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Agronomy Bulletin 109 ─ Grid Sampling

Take 10 random samples per grid cell when grid sampling.

Situation

An accurate soil map is important when efficiently managing fields and soil fertility levels. Grid sampling is an effective soil sampling method to use when fields have a high number of soil types or textures, and when previous cropping and management practices have changed or are unknown.

Factors to Consider

  • Time of last soil sampling
  • Cost
  • Number of soil types per field
  • Previous management strategy
  • Cropping history

Action Plan

  1. TAKE INTO ACCOUNT TIMING AND COST. Soil maps should be updated every four to six years and at the same time of year to properly compare new and old maps. Although grid sampling can be a costly soil sampling practice, it does provide a detailed analysis of which and what levels of fertility inputs should be applied to fields, especially when previous management and cropping histories are unknown or ineffective.
  2. CREATE GRID. Divide the field into separate grid cells to sample individually. An average cell size is 21/2 acres. Smaller grid cells result in more samples and, therefore, a more accurate soil map.
  3. COLLECT SAMPLES. Treat each grid cell as its own field, taking up to 10 random samples per cell, to avoid systematic patterns such as starter or replant bands. Take each sample from a depth of approximately 8 inches to collect both mobile and nonmobile nutrients.
  4. SUBMIT SAMPLES. Soil samples can be taken to your county’s Extension office or other reputable private labs for testing and analysis. Samples can be submitted throughout most of the year, but fall sampling typically produces faster results.
  5. CONSIDER MANAGEMENT PLAN. Based on the results of your soil sampling, an updated soil map of your fields can help you create a management plan with the right inputs for maximizing yields.

Summary

Soil sampling is essential in determining which nutrients, and at what levels, are available in fields. Grid sampling is a good option for fields containing a variety of soil types, or when previous management and cropping methods are ineffective or unknown. After sampling, create a soil map and management plan for more productive fields and higher yields. Contact your local Mycogen Seeds customer agronomist or trusted agronomic adviser for more information on grid sampling or when considering a change in managing fields.

Published on Tuesday, October 29, 2013