Postharvest Fertility – Trees and Vines

By Dylan Rogers, Sales Account ManagerDylan Rogers, Sales Account Manager for Southern California

With almond and grape harvest underway here in California, it is easy to fall into the mindset that the finish line for yet another growing season is near. Unfortunately, that is not the case. In fact, the most important part of the growing season is still upon us. Postharvest irrigation and fertility can be the most crucial aspect of growing trees and vines. Growers, PCAs, and CCAs are always striving to increase yields and quality. Having a solid postharvest game plan plays a critical role in ensuring better yields and quality for next season’s crop.

After the stress of harvest, nitrogen, phosphorous, and potassium will begin to transition from leaves to spurs in almonds, and from leaves to roots and woody tissues in vines. In almonds, bud initiation and differentiation has already begun, so the fate of the 2020 crop is already underway. Water stress at this point in time will significantly reduce next year’s crop. Postharvest irrigation is also very important to ensure that the leaves stay active for as long as possible so they can continue photosynthesizing and storing much needed carbohydrates for next year’s crop. When dormancy breaks in early spring, trees and vines will be functioning solely on stored nutrients. Nutrient uptake from the soil is very minimal at this point due to cool soil temperatures as well as the lack of leaves. Adequate postharvest fertility to replenish nutrient reserves will ensure that your crop has the energy it needs to maximize production when dormancy breaks come spring.

Nitrogen (N)

Up to 20% of the total seasonal demand for nitrogen in almonds can be applied postharvest. This is also very similar for grapes. Postharvest nitrogen will help maintain leaf area and extend the time for photosynthesis to keep producing carbohydrates in the trees and vines. Postharvest N will also ensure that reserves are replenished and early shoot growth and leaf out will be strong in the spring. It is important to take in-season tissue samples into consideration when determining how much nitrogen to apply. Any soil-applied nitrogen in the nitrate form that is not taken up by the roots will be subject to leaching from rainfall and irrigations. Foliar-applied nitrogen is also a good choice for postharvest applications. It is common to use a fast acting nitrogen source in this situation, such as urea-based products.

Almonds ready for harvestPhosphorous (P)

The amount of phosphorous used by trees and vines is much less compared to the demand for nitrogen and potassium. However, this does not mean it is less important for optimal growth and yields. A postharvest application of phosphorous will promote healthy fall and spring root flushes, as well as ensure the trees and vines have a good energy source when dormancy breaks in the spring. Choosing a phosphorous fertilizer that is protected from tie up from cations in the soil is important and will ensure that it is free and available for the plant to uptake as needed.

Potassium (K)

Potassium demand in almonds and grapes is even higher than that of nitrogen. A postharvest application of potassium is essential in order to restore reserves, even more so if your yields were above average this season. Potassium is an important aspect in plant water relations and cell reproduction. If potassium reserves are deficient when dormancy breaks in the spring, new fruiting spurs will develop at a slower pace or even die prematurely as compared to a tree that has optimal potassium reserves. Root uptake is minimal at this point, so a soil application of potassium will serve to replenish K reserves in the soil. A postharvest foliar application of potassium is a great way to ensure you get the potassium into the trees and vines to replenish those reserves. Choosing a K product that is free of chlorides and hydroxides, as well as effective at penetrating the leaf cuticle and easily translocated once in the leaf will provide the greatest return on your fertilizer investment.

Zinc (Zn)

Zinc is a very important micronutrient that plays a major role in synthesizing auxins. These auxins ensure a uniform bud break and a good fruit set in the spring. Almonds are commonly zinc deficient. This is due to a number of reasons, including certain rootstocks that are not adequate at taking up zinc from the soil. Zinc deficiencies are also common in areas with alkaline soils. Zinc is fairly immobile in the soil so postharvest foliar applications are most effective at correcting deficiencies and restoring reserves.

Boron (B)

Collecting hull samples to send off for boron analysis should be a staple in your postharvest game plan. Hull samples are the most effective indicator of boron levels in almonds. Boron is very critical for development of flowers, specifically pollen development and viability. If the hull analysis shows less than 80 parts per million boron, the trees are deficient and are most likely losing yield potential. Postharvest foliar applications of boron are an effective way to correct deficiencies and restore boron levels in the tree.

As you complete this year’s harvest, let your mind shift gears and begin thinking about next year’s crop. Its fate is already underway and having a solid postharvest irrigation and fertility game plan will ensure your trees and vines go into dormancy with adequate nutrient reserves. With a good postharvest fertility program, your crop will be off to a great start come spring and you’ll be well on your way to improving yields and quality year after year.

