Producing Enough Food for Producing Enough Food for the Worldthe World

Will there be enough food??

With human population growing and much of the world’s arable land being used, how will we keep pace with providing enough food for everyone??

Thomas Malthus: Population increases at

an exponential rate, while food supplies grow arithmetically. Basically, we’re doomed !!

Malthus…. Is he right?

So far….. He has been proven wrong.

Why????

(*This was in 1798)

We have enhanced the productivity of our

cultivated lands. – more produce, using the same amount of land.

Scientific and technological advances in agriculture. OUTCOME : FOOD PRODUCTION HAS KEPT

PACE WITH THE POPULATION GROWTH

Technology !!!!

How much of the Earth’s surface can be used for agriculture?

Limiting factors: water, temp, topography, climate, soil quality and available technologies

Earth’s Land Resources

All chemicals present, required for plant

growth Physical structure that lets air and water move

freely Retains water well High organic content Mixture of sediment particle sizes

Small – retains water Large – aerates soil

What makes high quality Agricultural Soil?

Liebig’s Law of the Minimum: The idea that

some single factor determines the growth and , therefore, the presence of a species.

“The growth of a plant is affected by one limiting factor at a time – the one whose availability is the least in comparison to the needs of the plant”

Different crops require different soilsRarely does soil have everything a crop needs

Usually there is 1 limiting factor

What do we grow?

500,000 plant species

3000 used in agriculture Crops

150 cultivated on lg. scale

200 sp. Grown in US 14 sp. Provide most

of the worlds food

Crops and Animals

Wheat Rice Maize (corn) Potatoes Sweet potatoes Manioc Sugarcane Sugar beet Common beans Soy beans Barley Sorghum Coconuts bananas

Chickens Cattle Sheep Ducks Pigs Goats Buffalo camels

Good words to know

Forage: food grown for animals – alfalfa, sorghum, grasses

Rangeland: provides food for grazing, w/o plowing or planting

Pasture: plowed, planted and harvested for forage for animals

37 % of the Earth’s land area is agricultural land.

11% is used for crops – the rest is pastureland.

Pastureland : cultivated or wild forage crops and open land used for grazing.

United Nations Food and Agricultural Organization (FAO) states: ¾ of Earth’s land surface is unsuitable for growing rain-fed crops (w/o irrigation) 3.5% of the Earth’s surface is suitable for agriculture w/o any physical constraints (More inputs necessary, ie: fertilizer)

How is the Earth used?

Converting Land

Desert turned Farm in California

Farmland turned urban

In the US, Europe and Japan: Land is being

withdrawn from Agriculture. Productivity is higher than demand.

In these areas they rely on Agricultural Intensification to keep a high output on shrinking farmland

In developing worlds: land is being converted to agriculture. This also requires Agricultural Intensification.

Agricultural Intensification: fertilizers, irrigation, GM seed – High inputs

CO2 + H2O + sunlight → (CH2O)n + O2

Plants convert CO2 and water into plant tissue. This is the foundation of agricultural productivity.

We need to understand the roles of water and nitrogen (N).

We need to understand photosynthesis as a key input

Drought id the biggest limit on agricultural

productivity – plants need an enormous amount of water.

Plants use the energy from the sun to convert CO2 and water into carbohydrates. The ratio of water to CO2 is not equal. It is 400 to 1.

98% of the plants water travels upward through the roots and evaporates – exiting the leaf as water vapor through the stomata TRANSPIRATION

Water

Principle reason for transpiration is to allow

uptake of CO2 from the atmosphere. Water diffuses out of the plants leaves into the

surrounding atmosphere. (100% humidity in plant; 50% humidity in atmosphere – higher conc. To lower conc.)

CO2 diffuses into the plant.

CO2 diffusion is at a lower rate due to the conc. Of CO2 in atmosphere is .037% and zero in the plant

Transpiration

stomata

Stomata open to promote gas exchange when water

is plentiful, and constrict or close when water is scarce

The diffusional relationship between water and CO2, explains why drought is the major factor limiting

agricultural yields worldwide

Another critical resource for photosynthesis. Nitrogen is a limiting factor. It is an essential component of proteins,

especially the enzyme ribulose-biphosphate-carboxylase-oxygenase (RUBISCO)

This enzyme catalyzes the incorporation of CO2 into an organic molecule.

