Remote Data Monitoring – 1st Install at Pete’s Greens

As an engineer, I love data.  It turns out farmers do also.  At least, Pete Johnson and Isaac Jacobs at Pete’s Greens in Craftsbury, VT do. “Is it working yet?” Isaac asks as I put the finishing touches on the remote data monitoring system we have been installing in the four zone drive-in cooler. “Just about… I think.” I say with trepidation. Isaac has been up and down in a scissor lift several times at placing and removing a sensor that was being difficult. And I’ve been wrestling with a data station to make it communicate over the wireless network so that we can actually see the data being collected by the new remote monitoring system.

Installing Remote Sensor in Cabbage Room
Isaac Jacobs of Pete’s Greens (Craftsbury) installs a remote temperature and relative humidity sensor in the cabbage room of the farm’s cooler.

This is the first time we’ve installed this kind of system which consists of a “base station” and “remote sensors”.  The remote sensors in this case measure temperature and relative humidity (RH), both parameters which can drastically influence the storage life, quality and food safety of produce.  In fact, the motivation for multiple storage “zones” in the cooler is to provide each group of vegetables their desired set of conditions; e.g. potatoes at 38 °F and 90-95% RH, onions at 32 °F and 65-70% RH, cabbage at 32 °F and 99% RH and squash at 55 °F and 70% RH.

Setting up the Data Logger
The items to the left of the laptop are the remote data logging system. Each of the five sensors can measure temperature and relative humidity over a wide range and report it back to the base station which uploads it to a website for review. Alarms can be set to alert users via email if conditions exceed high or low limits.

“What are those spikes in temperature?” Pete asks as we glance over the first set of data that pops onto the screen.  There are spikes in temperature every 8 hours in the potato room that last about one hour.  Not big spikes (2 °F above the nominal), but they stand out.  And perhaps as important, relative humidity drops by 2% when the temperature goes up.

Later, when Isaac and I are looking at the electrical wiring to see where we can plug in additional sensors we note that evaporator defrost system in that room is on an 8 hour timer; that’s the source of the heat.  “Well, they don’t even need to be on right now, that room isn’t even being cooled.” The circuit breakers for the evaporator heaters (intended to defrost the evaporator when it freezes up) are shut off, reducing the farm’s electric bill slightly over the next few months. And this is only two hours after we started getting data.

The power of data is three-fold.  First it is inspired by inquisition. It then raises additional questions and with further review, it should answer questions and improve life.  The principle behind this project is to allow for easier access to process data for Vermont’s growers and to demonstrate this type of system. As farms push the seasonal envelope in response to increased local demand, year-round production and long term storage of fruits and vegetables will be increasingly important. I plan to use this system at multiple locations in Vermont to collect data on refrigerated storage, greenhouse and high tunnel production, and whatever else comes along that is interesting and makes sense.

UC Davis Guide: Small-Scale Postharvest Practices

This guide from the UC Davis Postharvest Center is jam packed with information relevant to VT’s small-scale growers seeking improved post-harvest handling and processing. I think it is a nice companion to the New England Vegetable Management Guide and USDA’s Handbook 66. The UC Davis Postharvest Center has a wonderful on-line library with many other titles which may be of interest including an overview of small-scale cold room options and one on root cellars and other passive storage options.

One question that seems to come up regularly is “how big a cooler do I need?”  I’d recommend grower’s review Table 7 in Heatcraft’s Engineering Manual which includes typical “product loading densities” in pounds per cubic foot.  Based on your typical yields and acres in production you can use this to estimate a reasonably sized storage space.

“The three main objectives of applying postharvest technology to harvested fruits and vegetables are:

  1. to maintain quality (appearance, texture, flavor and nutritive value)
  2. to protect food safety, and
  3. to reduce losses between harvest and consumption.

Effective management during the postharvest period, rather than the level of sophistication of any given technology, is the key in reaching the desired objectives. While large scale operations may benefit from investing in costly handling machinery and high-tech postharvest treatments, often these options are not practical for small-scale handlers. Instead, simple, low cost technologies often can be more appropriate for small volume, limited resource commercial operations, farmers involved in direct marketing, as well as for suppliers to exporters in developing countries.”

VPR Series on VT Food – All Week on Morning Edition

Visit VPR’s site to listen to archived episodes.

“VPR looks at the economic impact of food production in Vermont in the special series The Business of Food.

All this week during Morning Edition, we’re looking at the expansion of farmer’s markets from a summer calendar schedule to a year-round operation, how community planners in southeastern Vermont say it’s time to go beyond co-ops and plan for a “post-oil” world, how “farm to plate”initiatives have resulted in good social policy and how downtown planners are using food co-ops as a lure to enliven central business districts.

Listen this week at 7:50 a.m. during Morning Edition.”