Find a crop nutrition expert in your area to discuss your program.

California permanent crops

The Benefits of Soybean Foliar Fertilizer Application

John Leif, Field Agronomy Manager

The debate of the benefits of foliar fertilizer applications on soybeans has been ongoing for more than 20 years. Some of the benefits to foliar fertilizer applications include quick reaction to deficiency symptoms or low tissue analysis. Foliar feeding enables a bypass of soil issues [such as cold, infertile soil; nutrient fixation, drought; sodium, etc.] or insufficient root growth, which would cause soil-applied fertilizer to not be as readily absorbed. Foliar fertilizer has a relatively low cost, especially if nutrition is added to a foliar crop protection, such as fungicide, plant growth regulators, or herbicide application. It is also possible to target mid-season growth stages with specific nutrients.

Things To Consider

There are several things to consider when planning a foliar fertilizer program in soybeans. Nutrients must be taken in to the plant before the plant can utilize them, whether applied through the soil or as a foliar spray. When applied as a foliar spray, a nutrient must penetrate the leaf surface and be taken in to the leaf. Soybean leaves, as well as leaves of most plants, have a waxy layer at the surface known as the cuticle. The cuticle is present on the upper and lower sides of the leaf, but cuticle thickness is usually less on the underside of the leaf. The cuticle and related structures help protect the plant from extremes in temperature, humidity, and pest damage.

Leaves also have stomata, which regulate the exchange of carbon dioxide and water transpiration in the plant. Most of the stomata on soybean leaves are located on the lower side of the leaf. The absorption of nutrient solutions by the leaf surface may occur via the cuticle, cuticular cracks and imperfections, and the stomata.

The soybean plant is affected by a number of environmental conditions, and that can influence the effectiveness of the fertilizer application. Temperature and relative humidity have the most influence of any environmental conditions. Excessive heat and cold causes stomatal openings to close and restrict nutrient and water movement. Also, plant metabolism slows in these conditions, potentially limiting the ability of the plant to absorb and utilize nutrients. Therefore, it is important to apply foliar nutrition during optimal temperature ranges when plant photosynthesis and respiration are not inhibited. Ideal temperature range for corn and soybeans is 70-85° F.

High humidity delays the drying of spray droplets from application, giving the plant a longer time for optimal absorption. Stomata remain open for longer periods in higher humidity conditions. In dry, lower humidity regions, plants develop thicker waxy cuticles, which limit nutrient uptake through the leaf. Drought stress also can reduce the effectiveness of foliar fertilizer applications.

Application timing is a critical to the potential success of a foliar nutrient treatment.  It is important to match the nutrient application to the growth stage of the plant. For example, boron is an important nutrient for flowering and pod establishment in soybeans. A foliar application of boron should be applied no later than early flowering stages (R1 – R3) in order for the plant to benefit from that application. Nutrients such as potassium and manganese, however, are utilized by soybeans at many growth stages so the plant can benefit from a foliar treatment of those nutrients across a wider application window.

Minimize Yield Loss

Ideally, foliar nutrition should be a component of a complete crop nutrition program. However, foliar nutrition can be used to address nutrient deficiencies that are observed in the field. Early, accurate identification and treatment of nutrient deficiencies with foliar fertilizers will minimize the yield loss in that crop. It is generally understood that yield losses are possible when deficiency symptoms are visible and those losses cannot be reversed by foliar fertilizer, but the remaining yield potential can be protected with a foliar treatment.

Application techniques can also influence the success of a foliar fertilizer treatment. Complete coverage of the leaf area maximizes the stomata exposed to the nutrients for uptake. Small droplet sizes applied at high pressure allow the product to reach all plant surfaces. In some cases, surfactants can be used to improve droplet coverage as well.

Plant nutrients can be applied in combination with crop protection products. This saves on application costs and potential mechanical damage from driving through a field. It is important to read and follow the label(s) of all pesticides used in tank mix combination with crop nutrients.

Fertilizer product quality plays an important role in the effectiveness of a foliar nutrient application. Some fertilizer products are very effective as soil applied products but are not effective as foliar sprays. Certain nutrients, especially nitrogen and sulfur, can cause leaf burn and other crop damage if a product not designed for foliar application is used. It is also important to make sure water-soluble granular fertilizers are well mixed in the spray tank to provide adequate nutrition and avoid filter or nozzle plugging.

Minimize Risk

AgroLiquid’s Flavonol Polymer Technology™ makes many of our products effective when applied as foliar sprays. This technology utilizes naturally derived sources that are quickly broken down by plants and used as metabolites in foliar applications, making the nutrients available for the plant to uptake. Many AgroLiquid fertilizer products have been designed to be safe for foliar applications in soybeans, minimizing the risk of crop injury and improving the availability of those nutrients in the plant.

