Planting is underway (or soon will be) throughout much of the Great Lakes regions. Early season field scouting is essential to ensure good emergence, detect potential weed and insect pressure, and monitor the effectiveness of your fertility program. The earlier an issue is detected, the better chance there is to correct the issue. One tool to help detect potential fertility problems is plant tissue analysis. However, to get useful results back from the lab, the proper plant part must be collected for the current growth stage of the crop.
The proper method for collecting early season corn tissue samples is to collect 15 or more whole plants to comprise a single sample. This is only referring to the above ground portion of the plant. This method is appropriate for corn up to 12 inches tall, or approximately V4 to V5. However, corn can be sampled too early to provide useful data for making decisions. During the first three weeks after emergence, much of the nutrient content of the young plant is not coming from the soil, but from the embryotic tissues within the seed. The young plants also have a very small seminal root system during the first few weeks which are not able to access the nutrients in a large volume of soil; the main role of this root system is to get water to the seed and new leaf tissues. Nutrient deficiencies during the first few weeks are likely caused by environmental conditions and do not necessary reflect low nutrient levels in the soil. An example of this situation is young corn plants turning purple. Purpling of young corn plants can be a symptom of a phosphorus deficiency, but can also occur on soils with adequate phosphorus levels when nighttime temperatures are low. Cool spring nights slow metabolic processes in the plant resulting in the buildup of anthocyanins, which appear purple. Tissue sampling in corn should be delayed until 3 to 4 weeks after emergence, or until the plants have developed a functional nodal root system in order to ensure that the tissue analysis is representative of the nutrients that are available to the plant.
Image 1: V4 corn plant showing purpling. Source: purdue.edu
Similar to corn, soybeans can also be sampled too early. Proper tissue sampling for all growth stages for soybeans is collecting 25 or more of the most recently mature trifoliates without petioles. The first leaves to appear on a recently emerged soybean plant are unifoliates, or cotyledons. The nutrient content of the cotyledons, sometimes referred to as seed leaves, does not accurately represent the nutrients available in the soil. Tissue sampling in soybeans should be delayed until the V2 growth stage. The V2 growth stage is reached when the second trifoliate has completely unrolled. It will generally take a minimum of 3 to 4 weeks after emergence to reach this stage. At this point, the first trifoliate is considered mature, and can be collected for tissue analysis.
Image 2: V2 soybean plant. Source: clemson.edu
Spring tissue sampling of winter wheat can be a very useful management tool. The timing of wheat sampling does not correspond to a specific growth stage though. The important factor when determining the appropriate time to sample wheat is that the wheat has broken dormancy and is actively growing again. Generally, wheat will be at a growth stage of Feekes 3 or 4 when this occurs. The appropriate method for collecting wheat samples at this stage is to collect 25 or more whole plants from ½ inch above the soil surface. One of the benefits of early season wheat sampling is to fine tuning a “green-up” nitrogen applications based on the nitrogen content of the plant at Feekes 5 (please visit the Purdue Extension News Release for more information).
Image 3: Feekes 5 wheat. Source: Kansas State University
Accurate plant tissue testing begins with proper sample collection and handling. Make sure to collect the proper plant part for the current growth stage of the crop, and collect the proper number to make the sample. This information can be found on the plant analysis page at algreatlakes.com. Always avoid soil contamination in your plant samples. Package samples in paper bags. If shipping is delayed, store samples in a cool location, but do not freeze. Never include roots with a plant sample. If you have any questions on proper plant tissue sampling, please contact the lab for assistance.
