Natural fertilizers can support abundant flowers as well as vegetables.
According to the Colorado Master Gardener Program, "fertilizer" refers to a soil amendment that guarantees at least minimal percentages of the essential plant nutrients: nitrogen, phosphorus and potash. In general usage, a "natural fertilizer" is any fertilizer derived from natural sources, including plant and animal by-products, seaweed, powdered rock, soil conditioners and inoculants. Most of these are organic or carbon-based sources, but powdered rock and similar substances are inorganic.
Advantages
Nutrients in natural fertilizers are less concentrated than in synthetic fertilizers, and are less likely to "burn" plants or roots on contact. Nitrate pollution of streams, rivers and groundwater is less likely, because nutrients are released slowly in the soil and usually taken up completely by plants before runoff or leaching can occur. Slow-release nutrients support sustained growth. Using natural or organic fertilizers supports overall soil health. Using natural fertilizers means less reliance on petrochemicals.
Disadvantages
Natural fertilizers release nutrients slowly. Gardeners accustomed to that sudden flush of green from sprinkling ammonium nitrate on the lawn are often disappointed. Natural fertilizers also offer lower levels of nitrogen than most synthetic fertilizers, so you need more fertilizer--or combinations of fertilizers--to provide the same amount. However, relative phosphorus levels can be higher, so use caution to avoid phosphate excess. Some natural fertilizers are very expensive.
Nutrient Uptake
The key plant nutrients in fertilizers--the three numbers on fertilizer labels--are always listed in this order: nitrogen, N; phosphorus, P; and potassium, K. Other nutrients are needed in minute amounts and are called micronutrients. The ability of plants to utilize nutrients from natural fertilizers depends on soil microbes that require warmth, moisture, soil pH and adequate levels of other nutrients. Using mulch, monitoring soil moisture and improving drainage help improve the soil for effective use of natural fertilizers.
Plant-Based Fertilizers
A variety of vegetation-based products are used as natural fertilizer, including alfalfa and canola meal pellets. Highest in nitrogen are soybean meal, cottonseed meal and corn gluten meal. Seaweed is the best overall source of micronutrients. "Green manure" cover crops including legumes can enrich soil with nitrogen and other nutrients, and add organic matter when tilled in.
Animal-Based Fertilizers
Bat guano is high in nitrogen and can be tilled into the soil or applied as a foliar spray. Composted or well-rotted chicken, horse and cow manures are also used. Blood meal, manufactured from dried slaughterhouse waste, is pure nitrogen--one of the highest nonsynthetic sources. Bone meal is particularly high in phosphorus, though it's available to plants only at low pH. Fish powder or meal, fish emulsion and feather meal are other natural fertilizers.
Rock Products
Rock phosphate and colloidal phosphate, or soft rock phosphate--clay particles coated in natural phosphate--are key phosphorus sources, though animal and plant sources are considered better sources. Gypsum and lime provide calcium when it's needed. For potash or potassium, natural sources include greensand, feldspar and potassium sulfate.
Compost
Though compost is organic and typically natural, it's generally not considered a fertilizer because it contributes minimal amounts of the key plant nutrients. However, compost helps maintain soil moisture and warmth and supports soil microbes, so is also crucial for successfully using natural fertilizers.
Related posts
What Is Plant Fertilizer Made Of?Fertilizers in the hands of skilled gardeners are like spices in the hands of Cordon Bleu chefs. They are the final ingredient in the process producing the healthi...
Even when side-by-side, lawns and gardens have different fertilization needs.Lawns and gardens serve different landscape purposes and have different care requirements. Crucial elements such as wat...
Potash (or potassium), along with nitrogen and phosphorous, is present in nearly every type of commercial fertilizer. As one of the top three required nutrients for plant growth, potash encourages...
Organic fertilizers are made from plant matter and animal byproducts.For healthy growth and development, plants need adequate supplies of 13 mineral nutrients, including nitrogen, phosphorus and p...
All plants require phosphorus for adequate growth.Plants require phosphorus in large amounts for adequate growth. A plant deficient in phosphorus will show stunted growth or leaf browning that spr...
