Vegetables & Sustainable
|Topic||Questions and Answers About Soils and Fertilizer in the Garden.|
Q: What exactly is meant by “soil texture”?
Q: What is “soil structure”?
Q: What does the soil pH refer to?
Q: Why are soil pH, acidity, and alkalinity levels important?
Q: What does it mean when a soil is high in salt or it has high salinity?
Too much salinity can damage susceptible plants. Many ornamental, fruit, and vegetable plants are very susceptible to salinity. Saline soils should be irrigated with water beyond the amount required by the plants in order to wash away the excess salts from the root zone.
Soil salt concentration is measured as electrical conductivity (EC). in units known as deci-Siemens per meter (dS/m). A salt level of 2.0 dS/m or greater can affect sensitive plants, but many plants tolerate an EC level of about 4.0 dS/m. Levels of two to four times this amount are usually necessary before easily diagnosed foliar symptoms (leaf burn or scorch, leaf drop) are expressed. Measuring salinity or electrical conductivity requires technical knowledge.
Q: What nutrients are required by plants?
Is fertilizer always needed when planting in the garden or landscape?
What plant nutrients are most commonly needed for fertilizers to supply?
Q: Are there regulations on fertilizer products in California?
Q: Is there any difference between a “fertilizer” and a “soil amendment”?
Q: Is it better to use organic fertilizers?
Q: What are the differences between organic fertilizers and other fertilizers?
Other fertilizers, sometimes called synthetic, chemical or inorganic fertilizers, are comprised of mined minerals and man-made chemical compounds that provide combinations of plant-essential nutrients. Common examples are urea, ammonium nitrate, ammonium sulfate, superphosphate, and muriate of potash.
Q: What are the advantages and disadvantages of using organic versus inorganic or synthetic fertilizers?
Inorganic fertilizers are characteristically fast-acting and relatively low in cost per pound of actual nutrient. Some inorganic fertilizers, such as ammonium sulfate based fertilizers, can acidify the soil (lower the pH) with long-term use, while others such as calcium nitrate will tend to raise pH. Because inorganic fertilizers are salts, they dissolve and release nutrients readily. Key disadvantages are their potential to (a) contaminate the environment through runoff or leaching of irrigation and rain, and (b) burn crops if over-applied or mismanaged. Slow-release nitrogen fertilizers are available at much higher cost, and their release rates are governed by environmental factors such as soil moisture content and temperature. Slow-release inorganic nitrogen is sometimes called water-insoluble nitrogen (WIN). Use of these products reduces the chances of environmental contamination and crop injury because relatively small amounts of nitrogen are present in a soluble form at any time. When used properly, plants receive a consistent supply of nitrogen, and the number of applications can be reduced versus using traditional fertilizer.
Q: How should I apply and use organic fertilizers to get the most benefit for my plants?
Q: How do I decide which fertilizer product to buy, besides the price?
With synthetic or inorganic fertilizers, there is the choice of whether to use a “complete” fertilizer (one that provides nitrogen, phosphorus, and potassium) or a single source one (one that provides only nitrogen, phosphorus, or potassium). When looking at single source fertilizers, there is also the question of what impact will it have on soil pH. Ammonium sulfate based fertilizers lower pH and nitrate ones tend to raise it. There are also synthetic fertilizers that contain more plant-essential nutrients than nitrogen, phosphorus, and potassium. These products are usually needed only when deficiencies of the additional elements are known or when fertilizing plants grown in containers.
Q: Is foliar feeding a good way to fertilize plants?
Q: When and how much should I fertilize my lawn?
Q: How should I apply fertilizer to a large area like my lawn or large beds?
Q: How much fertilizer does a vegetable garden need?
Q: How can I most efficiently fertilize a row of newly planted seeds?
Q: What is the most efficient way to apply fertilizer to vegetable plants as they are growing?
Q: How much should I fertilize landscape trees and shrubs?
Trees and shrubs less than 2 years old often benefit from fertilization. Apply 0.2 pounds of nitrogen with an area no more than 3 feet by 3 feet around the base of each plant. Apply immediately after planting, about 2 months later, then the following spring.
Q: How and where can I obtain a soil test?
A: Look at this guide, Selected Plant and Soil Laboratories in
Our thanks to Dennis Pittenger, Area Environmental Horticulturist University of California Cooperative Extension, Central Coast & South Region/Los Angeles County/U.C. Riverside for providing content for the soil & fertilizer section of California Gardening.