org/wiki/Soilhttp://en.wikipedia.org/wiki/Erosionhttp://en.wikipedia.org/wiki/Acidhttp://en.wikipedia.org/wiki/Salinizationhttp://en.wikipedia.org/wiki/Soil_contaminationhttp://en.wikipedia.org/wiki/Soil_contaminationhttp://en.wikipedia.org/wiki/Environmental_soil_sciencehttp://en.wikipedia.org/wiki/Environmental_soil_sciencehttp://en.wikipedia.org/wiki/Soil_contaminationhttp://en.wikipedia.org/wiki/Soil_contaminationhttp://en.wikipedia.org/wiki/Salinizationhttp://en.wikipedia.org/wiki/Acidhttp://en.wikipedia.org/wiki/Erosionhttp://en.wikipedia.org/wiki/Soil -
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WAYS TO SOIL CONSERVATION
choice of vegetativecover
erosionprevention
salinitymanagement
acidity control
encouraging health of beneficial soil organisms
prevention and remediationof soil contamination
mineralization 2
http://en.wikipedia.org/wiki/Vegetationhttp://en.wikipedia.org/wiki/Erosionhttp://en.wikipedia.org/wiki/Salinityhttp://en.wikipedia.org/wiki/Liming_(soil)http://en.wikipedia.org/wiki/Soil_biologyhttp://en.wikipedia.org/wiki/Environmental_remediationhttp://en.wikipedia.org/wiki/Soil_contaminationhttp://en.wikipedia.org/wiki/Soil_contaminationhttp://en.wikipedia.org/wiki/Environmental_remediationhttp://en.wikipedia.org/wiki/Soil_biologyhttp://en.wikipedia.org/wiki/Liming_(soil)http://en.wikipedia.org/wiki/Salinityhttp://en.wikipedia.org/wiki/Erosionhttp://en.wikipedia.org/wiki/Vegetation -
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no till farming
contour plowing
wind rows crop rotation
the use of natural and man-made fertilizer
resting the land (Shmita)
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Discipline of science in soil
management
Many scientific disciplines are involved in
these pursuits, including agronomy,hydrology, soil science, meteorology,
microbiology, and environmental chemistry.
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Decisions regarding appropriate crop
rotation, cover crops, and plantedwindbreaksare central to the ability of
surface soils to retain their integrity, both
with respect to erosive forces and chemical
change from nutrient depletion. Crop rotationis simply the conventional alternation of
crops on a given field, so that nutrient
depletion is avoided from repetitive chemical
uptake/deposition of single crop growth.
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Cover crops serve the function of protecting the soil fromerosion, weed establishment or excessevapotranspiration; however, they may also serve vitalsoil chemistryfunctions
[1]. For example, legumes(Kekacang) can be ploughedunder to augment soil nitrates, and other plants have theability to metabolize soil contaminants or alter adversepH. The cover crop Mucuna pruriens (velvet bean) hasbeen used in Nigeria to increase phosphorusavailability
after application of rock phosphate[2]. Some of thesesame precepts are applicable to urban landscaping,especially with respect to ground-cover selection forerosion control and weed suppression.
http://en.wikipedia.org/wiki/Evapotranspirationhttp://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Soil_conservationhttp://en.wikipedia.org/wiki/Legumehttp://en.wikipedia.org/wiki/Nitratehttp://en.wikipedia.org/wiki/PHhttp://en.wikipedia.org/wiki/Velvet_beanhttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Phosphatehttp://en.wikipedia.org/wiki/Soil_conservationhttp://en.wikipedia.org/wiki/Soil_conservationhttp://en.wikipedia.org/wiki/Phosphatehttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Velvet_beanhttp://en.wikipedia.org/wiki/PHhttp://en.wikipedia.org/wiki/Nitratehttp://en.wikipedia.org/wiki/Legumehttp://en.wikipedia.org/wiki/Soil_conservationhttp://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Evapotranspiration -
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Erosion prevention
Contour plowing, Pennsylvania 1938. The
rows formed slow water run-off duringrainstorms to prevent soil erosion and
allows the water time to settle into the soil.
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Human overpopulationis leading to
destruction of tropical forestsdue to
widening practices of slash-and-burnand
other methods of subsistence farmingnecessitated by famines in lesser
developed countries. A sequel to the
deforestation is typically large scaleerosion, loss of soil nutrients and
sometimes total desertification.
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Salinity management
Salt deposits on the former bed of theAral Sea
Main article: Soil salinity control
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The ions responsible for salination are: Na+, K+,
Ca 2+,Mg 2+and Cl-. Salinity is estimated to
affect about one third of all the earths arable
land[6]. Soil salinity adversely affects themetabolismof most crops, and erosion effects
usually follow vegetationfailure. Salinity occurs
on drylandsfrom overirrigationand in areas with
shallow saline water tables. In the case of over-irrigation, salts are deposited in upper soil layers
as a
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byproduct of most soil infiltration; excessive
irrigation merely increases the rate of salt
deposition. The best-known case of shallow
saline watertable capillary actionoccurred inEgyptafter the 1970 construction of theAswan
Dam. The change in the groundwater level due
to damconstruction led to high concentration of
salts in the water table. After the construction,the continuous high level of the water tableled
to soil salinationof previously arable land.
