Soil solarization: an environmentally-friendly alternative
Driving through the Imperial Valley during the summer you may have noticed what looks like a dirt field being flooded. However, upon closer look what appeared to be water was actually plastic liners covering a field.
This practice, called solarization, is primarily used by farmers to prepare their land for the planting process of an organic crop.
There has been a rapid rise in consumer interest in organic produce over the past few years. As a result, the amount of acreage and number of farmers producing organic crops in Imperial County has risen expeditiously. In 2012, 26 farmers produced nearly 12,000 acres of organic commodities resulting in a gross production value of $39 million. Fast forward four short years, in 2016 Imperial County saw an increase in organic fields to over 33,000 acres produced by 48 farmers with a gross production value estimated at $242 million.
Regulated by the United States Department of Agriculture, organic style farming avoids the use of man-made or synthetic pesticides, petroleum-based fertilizers and genetically modified organisms (GMOs) to produce commodities.
Soil solarization is an alternative for organic farmers to control weed seeds before a crop is planted. Fields are rid of unwanted weed seeds as they are covered with plastic film and heated by exposure to sunlight during the warm Imperial Valley summers.
Primarily used in spinach and spring mix lettuce crops which are mechanically harvested, solarization virtually eliminates the need for increased labor for weeding tasks.
Plastic sheets may be laid by hand or machine. Transparent or clear plastic is most effective for solarization. Black plastic is sometimes used; however, treatment time must be lengthened for best results as it does not heat the soil as well as the clear alternative.
Depending on the crop and field, the plastic is laid either in complete coverage, where the entire field or area to be planted is treated or strip coverage, where only beds or selected portions of the field are treated.
Wet soil conducts heat better than dry soil and makes the organisms being attacked more vulnerable to heat. The process changes physical, chemical and biological properties and thereby improves soil health.
The solarization process takes approximately 45 days to allow the soil heat to penetrate the greatest depth possible. Once the plastic is removed, a farmer can begin the process of prepping the beds for planting.
Farmers utilize recycling services for disposal of used plastic once the process is complete.
As technology advances, so too are the processes by which our food is grown.