Individual commodities, however, have fared very differently. Between 1990–92 and 2008–10, average U.S. fresh-market asparagus production declined 50%, while fresh-market strawberry production increased 137%. The U.S. produce industry competes with producers in many other countries with lower farm wages, and imports are increasing as a share of U.S. consumption—up 152% for fresh fruit and 109% for fresh vegetables over the past two decades. Some of these imports arrive when the United States does not produce that product while others compete with U.S. production, as in the case of some asparagus imports. Hired workers have long done most of the farm work on California’s fruit and vegetable farms. California has required farm employers to pay unemployment insurance taxes on the wages of workers who earn more than $100 a quarter since 1978, making unemployment insurance data a “census” of hired workers. In 2009, California’s 17,300 agricultural establishments hired an average of 374,000 workers. Even if each of these establishments had three full-time operators and unpaid family workers, hired workers would have done almost 90% of the work on California farms. Most hired workers are men born in Mexico. The U.S. Department of Labor’s National Agricultural Worker Survey , which surveys workers employed on U.S. and California crop farms, reported that almost three-fourths were born in Mexico and a quarter were born in the United States. Over half of the workers interviewed between 2005 and 2007 were unauthorized. Most hired workers stay in the seasonal farm workforce a decade or less. The NAWS found that 15% of crop workers were newcomers, in the U.S. farm workforce for less than a year. Those attracted to seasonal jobs on fruit and vegetable farms are generally workers whose alternative U.S. job options are limited by lack of English-language skills, education, and other factors. According to the NAWS,fodder growing system hired crop workers earned an average $8 an hour in 2006, just over half of what U.S. non-farm production workers earned.
The NAWS also found that crop workers were employed on U.S. farms for about two-thirds of the year. Earning half as much and working less means that the annual earnings of crop workers averaged a third of the annual income of non-farm production workers, who earned almost $35,000 per a year. What would happen to U.S. fruit and vegetable production if farm labor costs rose? Several adjustments are possible. First, farmers could change their production processes to reduce the need for hand labor by mechanizing. They could also use chemicals or precision planters to reduce the need for hand-weeding and hand-thinning of crops. Second, imports could increase if rising U.S. farm labor costs made U.S.-produced commodities less competitive. Third, farm operators could increase the productivity of farm workers by picking fields less often or providing workers with productivity increasing harvesting aids, such as conveyor belts that reduce the time required to carry harvested commodities, lightweight ladders for climbing trees, or dwarf trees that reduce the need for ladders. The adjustment an individual commodity group might pursue will vary depending on the characteristics of the crop, status of mechanization or labor aid technology, and the economic conditions of the industry.The U.S. raisin industry, centered in Fresno County, California, faces several challenges, including declining U.S. per capita consumption and increased competition in a globalizing market. The United States and Turkey are the world’s largest raisin producers, accounting for over half of global supply, but Turkey is the world’s largest exporter and a lower-cost producer than California. The U.S. raisin industry depends on a complicated set of state and federal marketing programs to remain competitive in export markets. Harvesting raisin grapes was traditionally the most labor-intensive farm task in North America, with 40,000 to 50,000 workers hired each fall to cut bunches of green grapes and lay them on paper trays to dry into raisins. The key to harvest mechanization was developing grape varieties such as Selma Pete that reach maturity in early rather than late August.
The canes of early maturing grape varieties can be cut in August, so that green grapes can dry into raisins on the vine—this is the dried-on-the vine method of harvesting. A modified wine-grape harvester shakes the dried raisin grapes off the vines. Replanting a vineyard and using DOV harvesting requires an investment but increases yields dramatically. Before 2000, only a few growers used DOV production techniques. The price of raisins fell sharply in 2000 after a very large crop and in 2001 a modified mechanical wine-grape harvester was introduced to harvest DOV raisins. By 2007, an estimated 45% of California’s raisins were harvested using some form of DOV mechanization . Complete harvest mechanization has been delayed, in part, by the large number of small raisin-grape farms, many of which have older owners who are reluctant to mechanize or perhaps replant. Most of the 80,000 acres of raisin type grapes removed in the past decade were older vineyards not suitable for machine harvesting. Although acreage of raisin-type grapes has declined, yield has increased, and production of grapes for raisins in 2010 was about the same as 1990. The spread of DOV has reduced the demand for raisin harvesters to about 25,000 workers. If labor costs rose, the switch to mechanical harvesting would likely accelerate, resulting in fewer and larger raisin producers and less demand for hired labor.U.S. per capita consumption of fresh asparagus increased 115% since 1990, but 87% of the fresh asparagus consumed in the United States is now imported, primarily from Peru and Mexico. Some imports come into the United States during seasons when there is no domestic production, but some compete directly with U.S. production. U.S. production of fresh asparagus fell 50% between 1990-92 and 2008- 10; production in California fell 59% . The Food, Conservation, and Energy Act of 2007 provided funds to cushion U.S. asparagus producers from rising imports, and researchers are working on mechanical harvesters.When the weather is warm, fields may be harvested daily rather than the more typical two or three times a week. Labor costs rather than labor availability have been the main issue for growers. Asparagus is often the first crop harvested in the spring, minimizing competition for labor from growers of other