by Sally Colby
Michael O’Gorman says the principles of growing vegetables are the same no matter what the scale of the farm, from small market plots to large acreage. After spending 40 years in commercial vegetable production, O’Gorman is the founder and director of the Farmer-Veteran Coalition. Throughout his career in growing, he focused on the skills required for efficient production and believes that basic skills make a difference in profitability.
“There’s one equation that you’ll take with you your whole life in vegetable production,” said O’Gorman. “What you produce per acre, how many boxes or pounds you produce, the price it’s sold for, minus what it cost to produce. What’s left over is profit or loss. So while yield might be how many green beans or carrots you produce from an acre, productivity is how many green beans you are able to pick in an hour or a day. In every decision you make in vegetable production, you’re weighing the benefit of increasing yield or increasing productivity. There’s constant friction between those.”
Thinking about yield begins with thinking about the individual plant, and O’Gorman believes that seeds can influence profit. “Varieties make a difference, and even strains within certain varieties make a difference,” he said. “Having vigorous seed in the right varieties has a direct effect on whether you can grow that item.”
O’Gorman explains that each vegetable has a growing/temperature threshold, and below that threshold, they don’t grow. “When I was in production mode, I watched night temperatures more than day temperatures,” he said. “Night temperatures meant, were my plants going to ‘sleep’ or were they growing all night? How many hours and how many degrees of temperature were they above the growing threshold? That dictated how fast growth was.”
Obtaining optimal yields begins with using ideal plants. “If you want a 4-inch onion, don’t plant them every 3 inches,” said O’Gorman. “Ideal spacing is just enough to grow the plant without extra space. Calculate the number of plants per row, multiply by rows per acre and multiply by time in the ground.” O’Gorman emphasized the fact that optimum fertility is also important, and includes consideration of nitrogen, phosphorus, potassium, calcium, sulfur, magnesium and micronutrients along with sufficient organic matter. He says that the biggest deterrent to optimal growth is weeds. “Getting rid of weeds is a cost,” he said, “and may be a very high cost in a new farm. Insect pests damage plants and have the potential to spread disease, so identify and control those.” Human and mechanical damage can deter growth, as can weather events such as hot dry wind, too little or too much rain or unseasonable temperatures.
O’Gorman says that the ideal plant population is determined by maximizing the number of plants without reducing the optimal growth or creating unacceptable loss of productivity. He noted that some farms that are growing a variety of vegetables have not looked ahead to determine the space required for harvest – where will people walk, is there space for equipment?
“A lot of your cost will be per-year area,” said O’ Gorman. “You bought a farm, and have 10 acres of tillable land. You built a 30’ x 90’ foot greenhouse. How are you going to maximize that space and your yield for that area? You also have to consider your time in the ground, even when you have the most dense crop planted there.”
For optimum fertility in organic production, O’Gorman says the best practice is cover crops. “There’s nothing you can do to add enough fertilizer or organic matter that is equal to cover cropping,” he said. “Also helpful is large volumes of compost – at least 20 tons/acre yearly – and locally sourced manure. There are also blended fertilizers out there that work well. Fertility is no longer an issue for organic farmers.”
Soil temperature is an important consideration – any time a crop is planted prior to adequate warming, it won’t grow well no matter what. Also make sure crops come up quickly by providing adequate moisture prior to planting seeds. “Transplants can take five to eight weeks off days to harvest,” said O’Gorman. “They also have a head start over weeds, and allow more precision in plant placement.”
It’s important to determine the ideal plant spacing to obtain the ideal marketable crop. The grower can manipulate plant size and harvest by spacing. “A cabbage, given enough space and fertility, will get enormous,” said O’Gorman. “But the commercial market wants a two or three pound head, trimmed back, in a 40-pound box.”
Increasing the number of plantings per season increases profits. O’Gorman says that as a grower, the two most important records he kept were yield and days to harvest. “Days to harvest changes as the season goes,” said O’Gorman. “The closer you are to the equinox, the faster something grows. For example, when we grew celery for the organic market, the market wanted it 52 weeks of the year. We had 52 plantings, but plantings were as far apart as every three weeks in the spring going into warm weather, and as close as every three days in August.”Precocious seed varieties can help with rapid germination and fewer days to harvest.
Growers can lengthen the duration of harvest by maintaining plant health and providing plants with adequate nutrition and water throughout the growing period. Timely harvest management and abandoning harvest when yield or quality declines is also important. “Zucchini is a good example,” said O’Gorman, adding that novice growers often proudly post photos of themselves with 10-pound zucchini on social media. “The reality is that once that zucchini is left on the plant, the plant is triggered that it’s time to produce seed and die.”
Another profitable move is to reduce turnaround – the time between the last harvest of one crop and the next planting. “This usually happens in prime time, in the middle of the season,” said O’Gorman. “You want to be able to utilize the longest growing days and reduce the amount of time that that field is sitting idle. Going into fall, delaying a new planting one week may delay harvest three weeks, and may present the risk of frost or heavy rain damage.”
O’Gorman says that where he was a grower in the Salinas and Imperial Valley areas of California, raised seedbeds were prepared once a year, in spring. Because tractors, equipment and people’s feet don’t make contact with raised beds, once a crop is harvested and plant waste is removed, the bed is ready for the next crop. “If there is too much (vegetable matter) to break down, cut it down, take it out and compost it,” he said. “If there isn’t a lot of matter left, turn it under and water immediately.” O’Gorman added that in commercial production he was involved with, a tractor would follow the harvest crew within hours to turn under the soil in raised beds and prepare for the next crop.
No matter what the stage or scale of production, O’Gorman says that producers can begin to record information including the planting date – the date of seeding or transplant, and the exact acreage. “When was the first harvest, the frequency of harvest, duration of harvest and the total yield?” he said. “As you start gathering this information, you will learn how day length affects days to harvest, how planting different varieties affects days to harvest, how plant spacing affects yield, and how your farming practices affect productivity.”
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