There are a number of difficulties farmers face when growing strawberries, and below we will highlight some of the ways that we believe that wireless sensor networks (WSNs) may help with these problems.
A good analogy for maximizing plant growth is driving in a car. We know you can’t go any faster than the speed limit (maximum plant growth). If you hit traffic or keep tapping your foot on the brake, it is going to take longer to get to your destination. Applying water or fertilizer at the wrong time is like going slower than the speed limit, it takes you longer to get where you are going. Plants are sensitive to their environment, so even minor stresses (water and fertilizer) can reduce growth. WSNs help growers make the best decisions about when to apply water, and how much to apply, so plant growth is maximized, and growers are able to produce the healthiest and best quality plants possible.
There are two typical ways to produce strawberries: matted row production, and plasticulture production.
Plasticulture strawberry production
New strawberries are planted every year, which requires higher labor inputs for land preparation, planting etc. This production method produces larger yields per acre, and has been found to reduce fertilizer and sediment loss (Stevens et al., 2009). Plastic is removed at the end of the season, and fields are prepared and replanted in the fall.
Matted row strawberry production
Strawberries are maintained for 3-5 crop harvests (years) before a field is renovated and replanted, but produces fewer pounds per acre compared with plasticulture. These fields require less labor once they are established. There is the possibility of higher sediment runoff and nutrient leaching, especially during the first year, since this type of system is open to rainfall (Stevens et al., 2009).
Environmental factors
One of the major benefits of WSNs is that irrigation is only applied when needed, and the volume of irrigation can be precisely controlled, so water and nutrients remain in the root zone where they provide the most benefit to the strawberry plants. When nutrients such as nitrogen and phosphorus are kept in the root zone, they are better utilized by the plants. This is particularly important for controlling nutrient and sediment runoff to surface waters such as the Chesapeake Bay and other impaired waterways, since runoff can impact surface waters, contributing to algal blooms and reduction in aquatic vegetation and benthic organisms, which are essential for the health of our rivers and bays. We believe that WSNs can greatly reduce nutrient and sediment runoff, by reducing irrigation volumes, and keeping nutrients in the root zone. More advanced soil sensors are also able to monitor electrical conductivity (EC), which can help growers determine the frequency and amount of fertilizers they should be applying to match plant uptake.
Strawberry production is labor intensive
Depending on the type of production (plasticulture or matted row), labor is required for many aspects of production. We believe that WSNs should be able to help reduce labor in the following areas:
- Irrigation
- Fertilization
- Better timing and reduced use of other agrochemicals, such as fungicides
- Frost protection
Irrigation and fertilization (based on electrical conductivity or EC) levels are monitored in real time using various sensors, and recent advances allow for WSNs to control irrigation (turn it on and off as needed) under most circumstances, so the plants receive water when and how much is needed, without direct human oversight. We also recommend installing a weather station, which provides site specific temperature, relative humidity, rainfall, and other data in real time. More information about a weather station can be found on the sensor network page.
Water and fertilizer use
Strawberry production requires inputs of water and fertilizer to maximize fruit size and quality. We want to determine if WSNs can be used to identify when irrigation and fertilization should be applied to maximize plant growth, fruit quality, and strawberry yield, while reducing environmental impacts from over application of water and nutrients
Frost protection
(C) 2014 freebigpictures.com
During the spring, strawberry flowers and developing fruit are very sensitive to frost. When frost occurs during flowering, growers typically apply row covers and/or overhead irrigation to reduce frost damage. This is a very labor intensive process, which also uses large volumes of water to protect the plants (about 17,000 gallons of water per acre per hour).
Growers usually purchase frost prediction information from a company that uses satellites to monitor and predict frost events. Satellite prediction is a good first step to alert growers when to watch for frost, but growers must then monitor temperatures at their operation throughout the night, taking into account the different microclimates at their operation (valleys, prevailing winds etc.) and apply irrigation when necessary. WSNs should be able to provide more precise information since we can measure temperatures right in the plant canopy. WSNs can also send alerts to a cell phone, (based on how the grower sets it up) to make sure they have enough time to take action when necessary. We believe that WSNs will allow growers to more accurately monitor temperatures, and apply irrigation only when necessary, saving labor, water, time, and giving growers some much needed sleep. We will also be testing whether WSNs can automatically control irrigation for frost protection at our test site at the Wye Research and Education Center. If automatic frost protection is successful at the research site, growers may be willing to implement it at their operations in the future.
There are a number of areas where WSNs have the potential to help farmers produce better strawberry crops with lower water and labor requirements, while also benefiting the environment. As part of this project, we will help identify where WSNs are beneficial to growers and the environment, and quantify those benefits.
Check back as we move forward with this project!
Literature cited
Stevens, M. D., B. L. Black, J. D. Lea-Cox, A. M. Sadeghi, J. Harman-Fetcho, E. Pfeil, P. Downey, R. Rowland, and C. J. Hapeman. 2009. The comparison of three cold-climate strawberry production systems: environmental effects. HortScience. 44(2):298-305.