Changing Vegetable Crop Production Practices
Change is a constant factor in the vegetable production industry. For example, take a minute to think about how lettuce was produced 40 years ago compared to today. Developments over the past 40 years in planters have led to more precise placement of seed, disease-resistant varieties have helped combat soilborne diseases such as corky root, and drip irrigation has allowed for more precise management of applied water and nutrients.
As a result, we now have greater and more reliable yields of lettuce per acre. The improvements in production have had to keep pace with greater demands by the market which have also changed dramatically in the last 40 years. For instance, value-added products such as washed and bagged salad have changed the way lettuce is harvested by spurring the need for partially processing the lettuce in the field by removing the core of head lettuce or by trimming romaine heads down to just usable leaves.
Another key change in the production of lettuce, as well as other crops, has been the shift from 40-inch wide beds to 80-inch wide beds. The majority of this change has taken place in the last 15 to 20 years and has allowed for great intensification and efficiency in the use of land.
By increasing productive surface of each farmed acre, growers are able to make better use of applied inputs such as water, as well as make greater use of dollars expended on rent. High-density plantings of crops such as spinach, baby lettuce, spring mix, and cilantro are now nearly exclusively grown on 80-inch-wide beds, but other crops grown in rows such as broccoli, cauliflower, and leeks are also increasingly grown on wide beds.
The Switch To Wide Beds
The movement to wide beds has brought about a wholesale change in production equipment. Everything from listers, planters, mulchers, and harvest equipment has been recon-figured to efficiently farm these beds.
A great advantage of wide beds for spinach and baby leaf lettuce has been the production of a more uniform harvested product. This is due to more uniform spacing between individual plants across the bed and fewer plants along the edge of the bed which tend to have larger leaves. The wide beds have also improved the efficiency of mechanically harvested crops such as spinach, baby lettuce, and cilantro.
The use of wide beds has also created challenges. The plant lines in high-density plantings are so close that it is not possible to mechanically cultivate the beds for weed control or soil aeration. In fact, disrupting the smooth surface of the bed is a disadvantage for mechanical harvest operations. As a result, for successful production of crops on high-density 80-inch-wide beds, there is a critical need for excellent weed control.
Reducing Weed Pressure
The processing plants where spinach and baby lettuce are washed and bagged demand a weed-free product, and growers go to great extremes to achieve that goal. Growers use basic cultural practices as well as registered herbicides to reduce weed pressure. Depending on the crop, registered herbicides provide reasonable weed control. However, in spite of all these efforts, it is not uncommon for growers to spend more than $300 per acre to hand-weed these crops in order to prepare the field for mechanical harvest.
The production of cilantro on high-density beds illustrates the difficulties that a rapidly changing industry faces at times. Due to the minor crop status of cilantro, it took nearly a decade to complete the registration process for prometryn (a herbicide). In the meantime, cilantro production shifted to high-density beds, and more mechanical harvest leaving the growers vulnerable to high weeding costs. This example illustrates that changes in the vegetable industry can create needs that get ahead of regulations or other factors that may affect the industry.
Change in the vegetable industry is a constant. We can expect more changes in the industry in the near future as growers adapt to changes in the economics of production. In addition, improvements in technology will have impacts on harvest equipment, weed control, transplanting, and tractor guidance. Improvements in plant breeding will provide greater disease and insect resistance, and hopefully improvements in the use of nutrients and applied water. Regardless of the challenges, the vegetable production industry has shown tremendous resilience and ability to adapt and change to new conditions.