Vegetables need nutrients to grow and produce fruit. In an ideal world, a healthy soil provides these required plant nutrients. Nevada rarely has optimal soils due to a lack of organic matter and beneficial soil microorganisms. Gardeners must build their soil to supply a plant's nutrient needs.
There are 16 essential plant nutrients. The primary ones are nitrogen (N), phosphorus (P) and potassium (K). Secondary nutrients include calcium (Ca), magnesium (Mg) and sulfur (S). Micronutrients are Zinc (Zn), iron (Fe), manganese (Mn), copper (Cu), boron (Bo) and molybdenum (Mo).
The earliest fertilizers were animal manures, plant and animal residues, ground bones and wood ash. For years manufactured fertilizers replaced manures and compost. The latest trend in plant nutrition is once again to feed the soil with organic matter. Plants grown in soils high in humus (decomposed organic material) are not only hardier, less disease- and insect-prone, but often more nutritious.
Soil fertility doesn't have to be complicated even though different vegetables require different nutrients. High amounts of nitrogen encourages excessive green growth. To produce quantities of tomatoes, peppers, cucumbers and most vegetables, add small amounts of nitrogen. On the other hand, nitrogen benefits leafy crops such as lettuce, kale and chard. Adding a complete fertilizer - with an analysis such as a 16-16-16, 5-10-5 or something similarly low - can be beneficial to plants. Alternatively, apply a monthly application of liquid seaweed or fish emulsion and compost.
Some crops are "heavy feeders" and need a good balance of nitrogen, phosphorus and potassium. Heavy feeders include the cabbage family (broccoli, cauliflower, mustard greens, Brussels sprouts and bok choy).
Cucumbers, melons, potatoes, eggplant, lettuce, beets, spinach and chard are also heavier feeders. Give heavy feeders lots of organic matter worked into the soil and as a mulch, a balanced inorganic fertilizer two to three times during the growing season, or regular applications of fish emulsion or other organic fertilizer.
Light-feeding crops include carrots, peppers, radishes, turnips, peas and beans. Regular applications of compost may be adequate for these plants depending on the soil.
Some crops have special needs. Melons, squash and cucumbers need magnesium. Garlic, onions, squash and tomatoes do well with extra phosphorus and potassium. Some plant growth problems are due to a lack of nutrients. Some are not. A soil test is the best way to tell which nutrients are present or lacking in a soil.
JoAnne Skelly is the Carson City/Storey County Extension educator for University of Nevada Cooperative Extension and may be reached at skellyj@unce.unr.edu or 887-2252.