With higher yield goals, foliar feeding may provide optimal results. Timely applications of nutrients can help rectify some nutrient deficiencies, but more important, foliar applications can provide necessary nutrients at times of high demand for plants.

Using Almond Tree Fertilizer to Restore Potassium

almond tree fertilizer to prevent potassium deficiency

For every 1,000 pounds of almond kernels harvested, around 80 pounds of potassium (as K2O5) leaves the soil. This places enormous nutrient demands on the soil, year after year. Without additional nutrients, potassium deficiency can quickly affect yield and the health of the almond grove. However, many almond tree potassium fertilizer products also damage the health of the soil by leaving residual salts and chlorides while tying up nutrients. It is possible to restore potassium in the soil and even correct potassium deficiencies throughout the year using an agile almond tree fertilizer that is easy to apply.

Almond Tree Fertilizer Restoring Potassium Without Soil Damage

How Much Potassium is Available to My Almond Trees?

almond treeAlthough most soils contain large amounts of potassium, relatively small amounts of it are in a form plants can use. Consequently, growers should base management decisions on how much potassium is available when the plants need it, rather than on how much potassium is available in the soil.

Each almond orchard is a unique environment, and different soil types hold varying amounts of potassium and release it differently. This can make it tricky to manage K effectively.

“Growers who want to maximize yields need to stay on top of their K applications,” says David Doll, University of California Cooperative Extension nut pomology farm advisor for Merced County. “Otherwise, deficiencies will reduce return bloom and decrease spur longevity, which affects yields over time.”

Potassium uptake in almonds is linear, with as much as 70 to 80% of total uptake complete by mid-June. This means continuous potassium supplements will support the almond tree’s growth throughout the growing season, stimulating the growth of fruiting wood, more buds, and improved harvests. Different soil types present different challenges for maintaining potassium levels. Sandy soils and sandy loams cannot retain potassium as well as others, and require smaller, more frequent almond tree fertilizer applications. Heavier soils like clay hold on to nutrients longer, and don’t need as many applications.

Do My Almond Trees Have a Potassium Deficiency?

potassium deficiency in almonds
Leaf curling, scorching and discoloration at the margins is a sign of potassium deficiency in almonds.

Deficiencies develop gradually over time and visual symptoms can take years before they show up. Plants lacking in potassium often show delayed or stunted growth. Other deficiency signs include inward curling of leaves, discolored leaf tips and marginal scorching. When severe, potassium deficiencies can increase the loss of fruiting wood, which results in reduced crop loads.

Continued monitoring and fertilization in the orchard helps growers build and maintain K at levels where deficiencies are less of a concern. Regular soil testing can help almond growers identify nutrient trends over time. Additionally, annual leaf samples help growers keep track of K levels.

“Mid-July leaf samples work well because tissue levels are relatively stable at that time of year,” says Doll. “Take two to three leaves from five non-fruiting spurs for at least 15 to 20 trees across the block. Trees should be 100 feet apart. To maintain sufficient levels across the orchard, UC Davis recommends shooting for a target potassium level of 1.6 to 1.8 percent.

Flexible Application Methods for Almond Tree Fertilizers

irrigation system watering treesMaintaining optimal potassium levels for almonds requires almond tree fertilizer treatments at harvest and throughout the year. Almond tree fertilizers with multiple application options give growers the flexibility to accomplish this.

AgroLiquid fertilizers can be applied in many different ways. They can even be used in combination with each other or with other crop protection products, so they can be quickly and easily applied.

With the ability to mix our almond tree fertilizer with other crop protection products, you reduce the time and energy needed to feed your trees. This way, you can grow more almonds with larger size and higher quality, without adding extra tasks.

Almond Tree Fertilizer Products to Maintain Potassium and Soil Health

AgroLiquid has formulated high-efficiency liquid fertilizer for almonds to sustain the almond tree’s linear use of potassium throughout the season. Unlike other almond tree fertilizers, ours is chloride- and hydroxide-free, so it supports soil health, long-term sustainability, and won’t upset the soil’s salt index.

sure-KSure-K is a chloride- and hydroxide-free potassium fertilizer ideal for supporting orchards with high potassium requirements, like almonds. With a neutral pH, Sure-K helps to protect the health and longevity of the soil, while supplying essential potassium. It can be applied as a topdress, sidedress, foliar, or through fertigation, and it can be used with many crop protection products.

kalibrateKalibrate is similar to Sure-K, but supplies sulfur in addition to potassium. Similar to Sure-K, Kalibrate is chloride- and hydroxide-free, and it can be applied in a variety of ways. Kalibrate is ideal as an early-season potassium fertilizer to stimulate strong initial growth and production.


