© T. M. Whitmore

TODAY• Food Futures: Will there be enough food for

the 21st century? Opportunities to improve output Feeding the World: A Challenge for the

21st Century. 2000. Vaclav Smil. MIT Press.

• Institutional & Policy Changes to end hungerEnding Hunger in Our Lifetime. 2003. CF

Runge, B. Senauer, PG Pardey, & MW Rosegrant. IFPRI & Johns Hopkins U. Press.

© T. M. Whitmore

Reasons for Concern

•Population growth To 8-10 billion by 2050 (50% more

than today!)

•Dietary transitionsMoving up on the food chain

•Changes in agriculture/environmentPotential for slowing growth or

even stagnation or decrease

© T. M. Whitmore

Food Crisis now• World food prices are up ~50% since last year• The World Food Programme announced a

$500 million deficit for 2008• http://www.freerice.com/• Low-income countries that are net food

importers; have been hit hardestAlready, 37 countries--21 of which are in

Africa--are in a food security crisis according to the FAO

The World Bank recently announced that the current food situation could push 100 million people into deeper poverty

Poor households spend between 60 to 80% of their income on food, compared to only 10-20% in most industrialized countries.

© T. M. Whitmore

Raising Output: 4 major issues

1.Photosynthesis and crop productivity limits (last time)

2. Land, water/irrigation, (last time) and nutrient (NPK) limits

3. Agroecosystems and biodiversity4. Environmental change

© T. M. Whitmore

2) Nutrient limits I• Crop nutrient (NPK) limits

Typically need 10s of kg P & K and 100s kg N per ha in modern high output agriculture

Complete recycling of ALL organic residues from all harvested land and confined animals NOT able to supply all the NPK needed for high-yield agriculture (i.e., more removed by harvesting than could be replaced)

Only way to feed 10 b this way (all organic) would be to increase cropped area 2 - 3 times (e.g., all tropical rainforests)

© T. M. Whitmore

2) Nutrient limits II

• Nitrogen is the key elementWe do not know annual rates of

biofixation of N with certainty Clover alfalfa etc. fix about 150-200

kg/haBeans about 70-100 kg/haBacteria in rice fields ~ 30 kg/haEarth may be able only to support 3-4

billion w/o synthetic N added

© T. M. Whitmore

2) Nutrient limits III• Nitrogen continued

50 gm protein/capita/day for 6 b people in 2000 => only 19 m tons Nitrogen/yr removed from soil

• Current synthetic nitrogen production about 80 m tons/yr

• Energy cost to produce N: 40 giga joules/ton of N fertilizer (40%

energy; 60% feedstock)This equals only 7% of world's total

natural gas -- so energy is not a limit in the short run

© T. M. Whitmore

2) Nutrient limits IV• Phosphorus (P)

Complete recycling not able to support high-yield farming

But - mined rock not in short supply• Potassium (K)

Needed in even smaller quantities• Thus only N is a nutrient bottleneck

© T. M. Whitmore

3) Agroecosystem & Biodiversity

• Basic ecology => Increased species diversity =>

increased net primary productivity and nutrient retention

But NO clear link between natural system stability and diversity

© T. M. Whitmore

3) Agroecosystem & Biodiversity II• Concern: a very narrow biotic base of

modern ag• Traditional systems use far more species

than do modern monocultures (e.g., wheat in USA plains)

• 250,000 higher plants known; 30,000 edible; 7,000 have been cropped

• Only 15 major crop species• 15 species produce 90% of all food• Corn, wheat, rice produce 2/3 kcal and 1/2

plant protein!

© T. M. Whitmore

3) Agroecosystem & Biodiversity III

• Crop rotations, intercropping, and new cropsPerfected rotations => better yields, soil

protection, reduce pests (but not all are so good)

• Introduction of legumes in rotations can be very helpful Microorganisms (soil flora an fauna

primarily) diversity apparently NOT down overall

but this is NOT a well studied field correct applications of modern inputs

does not seem to hurt soil microbes (but not well studied)

© T. M. Whitmore

4) The last major concern is Environmental Change

•Changing soils

•Environmental pollution

•Climate change

© T. M. Whitmore

Changing soils I• Erosion - most talked about issue

Mismanagement => excess erosion on 180 m ha crop fields (about 1/5 of all cropped land)

Data are uncertain and scarceVaries with soil type and cropping typeBUT evidence is lacking to prove

widespread productivity loss

© T. M. Whitmore

Changing soils II• Qualitative soils degradation - often subtle

and long-termEven more difficult to prove or gather

data Again little hard data to prove

widespread problems (but vice versa)Salination is easier to show - but not

significant in global senseLoss of productivity hard to see because

of changes cultivars, fertilization, irrigation, etc.

