What are the inputs to agriculture? Pesticides Fertilizers Energy to prepare the land Water Labor

Kinds of agriculture Industrialized Intensive traditional subsistence Nomadic herding Shifting cultivation (swidden) Plantation agriculture

Industrialized agriculture Pesticides - high Fertilizers – high –Fossil fuel based Energy – high –Fossil fuel based Water -high Labor - low

Pesticide use is high In industrial agriculture, one crop is grown over a large area –Called: ``monocropping’’ (such a crop is a monocrop) –Crop is often genetically identical—seeds have been bred for certain characteristics –Therefore: vulnerable to pests

Mono-cropping creates ideal conditions for pests

Kinds of pesticides Insecticides: kill insect pests Fungicides: kill fungus Herbicides: kill plants

Rill erosion

Gully erosion Can’t be smoothed out with conventional tillage equipment

Crops like corn are highly erosive

Agricultural best management practices (BMPs) include buffer strips between fields and bodies of water Solutions to erosion Leave a buffer of vegetation between farm fields and water bodies. WHY?

Solutions to erosion Buffer strips What is the value of that large strip of grass in bottom picture? What are the tradeoffs for farmer of using a buffer strip? The USDA pays farmers to create buffer strips— what kind of policy is that?

Contour plowing Plow perpendicular to a slope

Terracing

No-till farming

Intensive traditional subsistence Pesticides – low (too costly) Fertilizers – medium –Manure and other natural kinds Energy – low (fossil fuel) –Use animals Water - medium Labor –high Intensive means growing enough to sell

Nomadic herding Pesticides – little to none Fertilizers – none Energy – low fossil fuel Water – low Labor – medium

Shifting cultivation Pesticides – low Fertilizers – low, use slash-and-burn Energy – little fossil fuel Water low Labor moderate

Shifting cultivation can work when population densities are low. WHY? –After cultivation, land can be ignored long enough for vegetation to regrow. Soil erosion is a major concern.  intense rains

Plantation agriculture a form of industrialized agriculture in tropical developing countries. CASH crops in large monocultures Pesticides - high Fertilizers - high Energy - medium Water - high Labor – medium Labor/energy tradeoff

1960s: Future looked gloomy to some Population growing exponentially Conventional and traditional agriculture would be unable to feed the growing population.

Doomsday delayed? Worst fears haven’t happened. Dramatic increases in food production. –How? More energy used More irrigation More pesticides More fertilizer More land in cultivation New varieties of high yielding plants and animals

Organic farming & food What are the benefits?

Organic agriculture Pesticides – not used with exceptions Fertilizers -- manures Energy –Low to high, depending on size Water –Low to high Labor –medium

Major differences between organic and conventional food and farming Three of five food safety concerns largely eliminated: – Pesticides – Animal drug residues/antibiotic resistance – GM food risks (e.g., novel allergens) (no strong evidence of risk to health yet; may be ecological risks) Help manage two other major food safety risks: – Mycotoxins – Bacterial contamination

Major differences between organic and conventional food and farming Worker safety Environmental impacts: – Build soil quality & increase terrestrial carbon sequestration – Promote biodiversity – Lower energy inputs Reduce impacts on birds, fish, pets, small mammals Increase N use efficiency,reduce the size of the Dead Zone in the Gulf

Organic principles Replenish and maintain soil fertility. Eliminate the use of toxic and persistent chemical pesticides and fertilizers. Restore, maintain, and enhance ecological harmony. Build and support biologically diverse agriculture.

Organic farming practices Rotate crops Use cover crops Release beneficial insects Use compost (including composted manure) Mixed vegetables in organic field in California. Note hedgerow in background

What are beneficial insects? Pollinators –Especially honeybees Predators –Prey on plant pests Parasitic wasps Praying mantis ladybugs

Pesticides Acute toxicity to people and non-target organisms Chronic (long-term) toxicity – cancer Heinz Center (2002): 75% of streams had more than 5 pesticide residues USGS (2006) 51 studies (’92-’01) –96% fish, 100% surface water, 33% ground water Had one or more pesticides

Pesticide risks: greater for workers Children of farmworkers in North Carolina (and the farmworkers themselves) had high levels of pesticide metabolites in their urine.

Is organic better for the environment? British report ( 2004, Biological Conservation) –More birds, butterflies, beetles, bats, and wildflowers on organic farms than on conventional farms

Is organic better for the environment? Another British study: –Many organic products have lower ecological impacts, but, –Many others, including milk, tomatoes, chickens are less energy efficient, and therefore may result in a larger ``carbon footprint’’ –Milk: organic production: 80% more land –More CO 2 than conventional (1.23kg/l vs 1.06kg/l

Some evidence that nutrient content/density is higher in organics Antioxidants – important nutrients in fruits and vegetables, help reduce the harmful effects of oxygen radicals –Avg. 30% higher in organics Other phytochemicals (plant chemicals that are thought to promote good health) found to be higher in organics

Agricultural problems Soil erosion and degradation –From plowing –Intensive use of soil, pulling nutrients out –Desertification: intensive use of drylands

Agricultural problems Salinization –Irrigation water that is not absorbed evaporates, or moves down, leaving behind salts –20% of world’s cropland is irrigated, UN estimates that 1/5 of that has reduced yields as result of salinization

Agricultural problems - 2 Waterlogging of soils –When large amounts of irrigation water added to move salts deeper. Water table rises Loss of beneficial insects –Broad spectrum insecticides kill bad and good Use narrower insecticides (Bt) Use IPM – integrated pest management