PRG logoPrG provides a full array of macronutrients, including nitrogen, phosphorus and potassium, as well as iron. PrG is ideal for trees that have not yet reached maturity. PrG is also ideal for stimulating growth and speeding up reproduction at the start of the season.


Let Us Design an Almond Tree Fertilizer Plan for You

The ideal AgroLiquid almond fertilizer plan is dependent on your location, climate, soil conditions, and goals with your crop. All of our fertilizer programs begin with a review of your soil samples and consultation with one of our expert agronomists. After our analysis, our team will provide you with a couple options that will help you meet your goals on a budget that won’t break the bank. Talk to an agronomist to get started.

Kentucky Corn Looking Great with AgroLiquid

So last week, Senior Sales Manager Galynn, SAM Rob and I went down to Hopkinsville, KY to visit the Security Seed & Chemical Research Farm.  It is a large facility where fertilizer plots are established each year to test different program, both old and new.  Fertilizer Agronomist Lang French met us at the plots to show us around.  AgroLiquid has been a standard program there for quite a few years now.  But that is challenged each year.  They do have really good looking corn down there.

inspecting corn

 The corn is in the silking stage now.  Here is a plot that received a preplant application of dry fertilizer (9-23-30).

corn in silking stage

 And right next to it is a plot that instead received a planter application of Pro-Germinator + Micro 500.  Notice that the silks are turning brown indicating that it is farther along in maturity.

corn silk turning brown

Lang said that they often see tassel emergence at least seven days earlier with AgroLiquid compared to dry treatments.  One of the many features explaining the high performance of AgroLiquid.  Go to their upcoming field day if you are in the neighborhood.

And if you want to see a video discussion of these plots (and who doesn’t?) go to @DrJerryCropDoc on Facebook.

Fast-Growing Corn (LAND OF LIQUID Blog)

So how fast does corn grow anyway?  I recently read an article in a Pioneer update that told about spraying a stalk with paint and then checking it the next day.  I shared this my friend Chris Cook who farms in SE Wyoming and thought it would be a good project for his young boys Brady and Matt.

how fast does corn grow?

And it was!  I got this pic right back from them showing the amount of growth overnight.  Pretty phenomenal.  Of course this corn had the advantage of using AgroLiquid.  But I’m pretty sure corn with other fertilizer would grow at least some in the same test.  Maybe.

Getting a Wheat Crop to Harvest Isn’t Easy (LAND OF LIQUID Blog)

So one more post from the Palouse in SE Washington.  We have a field trial with a grower and Eric and I walked it last Wednesday.  This is soft white winter wheat and it is looking good.

winter wheat field

 The heads are filling grain now, and grain protein is being made now too.  Yield and protein determine payment to the grower.  Outside of weather, one thing that can affect yield is insects like aphids.

winter wheat heads

 And here they are.  I believe these are Russian Wheat aphids.  (Someone will tell me if they are not.) I just happened to get this picture that is interesting.  I believe that larger brown one is what is referred to as a mummy, having been stung by a parasitic wasp that laid eggs inside.  The insect world isn’t pretty.  These aphids are sucking leaf juices and can cause the leaf to turn yellow.  And this is the flag leaf, the energy leaf of the plant.

wheat aphids with mummy

So there is a threshold.  It is an average of 20 aphids per plant at this stage.  This according to his crop scout.  So this field wasn’t there.  (I read where other experts say as many as 50 is threshold before damage exceeds cost of control.)  But the grower was nervous about not spraying.  Then there is the cost of the product (Dimethoate) and a plane.  A good yield is on the line, but wheat prices aren’t the best.  The field was pretty slick with aphid juice.  Too bad the wasps didn’t do more.  Not sure what he ended up doing.  No one said farming is easy.  And if they did, they are wrong.

