See What’s in the Trees

NovaCrop sap analysis provides an in-depth look at an orchard’s nutritional status, allowing growers to make accurate decisions in real time.

Growers employ a variety of tools to evaluate their crops’ nutritional status at key times during the growing season. Soil testing, leaf tissue tests, and pre-harvest fruit analysis all provide insight into nutrient levels. However, these tests only tell what nutrients present, not what nutrients are available – an important difference. Leaf tissue testing provides results that include levels of all nutrients in the sample, including those contained in the cell walls, leaf surfaces, petioles, and other leaf structures, most of which are not immediately available for use by the plant.

An alternative to leaf tissue testing is NovaCrop Leaf Sap Analysis, which evaluates only the sap moving through the plant. Think blood test versus tissue biopsy. Both are useful, but only one provides real-time analysis of what is circulating within and available to the body at the time the test is taken.

“Sap analysis shows the levels of 19 nutrients and five other nutrient and metabolic indicators,” says Sean Jacobs, Senior Sales Agronomist at Agro-K. “Young and old leaf samples are collected and processed separately, allowing for the comparison of not only nutrient levels in those plant parts, but also compare nutrient uptake, mobility, and remobilization among the old and new leaves. This comparison is also valuable for assessing nitrogen metabolism and the movement of sugars in the plant, which are the plant’s building blocks and energy source.”

The balance between nutrients in the sap is just as important as individual nutrient concentration levels, Jacobs says.

“Knowing and adjusting the nutrient balance may spell the difference between a mediocre crop and a stellar one,” he says. “It’s crucial to nutrient performance and the prevention of fruit nutrient disorders, which can affect yield, crop quality and shelf life. Nut size, protein levels, weight, and disease susceptibility can also be positively impacted by proper nutrition.”

The ability to see—in real-time—the levels of available nutrients flowing through the sap is advantageous, because plants need specific nutrients at specific times of development. Often, the window of opportunity is just one or two weeks. For nut crops, the first key timing for testing with NovaCrop sap analysis is when early leaves are fully developed, and new younger leaves are nearly full sized. For almonds, this is usually the end of March or early April. A test at this timing provides an early check on nutrient management practices in the orchard while time still remains to influence nutrients like calcium. While too much calcium can negatively impact, among others, potassium and phosphorus uptake and activity, too little calcium early on is detrimental to cell division, undercutting yield potential, Jacobs says, adding that leaves and nuts need to have around 80% of the total amount of calcium expected at maturity when these plant parts are only 30% of their final size.

A key timing for a second test is in late May. It’s especially important to analyze nitrogen levels at this point, Jacobs says. Excessive nitrogen in the plant is a leading contributor of favorable hull rot conditions. Elevated nitrogen levels also delay ripening, making nut shake more difficult. Failing to supply enough calcium early on is also a factor in disease susceptibility and nut shake efficiency.

“Sometimes farmers like to put on a little extra nitrogen as an insurance policy,” Jacobs says. “But, besides the additional cost, too much nitrogen makes leaves especially appetizing for mites and serious infestation and/or expensive control measures will result.”

Understanding Interactions Can Save Money

Getting a thorough look at nutritional levels prior to periods of anticipated demand allows farmers to make real-time, proactive decisions on what to apply and when. Jacobs emphasizes that the nutritional balance is just as critical as the nutritional content, as elements can have positive or negative impacts on the uptake or activity of other nutrients. An additional fertilizer application that isn’t necessary is not only a waste of money but can also lead to deficiency or toxicity of other nutrients due to these electrochemical and physiological interactions.

Often, when a particular nutrient is at a low level, the response is to add more, Jacobs says. However, the low level might simply be caused by an overapplication of another nutrient leading to antagonism.

“For instance, if your test shows you have a calcium deficiency, you actually may have enough calcium, but too much phosphorus (P),” Jacobs says. “You could possibly just cut back on how much phosphorus you’re applying, and that reduction could rebalance competing nutrients and solve your calcium problem. Many of these nutrients are rather costly, so assessing, identifying, and addressing available nutrient imbalances will likely lead improved fertilizer use efficiencies and plant productivity while actually applying less fertilizer instead of battling antagonisms.

These types of interactions occur primarily between currently available nutrients within the plant or within the soil. Elements that are chemically or structurally bound will show up in a tissue or soil test but are not having much of an interactive impact. This is where NovaCrop Sap Analysis really shines, Jacobs says.

“With a NovaCrop sap analysis report, growers can determine not just if nutrient deficiencies exist, but also the future potential for deficiencies,” he says. “They can evaluate the balance of nutrients and better understand how excessive or deficient levels of one or more elements can affect the uptake or activity of others. Fertility management plan modifications, when based on NovaCrop sap analysis and coupled with soil analysis, improve fertilizer-use efficiencies and decrease over-application of nutrients.”