Micro irrigation sounds interesting ... and small? It is not literally, what it sounds like.

Micro irrigation is the delivery of water to crops in a system that can directly deliver water to the plants roots. While this type of irrigation is not suited for all operations, it can be a very efficient and safe way to deliver water to fresh produce.

Micro irrigation typically appears as a trickle, drip or soak system. They are designed to efficiently apply water directly to root zone of plants by means of applicators at a low pressure. This system has benefits like reducing irrigation costs, protecting soil from erosion and compaction and reducing the amount of water lost due to environmental evaporation or structural components.

These systems are great for water and soil conservation, as they only deliver the amount of water needed for the plant and can effectively reduce how irrigation water can create situations that are unfavorable.

Compared to traditional irrigation methods, a drip/micro irrigation system can lead to water savings of up to 40 percent, according to the Natural Resources Conservation Service. Not only is this system great for conservation practices including decreased runoff, soil compaction, evaporation loss and more; but it can also lessen the risk of potential microbial contamination of the produce. This is because water introduces a risk in produce safety.

Agricultural water, and all water, has the potential to become contaminated with microorganisms. In agriculture, many farms use water from multiple sources like wells, municipal and surface water systems. Surface water used as agricultural water can pose a much higher risk because it is not an ‘enclosed system’ and open to environmental risks.

Wells are less risky as they are closed to the environment, but can be breached if the well is not in good condition. Municipal systems are the least risky as they are treated, but it is best to confirm that there is not presence of harmful organisms by receiving documents from the municipality on their treatment and testing levels.

In order to deter risks, farms have to go through rigorous water testing or water treatment to ensure that water used in production will not introduce unwanted microbes. They also should perform water system inspections to make sure everything is in working order.

The most common microorganism that is the culprit of water contamination that can reach and persist on food is the bacteria, E. coli. Using an irrigation system that directly feeds the plants root systems, allows for (the most part) water to not come into contact with the edible portion of the crop.

So if there is a chance of microbial contamination in the water, it is a lot less likely to make someone ill from consuming that produce by not directly touching it. There are certain plants, due to their physiological makeup that can uptake certain things in the root systems or by other means, and carry that microorganism for longer. Crops that could have potentially been contaminated can undergo a die-off period, where environmental conditions reduce the load of the bacteria or in severe cases it is recognized and is disposed.

Crops who may be at higher risk of holding onto bacteria if contaminated due to physical characteristics include strawberries and lettuces. These crops if exposed to ‘dirty’ water, may not have the ability to rid themselves of that bacteria through environmental die-off.

Many home gardeners utilize rain water as water for irrigation, and this is a great way to conserve water usage. This is considered surface water, so when applying it at home it is best to use a watering method that directly situates the water at the base of the plants. It’s also called indirect irrigation as it does not directly touch the edible portion of the crop. This is especially important for fruits or veggies that are eaten without undergoing a kill-step like cooking.

It is also good to monitor the system, and test this water often for generic E.coli if using it on produce that will be consumed raw.

Overall the approach is to assess what works best for your operation or garden while keeping in mind environmental and produce safety risks. Small shifts can make all the difference. Some food for thought; water delivery ‘ways’ to think on this winter for next season.

Michelle Jacokes is a Produce Safety Technician working with fresh produce growers on farms in Manistee, Benzie, Grand Traverse, Leelanau and Benzie counties. Services are free, voluntary and confidential. For more information about the Michigan On-Farm Produce Safety Program visit manisteecd2.org and locate the Produce Safety page under Landowner Assistance. Contact Michelle at michelle.jacokes@macd.org or (231) 889-9666 with questions.

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