Organic and Inorganic Fertilizers and Materials for the Home Gardener

Home gardeners today have many choices when considering how to improve the soil and add nutrients. With the renewed interest in gardening practices that emphasize conservation and sustainability of our natural resources, many people have an interest in using organics to build the soil and supply needed nutrients. 

Applying fertilizers and adding soil amendments can impact the pH of the soil. Speed and duration of the reaction depend somewhat on soil type, organic matter, temperature, available moisture, or fertilizer solubility in water. Soil pH is a measure of the acidity or alkalinity of the soil.

Managing soil pH is important for gardeners because plants grow best in certain pH ranges. Plants may also exhibit nutrient deficiency or toxicity symptoms as a result of soil pH. Correct soil pH only when it is substantially higher or lower than required by the plants you are growing.  Select plants that will grow in the natural pH of your soil rather than changing the pH, as long as the existing pH range provides good nutrient availability. Refer to Extension Publication 2571 Soil pH for Landscape Plants for more information on pH and the optimum pH ranges for common landscape plants.

This publication lists selected organic and inorganic fertilizers and amendments, their speed of reaction (nutrient availability), and effect on pH so homeowners and gardeners can develop strategies for better management of plant growth and soil productivity. This information is intended as a reference only and should not take the place of a soil test. 

Improper use of fertilizers can contribute to water quality problems, so always follow recommendations of a soil test to make sure you are applying only what is needed for healthy plant growth.

*Organic fertilizer is defined as a material containing carbon and one or more elements other than hydrogen and oxygen that are essential for plant growth. These organic materials also supply various secondary {sulfur, magnesium, calcium} and/or trace elements {boron, manganese, zinc, copper, iron, and molybdenum).

**The speed of reaction and effect on pH depend on how the manure is stored, the moisture content, and how it is handled before application.

*The nutrient content may vary from what is listed, depending on the manufacturer or purity of the product or other materials blended with the product.

**Soil type, organic matter, moisture, temperature, and water solubility of fertilizer used affect the reaction speed.

*Soil type, organic matter, moisture, temperature, and water solubility of fertilizer used affect the reaction speed.

Other MSU Extension Resources

Suppliers of Organic Fertilizers, Rock Minerals, Composts, and Pelletized Poultry Litter in the Deep South by Steve Diver, NCAT Agriculture Specialist National Center for Appropriate Technology - Arkansas office

Test soil to find its pH value.

Gardening vegetables: organic gardening.

Organic crops geared more toward commercial organic crop producers.

The authors acknowledge the contributions of Extension Information Sheet 372 Soil pH and Fertilizers revised by Geoff Denny, PhD, Assistant Extension Professor, Plant and Soil Sciences, and Keith Crouse, PhD, former Associate Extension Professor.

Publication 2572 (POD-03-19)

Reviewed by Geoff Denny, PhD, Assistant Extension Professor, Plant and Soil Sciences. Originally written by Keith Crouse, PhD, former Associate Extension Professor, Plant and Soil Sciences, and Judy Pennington, PhD, Warren County Master Gardener.

Copyright 2019 by Mississippi State University. All rights reserved. This publication may be copied and distributed without alteration for nonprofit educational purposes provided that credit is given to the Mississippi State University Extension Service.

Produced by Agricultural Communications.

Mississippi State University is an equal opportunity institution. Discrimination in university employment, programs, or activities based on race, color, ethnicity, sex, pregnancy, religion, national origin, disability, age, sexual orientation, genetic information, status as a U.S. veteran, or any other status protected by applicable law is prohibited. Questions about equal opportunity programs or compliance should be directed to the Office of Compliance and Integrity, 56 Morgan Avenue, P.O. 6044, Mississippi State, MS 39762, (662) 325-5839.

Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture. Published in furtherance of Acts of Congress, May 8 and June 30, 1914. GARY B. JACKSON, Director