© 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 21 st Century Vaclav Smil. MIT Press. Institutional & Policy Changes to end hunger  Ending Hunger in Our Lifetime CF Runge, B. Senauer, PG Pardey, & MW Rosegrant. IFPRI & Johns Hopkins U. Press.

© T. M. Whitmore QUESTIONS? Hunger model Irish Famine Example Nutrition Transition model

© T. M. Whitmore Reasons for concern I: Population Growth Population growth to 8-10 billion by 2050 (50% more than today!) All in less developed world (China = India each ~ 1.5 b)

© T. M. Whitmore Reasons for concern II: Dietary transitions Moving up on the food chain  Traditional diets => ~2400 kcal; 10% animal  Improved diets => ~3000 kcal; 25% animal Increased animal fraction => 4-5 times more animal feed (plant material) needs to be produced Overall need ~ 2x current harvest to get improved diet by 2050 for everyone

© T. M. Whitmore Reasons for concern III: Changes in agriculture Increases in pollution, erosion, and decreases in water availability potentially =>  Slow growth or even decrease Already slowing rates of growth of grain production per capita

© T. M. Whitmore Raising Output: 4 major areas of concern 1. Photosynthesis and crop productivity limits 2. Land, water, and nutrient (NPK) limits 3. Agroecosystems and biodiversity 4. Environmental change

© T. M. Whitmore 1) Photosynthesis & crop productivity limits There is an energetic limit:  Photosynthesis is < 5% efficient in converting sunlight to vegetative matter (even less if water or nutrients are short)  One way to address this is to improve the harvest index (= edible part/total biomass)  This is an area of possible progress  traditional wheat %  green revolution wheat %

© T. M. Whitmore 2) Land limits I Agricultural land limits  ~ 1.5 giga (10 9 ) ha now cultivated and 1.6 giga ha (rainfed) potentially usable  Most area available for expansion in S.S. Africa & S. America savanna

© T. M. Whitmore 2) Land limits II Land use needed per-capita  Traditional vegetarian diet =>  ha /capita  Chinese diet (2800 kcal; 15% animal)  ~ 1.1 ha/capita  Rich Western diet  ~ 4.0 ha/capita (much wasted and high meat fraction)  Better diet with some animal protein  ~ ha/capita  if 10 b people in 2050 =>  need 800 million ha to 3 gig ha (3000 million)  Thus, no fixed limit due to amount of land if diet not excessive & all available land used

© T. M. Whitmore 2) Land limits III If 10 b people in 2050 =>  Need 800 million ha to 3 gig ha (now use 1.5 gig ha) Thus, no absolute limit due to amount of land if diet not excessive & all available land used – AND food can be moved from surplus areas to deficit areas Regionally per-capita land availability is more problematic for 2050  OK in Latin America  Adequate in Sub-Saharan Africa & Mid-East  Problematic in South & East Asia

© T. M. Whitmore 2) Water limits I Water: – in most systems water is the most important limit most years  Photosynthesis uses/needs lots of water also add evaporation and transpiration  mm water needed per ha for low- yielding crops  mm water needed by high yielding crops Current irrigation  ~ 250 million ha (only 8 m ha in 1800)  ~ 17% of all agriculture land  Creates 40% of all food

© T. M. Whitmore 2) Water limits II Current Water Use  Currently 5-7% of all available fresh water runoff used for agriculture  Even if water use only grew to match population => by 2050 agriculture will need 1/3 of all available fresh water

© T. M. Whitmore 2) Water limits III Crop and animal water use efficiency  Small grains and pulses => 0.25 m 3 of water /million joules energy to humans (or about 1 liter per kcal)  Animals via grain and feed => 25.4 m 3 water/m joules energy to humans (100x more!) or ~ 100 liters per kcal

© T. M. Whitmore 2) Water limits IV Water use in diets  Vegetarian diet (2500 kcal/day) =>  0.9m – 1.2 million liters/capita/year  Rich world diets (more kcal and more animal foods) =>  >> 2.0 m l/capita/year  Improved diets (more kcal and more animal foods than traditional vegetarian) =>  ~ 2 million l/capita/year  So – 10 b people =>  20,000 m 3 water or ~ 2/3 of ALL global runoff (assumes 2000 m 3 /capita/yr)

© 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 times (e.g., all tropical rainforests)

© T. M. Whitmore 2) Nutrient limits II Nitrogen is the key element  We do not know annual rates of biofixation of N with certainty  Clover alfalfa etc. fix about kg/ha  Beans about kg/ha  Bacteria in rice fields ~ 30 kg/ha  Earth 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

© 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 I: 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 crops  Perfected 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 scarce  Varies with soil type and cropping type  BUT evidence is lacking to prove widespread productivity loss

© T. M. Whitmore Changing soils II Qualitative soils degradation - often subtle and long-term  Even 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 sense  Loss 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 & atm.  Nitrates are widespread contaminates in surface and sub-surface water  Atmospheric deposition of nitrogen should => increased production – but good data 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 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 warming  Releasing CO 2 form biomass and soils;  N 2 O emissions from fertilizers;  Methane from rice fields and cow farts

© 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 CO 2 => increased crop yields (assuming no other constraints); lower water loss thru leaves (transpiration); better ability to withstand env. pbms. etc.  Doubled CO 2 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)

Changes in crop yield by the 2080s, under scenarios of unmitigated emissions Rosenzweig, C., M. L. Parry, G. Fischer, and K. Frohberg 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

© 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 recycling  N recovery from green manures is higher than for synthetic N fertilizers  Problem 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 canals  Plant more water efficient crops  Better timing of water application  Simple devices to judge soil water need  Manage tillage to reduce soil water loss  Use new efficient pumps and motors

© T. M. Whitmore Rationalizing animal food production Justification for animal use  There is no need to eat animals to lead healthy lives  But humans seem to be adapted to omnivory by evolution  Globally humans eat ~ kg annually - a quite small amt. by US standards ( kg annually 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 humans  But 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 sq meter land per million kcal; sq meter land per kg protein  water: gm water/kcal; gm/g protein  Eggs:  feed: 20-25% feed to edible energy; ~ % of feed to protein  land: need ~ sq m / m kcal; 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; ~ % of feed to protein  land: need ~ sq m / m kcal; 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; ~ % of feed to protein  land: 5 gm water/kcal; gm/g protein  water: need ~ sq m / m kcal; sq m/kg protein

© T. M. Whitmore Animal food production V Efficiencies and resource use of animals  Fish:  feed: farmed carp etc % 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; sq meter/kg protein  water: gm water/kcal; 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., a dairy cow produces 20 tons feces & urine annually)  Can be reused as manure – especially in places with concentrated industries  But 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 efforts  Pigs: 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 ( 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