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Waltham Fields Community Farm (incorporated as Community Farms Outreach, Inc.) is a nonprofit farming organization focusing on sustainable food production, fresh food assistance, and on-farm education. For more information about Waltham Fields check out our website!

Tuesday, August 2, 2011

Notes from the Field: Transition and Irrigation

This week we woke up and it was August. It's another time of transition, this time moving from July's wild and vigorous growth to fruition, the result of all that heat and photosynthesis. Slowly, if we've done our job right, the burden of our work shifts from planting to harvest over the course of the month. Storage onions fall over and need to be brought in. Cantaloupes begin to net and turn orange. Watermelons size up, and if we can keep them from the coyotes who are already stalking them, ripen up. Over the course of the month, the sweet potatoes will use all that green foliage they put on over the past couple of weeks to make some roots under there. In the meantime, the harvests of peppers, eggplant and tomatoes will pick up, and late summer will be upon us.

Over the past month, our farm has gotten 1.45 inches of rain, mostly scattered throughout the month, never more than about a quarter inch at a time. A quarter inch of rain definitely helps wet the surface of the soil so that irrigation water can soak in (there's that capillary action again). It doesn't do much for soil that hasn't had much water in a month. In general, vegetables like an inch of water... a week. In hot weather, even more. On dry soils (like ours), even more. Add that up, subtract one and a half inches in little bits here and there, and you get a whole lot of water that we've needed to use to keep crops going over the past month. That's farmer math.

You can see the results most vividly in the pick-your-own crops, where we haven't been able to irrigate yet, and the fall broccoli and cauliflower in the east field, where we ran overhead irrigation as we were transplanting -- the middle of the beds are beautiful, and the ends of the beds, where the overhead didn't quite reach, not so much. The last planting push of the season, when we're supposed to seed fall greens and turnips, is upon us this next week, and we're going to have to play the water game to see when -- and where -- we can get these crops in. The same is true for cover crops (more about those next week).

We use two kinds of irrigation on the farm. Overhead, the big silver pipes with impressive jets of water that turn in circles and make a reassuring "swish-swish" sound, is moved around the farm and used for everything from carrots to broccoli. We set up a line, flush it, and run it for 2-3 hours to make sure that the water soaks down to the roots of the plants. In the meantime, we set up another line so that when the first one is done we can turn another one on immediately. Shut down the first, turn on the second, and begin the process of dismantling the first line and moving it down the field to water another thirsty section. It's hard physical work, carrying 16 foot lengths of pipe several times a day, and hard mental work to try to set up a watering schedule that hits both the most vulnerable crops (newly planted seedlings), those that will benefit most in yield this year if they get water now (carrots, celeriac, broccoli, for example) and those that will benefit in yield next year if they get water now (strawberries, for example).

For tomatoes, cucumbers, squash, peppers, eggplant, melons, sweet potatoes and raspberries, we use drip irrigation under biodegradable plastic mulch. Drip irrigation is more efficient than overhead, and it doesn't have the same effect of spreading soil borne diseases through splash onto leaves, since it delivers water right to the roots of the plants. We can also fertilize through the drip lines, sending regular doses of fish and kelp, beneficial bacteria, and necessary plant micronutrients to the crops in their irrigation water. Because it takes time to set up and take down, we only put drip irrigation on crops that will be in for the whole season and that we won't double crop, and we try to plant these crops in big blocks so that we can water them in cycles. Once this system is in place, it takes lots more mental than physical work to keep it going.

Now, here's the thing: a dry year is hard on us in many ways. It takes more labor to irrigate, it takes more mental gymnastics to figure out the timing of planting and cultivating, and it really does decrease yields at our Lyman Estate field, which is not irrigated. Plant nutrition is dramatically curtailed in very dry soils, so plants are not only stressed by the lack of water, they're stressed by the lack of nutrients as well. Insects sense the stress and move in, and... well, you can imagine the rest. It's not pretty. All of that being said, however, a dry year is much, much better for us in terms of lessening disease pressure in some key crops (tomatoes, anyone?). Chances for a beautiful crop of tomatoes and colored peppers are much higher in a dry year. There's always a bright side. And now that we're turning the corner into the late innings of the season, with the big fall brassica planting behind us, the weed fires beginning to subside, and the tomatoes staked and tied up, hopefully we can begin to see the good results of that side even as we continue to irrigate.

Dan and Erinn are on vacation at the beach this week. We are so happy that these two hardworking farmers are able to go away for a week at the height of the season. It makes all of us relax a little to imagine them eating salt water taffy, doing crossword puzzles, and watching the waves roll in. Wherever you are, hope you can relax and enjoy the transition to late summer. Enjoy the harvest.

-- Amanda, for Andy, Erinn, Dan, Larisa and Lauren

Images by Rebekah Carter (2011).

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