A&L Great Lakes Laboratories, Inc. receives many calls relating to compost quality. Frequently the question is somehow related to: “How can I tell if my compost report numbers are good or not?” The answer can vary depending on what the client is using the compost for and if there is an EPA, state, county, or municipal requirement that must be met. Sometimes the compost is mixed in with soil or other material to make a blend which is governed by private engineering or governmental regulations, such as DOT (Department of Transportation) specifications. All of this can lead to confusion, especially to the end consumer. The US Composting Council has provided some very useful guides outlining the “preferred” and “acceptable” ranges of compost for different consumer uses. Below is an example guide for use in a Flower and Vegetable Garden:
While these guidelines provide excellent direction for evaluating compost quality, government and engineering specifications do not always align exactly with the US Composting Council’s ranges. The laboratory has analyzed composts that are perfectly good and viable (as a growing medium), and within all the USCC’s recommended ranges, but failed to meet a specific engineering specification. This can be very frustrating for the compost producer. In one particular instance, the lab tested compost that met all the human safety requirements (Bacteria and EPA 503 Heavy Metals), plants grew well in it, and it was mature. In addition, the nutrient content, pH and soluble salt levels were spot on. However, it still failed to meet a specification because the organic matter was 20%, which was considered too low. In this example, the engineer was creating a blend that required a minimum organic matter content and, if using the planned blending recipe, the final blend would not have met their specifications. Rather than invalidate this compost, an alternative was to change the blending recipe by increasing the amount of the compost used to achieve a blend that would have met the specs. Another alternative would have been to evaluate the specifications of the final blend to determine if the specified minimum organic matter content was actually necessary to meet the needs for this situation.
A number of different compost parameters can be analyzed, but some parameters are more important in different situations than others. For example, nutrients, fecal coliform and heavy metals may be important for composts that contain animal manures or biosolids and that might be land applied, while sieve size, odor presence, organic matter content and weed seed viability may be important to landscapers. Also, where quantifying the concentration of man-made materials such as glass, plastic, and metal, may be appropriate for yard trimmings compost, it may not be appropriate for biosolids or food by-product compost.
A PDF document entitled “Compost Characteristics and Their Importance,” as well as a basic A&L Great Lakes Laboratories Compost “FACT SHEET” are available to help you understand compost data better. If you are interested in receiving either of these publications, or would like to discuss your particular compost or composting project, please contact Greg Neyman email@example.com.
The staff at A&L Great Lakes works together as a team to support local and regional charities and programs as part of the ongoing commitment of the Benevolence Committee to support worthy causes. In addition to the work of the Benevolence Committee, many of the staff members reach out on their own to support worthy causes.View full article →
The 2015 Soil Test Data Summaries for the Great Lakes region are now available on our website at www.algreatlakes.com/pages/2015-soil-test-summaries. The summaries are compiled for the Great Lakes region as a whole, as well as broken down by state and into geographic quadrants within each state.View full article →
Today at the Great Lakes Expo, A&L Great Lakes Laboratories, an elite provider of agricultural testing and analysis services throughout the Midwest, unveiled its new brand. The firm distilled its essence through a comprehensive brand-discovery process that led A&L Great Lakes Laboratories to recognize that the scientific and agronomic depth at the heart of its business benefits customers more because the company delivers its services with a human touch.View full article →
How many times in our lives have we faced a situation that generated both happy and sad emotions at the same time? We’re facing that right now at A&L Great Lakes Laboratories. Lois Parker has officially retired, effective at the end of September and for those of us who have worked with her for so many years, this is indeed a sad time. She will be greatly missed.Read More (PDF)
UAN (urea-ammonium-nitrate) solutions are routinely applied in the late spring and early summer to deliver nitrogen (N) to young crops. Because UAN is a nonpressurized solution, it can be used without the hazards associated with anhydrous ammonia and can be spread more uniformly than granular fertilizer. Certain pesticides may also be added, eliminating an extra pass through the field.Read More (PDF)
Nitrogen (N) is one of the most critical elements in all living organisms, and is often one of the most limiting nutrients in crop production. In addition, N is perhaps the most dynamic nutrient in the soil, and a number of factors can influence the amount, form and plant availability of N.Read More (PDF)
Phosphorus (P) is a key nutrient for crop production, and keeping adequate levels of P in the soil is important for maximizing plant growth and development. However, understanding the various analytical methods for determining soil phosphorus can be challenging.Read More (PDF)