Testing your soil is an important part of growing food- especially in areas with geologically old, nutrient-depleted, acidic soils as are commonly found in the Eastern United States.
Fall is the perfect time of year to get your soil tested to see what type and quantity of soil amendments you need to give your plants the nutrients they need without adversely affecting the soil or environment.
Application of too much nitrogen and phosphorus, for example, can leech into waterways and cause harmful algal blooms. These ‘blooms’ in turn cause an explosion of bacteria which result in low water oxygen levels, killing massive amounts of fish and has environmental effects all the way up the food chain. While important to plants, application of too much zinc, or too little or too much lime, can cause soil toxicity and limit availability of many other important nutrients. Having the right mix of nutrients will turn your garden into delicious abundance. Luckily, for North Carolina residents this testing is free April-November and Fifth Season Gardening in Carrboro now has soil test boxes that you can pick up to get the process started.
How to sample your soil properly:
1. Download and print a routine sample form (AD-1) to accompany your sample box(es): http://www.ncagr.gov/agronomi/forms.htm
2. Use a soil probe, spade, hand garden trowel, or shovel to collect samples. Do not use brass, bronze, or galvanized tools because they will contaminate samples with copper and/or zinc.
3. Choose a day when it is not raining or a time between waterings so that the soil is not too wet.
4. Sample from various parts of an area in a zigzag like fashion and make sure to keep samples from unique areas of your yard, garden or farm separate in their own box with a different sample ID (See Fig.01). The Farm & Sample IDs can be anything you’d like; just keep track of which sample ID matches which area and maintain the same Farm ID for each sample.
5. Remove any vegetation or mulch and dig down or probe through the first two layers of soil, about 4-8 inches (4 for undisturbed areas; 8 for plowed or double dug areas).
5. Mix the unique area zigzag samples in a clean, plastic bucket and put in properly labelled box.
Tips on filling out your form: The form asks for the first crop and second crop for each corresponding box sample. First crop refers to the crop that you are growing presently or most recently including lawn (026) and second crop refers to the crop you wish to grow. Codes are on the second page. If the test is for a general annual vegetable garden use code 024. Be more specific for areas with blueberries and other perennials. For example, blueberries prefer more acidic soils and micro-nutient availability than most food crops while most annual vegetables thrive best in only slightly acidic soils with high macro-nutrient availability.
You’re ready to send in your test! Allow several weeks for processing. Once your soil test is complete, you will receive an email linking to the results. It will also be available online here: http://www.ncagr.gov/agronomi/pals/
For more information, see NCDA&CS Agronomic Services Soil Testing Information or visit us here at Fifth Season. We can help you interpret your results and figure out the amendments that will best serve your soil and fill your dinner plate!