1. Producing Enough Food for the World

2.  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 !!

3.  Malthus…. Is he right?  So far….. He has been proven wrong.  Why????  (*This was in 1798) 

4.   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 !!!!

5.   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

6.   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?

7.   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 soils Rarely does soil have everything a crop needs Usually there is 1 limiting factor

8.  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 

9.  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

12.  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

13.   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?

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15.  Converting Land  Desert turned Farm in California  Farmland turned urban

16.   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

17.   CO 2 + H 2 O + sunlight → (CH 2 O) n + O 2  Plants convert CO 2 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

18.   Drought id the biggest limit on agricultural productivity – plants need an enormous amount of water.  Plants use the energy from the sun to convert CO 2 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

19.   Principle reason for transpiration is to allow uptake of CO 2 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.)  CO 2 diffuses into the plant.  CO 2 diffusion is at a lower rate due to the conc. Of CO 2 in atmosphere is.037% and zero in the plant Transpiration

20.  stomata  

21.   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

22.   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

23.  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 

24.  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

25.   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

26.   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

27.  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.

28.  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

29.  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

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31.  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

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33.  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

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35.   Insects, mice, rats, weeds, fungi, bacteria and viruses  Natural control : salt, sulfur and arsenic  Synthetic pesticides are more effective:  1 st 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

36.   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

37.   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

38.   Marasmus

39.   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

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42.   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

43.   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

44.   Organic agriculture introduced 10,000 yrs. Ago.  18 th & 19 th centuries (industrial revolution)- shift to mechanized or demand based agriculture  20 th century- return to resource based agriculture  Today – growing interest in organic agriculture & use of genetically engineered crops History of Agriculture

45.  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 Irrigation expensive and found in developed countries Increasing the Yield per Acre

47.   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

48.   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