Retention of soil organics via using crop residues etc. probably key here

© T. M. Whitmore

Environmental Pollution I• Has been implicated in reducing crop

yields• Agriculture is a major polluter itself• Nitrogen issues

Compared to pre-industrial era humans now have doubled all inputs of nitrogen to soils & atmosphere

Nitrates are widespread contaminates in surface and sub-surface water

Atmospheric deposition of nitrogen should => increased production – but good data are scarce

© T. M. Whitmore

Environmental Pollution II• Ozone

Loss of stratospheric ozone => higher levels of ultraviolet radiation => damage to crops

High levels of surface ozone also degrades agriculture production in places like W Europe; E North America; E Asia

© T. M. Whitmore

Climate Change I• Mostly due to increase in greenhouse

gasses• Key issues for agriculture

Surface heating (~ 2º C - greater more pole-ward)

Intensified water cycling (more in high latitudes)

• Uncertain local effects but droughts, storms, or surplus water quite possible

© T. M. Whitmore

Climate Change II

• Probably increasing instability in climate system (i.e., storm intensity and variability)

• Agriculture is a major contributors to greenhouse warmingReleasing CO2 form biomass and soils; N2O emissions from fertilizers; Methane from rice fields and cow farts

© T. M. Whitmore

Food’s contribution to climate change• Worldwide, agriculture contributes to nearly

14% of total greenhouse gas emissions.

• In the U.S., the food we eat accounts for 17% of our total fossil fuel consumption (which is huge per capita).

• The annual carbon footprint of an average American diet is 0.75 tons CO2-eq, without accounting for food transportation.

• On average, food travels 1,500 miles between the production location and the market.

• Meat products have a larger carbon footprint than fruits, vegetables, and grains: the carbon footprint of the average meat eater is about 1.5 tons CO2-eq larger than that of a vegetarian.

CO2 emissions due to land use

© T. M. Whitmore

Climate Change III• Consequences for agriculture

Overall agriculture output may not change much in near term – but regionally there may be problems

Increased CO2 => increased crop yields

(assuming no other constraints); lower water loss thru leaves (transpiration); better ability to withstand env. pbms. etc.

Doubled CO2 should boost yields in well

fertilized crops of about 7-30% (C3 species benefit most - all staple cereals except corn and sorghum)

© T. M. Whitmore

Climate Change IV• Consequences for agriculture II• Rising temps

Improve efficiency of C3 plants (if too high => lower yields)

Temporal timing also key (all in summer? all in winter? – all this is unclear); but too hot could => drought-like stress

Increase cropping area overall in higher latitudes

© T. M. Whitmore

Climate Change V• Consequences for agriculture III• More rapid water cycling

More water available for irrigation but regionally much more uncertain

Changes may be gradual so adaptation may help

Regional scenarios: high latitude areas may benefit (Canada, Russia); drier tropics and sub-tropics may be big losers (SS Africa etc)

© T. M. Whitmore

Opportunities to improve things I

(see details at end)• More efficient fertilizationReduce lossesProper timingChoosing varieties that need lessMore natural N fixation

• Better use of waterPricing to reduce wasteBetter irrigation loss control

• Precision farming and low till

• Rationalizing animal food production

© T. M. Whitmore

Opportunities to improve things II

• Precision farming and low tillWithin field adjustments (GPS/GIS technology)No till ag to reduce nutrient and CO2 losses

• Rationalizing animal food productionNo real need to eat animals (but humans seem

to be omnivores)More efficient use of animal products (in order)

Milk Eggs Chickens Pork Fish Beef

© T. M. Whitmore

Opportunities to improve things III

• Reducing harvest & storage losses15+% lost in traditional ag

• Post-harvest storage lossesMaintain vitamins etc.

© T. M. Whitmore

Opportunities to improve things: Higher cropping efficiency via more efficient fertilization

• Late 1990s global use of N fertilizers (80 m tons/yr) about 60% to 3rd world – in future will account for more (predicted to grow at 2%/yr)

• Most need in SS Africa where soil losses in NPK are not matched by fertilizer applications

© T. M. Whitmore

More efficient fertilization II• Asia is reverse – HYVs and heavy fertilizer

use

• Problem is much applied nutrient does not serve plants at all (leaching, and erosion especially of N) and pollutes

• N losses are commonly 10-15% of applied ammonia and 30-40% of manures (aggregate perhaps 45-50% loss in rain-fed and 30-40% loss in irrigated)

© T. M. Whitmore

More efficient fertilization II

• Reducing fertilizer losses

• Soils testing

• Use of more stable fertilizers

• Unbalanced (excessive) N use is a main problem

• Proper timing

• Proper application

© T. M. Whitmore

More efficient fertilization III• Increased reliance on biofixation (rotation

with legumes primarily and use of green manures) and nutrient recyclingN recovery from green manures is higher

than for synthetic N fertilizersProblem is needed output is forsaken by

growing of green manures

• Choosing cultivars that require less (e.g, Brazil’s choice of soy with low N need => low use of N fertilizers)

• Possible to inoculate fields with N-fixing bacteria to set up self-sustaining N fixation

© T. M. Whitmore

Better use of water• Water seldom priced appropriately to

regulate use• Irrigation efficiencies

Losses maybe 60-70% of initial total; 20-30% improvements possible => enough water to feed 100 m more people

Reduce loss in canalsPlant more water efficient cropsBetter timing of water applicationSimple devices to judge soil water needManage tillage to reduce soil water lossUse new efficient pumps and motors

© T. M. Whitmore

Rationalizing animal food production

• Justification for animal useThere is no need to eat animals to lead

healthy livesBut humans seem to be adapted to

omnivory by evolution Globally humans eat ~ 10-20 kg meat

annually - a quite small amt. by US standards (70-110 kg annually + 300 kg milk)

Adding meat and milk to diets is an “easy” way to improve protein, calcium, vitamin, and etc.

