Amend soil nutrients after analysis
Getting a soil analysis and making recommended improvements are vital for garden health. Testing early in the growing season allows for an accurate determination of soil nutrients and time to improve soil condition before planting.
In last week's column, we discussed preparing soil samples for testing. Today, we'll talk about how to interpret your results report and amend your soil, with a focus on major nutrients.
Penn State returns your soil test results in about two weeks. The soil analysis covers only the upcoming season and is for the crop selected on the analysis test form — for example, flower bed.
The report lists pH and soil nutrient levels. Nutrients measured include phosphate, potash, magnesium and calcium. A bar graph indicates whether pH and each nutrient is below optimum, optimum, or above optimum for your intended use.
These nutrients and pH level are the most important factors in soil health. Soil pH influences how easily plants can absorb nutrients and is measured as neutral (7.0), acidic (below 7.0) or alkaline (above 7.0). Most plants do best in slightly acidic soil; i.e., with a pH value between 6.0 and 6.9. Exceptions include oaks, pines, blueberries and raspberries, which prefer more acidic soil. Depending on use, your soil's pH may need to be more alkaline or acidic.
Phosphate is important for cell division and new tissue growth; it also stimulates root growth and promotes winter hardiness.
Potash promotes plant growth and reproduction, and supports processes related to photosynthesis, water uptake and regulation.
Magnesium serves as the foundation for plant photosynthesis, which includes chlorophyll production that gives leaves their green color.
Calcium helps to maintain a proper chemical balance in the soil. It reduces soil salinity and promotes water penetration.
Based on the amounts of these nutrients in your soil and its pH level, your test results include recommendations to bring the soil to optimal nutrient health.
Recommended nutrient amendments are given in pounds per square foot, so you will need to know the square footage of the area to be treated.
Recommendations may include limestone, magnesium and/or gypsum application. Limestone makes the soil more alkaline, while magnesium and gypsum bring magnesium and calcium levels to optimal ranges.
The report makes recommendations for nitrogen, phosphate and potash. Nitrogen promotes growth, and is the N of the N-P-K — nitrogen, phosphate and potash — in fertilizer mixes.
For a variety of reasons, nitrogen levels in soil can change very rapidly, so nitrogen level is not tested in the initial soil analysis. In the N-P-K section, the nitrogen recommendation is based on the known needs of the plant you plan to grow. Phosphate and potash recommendations are given to bring those nutrients to optimal levels.When purchasing the recommended fertilizers, take your report to a reputable garden center for advice. Double check your calculations for square footage and the amount of product you will need. Organic fertilizers and amendments slowly change the soil nutrient levels to promote optimal plant growth.Organic fertilizers obtain their nutrients from natural sources — for example bone meal, kelp, alfalfa meal or bat guano.When applying fertilizers and amendments, select a day that is free of wind and rain. Wear gloves and a mask. Follow the package directions in applying the amendments, then allow the soil to rest for one or two weeks before planting seeds or seedlings.For help with interpreting your soil test results, call the Master Gardener Greenline at 724-287-4761, Ext. 229.
