Soil Fertility

Is your soil fertile? A balance of nutrients is essential for plants to thrive. Too much of one can be just as bad as too little.

Plants need Nitrogen (N), Potassium (K), and Potassium (K), expressed as NPK, in the largest quantities. They need other trace elements as well.

What is fertile soil? Fertile soil is dark and crumbly and has a fresh, earthy smell. It holds water well. Get to know your soil by observing the color, smell, and feel of it.

The first step to healthy soil is in performing a soil test. All of Southside Community Land Trust’s gardens test their soil before any food is grown.

Many times, city soils will show high levels of contaminants. If this is the case, it’s best to build a raised bed and purchase healthy soil. 

Additionally, you can add nutrients to the soil through planting cover crop and adding compost.

Soil Textures

Sandy - sandy soil is gritty and does not hold together when wetted and squeezed. It has good drainage, but is low in nutrients and doesn't hold water well.

Clay - clay soil and silt stick together when wetted. When dry, they are rock hard. They contain important nutrients, but are difficult for roots to break through.

Loam - loam is a combination of sand, silt, and clay. When wetted, it is crumbly. It holds water and nutrients well and is easy for roots to penetrate.

Soil Nutrients

Nitrogen - gives plants lush, green, leafy growth

too little: small, pale or yellow leaves

too much: rapid growth, nitrogen burn, disease, sucking pests, delayed flowering

sources: alfalfa meal, blood meal, compost, cover crops, fish meal/fish solids, barnyard manures


Phosphorus - helps stimulate flower, fruit, and root growth

too little: purplish leaves or stems, poor flowering

too much: aborted flowers

sources: bone meal, cover crops, poultry or rabbit manures, soft rock phosphate


Potassium - helps with growth and disease resistance

too little: crispy brown leaf edges, curled lower leaves

too much: delayed flowering, poor roots

sources: compost, granite meal, kelp meal, wood ashes


Calcium - needed for cell reproduction and protein synthesis

too little: curled leaves, weak stems

too much: delayed flowering

sources: lime, gympsum

Trace minerals: iron, manganese, zinc, copper, boron, and molybdenum are needed by plants in trace amounts. Too much will harm plants.

 Kick the chemical habit! Organic fertilizers provide soil with organic matter and nutrients. They are better for your soil and the environment, and help build up your soil in the long run.