(RUBISCO is thought to be the most abundant protein on Earth – leaves are typically 2% Nitrogen- by dry weight)

Nitrogen

Fertilizer

Prior to WWI, main source of nitrogen fertilizer was manure

In S. America, nitrogen was mined; as saltpeter – through WWI

US gov’t allowed the acquisition of Guano Islands

1908 – German Chemist – Fritz Haber In an effort to create

munitions, created nitrogen fertilizer

Increasing Yields

Compared to undisturbed ecosystems (self maintained, nutrients cycle) agricultural, harvests crops – which removes material from the system permanently.

Farmers NEED to add nutrients and water to increase yields

Crops require 20 chemical elements Macronutrients: S, P, Mg, Ca, K, N, O, C, H Micronutrients: Cu, Zn, Mn, Fe, Molybdenum,

rarer metals Older soil is more likely to lack trace elements

because of leaching by water

Required Nutrients

Total output per unit of land Due to intensification

More technology inputs per acre Irrigation Synthetic fertilizers Pesticides and herbicides GM seeds

Higher yielding crops Larger portion of physical structure is devoted to

producing biomass. Growing deep root systems Plants with more seeds

Productivity

Green Revolution

A program established in the 1940’s

Distribution of high-yield crops varieties, synthetic fertilizers, irrigation techniques and pesticides to farmers in Asia and Latin America.

Helped to increase world food production at a pace greater than population growth.

1. Try to stop ecological succession and keep the agro-ecosystem in an early successional state

2. Monoculture: Large areas planted with a single species (entire crop vulnerable to disease, depletes soil of specific chemicals)

3. Crops are planted in neat rows – no hiding from pests or blending in

4. Farming greatly simplifies biological diversity & food chains

5. Plowing is unlike any natural soil disturbance – increases erosion and decreases organic matter

6. Genetic modification of crops?? What will this do?

Six Ways Agro-ecosystems Differ from Natural Ecosystems

Types of agriculture

Mechanized Agriculture: Production is

determined and limited by economic demand – NOT by resources

(land, water and fuel)

Old time farming. Supply and demand

Resource Based Agriculture

Production limited by environmental sustainability and available resources

Economic demand exceeds production Based on

biotechnology and conservation of land, water and energy

Organic Farming

Off shoot of Resource based farming

More like natural ecosystem

Minimizes negative environmental impact

Food does not contain artificial compounds

12,000 farmers in US - growing 12% per year

Insects, mice, rats, weeds, fungi, bacteria and

viruses Natural control : salt, sulfur and arsenic Synthetic pesticides are more effective:

1st pesticides: aldrin, dieldrin, heptachlor – human health effects – no longer used in US

DDT – Caused thin egg shells in predatory birds. – no longer used in US

Now: target specific pesticides Many pests are resistant

Combating Pests

Aquaculture

The farming of food in aquatic habitats Carp, tilapia, oyster, shrimp US – crayfish, salmon, trout and catfish China has been doing this – traced back to 475

BC

Mariculture The farming of ocean fish

Aquaculture

Undernourishment – lack of sufficient calories in available food. Manifested in famines that are fast acting (lack of food supply)

Problems with undernourishment: Marasmus: progressive emaciation due to lack of

protein & calories Kwashiorkor: lack of sufficient protein in infants –

failure of neural development Chronic hunger: enough food to stay alive, but not

enough to live a productive & satisfactory life

How we starve

Marasmus

Malnourishment – lack of specific chemical

components of foods ie: proteins, vitamins, etc. - Long term

(Eating, but not eating foods with enough nutrition)

How we starve

Africa – the continent with the most acute food

shortages due to weather & strife Food distribution fails because:

Poor cannot pay for food and/or delivery Transportation is lacking and too expensive Food is withheld for political & military purposes

Food aid is a short term answer

Must solve the problem of food distribution and increase local production ie: long term sustainable agriculture - locally

Food Aid

Organic agriculture introduced 10,000 yrs.

Ago. 18th & 19th centuries (industrial revolution)-

shift to mechanized or demand based agriculture

20th century- return to resource based agriculture

Today – growing interest in organic agriculture & use of genetically engineered crops

History of Agriculture

1. The Green Revolution- Programs that have led to the development of

new strains of crops with higher yields, better resistance to disease or better ability to grow under poor conditions- Ex: hybridized rice (increased yield)- Maize (disease resistant)

2. Improved Irrigationexpensive and found in developed

countries

Increasing the Yield per Acre

Genetically Modified Crops are modified by

genetic engineers to produce higher crop yields and increase resistance to drought, cold, heat, toxins, plant pests and disease.

Genetically Modified Food

High yields Nitrogen fixing – reduces need for fertilizers Drought tolerant (also: cold, heat and toxic

element tolerant) ¾ soybeans, 1/3 corn and more than ½ of the

plants used to produce canola oil are GMF

GMF’s