© T. M. Whitmore

Animal food production II • As long as animals eat foods we cannot

they do not compete with humansBut the problem is that increasingly we

feed grain to animals; in 1900 ~10% of grain to animals; by late 1990s ~45%!; > 60% in USA

If all grain fed to animals were devoted to humans => 1-3 billion could be fed!!

© T. M. Whitmore

Animal food production III• Efficiencies and resource use of animals

Milk: inherently efficient energy conversion feed: 30-40% of feed to edible energy;

~30-40% of feed to protein land: need about 1-1.5 sq meter land

per million kcal; 19-28 sq meter land per kg protein

water: 10-15 gm water/kcal; 200-300 gm/g protein

Eggs: feed: 20-25% feed to edible energy; ~

30-40% of feed to protein land: need ~ 1.5-2 sq m / m kcal; 19-25

sq meter land per kg protein water: 1.5 gm water/kcal; 15 gm/g

protein

© T. M. Whitmore

Animal food production IV• Efficiencies and resource use of animals

Chickens: feed: 15-20% feed to edible energy; ~

20-30% of feed to protein land: need ~ 2.5-3 sq m / m kcal; 13-15

sq meter land per kg protein water: 6 gm water/kcal; 50 gm/g protein

Pork: inherently efficient due to low basal metabolism; rapid reproduction and growth feed: 20-25% feed to edible energy; ~

10-15% of feed to protein land: 5 gm water/kcal; 150-200 gm/g

protein water: need ~ 2.0-2.5 sq m / m kcal; 80-

100 sq m/kg protein

© T. M. Whitmore

Animal food production V• Efficiencies and resource use of animals

Fish: feed: farmed carp etc. 15-20% feed to

edible energy; ~ 20-25% of feed to protein;

farmed salmon 35-40% feed to edible energy; ~ 40-45% of feed to protein (but carnivorous => need high protein feed)

Beef: US-style feedlot feed: 6-7% feed to edible energy; ~ 5-

8% of feed to protein land: need ~ 6-10 sq m / m kcal; 180-

310 sq meter/kg protein water: 25-35 gm water/kcal; 700-800

gm/g protein

© T. M. Whitmore

Opportunities for meat and milk

• Benefits of animal food are the ability to turn non-edible stuff into relatively high quality protein

• Improved feeding: fine-tune feeding quantity and quality to improve efficiencies (as has been done in US over past 50 yrs)

• Major costs/problems are wastes (e.g., 1 dairy cow produces 20 tons feces & urine annually) Can be reused as manure – especially in

places with concentrated industriesBut cheap synthetic nitrogen fertilizers and

transport/storage costs etc. make manures less attractive

© T. M. Whitmore

Opportunities for meat and milk II

• Strategies Milk: efficiency of milk => a good place

to put effortsPigs: since they are 40% of ALL meat

consumed worldwide and are omnivorous and can gain on many foods (e.g., cassava, bananas, brans, brewery byproducts, etc.)

Water buffalo: since they are more efficient converters of roughage to protein than cows

© T. M. Whitmore

Opportunities for meat and milk III

• Strategies Fishing:

Yield is poor in open ocean; far better inshore on continental shelves due to greater nutrient availability

As of late 1990s the ocean is fully fished (no opportunities for expansion, probably contraction)

© T. M. Whitmore

Opportunities for meat and milk IV• Strategies

Aquaculture: Now provides about 20% of all fishes; 80% of

all mollusks; ~ 1/5 of all shrimp; 1/3 of all salmon

Total greater than all mutton and lamb and ~ 1/3 all chicken

Tilapia is especially attractive: likes warm climates; is omnivorous; an be raised intensively or extensively; mild taste

Has many advantages: improved diets; can be integrated into agriculture systems (e.g., rice)

e.g., Chinese carp polyculture system is good: 2-4 tons/ha (700kg protein) of fish plus other vegetables etc. on very small farms (0.2-.05 ha)

© T. M. Whitmore

Opportunities for meat and milk V• Strategies

Aquaculture – problems: Humans have less experience raising fish

(especially outside Asia) so predicting expansion is harder

More intensive production is possible But pollution problems already

Changes in crop yield by the 2080s, under scenarios of unmitigated emissions

Rosenzweig, C., M. L. Parry, G. Fischer, and K. Frohberg. 1993. Climate change and world food supply. Research Report No. 3. Oxford: University of Oxford, Environmental Change Unit.

Changes in crop yield by the 2080s, under scenarios of stabilization of CO2 at 750 ppm

Changes in crop yield by the 2080s, under scenarios of stabilization of CO2 at 550 ppm