Climate Change and Soil Quality

R. LalCarbon Management and Sequestration CenterThe Ohio State University, Columbus, OH 43210

Soil Quality

Capacity of a soil to perform ecosystem functions

• Enhancing NPP• Moderating climate• Purifying water• Cycling elements• Increasing biodiversity• Etc.

Biota560 Gt

Atmosphere780 Gt

+3.5 Gt/yr

Soils2,500 Gt

(i) SOC - 1,550 Gt(ii) SIC - 950 Gt

Ocean38,400 Gt + 2.3 Gt/yr

(i) Surface layer: 670 Gt(ii) Deep layer: 36,730 Gt(iii) Total organic: 1,000 Gt

Fossil Fuels4,130 Gt

(i) Coal: 3,510 Gt(ii) Oil: 230 Gt(iii) Gas: 140 Gt(iv) Other: 250 Gt

120 + 2.0 Gt/yr (photosynthesis)Plant respiration

60 + 1.6 Gt/yr

60 Gt/yr

7.5 Gt/yrFossil fuelcombustion

90 Gt/yr

0.6+0.2 Gt/yr(deposition)

60 Gt/yr (soil r

espiration)

Accelerated soil erosion

1.1+ 0.2 Gt/yr (erosion)MRT = 5Yr

MRT = 25Yr

Mean Residence Time (MRT) = 400Yr

1.6 + 0.8 Gt/yrDeforestation

MRT = 6Yr

92.3 Gt/yr

Biofuel offset?

Coupled Cycles of C and Water in Soil Ecosystem

Biota Atmosphere

Soil• + ΔΔΔΔ SOC• + ΔΔΔΔ Soil H 2O

Ocean

Biomass –C input

H2O uptake

Soil Respira

tion

Precipitatio

n

H 2O Evaporatio

n

H2O Transpiration

Plant Respiration

Photosynthesis

Uptake Emission

Eva

pora

tion

C Erosion

Water Runoff

Coupled Cycling of C,N, H 2O

C H2O

N Soil Quality

Mean Crop Yield in India, Kenya and Developed Countries (FAO, 2005)

7980814Chickpea

1790332Cowpea

3910797Sorghum

83401907Maize

31102601Wheat

68103284Rice

Developed Countries

India

Yield (kg/ha)Crop

Climate Change

• Projected climate change may exacerbate the problem of desertification, drought and soil degradation.

• It is essential to identify and implement coping (mitigation) and adaptive strategies.

Drought

It refers to a prolonged period during which the availability of fresh water supply is less than the demand, especially in arid and semi-arid regions.

Types of Drought

When infiltration rate of soil decreasesWhen available water is less than the need for agricultural use

3. Edaphic

4. Agricultural

B. Non-Climatic

When rainfall is deficientWhen runoff in rivers declines

1. Meteorological2. Hydrological

A. Climatic

Maingnet and De Silva (1998)

Other Soil Related Constraints In South Asia

• Low AWC in rainfed soils• Poor quality soils• Depleted of nutrients and SOC• Extractive farming

Agricultural Intensification

Cultivating the best soils with the best management practices to produce the optimum sustainable yield and save marginal lands for nature conservancy

BT

N, P, K, Zn, H2O

Delivering nutrients and water directly to roots of improved plants using nano-

enhanced molecules

Agricultural Intensification

Estimate of Increase in Food Production in LDCs by Increasing SOC Pool by 1 Mg C

ha-1 yr-1

30.4 – 50.8532Total

6.6 – 11.334Tubers

2.0 – 3.268Legumes

21.8 – 36.3430Cereals

Production Increase(106 Mg yr -1)

Area (Mha)Crop

SOC Pool

Soi

l Qua

lity

Microbial biomass

Nutrient Retention

Available water capacity

Aggregation

Infiltration rate

Aeration porosity

SOC Pool

Soi

l Qua

lity

Agronomic producti

vity

WUE

NUE

EUE

SOC Pool

Soi

l Qua

lity

ErodibilityCrustingCompaction

Runoff

Crop yield and productivity effects of SOC pool

SOC Pool

Cro

p Y

ield Unfertilized

Fertilized

SOC Pool

∆∆ ∆∆Y

ield

TenTenets of Soil and Water

Management

Law #1 Causes of Soil Degradation

The biophysical process of soil degradation is driven by economic, social and political forces.

Law #2Soil Stewardship and

Human Suffering

When people are poverty stricken, desperate and starving, they pass on their sufferings to the land.

Law #3Nutrient, Carbon and Water Bank

It is not possible to take more out of a soil than what is put in it without degrading its quality.

Law #4Marginality Principle

Marginal soils cultivated with marginal inputs produce marginal yields and support marginal living.

Balancing Input and Output for Sustainability

Law #5Organic Versus Inorganic Source

of Nutrients

Plants cannot differentiate the nutrients supplied through inorganic fertilizers or organic amendments.

Law #6Soil Carbon and Greenhouse Effect

Mining C has the same effect on global warming whether it is through mineralization of soil organic matter and extractive farming or burning fossil fuels or draining peat soils.

Law #7Soil Versus Germplasm

Even the elite varieties cannot extract water and nutrients from any soil where they do not exist.

Law #8Soil As Sink For Atmospheric CO2

World soils can be a major sink for atmospheric CO2 and CH4 through conversion to a restorative land use adoption of recommended management practices. The C sink capacity of the pedosphere (~ 1 Pg C/yr) also has numerous ancillary benefits. It is essential to advancing global food security.

Law #9Engine of Economic Development

Sustainable management of soils is the engine of economic development, political stability and transformation of rural communities in developing countries.

Law #10Traditional Knowledge and

Modern Innovations

• It is not an “either or” scenario. • Modern science must synthesize the

traditional knowledge. • Those who refuse to use modern

science to address urgent global issues must be prepared to endure more suffering.

Soil CarbonAnd

GreenhouseEffect

Soil Stewardship

and Human

Suffering

Nutrient, Carbon

and Water Bank

Engine ofEconomic

Development

Organic Versus

Inorganic Source

of Nutrients

Marginality Principle

Causes of Soil

Degradation

TraditionalKnowledge

AndModern

Innovations

Soil VersusGermplasm

Soil As SinkFor

AtmosphericCO2 Sustainable

Management of Soil

Mother of the Necessity: The Soil

If soil and water resources are not restored or judiciously managed:

• Crops will fail even if rains do not• Hunger will perpetuate even with emphasis on biotec h and GM

crops• Civil strife and political instability will plague the world even

with sermons and mantras on human rights and democr atic ideals, and

• Humanity will suffer even with great scientific str ides

Soil and Survival

“Upon this handful of soil our survival depends. Husband it and it will grow our food, our fuel, and our shelter and surround us with beauty. Abuse it and the soil will collapse and die, taking humanity with it.”

From Vedas

Sanskrit Scripture 1500 BC