answer the questions.
Reminders & updates… •survey about environmental (in)justice reading due tonight @ 11:45 pm •second survey of assignment 2 due Tuesday @ 11:45 pm •Quiz 5 scheduled for Tuesday the 23rd –no other activities that day (but a post-lecture survey is due) •this is a two-part lecture (survey due 4-23) 1 Lectures 22 & 23: conventional agriculture 2 30% 21% http://www.esajournals.org/doi/abs/10.1890/070062 (35% in OH) 3 Conventional agriculture = high input Inputs = energy, irrigation, fertilizer, pesticides, antibiotics, ‘GM’ crops… 4 Remember this? 5 Conventional agriculture = high input Inputs = energy, irrigation, fertilizer, pesticides, antibiotics… 6 Why do crops and other plants need water? 7 Photosynthesis: CO2 + H2O → C6H12O6 + O2 sunlight (N-rich) 8 (90%) •agriculture (99.5 >99.5 from Raven et al, Biology of Plants (1986) 17 PO4 ➔ water-soluble http://www.sciencedirect.com/science/article/pii/S095937800800099X 18 19 industrial N2 fixation (Haber-Bosch process) requires lots of energy 20 N transformations and reactive N forms +PO4 • NO3 (nitrate) ➔ water-soluble and mobile in soil, a pollutant and toxic to humans at higher levels, and a precursor to N2O • NH3 (ammonia) ➔ not as mobile as NO3 in soils, but it is volatile, soluble in water (where it becomes NH4 or ammonium), and can ultimately be converted to NO3 • N2O (nitrous oxide) ➔ greenhouse gas 21 Why does it matter that NO3 & PO4 are water soluble & mobile? +PO4 22 http://science.sciencemag.org/content/321/5891/926 23 https://earthobservatory.nasa.gov/IOTD/view.php?id=44677 24 algal blooms low O2, dead zone 25 N transformations and reactive N forms • NO3 (nitrate) ➔ water-soluble and mobile in soil, a pollutant and toxic to humans at higher levels, and a precursor to N2O • NH3 (ammonia) ➔ not as mobile as NO3 in soils, but it is volatile, soluble in water (where it becomes NH4 or ammonium), and can ultimately be converted to NO3 • N2O (nitrous oxide) ➔ greenhouse gas 26 Earth-system trends… 27 Let’s consider the geography of fertilization 28 some crops are overfertilized more than others http://www.ers.usda.gov/amber-waves/2011-september/nitrogen-footprint.aspx 29 http://www.ers.usda.gov/amber-waves/2011-september/nitrogen-footprint.aspx 30 Nitrogen “footprint” 31 Pesticides http://www.nature.com/nature/journal/v418/n6898/full/nature01014.html 32 http://www.pewinternet.org/2015/01/29/public-and-scientists-views-on-science-and-society/ 33 http://water.usgs.gov/nawqa/pnsp/usage/maps/compound_listing.php 34 Atrazine in drinking water http://ehp.niehs.nih.gov/0900784/ 35 36 (of salamanders after exposure as embryos and larvae) Atrazine and amphibians http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1332655/ 37 38 Energy and agriculture 39 Energy and agriculture 40 Energy and agriculture http://www.annualreviews.org/doi/10.1146/annurev-environ-081710-161014 41 Carbon footprint (and nitrogen and water) 42 Antibiotics and agriculture 43 Antibiotics and agriculture https://www.nejm.org/doi/full/10.1056/NEJMp1311479 44 45 46 Genetic engineering and agriculture 47 http://www.pewinternet.org/2015/01/29/public-and-scientists-views-on-science-and-society/ 48 http://www.ers.usda.gov/data-products/adoption-of-genetically-engineered-crops-in-the-us/recent-trends-in-ge-adoption.aspx 49 Conventional agriculture = high input +land sparing Inputs = energy, irrigation, fertilizer, pesticides, antibiotics… 50 Not just ↑ production, ↑ production per acre http://onlinelibrary.wiley.com/doi/10.1111/j.1728-4457.2013.00561.x/abstract 51 ↑ prod. per acre: not just corn, not just here 52 ~38% of what would be required if yields per acre had not increased! https://ourworldindata.org/grapher/cereal-land-spared “land sparing” ↑ prod. per acre led to > than the U.S., Europe, and India combined 53 Now you should understand this graph better… 54 Conventional agriculture = high input +land sparing Inputs = energy, irrigation, fertilizer, pesticides, antibiotics… 55 Conventional agriculture = high input This hasn’t happened everywhere! 56 http://www.nature.com/nature/journal/v490/n7419/full/nature11420.html 57 http://www.nature.com/nature/journal/v478/n7369/full/nature10452.html 58 Conventional agriculture: summary • rising economic development (think, GDP per capita) and population size have increased demand for agricultural products; this resulted in increased use of water, fertilizer, pesticides, energy, and antibiotics to ‘grow’ agricultural products – because crops grow more when you add water, nutrients, and pesticides, while livestock grow more when their feed is supplemented with antibiotics • in some places, much of the water used for irrigation is non-renewable groundwater and thus agriculture contributes to groundwater depletion and unsustainable water use (e.g., the Ogallala/High Plains aquifer, the Upper Ganges aquifer in India) • nitrate (NO3) and phosphate (PO4) are water soluble and thus mobile, so fertilization of farms results in nutrient losses to streams and rivers, reducing water quality in those water bodies and the lakes and coastal areas where rivers end – nutrient pollution of lakes and the ocean causes dead zones – use of N fertilizers has also increased the concentration of N2O, a greenhouse gas, in the atmosphere • meat products, especially beef, require the most energy, water, and nutrient inputs/pollution to produce; this is reflected in high C, N, and water ‘footprints’ of meat as compared to other agricultural products – fruits, nuts & vegetables usually have lower footprints, while eggs & dairy products often have intermediate footprints 59 Conventional agriculture: summary • like fertilizer, pesticides don’t stay on the farm; pesticides move into streams, rivers, lakes and can even be found in drinking water; exposure of humans and animals to pesticides can have negative health consequences (e.g., atrazine, chlorpyrifos) • more antibiotics are fed to livestock than are used to treat humans and this agricultural use of antibiotics has increased in recent decades – agricultural use of antibiotics makes it more likely that human pathogens (e.g., MRSA) will become resistant to antiobiotic drugs; thus, the widespread use of antibiotics in agriculture is a risk to human health • in the U.S., most of the major crops planted are now genetically engineered to be resistant to either herbicides used to kill weeds (e.g., Roundup Ready corn, cotton, and soybean) or toxic to insects that eat crops (e.g., Bt corn and cotton) • all of these ‘inputs’ (e.g., irrigation, fertilizer, etc.) have negative consequences, but also have allowed food production to increase rapidly to meet the growing demand associated with population and economic growth • conventional agriculture has had a ‘land sparing’ effect because it results in higher yields per acre (this makes conv. ag an important part of sustainable ag) • food production can be boosted in some ‘developing’ regions by implementing conv. ag 60 Post-lecture survey due Tues. the 23rd @11:45pm Do it! 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