http://en.wikipedia.org/wiki/Infiltration_(hydrology)http://en.wikipedia.org/wiki/Saline_waterhttp://en.wikipedia.org/wiki/Capillary_actionhttp://en.wikipedia.org/wiki/Egypthttp://en.wikipedia.org/wiki/Aswan_Damhttp://en.wikipedia.org/wiki/Aswan_Damhttp://en.wikipedia.org/wiki/Damhttp://en.wikipedia.org/wiki/Water_tablehttp://en.wikipedia.org/wiki/Soil_salinationhttp://en.wikipedia.org/wiki/Soil_salinationhttp://en.wikipedia.org/wiki/Water_tablehttp://en.wikipedia.org/wiki/Damhttp://en.wikipedia.org/wiki/Aswan_Damhttp://en.wikipedia.org/wiki/Aswan_Damhttp://en.wikipedia.org/wiki/Egypthttp://en.wikipedia.org/wiki/Capillary_actionhttp://en.wikipedia.org/wiki/Saline_waterhttp://en.wikipedia.org/wiki/Infiltration_(hydrology) -
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Use of humic acidsmay prevent excesssalination, especially in locales where excessiveirrigation was practiced. The mechanisminvolved is that humic acids can fix both anions
and cationsand eliminate them from root zones.In some cases it may be valuable to find plantsthat can tolerate saline conditions to use assurface cover until salinity can be reduced; thereare a number of such saline-tolerant plants,
such as saltbush, a plant found in much of NorthAmericaand in the Mediterraneanregions ofEurope.
http://en.wikipedia.org/wiki/Humic_acidhttp://en.wikipedia.org/wiki/Anionhttp://en.wikipedia.org/wiki/Cationhttp://en.wikipedia.org/wiki/Root_zonehttp://en.wikipedia.org/wiki/Saltbushhttp://en.wikipedia.org/wiki/North_Americahttp://en.wikipedia.org/wiki/North_Americahttp://en.wikipedia.org/wiki/Mediterraneanhttp://en.wikipedia.org/wiki/Europehttp://en.wikipedia.org/wiki/Europehttp://en.wikipedia.org/wiki/Mediterraneanhttp://en.wikipedia.org/wiki/North_Americahttp://en.wikipedia.org/wiki/North_Americahttp://en.wikipedia.org/wiki/Saltbushhttp://en.wikipedia.org/wiki/Root_zonehttp://en.wikipedia.org/wiki/Cationhttp://en.wikipedia.org/wiki/Anionhttp://en.wikipedia.org/wiki/Humic_acid -
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Soil percent hydrogen (pH)
Soil pH levels in Lake Titikaka tend to crop growth can occurnaturally in some regions; it can also be induced by acid rainor soilcontaminationfrom acidsor bases. The role of soil pH is to controlnutrient availability to vegetation. The principal macronutrients(calcium, phosphorus, nitrogen, potassium, magnesium, sulfur)prefer neutral to slightly alkalinesoils. Calcium, magnesium and
potassium are usually made available to plants via cation exchangesurfaces of organic materialand clay soil surface particles. Whileacidification increases the initial availability of these cations, theresidual soil moisture concentrations of nutrient cations can fall toalarmingly low levels after initial nutrient uptake. Moreover, there isno simple relationship of pH to nutrient availability because of thecomplex combination of soil types, soil moisture regimes andmeteorological factors.
http://en.wikipedia.org/wiki/Acid_rainhttp://en.wikipedia.org/wiki/Soil_contaminationhttp://en.wikipedia.org/wiki/Soil_contaminationhttp://en.wikipedia.org/wiki/Acidhttp://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Macronutrienthttp://en.wikipedia.org/wiki/Calciumhttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Potassiumhttp://en.wikipedia.org/wiki/Magnesiumhttp://en.wikipedia.org/wiki/Sulfurhttp://en.wikipedia.org/wiki/Alkalinehttp://en.wikipedia.org/wiki/Organic_materialhttp://en.wikipedia.org/wiki/Cationhttp://en.wikipedia.org/wiki/Cationhttp://en.wikipedia.org/wiki/Organic_materialhttp://en.wikipedia.org/wiki/Alkalinehttp://en.wikipedia.org/wiki/Sulfurhttp://en.wikipedia.org/wiki/Magnesiumhttp://en.wikipedia.org/wiki/Potassiumhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Phosphorushttp://en.wikipedia.org/wiki/Calciumhttp://en.wikipedia.org/wiki/Macronutrienthttp://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Acidhttp://en.wikipedia.org/wiki/Soil_contaminationhttp://en.wikipedia.org/wiki/Soil_contaminationhttp://en.wikipedia.org/wiki/Acid_rain -
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Soil organisms
Promoting the viability of beneficial soil organisms is an element ofsoil conservation; moreover this includes macroscopic species,notably the earthworm, as well as microorganisms. Positive effectsof the earthworm are known well, as to aerationand promotion ofmacronutrientavailability. When worms excrete egestain the form ofcasts, a balanced selection of minerals and plant nutrients is made
into a form accessible for rootuptake. USresearch shows thatearthworm casts are five times richer in available nitrogen, seventimes richer in available phosphatesand eleven times richer inavailable potashthan the surrounding upper150 mm of soil. Theweight of casts produced may be greater than 4.5 kg per worm peryear. By burrowing, the earthworm is of value in creating soilporosity, creating channels enhancing the processes of aeration anddrainage[7].
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Yellow fungus, a mushroomthat assists in organic decay.
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The viability of soil organisms can be
compromised when insecticidesand herbicides
are applied to planting regimes. Often there are
unforeseen and unintended consequencesofsuch chemical use in the form of death of
impaired functioning of soil organisms. Thus any
use of pesticides should only be undertaken
after thorough understanding of residualtoxicities upon soil organisms as well as
terrestrial ecological
Degradation and contamination
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Killing soil microorganisms is a deleterious
impact of slash and burnagricultural methods.
With the surface temperatures generated, virtual
annilation of soil and vegetative cover organismsare destroyed, and in many environments these
effects can be virtually irreversible (at least for
generations of mankind). Shifting cultivationis
also a farming system that often employs slashand burnas one of its elements.
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