My Hometown Gardening
Understanding fertilizers to help your garden grow by Kristina Gabalski Nitrogen is one of the major plant nutrients, and fertilizers contain nutrients. They are not “plant foods,” however. Nutrients are directly absorbed by plant roots and, in some cases, by foliage. According to the University of Maryland Extension (UME), plants use nutrients to make carbohydrates, proteins, defense compounds as well as other compounds. Plants growing in the wild don’t need fertilizers, UME explains, because they get their nutrients from the air, water, soil minerals, and soil organic matter – plants, fallen leaves, microbes, and animals that die and decompose. Our gardens likely DO need fertilizer because soils around homes have often been disturbed and topsoil removed. Fruits, vegetables, and flowers growing in your garden like these tulips, are more likely to need fertilizer to Organic matter is less abundant reach their full potential than plants growing in the wild. Photo by Kristina Gabalski. because leaves and other yard waste may be cleared away and sent to the landfill. Native and non-native trees and shrubs can Remember that inorganic fertilizers are mineral salts with nuthrive in our yards without fertilizer, but vegetables, fruits, and trients in a soluble form which helps with uptake but can leach flowers are more likely to need fertilizer and/or additions of organic easily into the soil. matter to reach their full potential. Good plant health depends on Organic fertilizers are derived solely from remains, the bya continuous supply of available nutrients from the soil. products of once-living organisms. Wastes and by-products of the The University of Maryland Extension explains that fertilizers plant and animal processing industries can be used as fertilizers. are regulated materials that contain at least one plant nutrient. Cottonseed meal, blood meal, bone meal, horn meal, and all maThe nutrient content is guaranteed by the three numbers found nures are examples of natural organic fertilizers. There are some on bags and containers of fertilizer. Also known as the nutrient human-made or synthetic organic fertilizers, which include urea, analysis, these numbers represent the percentage, by weight, of ureaform, and IBDU. Organic fertilizers are beneficial for improving nitrogen, phosphorus, and potassium. A five-pound bag of 10-5-5 the soil’s physical structure and increasing bacterial fungal activity, fertilizer, for example, contains 0.5 pound of nitrogen; 0.25 pound Cornell says. of phosphorus (expressed as phosphate); and 0.25 pound of potasFinally, special-purpose fertilizers – packaged for certain uses sium (expressed as potash). or types of plants, such as Rhododendron and Azalea Food, Holly Cornell University says there is often confusion over the terms Tone, or Rose Food – contain compounds that leave an acid residue inorganic, synthetic, organic, natural, and special-purpose fertil- that helps acidify the soil. However, these “acidic” fertilizers are izers. not expected to permanently change your soil from alkaline to There are some inorganic fertilizers that exist in nature as in- acid, and, Cornell adds, there are limitations on how much fertilsoluble parent/rock materials such as rock phosphate, sodium izer can alter soil pH. nitrate, and potassium sulfate, Cornell says. Others are manufacCornell warns that fertilizers packaged for specific plants – like tured products made from non-living materials. These are referred roses – don’t often have a valid research basis for being called to as synthetic or chemical fertilizers. Examples include ammonium “special.” It is best to perform a soil test before purchasing any exsulfate – used on acid-loving plants like blueberries and azalea; pensive special-purpose fertilizer. The reserve of nutrients already superphosphate; granular fertilizers like 10-10-10; and liquid fertil- in the soil changes with every soil type and location. izers like Miracle-Gro.
My Hometown April 2022 | 13