commodities. The major issue is how to reduce harvesting costs. Selective mechanical harvesters could damage asparagus that is not yet mature, limiting their use, and the lack of uniform-ripening varieties restricts the use of once-over harvesters. Without a harvest mechanization break-through, imports are likely to displace more U.S. fresh asparagus production and further reduce labor demand for this crop. Asparagus may follow the path of green onions, a labor intensive commodity only rarely grown in the United States now. Almost all green onions consumed in the United States are imported from Mexico.Almost 90% of U.S. fresh-market strawberries are produced in California and all are picked by hand. Total U.S. strawberry production increased 107% between 1990-92 and 2008- 10 and California production rose 135%; yields increased 73% and U.S. consumption of fresh-market strawberries doubled over this period. Imports of fresh strawberries, 8% of U.S. consumption, are held down by year-round U.S. production and the difficulty of transporting fragile and perishable strawberries long distances. However,chicken fodder system imports of processed strawberries, usually frozen, account for almost a third of U.S. consumption. While California strawberry growers aim for the fresh market, processing is an important residual market that is becoming less profitable with increased imports. Strawberries are among the most labor-intensive commodities. Up to 1,000 hours of labor are required to harvest an acre, as fields are often picked several times a week over four-to-six months. Workers place strawberries into the plastic clam shells in which they are sold; the clam shells are in a cardboard flat mounted on a small wheelbarrow. In most fields, workers stop harvesting when a flat is filled, take the full flat to a truck at the end of the row to unload and receive credit for picking it, and return with an empty flat and resume picking. A labor aid can increase worker productivity by reducing the time spent carrying full flats of berries. In the large and flat fields of Ventura County in Southern California, many growers are now using a slow-moving conveyor belt that moves down the field in front of the harvest crew.
Harvesters still fill flats mounted on wheelbarrow devices, but walk fewer steps to put full trays on the belt, get an empty flat, and resume harvesting, which can reduce harvesting hours by a third or more in large fields. Adoption of the conveyor belts, which cost over $100,000 each, has been slowed by disputes over how much harvest piecerate wages can be reduced to reflect increased worker productivity. Growers outside Ventura County have been less likely to adopt the conveyor belt. If labor costs rose, more growers would likely adopt conveyor belts, including versions that are more appropriate for smaller and more hilly fields. A number of research efforts aim to mechanize the harvest, including a scout and harvesting system that uses one machine to identify ripe fruit and another to harvest it; this research is, however, still in an early stage. If higher labor costs were passed on to consumers, the rapid growth in strawberry consumption might slow.Since 2014, the World Economic Forum has identified water crises in the top-five global risks to society in terms of impact, based on a broad survey of risk perception among participants in business, academia, international organizations, and government . Where food and freshwater are scarce, they often become central to social stability. Because fluid nature, freshwater systems often cross political boundaries, allocation of this scarce resource has been a source of numerous conflicts throughout history . At the margin, our thirst for this resource becomes flexible and yields goods, services, and other productive activities . When these activities take place at times and scales far removed from their input resources, it can be useful to quantitatively evaluate the inputs, outputs, and environmental impacts of a product or activity, over its entire life cycle. Life-cycle assessment can refer to both the standardized method of evaluating these impacts, or the result of the method . Related to LCA are a family of “footprints”, sustainability indicators that relate economic activities to physical quantities of resources consumed . Carbon footprints are a popular concept, that describe quantities of greenhouse gas emissions required to enable a consumptive activity . Ecological footprints relate consumptive activities to the biosphere’s regenerative capacity, which can be expressed in terms of the annual productive capacity of a unit of land area . Most industrial activities, are unable to be entirely supported by the natural resources of adjacent lands, and the remainder of the ecological footprint is met through appropriations from other regions. Global ecological footprint assessments have calculated that the rate of current human resource consumption exceeds the rate of natural production by over 1.5 times . This description does not forecast when the rate of overshoot will deplete global stocks, but it does serve a benchmark for evaluating the sustainability of human activities. Water footprints were inspired by ecological footprints and describe the quantities of water required to enable different consumptive activities . Water footprints are closely related to the virtual water concept, which describes the presence of virtual volumes of water traded between nations in the form of water embodied in goods or services . Alan described the option of importing virtual water as a means for water scarcenations in the Middle East to alleviate pressure on domestic water resources. The water footprint concept extends this metaphor with an allusion to ecological footprints, by describing the volumes of water required to enable different consumptive activities, or societies as a whole . In popular literature, the footprint metric has seen some success in the ability to relate the large magnitude of human resource consumption, to more relatable per-capita quantities . It has also earned criticism outside of the water resources field from the aesthetic perspective of over-burdening the footprint metaphor and from the practical perspective of having questionable utility for policy support . More generally, the family of life-cycle sustainability indicators are derivative metrics, which accumulate uncertainty from the numerous observations and estimations that are incorporated into the final assessment .