Grab a Tissue
Matthew Wilde 7/01 8:00 AM
ANKENY, Iowa (DTN) -- As crops race toward maturity, some may need more nutrients to reach the finish line at full stride. Tissue analysis is an effective way to determine if and how much is needed to maximize yield potential.
Bobby Golden, a Mississippi State University (MSU) Extension rice and soil fertility agronomist, covered the do's and don'ts of proper in-season tissue collection and handling on a variety of cash crops during a webinar June 25 hosted by Nutrien.
The company periodically hosts eKonomics webinars to help farmers understand and profit from the latest crop nutrition research and provide advice.
Watch the tissue sampling discussion here: https://nutrien-ekonomics.com/…
Mike Howell, Nutrien senior agronomist, said tissue sampling is one of the best ways for farmers to verify if crops need more nitrogen, phosphorus, zinc or other nutrients at various growth stages, but specific protocols need to be followed.
"If (farmers) are taking tissue samples incorrectly and not handling them right, they're going to get bad data," Howell said. "We won't know exactly what to do. Like anything else, we only get what we put into it (good samples and data)."
Golden said tissue samples are taken to check plant health in-season, similar to yearly wellness checks for people. Multiple nutrient deficits in crops, such as sulfur, potassium and nitrogen in corn, would be difficult to diagnose without a tissue test, he added.
"It can get really muddy to know what you need to apply to correct (multiple) deficiencies because the classical symptomology isn't there," Golden said. "(Tissue sampling) is a good way to spend a small amount of money to save from spending a bigger amount of money applying the wrong nutrient."
Tissue tests generally cost between $10 to $20, depending on the laboratory, Golden said. MSU charges $8 per test, which is a little cheaper than the industry standard since it's a public institution.
Farmers need to be cognizant of crop growth stages when collecting tissue samples and make sure leaves or whole plants that are submitted for analysis are free of soil, pollen or other residue that could lead to erroneous results. "It's the key to getting a good result and saving money," Golden said.
A minimum of 0.5 grams of dry plant tissue is needed to test. In general, it will take 20 to 25 leaves or plants -- depending on the crop and growth stage -- to equal one tissue sample for analysis. Farmers can submit one or multiple tissue samples per field.
Here are Golden's tissue sampling tips at different growth stages:
-- Small plant up to V6: The whole plant is needed. Cut the plant at the soil surface. Remove dead leaves and roots. Gently scrape or wash off dirt with water if needed.
-- V9 or V10: Take the oldest, most mature leaf of the young growth. Start at the whorl and work backward to the most fully expanded leaf that's mature and formed a leaf collar. Pull that leaf. Each part of the leaf has a different nutrient value, so make sure the whole leaf is removed.
-- R1 (silking): Remove the leaf that's opposite and one down from the ear leaf or the ear leaf itself. Again, make sure the whole leaf is taken.
-- Ear formation or brown silk: The procedure is the same as R1, but this is the stage farmers need to be sure pollen residue doesn't contaminate samples.
For nutrient analysis, Golden said green tissue isn't a must, but samples need to be as dry as possible. "It's OK to leave samples on the dash of the truck for a day, as long as it's clean."
-- V5 or younger: Send in the whole plant. Cut the plant at the soil surface. Soybeans are trickier than corn, according to Golden, since soil and dust tend to collect more on the underside of leaves. Carefully clean plants with water and dry before shipping to a diagnostic lab.
-- V6 to R1: Count down from the top to get the uppermost fully matured trifoliate. You don't want to send just the trifoliate leaf. Clip the petioles off and send in the trifoliate to the lab. Only send in clean, healthy tissue.
"If a farmer is doing a plant health checkup, send in random tissue samples throughout a field. If trying to confirm a deficiency, concentrate samples from that bad area, but we also need samples from the good area to compare," said Golden, which goes for all crops.
-- Send in the uppermost, fully expanded vegetative branch located under a reproductive branch. Farmers can either submit samples with or without petioles for analysis. However, find out whether the lab's tissue test is correlated to petioles or leaves to know what to send in.
-- The leaves are usually the youngest photosynthetically active mature leaves, which are the best indicator of current nutrient status.
-- Submit whole plants for analysis up until midseason, when inner nodal elongation and joint expansions starts to occur. This generally occurs after the mid-tillering phase, when plants start to robustly grow.
-- For bigger rice plants after midseason, collect the uppermost three to five leaves as plants near heading.
-- Rice differs from other crops due to smaller leaf size. Forty to 50 plants are likely needed for a sample to analyze.
Here's a few other helpful hints:
-- All plant material needs to be dry and mailed or transported in a paper bag or other breathable material to prevent mold growth, which can destroy samples and cause inaccurate results.
Here's a previous DTN story on this subject: https://www.dtnpf.com/…
-- Mail or deliver samples to diagnostic labs at the beginning of the week to expedite processing. This also avoids samples arriving on a weekend or at the end of the work week, when they could sit and deteriorate.
-- Compare test results with soil tests and yield data, which provide extra layers of information to make in-season nutrient decisions.
-- Labs often interpret samples differently, providing different nutrient recommendations.
"The more data a farmer has, the better apt they are to make a good, economical decision to benefit their bottom line," Golden said. "Taking tissue samples ... will let you hone in on what's limiting your crop's growth potential."
Matthew Wilde can be reached at email@example.com
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