Environmental Science Chapter 15 Review Arable land – able to grow crops Soil formation –involves bedrock decomposition Topsoil – upper layer of soil - rock particles, water, air, organic matter Yield – amount of a crop per hectare (acre) Soil erosion (fields) – caused by farm machinery Desertified farmland -domestic animals overgraze the land -too many crops are grown/looses fertility -as a result of erosion

Environmental Science Chapter 15 Review Irrigation water usually comes from rivers & groundwater. Salinization – accumulation of salts in the soil caused by irrigation & low rainfall Using rainwater instead of groundwater on crops reduces soil salinization. Using strips of vegetation in between plowed land reduces soil loss caused by wind & water.

Environmental Science Chapter 15 Review No-till farming – seeds planted among roots of previous crop. Livestock – cattle, goats, pigs, sheep, chickens Ruminants – cud-chewing mammals Wheat requires less energy than cattle or cows. Modern Agricultural methods use plowing machines, drip irrigation systems, and chemical fertilizers.

Environmental Science Chapter 15 Review DDT harmful to environment -does not break down easily in environment -causes some birds to lay thin shelled eggs -concentrates in animal bodies (persistent pesticides) Pest - organism that occurs where it is not wanted - can become resistant to pesticides

Environmental Science Chapter 15 Review Integrated pest management – chemical, biological & farming methods Food production has not been increasing as fast as the human population – many go hungry Famine – widespread food shortage Malnutrition – health problem due to not eating necessary nutrients

Environmental Science Chapter 15 Review Humans need 8 essential amino acids from the proteins they eat. Carbohydrates supply energy for the body. Lipids (fats & oils) help form membranes/hormones.

Environmental Science Chapter 15 Review Aquaculture - raising of aquatic organisms for human use – reduce seafood overharvesting No fishing zones – reduce effects of overharvesting Genetic Engineering – desirable traits transferred

Environmental Science Chapter 15 Review Living organisms maintain soil fertility -fungi, bacteria, microorganisms decompose dead plants/animals/excrement -certain bacteria convert atmospheric nitrogen into forms plants can use. -earthworms, insects, small animals break up soil, letting in water/air.

Environmental Science Chapter 15 Review Reducing water erosion of farmland -mixing in stems, roots from previous crops -loosens topsoil so water soaks in/not run off -worms attracted to this organic material -aerate topsoil so water soaks in/not run off -contour plowing stops water running downhill

Environmental Science Chapter 15 Review Biological insecticides (bacteria, reproductive-interfering agents) - target pests but do not harm others. Chemical insecticides can persist or build up and then harm other species which feed on the insects.

Environmental Science Chapter 15 Review Erosion in farming only recently a serious problem (modern machinery & practices) previous farmers did not leave bare soil exposed in huge fields small fields & gardens = less runoff practiced crop rotation fields allowed to lie fallow every few seasons

Environmental Science Chapter 15 Review Explain how pests develop a resistance to pesticides. Word bank = aquaculture, famine, genetic engineering, livestock, malnutrition, meat, overharvesting, pest, ruminants, salinization, topsoil, yield.