Soil Sampling for Success

By , On , In Best Practices

If you were following a recipe and baking something, would you throw in random additional ingredients? It’s highly unlikely that it would work out. Recipes are often rigid and precise for a reason, and following the instructions accurately should provide the intended result.

Soil sampling is like baking in a way. If a recipe doesn’t work out, you need to analyze the ingredients to understand why. Once you understand why, a judgment call can be made regarding what is missing and needed.  In the same way, you need to understand the components, deficiencies and condition of your soil to understand what nutrients are missing. The proper use of nutrients is one of the most important inputs of a successful crop.

Fertilizer requirements can be determined in a number of different ways. These different methods have advantages and limitations so it is encouraged that all of them be used on a regular basis. Examples of these methods are highlighted below:

  • Visual observations: nutrient deficiency, toxicity symptoms and the length of the one-year-old shoots as a vigor assessment. This helps to determine nitrogen application rate
  • Using soil tests
  • Using tissue analysis

Soil and petiole analyses are good for providing important information for determining fertilizer requirements for bearing and non-bearing vineyards and orchards. These complement each other, so using both methods is best. It is common for nutrient deficiency or toxicity in the soil to minimize the availability of other nutrients and using the petiole/tissue analysis gives you a more accurate idea of what nutrients the plant is actually getting.

soil sampling is best done in the spring or fall, but it is best to ensure they are taken at the same time each year, for year-to-year comparisons.

Sampling Strategies

These need to align with your overall goals and objectives. For example, if your goal is to perform a routine sampling or solve a specific problem, it is beneficial to take samples from both healthy and unhealthy areas so that you can compare the two. You should also take a soil sample before planting to determine the soil fertility. It gives you a chance to perform any needed amendments as cultivation is difficult once the land has been planted.

When and How to Sample

Soil samples are best taken in the fall or spring but it is important to ensure that they are taken at the same time each year, for easy year-to-year comparison. Sampling in the fall will help with planning a fertilizer program for the spring growing season. Sample every field at least once every 3 to 5 years (sample more frequently if something changes significantly with your soil or farm). Sample from the same spots every time, so that you can monitor your fertilizer program. Draw a map of the sampling areas and flag or mark the spot with a steel or wood peg, so you can easily find the area from where you sampled.

When taking your samples, look for different soil characteristics in your block and monitor the texture changes. Differences in elevation should be observed, as higher and lower elevation can have different soil types.  If, for example, the top of the soil is a rocky texture and the bottom of the soil is a loose texture, you should consider sampling the different areas separately. Also note if the consistency is the same throughout the layers, and sample in a random or zig zag pattern. Fetch between 10-20 samples, then combine the samples in a clean plastic pail. Take 2 cups of sample and place it in a paper bag, this gives you one sample to work with. Different soil types should be treated as different samples too.

Sampling Tools and How Much to Sample

There are many different tools that can be used to perform a soil sample. Examples of the most commonly used tools include a soil sampling probe, soil auger or a shovel. If the soil is too rocky, you might have to rely on the good old shovel. When using a shovel, clear away the surface matter and dig a U-shaped hole in the soil that is about 12 inches deep. Take a slice off the edge of the hole, about 1 inch thick. Collect sub-samples in a clean plastic bucket and make sure to mix thoroughly. Remove any rocks or root and turf debris.

The recommended amount is between 10 and 20 subsamples per sample. 10 to 15 can be used if you are sampling everywhere and 15 to 20 can be used if you sampling on the band where you applied your fertilizer. Place about 2 cups in a paper bag or Ziplock bag. Remember to label the bag with the block identifier, date and name.

Soil sampling and analysis can be tricky and time consuming, yet it is a vital aspect of your overall soil and crop health and should not be overlooked. Understanding your soil and analyzing what does and does not work and the proper use of nutrients is one of the most important inputs of a successful crop.

The good news is that Growers Supply Co. is here to help. Reach out to a Growers Supply Co. expert for more tailored advice or to get started with your samples. You’re always welcome to visit a Growers Supply Co. Store to chat to an expert or to stock up on those much-needed soil sampling tools and products.