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Plasticization of Pajaro Valley: Plasticulture vital to strawberry...

Tovin Lapan, Santa Cruz Sentinel

Plasticization of Pajaro Valley: Plasticulture vital to strawberry growers, but sustainability concerns are raised

PAJARO -- Plasticulture to strawberry growers is like coffee to the working masses.

It increases productivity and, while the fundamentals are consistent, everyone has their own unique set of preferences. The cream and sugar of plasticulture are color and type of plastic.

"I was the first to try brown plastic, and now I'm the first to try green," said Edward Ortega, while standing in one of his rented fields planted with strawberries off Trafton Road. "Every grower has their own way of doing it, using different plastics, different colors, to get the results they want."

Plasticulture, using plastic materials for agricultural applications, is a boon for strawberry and bush berry growers. In strawberries, using plastic mulch can prevent the soil from getting too warm or too cool, allowing growers to time their harvest better and even speed up the cycle. It helps suppress weeds and protect strawberries from dirt, mold and fungus. Bush berry growers use plastic-covered hoop houses to protect their crops.

While plasticulture is ubiquitous in Watsonville and the Pajaro Valley, and has increased the quality and value of strawberries, critics point out that recycling the plastic is problematic and the method is not sustainable.

As technology improves, measures are being developed, such as biodegradable plastics and shipping the plastic to China for recycling, to address those concerns.


Driving along Highway 1 in South County, field after field is covered in rows of plastic.

It may seem like a simple process, but the thinking behind it is intricate and precise. There are different plastics of varying thickness and texture, and an array of colors that alter how much heat is trapped and pace growth.

This year, Ortega is trying a new plastic concoction, clear on half his field, green on the other half, in an effort to stagger harvest times. Plastic manufacturers are constantly pushing new colors and styles, but the ideas thought up in the lab do not always fit into the realities of farming.

"They were pushing a silver plastic on me, telling me how great it was," Ortega said. "So I sampled it, and the silver coloring reflected the sun, making the beds too cool. It didn't work."

Around July, Ortega starts prepping his fields, injecting methyl bromide 18 inches deep into the soil, and covers it in plastic fumigation tarp.

That plastic is then removed before the planting process begins around November, after which the plastic mulch is applied.

Running through the strawberry beds in Ortega's field are two lines of plastic tubing called drip tape that serve as the drip irrigation system.

The plastic mulch is bought in 80-pound rolls for about $135 each. Ortega estimates he uses a little less than 300 pounds of plastic mulch on every acre of land and a similar amount of fumigation tarp, which is lighter weight and costs less. Drip tape is heavier plastic, and comes in reels of 12,000 feet for $150 per reel.


In Watsonville and Salinas, the California Strawberry Council estimates just over 14,000 acres are planted with strawberries, and many of those acres are covered in plastic.

While organic farmers would not fumigate, they are allowed to use the plastic mulch as long as it is all removed at the end of the cycle.

Based on the cost of "virgin" resin used in plastics manufacturing and the relatively high cost of processing agricultural film, recycling the plastics used in agriculture is not cost effective in the United States and it's difficult to find plants to process it, Ortega said.

Instead, last year he started contracting with a company that pulls the fumigation tarps and plastic mulch and packages them for shipment to China. There, the market for agricultural recycled plastics is greater, according to Doug Spitzer, the owner of local scrap plastic wholesaler Monarch Enterprises and the former manager of a Chinese plastic recycling factory.

"[In China] labor costs are lower, the cost of almost anything is lower," Spitzer said. "But you also got to have the market. There is more of a market for the reprocessed resin than we have in the states ... Any third world economy is trying to reuse, recycle, reprocess and make the most of everything they can. We are the ones who throw things away."

One of the biggest problems with recycling agriculture plastics is dirt, which needs to be cleaned off before the plastic can be processed, adding to the cost and labor.

Marvin Pritts, a Cornell University professor of horticulture who studies plasticulture and berry cultivation, says the amount of plastic used limits plasticulture's sustainability. Strawberries are efficient in converting water into fruit, and do not require a great deal of fertilizer.

"I don't see how [shipping the plastic to China] could help, because you are still expending a great deal of fossil fuels to ship it," Pritts said.

New biodegradable plastics made from corn starch cut out fossil fuels, but are also three to four times more expensive.

Ortega says the biodegradable plastics he has encountered are problematic, especially for the vegetable growers who typically come in after a strawberry harvest for crop rotation.

"They decompose in the sun, but what if there is a shady spot? In some spots the plastic is gone, but in others there are scraps of plastic everywhere. Now the lettuce or spinach grower coming in behind me doesn't want scraps of plastic all over the field messing up his machines and planting."

Pritts has also been studying an alternative to the plastic mulch, using a grassy cover crop such as rye that leaves a resin on the ground once removed that prevents weeds. However, this method has been tested on the East Coast, and implementing it in California would take adjustments.

California land values are higher, making the cost of planting the cover crop and delaying cultivation of the strawberries prohibitive. Also, instead of warming the soil as the plastics do, the residue from the cover crop would cool the ground.

For growers, no other method offers the economic and yield benefits of plasticulture.

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