Organic Farmer February / March 2020

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MANAGING NUTRITION FOR ORGANIC VEGETABLES BY: DANITA CAHILL | CONTRIBUTING WRITER Abelardo Orozco, Duncan Family Farms Director of Farming Operations (Southern California and Arizona) checks on a crop of baby spinach, while employees weed and survey the fields. All photos courtesy of Danita Cahill. It’s not generally possible to increase the soil organic matter by more than one percent. But even that one percent can markedly improve soil fertility. “Feed the soil to feed the plant” is the organic farmer’s adage, and organic matter is the go-to organic fertilizer option to do just that. Organic matter is also a significant source of micronutrients such as iron, copper and zinc. As organic matter is mineralized, it either becomes bound to soil minerals, or it becomes available for plant growth. With vegetable crops, color, product size and uniformity are often as important for market share as yield. To obtain these attributes, nitrogen management is key. But managing soil nitrogen levels with organic matter is tricky, according to Nick Andrews, Oregon State University (OSU) Organic extension agent. “Nitrogen is often the most limiting nutrient. It’s a little bit more complex,” Nick said. The label of an organic fertilizer gives the NPK (nitrogen, potassium, phosphorus) numbers, but those amounts won’t necessarily be available to the plants. Nitrogen (N) Through the process of mineralization, some of the nitrogen from organic matter is changed into plant-available minerals—ammonium and nitrate, for instance. The problem is this process doesn’t always coincide with crop growth. Several factors are at play: 1) Temperature. Mineralization in soil temperatures below 50 degrees is insignificant. It does, however, increase as soil warms. 2) Moisture. Soil moisture is important. Mineralization happens rapidly in moist soils, but slows considerably in extremely wet or extremely dry soils. 3) Tillage. Tilling creates a surge of microbial activity, but that burst doesn’t last long—it subsides within weeks or even days. Some short season crops have low nitrogen requirements. Using the available nitrogen in soil organic matter, residues from cover crops and/or applications of compost, crops such as radishes and leafy greens may still produce well. Crops with longer seasons and higher nitrogen needs will often need supplemental sidedressings of organic nitrogen fertilizers. Heavy feeders such as peppers and tomatoes will benefit greatly from additional nitrogen. Nitrogen fuels green, leafy growth, which helps plants photosynthesis, producing the food required to set and develop fruits and vegetables. Here are some animal-based organic fertilizers to supply nitrogen quickly. These are good for cool season plantings: Blood Meal, 13-0-0—Blood meal, made from dried cattle blood, is a good nitrogen source for early spring or fall plantings. Chicken Manure, 1.0-0.8-0.5—Chicken and other poultry manures are a good choice if your crop needs a quick hit of nitrogen. Poultry manures release nitrogen rapidly—up to 75 percent is released into 26 Organic Farmer February/March 2020
the soil the first year. Most other manures release only about a third of their nitrogen the first year. Nick cautions against using only manures for nitrogen. “If you’re using enough manure to supply your nitrogen, you’ll have more phosphorus and potassium than you need.” Fish Meal, 9-4-1—Fish meal is made from ground-up fish. It’s an excellent nitrogen source for cool-season vegetables, especially for early spring plantings. Blood meal and fish meal may attract animals, including raccoons. The following are organic fertilizers that supply nitrogen slower. These are good for later-season crops: Feather Meal, 12-0-0—Feather meal, made from ground-up chicken feathers, is a good source of nitrogen for late-season growth. Good choice for tomato and pepper crops. Barnyard Manures—these are well-balanced fertilizers, supplying small amounts of nitrogen, phosphorus and potassium in an organic base. Well composted and cured manure should smell earthy. It shouldn’t smell strongly of ammonia. (50-60 parts per million). Phosphorus is especially important early in the season because it stimulates early shoot and root growth. Optimal crop yield calls for adequate levels of soil phosphorus, the second primary nutrient. Phosphorus helps plants store and move carbohydrates, or plant energy. It also promotes development of roots, flowers and fruits. Low phosphorus levels slow plant growth. Only about one percent of the soil phosphorous is available to plants. But too much isn’t good, either. Excessive levels can create field run off into streams and rivers, which can cause algae bloom, resulting in oxygen depletion and fish kills. Phosphorus soil level is something to keep an eye on. Potassium (K) Potassium is the third primary nutrient. It helps plants with root growth and disease Continued on Page 28 Navel Orangeworm Control! Mating disruption product for conventional and organic California tree nuts!! LESS DAMAGE – MORE PROFIT SEASON-LONG CONTROL THROUGH POST-HARVEST Different crops have different nitrogen needs. Crops with low nitrogen needs include spinach, baby greens, arugula, collard greens, Swiss chard, kale and radishes, as well as parsnips, peas, beans and squash. Crops with medium nitrogen needs include carrots, onions and garlic. Also with medium needs are lettuce, sweet corn, pumpkins, cucumbers, zucchini, rutabagas, potatoes, scallions and watermelon. Crops with higher nitrogen needs include not only tomato and peppers, but cruciferous vegetables such as broccoli, Brussels sprouts, cauliflower and cabbage. High nitrogen is also needed by celery, kohlrabi, turnips, cantaloupe and honeydew, squash and eggplants, as well as cruciferous vegetables like broccoli, cauliflower and cabbage. Phosphorus (P) Organic matter not only provides nitrogen, it also provides phosphorus, a macronutrient. Warm season vegetables require less phosphorus (20-25 parts per million in soil levels) than cool season vegetables MATING DISRUPTION PRODUCT FOR NAVEL ORANGEWORM IN ALMONDS, PISTACHIOS & WALNUTS © 2019, Trécé Inc., Adair, OK USA • TRECE, PHEROCON and CIDETRAK are registered trademarks of Trece, Inc., Adair, OK USA • TRE-1491, 4/19 Navel Orangeworm, Amyelois transitella • Up to 80% or more potential reduction in damage vs. current insecticide program • Season-long control through post-harvest • Easy application with ready-to-use carrier pack • No moving parts, no batteries, no gummy deposits • Removal not required INCORPORAT ED INSECT PHEROMONE & KAIROMONE SYSTEMS Your Edge – And Ours – Is Knowledge. Contact your local supplier and order now! Visit our website: www.trece.com or call: 1- 866-785-1313. ® 27 Organic Farmer February/March 2020 February/March 2020 www.organicfarmermag.com 27
Page 1 and 2: February/March 2020 Organic Poultry
Page 3 and 4: Organic FARMER 4 IN THIS ISSUE Orga
Page 5 and 6: California Organic Fertilizers, Inc
Page 7 and 8: The Egg Handling and Meat Processin
Page 9 and 10: USDA Organic Regulations for Poultr
Page 11 and 12: maintain or improve, so approaches
Page 13 and 14: Farm land that’s been in the fami
Page 15 and 16: Marty uses a corn chopper and a fee
Page 17 and 18: June 3, 2020 Turlock, California ST
Page 19 and 20: purpose of constant plant feeding?
Page 21 and 22: ® The Grower’s Advantage Since 1
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Organic Farmer February / March 2020

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