LAND RESOURCES

LokheshMithuna MaranMogan PrasadMohamed AbbasNandhakumarNandhiniPriyanka

E.V.S ProjectB.Arch (1st year)Section ‘B’

Soil, a limited resource we depend upon, but take for granted

Soil ErosionWhat causes soil erosion?How serious of a problem is it?Good news and bad news from the U.S.What is desertification?How do salts degrade the soil?

Wind

Water #1

People

Wind

Water #1

People

WHY CARE about soil erosion?

CAUSES OF SOIL EROSION

Impacts of Soil ErosionLoss of soil fertilitySediment runoff causes

problems in surface water (pollution, clog ditches, boat channels, reservoirs)

#1 source of U.S. water pollution

Renewable only on LONG timeframes (200-1,000yrs. for 1 inch)

Soil Erosion

On Ag. land in U.S. today, soil is eroding 16 times faster than it is created

Areas of serious concern

Areas of some concern

Stable or nonvegetative areas

Global Soil Erosion

Fig. 14-7 p. 280

Causes of DesertificationOvergrazingDeforestationErosionSalinizationSoil CompactionNatural Climate Change

OvergrazingDeforestationErosionSalinizationSoil CompactionNatural Climate Change

World Desertification

Fig. 14-9 p. 282

Desertification: causes and consequences.

•Occurring on 1/3 of world’s land

SALINIZATION1. Irrigation

water contains small amounts of dissolved salts

2. Evaporation and transpiration leave salts behind

3. Salt builds up on soil

Reducing and Cleaning Up SalinizationReduce irrigationSwitch to salt-tolerant crops

Flush soilsNot growing crops for 2-5 years

Install underground drainage

Reduce irrigationSwitch to salt-tolerant crops

Flush soilsNot growing crops for 2-5 years

Install underground drainage

Soil Degradation on Irrigated Land Salinization Salinization

Waterlogging

1. Precipitation and irrigation water percolate downward

2. Water table rises

3. Bad for roots

Waterlogging

1. Precipitation and irrigation water percolate downward

2. Water table rises

3. Bad for roots

EvaporationTranspiration

Evaporation

Waterlogging

Less permeableclay layer

Fig. 14-11 p. 283Fig. 14-11 p. 283

What controls soil productivity?

Water -infiltration, drainage, storage

Nutrients/toxins (12/17)Gas Exchange -CO2 out, O2 inStrength/rooting volumeWaste DisposalSeed/seedling nursery

Where is the best soil?

Where are the productive soils?

We see what we know. The more we know, the more options we realize we have w/ the world’s soils.

What are some threats?Finite arable land: 1.1 billion hectares

1961 0.32 ha/p; today 0.15 ha/p; 2050 0.12 ha/p

Erosion – today 12-40 Mg/ha 30% agricultural lands irreversibly damaged.

Desertification – e.g., 27% China affected w/ new 2500 km2/yr.

Salinization- affects 20% of world’s 250+ million hectares of irrigated lands.

Contamination w/ heavy metals.Urbanization and other competing uses.Problematic off-site issues & competing uses.

Threats? Think little things. Compaction or loss of porosity. Loss soil organic matter. Loss CEC other buffering potential. Doolittle Prairie

– e.g., 10% reduction in pore volume

= 152 m3/ha

= 2200 ft3/ac

-less gas exchange, water storage, root volume; poorer nursery.

-water quality & quantity, air quality

Soil ConservationWhat is soil conservation and how does it

work?What are some methods for reducing soil

erosion?Inorganic versus organic fertilizers

Soil ConservationInvolves many ways of reducing soil erosion and

restoring fertility to soil.

Conventional TillageFarmers plow the land and

then break up and smoothes soil to make a planting surface

Leaves soil vulnerable to erosion

Midwest tillage often down in fall (winter bare)

Conservation TillageDisturbing the soil as little

as possible while planting crop

Not tilling over winterPlanting without

disturbing soilSpecial equipment

“inject” soil with seed, fertilizer etc.

In 2003 45% of U.S. farms

Terracing

Used on steep slopes

Reduces erosion and water loss

Contour planting

Planting crops in rows across the slope

Strip Cropping

Alternating crops from row crops and crops that completely cover surface

Cover Crops: can be planted right after harvest to hold onto soil during winter

Alley Cropping: several cops planted together in rows (alleys) Increases shade (less water) Provide windbreaks

Windbreaks

SOIL RESTORATION Organic fertilizer

Commercial inorganic fertilizer

Animal manure

Compost

Crop rotation

Organic Fertilizer

Has decreased in the U.S. due in part because most farmers no longer raise livestock and it costs too much to transport

Poop Factory and Phillies Soil

Inorganic fertilizers have taken off

Inorganic FertilizersNitrogen,

Phosphorous, Potassium

Grown in usage worldwide

Credited with increasing crop yields (1/4 of world crops)

W/o could only feed 2-3 billion people

Many problems associated (see next slide)

“Conservation is a state of harmony between men and land.” - Ibid.

“What greater grief than the loss of one's native land.” -Euripides

“The land belongs to the future” -Willa Cather

Thank You