Roots and soil have quite a relationship, it's a relationship that goes beyond a place to anchor the plant or a place from which they get a drink of water. It's a complex relationship involving the elements of plant nutrition aided by fungi, bacteria, composted organic material and insects; however the subject of dirt and roots is a big yawn for most. There may come a day when you are tired of replanting the same spot in your yard where everything seems to die or you want the rose bush your family gives you every year for Mothers/Fathers Day to live for once. It could all boil down to a problem with your roots or the soil around them, so if that day is today, listen up!
The science behind soils, roots, and nutrient uptake is extensive, so this is the extremely short version for the rookie gardener. I am hoping it will be enough to start the problem solving process. Maintaining adequate soil moisture, understanding adequate air circulation, replenishing a level of soil fertility, and making sure conditions are suitable for the plant to easily use nutrients is the heart and soul of soil science. Soil is composed of sand, silt, clay and organic material and the percentages of each in the mix range from soils found in deserts to soils found in swamps, marshes, and everything in-between. Which plants grow in these various soil profiles can be limited to those considered to be “native” for the most extreme ranges, as in extremely dry or extremely wet, and will include greater variety for those in the middle ranges, like the ones in my backyard in the mid-atlantic.
I am sure you have all heard of pH balancing for skin and hair. Do you question why it matters or what it means? The pH number designation is merely a measure of acidity or alkalinity. The only way to actually identify the pH of soil and fertilizer needs is by having the soil tested. A soil test can identify levels of the macro-nutrients like nitrogen, phosphorous, and potassium; micro-nutrients; and pH levels as well as the soil profile percentages. Why soil pH varies is a whole other blog post, but knowing the current pH value in different parts of your yard can help with soil corrections that may be required to grow the specific plants you desire.
Dead spots in a yard can be caused by many factors. Sometimes the soil is too compacted, sometimes it is too wet, sometimes the soil is too acidic or too alkaline and these extremes can cause plant death. There can be “micro-environments” created by the dumping of a leftover bag of lime or ashes from the grill or salt from the roadway that can affect a plant's ability to grow. Soil testing can be a helpful tool in the arsenal to diagnose the problem and to provide recommendations to fix it.
Growing plants is, after all, a science and this is the part of the science that needs to be treated scientifically. Before you go squinching your nose, keep in mind plants have individual optimum ranges for soil acidity and soil alkalinity. It is pH that makes the pink hydrangea pink (alkaline) and the blue hydrangea (acidic) blue. It is always something that can't be seen that can be upsetting the balance of nature. So, okay, most homeowners ignore the pH. Most will replant and learn through trial and error. It may be attributed to the “black thumb” or the lack of “luck” with plants, but you don't need to be like most homeowners. You can send a soil sample from this location to a soil testing lab to find out what the pH is and what else may be out of balance.
The chart below, which is the go-to chart for checking nutrient availability at various soil pH's, shows how available several nutrients are at various pH's. I referred to this chart many times in my career. The element, Nitrogen, is less available at low pH of 5.5 (strongly acidic) and becomes more available up to medium alkaline, pH 8.5. This is a lovely wide range and I am very proud of Nitrogen for presenting itself over such a wide range of pH's but I am a bit disappointed in phosphorous. Phosphorous has made itself available over a much narrower range. Phosphorous is the go-to element in the making of flowers and the subsequent fruit (basically it is crucial to everything you want in a plant), so it requires a bit more attention than the Nitrogen.
Chart of the Effect of Soil pH on Nutrient Availability
I know you are struggling to keep your eyes open so I will leave you with this “pretty short” story...When I was in college, we grew vegetable seedlings as an experiment, leaving out one micro-nutrient per plant. Even those plants from which boron and molybdenum were withheld showed flaws in their cell division and grew in a very twisted and wonky way. It was evidence of the importance of each nutrient element (macro or micro) to a plant and why paying attention to the pH and nutrient levels ensures that they have the essential elements they need to grow properly. Plants are relatively simple organisms that are dramatically affected by the absence of even one nutrient element. I wonder what impact that would have on the human body with all of that cell division going on? It is a case for eating all fruits and vegetables of every color to make sure you get the full compliment.