Getting to the Root of the Problem: Soil pH and Nutrient Uptake
Similar to people, plants need the proper nutrients to flourish. Unlike people, plants are anchored in place by the very mechanism that takes in nutrients, their roots. In a world without people, plants would be found in their ideal location and part of a fragile cycle will keep those nutrients available as the plant grows. Add people into that equation and the cycle is thrown into disarray by being planted in areas that are typically not always the best environment. Knowing the relationship between soil pH and nutrient uptake can lead to a healthier landscape.
How do the plants take up nutrients?
First, it’s important to give you a short lesson in soil chemistry. When something dies, say a leaf, it falls onto the ground. Various insects, worms, or fungi start to break it down. This is an important part of the cycle as it makes the nutrients that the plant needs. Once it rains and those nutrients are moved by the water and start to travel between the sand particles that we call “Florida soil”. Now think of those grains of sand as weak magnets. As the nutrients pass by, the sand is able to pull nutrients to it’s surface and weakly hold on to them. Then, a root starts growing into the area and, like a straw, and begins to draw in the water. As it draws in the water, the pull is strong enough to dislodge some of the nutrients from the sand. The nutrients travel to various areas needed for growth and to produces leaves. Then the leaves and branches die and fall to the ground. Over time, this organic matter will break down into nutrients and continuing this cycle. As the tree grows up and out the roots also spread further out to uptake the added water and nutrients needed to sustain the growing tree.
And now the Human Element…
Now, lets add the human dimension. Mr. John Doe buys a plot of land to build a house. What is the first thing that needs to happen? The land is cleared of all or most of the vegetation. Next, the land is leveled and more top soil is brought to make the land higher. Gravel is put down or concrete is laid and the house goes up. Then the landscape is designed for aesthetic appeal and not for function. So, a few shrubs and a couple trees are installed along with a lush carpet of grass. Mr. Doe moves in and decides to add an azalea and a citrus tree and a phoenix palm to the landscape. Things go well for a few years as Mr. Doe manicures the landscape an lawn, trims the trees and shrubs, and rakes up all the grass. Then the plants start to decline.
Soil Testing as a Diagnostic Tool
There are many reasons a plant may decline and many show the same symptoms. Three main reasons are nutrient deficiency, lack of water, and planting too deep. For now we will focus on nutrients. Some of the common signs of a nutrient deficiency include yellowing of the leaf edge, yellow leaves with green veins, brown tips, deformed leaves, and red blotching. Mr. Doe could start by adding fertilizer, however submitting soil for testing can help pinpoint the specific problem. A soil pH test is the best place to start as pH plays a significant part in absorbing nutrients and plant health. In an ideal situation Mr. Doe should submit a soil sample for testing before he planted. Plants like azaleas, camellias and blueberries need a lower soil pH than most landscape plants. Since he has already planted, a soil test will give insight as to why the specimens’ health has declined. It will also provide a guide to the types of plants and trees to plant that will flourish in his landscape.
Recommended Landscaping Checklist
- Observe the site several times during the day to see how much sun it gets
- Contact 811 to find your utilities
- Perform a soil test via the UF/IFAS soil testing
lab ($10 per test)
- Research intended plant’s needs (pH,
light/shade needs, soil drainage)
- Add soil amendments only as directed by the
soil test results
- Purchase and plant
For More information:
- Nutrient Deficiency Symptoms of Woody Ornamental Plants in South Florida
- The Importance of Soil Health for Residential Landscapes
- Tools for Evaluating Soil Health