Soil Fertility Lessons for Gardeners Best Practices for Building and Maintaining Healthy Soil for Optimal Plant Growth

By Kirsten Ann Conrad, Virginia Cooperative Extension Agent

Every gardener at some point in their lives and their practice of producing healthy lawn, vegetables, trees, fruit, flowers or any other crop, has to address the question of whether their soil is good enough for producing that champion pumpkin or that perfect putting green.  Here are some lessons learned and some tried and true practices that you can employ that will help any gardener protect and promote soil fertility.

1. Remember it is the plant that produces its own food. When we maintain optimal conditions for plant growth we also optimize the ability of a plant to succeed.

Test the soil to learn the pH and nutrients already present.  Soil testing can give you a baseline knowledge of how acidic your soil is and whether your soil is lacking in any of the essential minerals that are needed for the plants you wish to grow in that soil. Optimal plant growth is generally achieved at slightly acidic pH levels of 6.5 to 6.8.  Some plants do like to grow best in soils that are more basic or “sweet” as the old-timers used to say, and some like azaleas prefer soil that is more acidic or “sour”.  If you go too far up or down that scale however, some of the essential nutrients will be unavailable to plants.

2. Nearly all plants need air to reach their roots as well as their leaves and stems. Soil compaction undermines the health of many plants and makes soil fertility management much harder.

Before undertaking planting projects make a plan to preserve soil structure as well as root systems of mature trees and shrubs. When heavy equipment rolls over soil it squeezes it and changes the balance of air and water for any roots that are growing there. Even constant human foot traffic can compact soil over time. Not only does compaction damage soil structure, it can crush plant roots and hurt their ability to get nutrients from the soil.

3. Flooded soils do not always have a puddle on the top of the ground. Soils that do not drain will foster anaerobic conditions that do not favor plant growth and will greatly deplete the available minerals and nutrients that are in that soil while damaging the microorganisms that assist with healthy plant growth

Determine soil drainage capacity before planting.  While some plants like it dryer and some like it wetter but heavy waterlogged soils will not favor healthy plant life.  Good drainage of water out of the soil is needed to preserve the population of mycorrhizae and other soil life that helps make soil nutrients available to plants. These microorganisms work with plants symbiotically to help transform compounds into forms that plants can use to enhance their growth.  They also help to break down organic matter ultimately leading to soils that drain better, provide more nutrients to plants, and that break down contaminants faster.

4. In clay soils, add organic matter to improve soil structure, drainage, and nutrient holding capacity. In sand soils, add organic matter to improve soil structure, water retention, and nutrient holding capacity.

Use compost to improve soil structure and fertility in lawns and gardens.  All soils employ both bacterial and fungal organisms in their soil building. In Virginia we have a fungal based soil that provides ideal growing conditions for our native woodland plants. It is also an ideal soil for vegetable and lawn growth. Our clay and sandy soils provide a mineral rich base and the decomposition of organic matter like wood, leaf mulch by microorganisms are essential to providing the ability of those minerals to be available to plants and to break them down into usable forms.  Composted plant materials, kitchen scraps, leaves, grass clippings and even many kinds of paper can be used to improve all kind soils and add valuable plant nutrients. Don’t throw away these sources of ‘black gold’.

5. If you value your soil and the plant nutrients it holds, don’t let it wash away! Hold on to it by discouraging erosion and repairing storm water drainage problems. Nutrient and soil runoff are a major pollutant of not only local waterways, but of the Chesapeake Bay as well.

Prevent erosion by maintaining vegetative cover using mulch, and correcting drainage problems on your land. The use of native, non-invasive ground covers and the maintenance of healthy plant growth will build strong roots, reduce the impact of heavy rains, and enable rainwater to be absorbed by the soil more readily. The use of soil testing to determine the need and the application of supplemental fertilizer products to meet that need will promote healthy plants with strong healthy roots.  Cover your bare ground with plant growth, organic mulch.  The preservation of good soil structure is one of the best ways we can help plants utilize the nutrients that are present and available.

6. Right Plant Right Place is a very important and most basic consideration for overall success by any gardener. If you don’t have 8 hours of direct sunlight a day, you will have trouble growing sun-loving plants like turfgrass. If you want to grow bottom-land, wet soil loving natives, they won’t be happy on a dry sunny hillside.

Select plants for the landscape that will grow in the existing soil. It’s not just the light or the water.  The chemistry that we have is determined by the underlying bedrock.  It’s hard to change the basic nature of the soil.  If you have a soil that is naturally near neutral 7.0, it’s going to be really hard to maintain that soil at a pH of 5.0 so you can grow blueberries.  If you have a soil that has always been an acid soil, growing grass on it will take a lot of lime and a lot of time.  The availability of certain nutrients is limited at specific pHs and every soil has its plant community that does best in that soil.  Try not to fight it.