MonthDayLectureActivityChap. Nov.21Ecosystems IIServices56 26Global C cycle56 Dec.3Thinking ecologically I 5Thinking ecologically II Eco. literacy 10Exam review 19Final examHere at 12:20 am

Agricultural production vs human populations

Factors driving increased food production New cultivars (breeds) of crops

Factors driving increased food production New cultivars (breeds) of crops Good cropland made better –Irrigation –Fertilizers –Pesticides –Mechanization

Factors driving increased food production New cultivars (breeds) of crops Good cropland made better –Irrigation –Fertilizers (N from fossil fuels) –Pesticides –Mechanization Marginal cropland put into cultivation –Irrigation –Fertilizers –Tillage

Energy use in agricultural production (in billions of Kcal) WhereTotal energy Energy per hectare Energy per capita Developed Nations North America Developing Nations

Energy use in US corn production , Year Energy input (x 1000 Kcal/ha)

Food versus fuel Food energy Fuel energy Bulk production12 Edible production13 Shipping13 Processing13 Preparing12

Modern agriculture is subsidized by fossil fuels 1 unit food energy = 12 units fuel energy

Modern agriculture is subsidized by fossil fuels 1 unit food energy = 12 units fuel energy Think back to the trophic pyramid... Does negative energy transfer efficiency make sense?

Agricultural carbon cycle does not balance! 1 unit food energy = x g C, so took y g C out of the atmosphere 1 unit fuel energy = x g C, so put z g of C (CO2) into the atmosphere

Problems of modern agriculture Practice Problem addressed Problem created MechanizationLabor inefficiency erosion negative C balance energy dependency larger farms fewer farmers loss of farm culture

Problems of modern agriculture Practice Problem addressed Problem created Inorganic N fertilizers Crop yieldwater pollution increased pests greenhouse gas emissions (N 2 O) energy dependency

Problems of modern agriculture Practice Problem addressed Problem created PesticidesCrop lossnew pests resistant pests water and soil pollution human poisoning energy dependency

Problems of modern agriculture Practice Problem addressed Problem created Hybrids and genetically narrow crops Crop yieldpest problems loss of local adaptations chemical dependency dependency on external seed source

Solutions... Erosion from mechanical tillage –No till or low till systems –Perennial crops –Field layouts –Controlled irrigation

Solutions... Fertilizer pollution of water and atmosphere –Keep litter on the fields –Increased use of organic fertilizers –Type and timing of fertilizer application

Solutions... Pesticide resistant insects, pollution and human poisoning –Integrated pest management –“Smart” application of pesticides –Changes in consumer expectations –Genetic engineering of “natural” pesticide resistance

Solutions... Loss of genetic diversity –“Seed saving” –Crop diversification –Consumer demand

Solutions... Fossil fuel dependency –Buy local –Buy less processed foods –Eat lower on the food chain –Buy organic (?)