Sustainable Agriculture: April 2008 Archives

Monarch butterflies migrate more than 2,000 miles and on the trip north to the same groves of trees, it can take THREE GENERATIONS to make the trip!

Watch a video about Monarchs --  to understand how much we have to learn about nature's natural systems.

Growers of fresh produce on the Central Coast of California currently face conflicting demands regarding measures to protect food safety and those to protect environmental quality. To explore the extent of conflicting pressures and identify the range of possible impacts on the environment, California Agriculture conducted a survey of Central Coast irrigated-row-crop growers during spring 2007.

The results indicate that growers are experiencing a clear conflict, and some are incurring economic hardships because their practices to protect the environment have resulted in the rejection of crops by buyers.


These actions could affect large areas of land on the Central Coast and, as indicated by growers, they are likely to increase over time.
 
The Central Coast contains some of the greatest biodiversity of any temperate region in the world. At its heart is the Monterey Bay National Marine Sanctuary, the largest marine sanctuary in the United States, and the Elkhorn Slough National Estuarine Research Reserve.

While the Central Coast houses many natural resources, according to the Central Coast Regional Water Quality Control Board (CCRWQCB), it also has some of the most polluted waters in California. The Pajaro River and Elkhorn Slough are listed as impaired for sediment and nutrients under California’s 2002 Section 303(d) of the 1972 Clean Water Act. The Salinas River is 303(d)-listed as impaired for sediment, nutrients, pesticides and pathogens.

In response, the CCRWQCB adopted a Conditional Waiver Program in 2005, which requires growers to enroll in the program, attend water quality training sessions, adopt farm water-quality management plans, complete management practice checklists and participate in water quality monitoring (Cal EPA 2007).

An important aspect of these efforts is the adoption of conservation practices, which aim to improve and protect water quality, prevent soil erosion, reduce the use of agricultural chemicals and protect wildlife. Vegetation on and around farmland is a key component, including vegetated field borders, grassed waterways, riparian buffers and constructed wetlands.

For the past decade, the Central Coast farming community has been proactively working with resource agencies to develop and implement voluntary conservation practices to improve water quality and reduce water consumption through the adoption and implementation of the Monterey Bay National Marine Sanctuary’s Agricultural and Rural Lands Plan (MBNMS 1999). Adoption of these practices has now become a key component for compliance with the CCRWQCB’s Conditional Waiver Program.

Despite an intensive investigation, the U.S. Food and Drug Administration (FDA) and the California Department of Health Services (CDHS) have not been able to conclusively determine the specific causes of the spinach outbreak (CDHS/ FDA 2007).

In early 2007, with oversight by the California Department of Food and Agriculture (CDFA), produce industry representatives developed the California Leafy Green Products Handler Marketing Agreement (see www.caleafygreens.ca.gov). More than 100 handlers (companies that move fresh produce products from growers to retail and food-service buyers) are signatories. Representing more than 99% of the leafy greens production in California, they are obligated to handle leafy green produce only from growers who adhere to the best management practices detailed in the Commodity Specific Food Safety Guidelines for the Production and Harvest of Lettuce and Leafy Greens, known as the “Metrics” (see www.caleafygreens.ca.gov). The Metrics were developed and continue to be updated through a process involving the produce industry, government agencies, natural resource organizations and scientists.

In addition to the Metrics, many companies and retailers who handle or sell leafy greens have developed their own company-specific food safety requirements, which also affect farm management practices. Because growers often sell their crops to multiple buyers, most now must meet at least one if not several different sets of requirements. In addition, field interpretations of the Metrics and company-specific guidelines vary.

Specific measures stated or implied in the Metrics and company-specific requirements may potentially conflict with efforts to improve and protect water quality and support wildlife habitat.

Eight percent (8.0%) of growers reported that their crops had been rejected based on the presence of practices to improve water quality or wildlife habitat on the farm. Some of the explanations shared by respondents included:

• Lost $17,500 worth of crop due to deer tracks.
• 1 acre of romaine lettuce rejected due to proximity to horse pen.
• 23 acres of head lettuce and 2 acres of mixed lettuce rejected due to contact with Salinas River floodwater.
• Crop rejected due to potential frog habitat.
• Portions of fields rejected by processor if frogs, tadpoles, snails, mice or other small animals were found.
• Harvest stopped due to the presence of frogs and tadpoles in creek.
• Crop rejected due to deer intrusion.
• Crops planted for processor near trees needed a buffer of 100 to 150 feet.

Some 88.9% of the survey respondents indicated that they had adopted at least one measure to actively discourage or eliminate wildlife from cropped areas

Wildlife exclusion. Some 88.9% of the survey respondents indicated that they had adopted at least one measure to actively discourage or eliminate wildlife from cropped areas

Conservation practice abandonment. Approximately 15% of all growers surveyed indicated that they had removed or discontinued the use of previously adopted conservation practices in response to suggestions made by auditors or buyers due to food safety concerns.

The survey results illustrate that growers are in the middle of a clear conflict between current food safety standards and continued efforts to address water quality and environmental concerns on the Central Coast.  

The process and standards for protecting food safety in leafy greens on the Central Coast of California set a precedent that will certainly be modeled for other crops and growing regions nationwide.  

M. Beretti is Program Director, Resource Conservation District of Monterey County, Salinas; and D. Stuart is Doctoral Candidate, Department of Environmental Studies, UC Santa Cruz.

READ the Rest of the Story, SOURCE:  California Agriculture

University of California researchers have studied the effects of irrigation on almonds for about 20 years. It has generally been thought that about 42 inches per acre per season is a reasonable estimate of water use by mature, productive almonds.

Seasonal water use follows a bell-shaped curve. Under this 42-inch model, water use starts out low after leafout at about 1.0 inch every 15 days, peaks at about 4.5 inches every 15 days in the first half of July, and declines back to about 1.0 inch every 15 days as the season ends.

In some situations, growers may have much less than 42 inches of water available from stored soil moisture and irrigation water. The challenge becomes managing crop stress over the course of the season.

One relatively effective approach that doesn't rely heavily on field monitoring is to attempt to sustain crop stress uniformly across all stages of tree growth and crop development by using estimates of crop water use. The limited water allocation is applied as a consistent percentage of the seasonal water use pattern. If 24 inches of irrigation water are available, representing about 60 percent of the potential water use, then the irrigation water would be allocated at about 60 percent of real-time or historic rates of crop water use over the course of the season.

UC water management specialist David Goldhamer of the Kearney Agricultural Center published results of a four-year study illustrating the effectiveness of the above approach.

Almonds were produced with 55, 70, 85 and 100 percent of a 42-inch water allocation.

Water was either cut back as a consistent percentage of estimated crop water use to try to sustain less pronounced crop stress across all stages of crop growth, or cutbacks targeted only pre-harvest, or post-harvest crop stages for higher crop stress.

The effect of limited water supply was minimized with uniform allocation of water across all crop stages. However, productivity was reduced particularly with 55 percent and 70 percent allocations.

• The uniform crop stress strategy gave both the highest four-year yields, and the largest average nut size within each water allocation.
  
• Sharp cut backs before harvest resulted in the second highest yields, but reduced nut size.
  
• Sharply withholding water after harvest affected bud development and reduced yield the next season.

UC Davis professor Ken Shackel was able to get by with a water allocation of about 85 percent of full supply with no short-term yield loss or effect on nut size by using a pressure chamber to actually track midday crop stress and keeping it within the -12 to -20 bar range in July during hull split.

For more information on on water management refer to UCManageDrought.ucdavis.edu.