When you are beginning to garden, setting out new beds, or planting trees and shrubs, it is important to get a soil test. Reading a soil test will allow you know what nutrients to add to raise or lower your pH, and improve your soil before planting.
What is pH (1)
The pH of your soil refers to the scale used to determine how acid or alkaline your soil is, based on the amount of hydronium ions in a solution. Soil is considered neutral if it has a pH of 7.0. Anything less than 7.0 is acid, and above is alkaline. The best growing conditions for the widest variety of plant is between 6.0 and 7.0.
Some plants, such as azaleas, hydrangeas, sweetspire, hollies, and blueberries prefer an even lower pH, between 5.0 and 6.0. To lower the pH of soil add pelletized sulfur or a acid fertilizer formulated for these plants.
What is P on the Soil Test
P refers to phosphorus. Phosphorus is a major plant nutrient that helps with plant growth and development and is essential for photosynthesis. When there is a deficiency of phosphorus in the soil, leaves of the plant turn purplish at the bottom first.
It has been discovered that many soils, especially former croplands are high in phosphorus and do not need amending. The nutrient graph (2) of K-State’s Soil Test shows the optimum range for pH, phosphorus, and potassium.
What is K on the Soil Test
K refers to potassium, an essential element. Potassium regulates the plants ability to gather CO2 by opening and closing stomata. It is also important for the building of proteins and starches, and it important for proper photosynthesis.
Potassium deficiencies are shown by brown scorching and curling of leaves (similar to herbicide drift), as well as yellowing between veins.
Why is Nitrogen Not on My Soil Test?
Nitrogen is not on the soil test because it moves freely through the soil and is difficult to determine on a single test. Recommendations are set via long-term research on lands and set for easy use for homeowners and farmers alike.
If you are still having trouble reading this soil test, or those from other sources, the best person to ask may be your local extension agent.