Source: Wilbur-Ellis
“Growers across all crop types have one main goal, and that is to produce the best possible yield in the most cost-efficient way,” said Dan Jones, branded products territory manager, Wilbur-Ellis Agribusiness. “Growers are often leery about using humic acids in their fields because they haven’t seen the desired benefits, but proper application rates can actually provide a big return on investment (ROI).”
Humic acids help improve nutrient availability by tapping into the soil’s nutrient-holding power and are easily added to liquid or dry fertilizer blends. From specialty to row crops, humic acids offer growers’ fields three main benefits:
1) Greater efficiency of phosphate fertilizers. There are several factors that influence the efficiency at which crops use essential nutrients, such as irrigation, nutrient form, soil pH, soil texture, and salinity.
Humic acids make your fertilizer work harder for you, as it allows the fertilizer to be more accessible to the plant for a longer period of time.
“Nutrients such as ammonium, calcium, and potassium are positively charged, and humic acids have the ability to hold, store and exchange those positively charged ions,” said Russell Taylor, certified crop adviser and president of the Humic Products Trade Association (HPTA). “Humic acids also work to mitigate negative interactions between nutrients like calcium and phosphorus, which helps to reduce unwanted nutrient tiebacks.”
2) Improved soil health. Organic acids — including humic acids —enhance soil structure, health and porosity to increase nutrient availability and plant uptake. They also impact beneficial microbes within the rhizosphere and act as a soil sponge for nutrients, air, and water. In fact, humic substances can hold seven times their volume in water, a greater water holding capacity than clay soils.1
3) Enhanced crop quality and increased yields. Jones said that growers tend to see humic acids really pay off at the end of the season. “I worked with a vegetable grower in California who didn’t believe that there was value in humic acids, but agreed to a trial. We started with applying the humic acid through drip irrigation to a field of Brussels sprouts. This not only improved the crop quality — it increased the yield by 19%.”
The 19 percent increase in yield equated to 200 more 25-pound boxes of Brussels sprouts per acre. “The grower was so pleased with the results; he implemented a humic acid program on the majority of the 30 different vegetables he grows.”
What makes selecting a humic acid product tricky?
Taylor said that a big challenge within the humic acid industry is the lack of a standardized test method for humic products — there are currently three different tests used that produce different results.
For example, a product that tests at 6% concentration in California could also be reported as 12% in Kansas. Growers may think that because a product has twice as much humic acid reported on the label and because the price is the same, it’s a better purchase. Unfortunately, this may not be the case when comparing products using different test methods.
Three testing methods, three results
- Colorimetric method: A qualitative measurement of the coloration that is accurate and quick, but easily fooled by non-humic substances. This method is recognized by most states.
- CDFA method: A gravimetric method that is accurate and quantitative for the humic portion of the liquid. Recognized by Arizona, California and Oregon only, this test is usually 50% lower than the colorimetric method on percent humic acid. This method does not correct for ash content which can inflate humic values.
- HPTA-endorsed method: This is the new international standard test for humic acid. It is the most accurate in reporting humic acids from other contaminants but is not yet widely used.
“States are starting to adopt the HPTA-endorsed ISO test for humic acid, but until all states are using one test, growers will need to identify which test was used to measure humic concentration percentages in order to make accurate product comparisons,” said Taylor.
Aside from the challenges with testing differences, some humic acids on the market are not as user-friendly, which has led to negative perceptions among growers.
“Many liquid humic acids have a lot of sediment in them, which makes them difficult to manage. Growers are often hesitant to try a humic acid because they had a previous experience with clogged nozzles or emitters and stained fertilizer tanks,” said Jones. To avoid this issue, he recommends using a
fully-extracted humic acid product that’s compatible with any liquid fertilizer blend.
Pinpointing the ideal application rate for your fields
There are many misconceptions when it comes to humic acid products and application rates, so Taylor and Jones encourage growers to work with a
local agronomic expert or pest control adviser when designing and implementing a humic acid program.
“At a certain point, there will be a diminishing return on humic acid effectiveness, and I like to compare it to eating scoops of ice cream,” said Taylor. “One scoop is good. Two scoops are twice as good. But somewhere along the way, you’re going to eat too much ice cream and get a belly ache.”
Applying too many humic acids to your field is similar to overeating ice cream — you can see excellent yields with 1-5 gallon per acre application rates spread throughout the season. Still, there will be a point where increased application rates don’t result in increased benefits. This threshold will depend on your soil, crop type, and irrigation method.
“Consulting a professional who has experience working with humic acids can help you determine the ideal application rate for your fields, and ultimately maximize your ROI,” concluded Jones.