Feeding Hungry Almonds in California (LAND OF LIQUID Blog)

So are you ready for some more almond updates?  Let me answer “Heck Yes” for you.  So I was back in CA last week and here is how the trees look now.  The blossoms are all gone.

almond trees no blossoms

The bees did their job as we see  loads of almonds growing now where there were flowers before.  And we did not see any obvious frost damage which was a big concern on an earlier visit.

almonds on trees

 Remember when Dylan held a small almond blossom pistil in his hand a few weeks ago?  Well now he’s holding the developing almond nut.  That almond is going to need some added nutrition to make it to harvest in the fall.  And that is where AgroLiquid comes in.

unripe almond

 Almond watchers SAM’s Dylan and Armando, plus Chemist Chris discuss all things almonds with the ranch manager and researcher.  Now AgroLiquid fertilizers are used in a number of commercial operations, but we wanted to design an experiment to prove the value of AgroLiquid’s different nutrient options.  Well that is the objective anyway.  I’m confident.  It’s time for some plot fertilizer application.

almond grove

This tractor is applying liquid fertilizer treatments to a plot of almond trees.  Several replicated treatments are applied in this long row of trees.

fertilizing almonds

Fertilizers are normally applied in the irrigation water, through that small sprinkler there coming out of the black water line.  To simulate fertilizer application, the fertilizer treatments are sprayed on the ground with the nozzles.  The nozzles are positioned to apply over the irrigated area.  To be realistic, the nozzles ran some earlier to wet the ground.  Then the sprayer applies the fertilizers in a high application volume of 200 gallons per acre.  This is to evenly spread the fertilizers over the zone.  Then after application,  the water is turned on again to thoroughly incorporate the treatments.  I’m convinced that this is as realistic as you can get for treatment application.  It was a beautiful day, warm and sunny.  And no wind.

almond fertilizer application

It helps that AgroLiquid fertilizers are all compatible with each other and can easily be applied all at once instead of in separate applications as is necessary with some fertilizers.  The researcher was impressed with AgroLiquid’s product compatibility.  There are a number of applications left, but that should hold them for now.  It takes well planned applications of a complete nutrient package to get best response.  So we will be following progress, and I plan to re-visit the test to keep you all posted.  There were some other interesting sights seen during the week, so stay tuned.

Increase Alfalfa Tonnage and Digestibility

Daniel Peterson, CCA, SSp

Field Agronomy Manager

As the order for the potash, phosphate, sulfur, and micronutrients is submitted, what are the reasons, or goals, for applying that fertilizer? Why fertilize alfalfa? Some reasons would likely include increasing or maintaining yield or avoiding “mining” the soil.

There is another reason that AgroLiquid customers are discovering, and it ties in with the industry’s understanding that the digestibility of a ration’s forage component has a large impact on a cow’s milk production. That is why cut timing is carefully managed, weather conditions are closely monitored, weeds and insects are controlled, and the bunks are filled and packed quickly. Recently the dairy industry is also paying more attention to alfalfa fiber digestibility.

For several years dairy customers have been saying that AgroLiquid fertilizers were doing something to their forages that went beyond more tons. They were getting more tons and more milk/cow/day when the AgroLiquid treated alfalfa was fed compared to their conventionally fertilized alfalfa. Then, last year, these personal accounts were put to the test when Poplar Farms Sales and Service near Manitowoc, WI, in cooperation with their Dairyland Seeds representative, decided to split north/south an alfalfa variety plot which was planted east/west. The field split compared conventional dry potash top-dressed against AgroLiquid’s Sure-K applied foliar at 6”. They tested each variety on each treatment for quality and digestibility in addition to dry matter yield. The results were significant, with markedly better Neutral Detergent Fiber Digestibility (NDFD), protein, Relative Feed Quality (RFQ), milk/ton and milk/acre on the Sure-K side. AgroLiquid Field Agronomy Manager for the upper Midwest, Dan Peterson, took note of these results and conducted an additional 11 alfalfa field and test plot trials across Michigan, Wisconsin, and Minnesota during 2016. He discovered the results were indeed repeatable, with all 11 trials showing positive results for the AgroLiquid treatments versus the conventional fertilizer treatments. This level of repeatability is unusual in agronomic testing, and provides strong evidence that AgroLiquid foliar products are doing something unique in the plant, something that other liquid foliar and dry fertilizers are not doing.

The 11 field splits and test plots were across several different conventional dry and foliar treatments and were compared side-by-side to various AgroLiquid foliar treatments. The average of the results across all fields and cuttings showed remarkable results from the AgroLiquid treatments:

  • 37.3% more dry matter/acre.
  • 2.6 more lbs of milk/cow/day (per NDFD).
  • Over 20% faster digestion rate (per the Dynamic NDF kd).
  • 5% more protein.
  • 40.5% more milk/acre.

The trials were from new seeding through 4th year stands, across different cuttings, soil types, soil fertility levels, and geographies. The AgroLiquid treatments were compared to conventional dry fertilizers, top-dress manure, and competing foliar products. Although the results varied, in every trial the AgroLiquid treatment resulted in a large ROI over the other treatments. In addition, in every trial the AgroLiquid treated side reached maturity between cuttings three to five days quicker than the conventional fertilizer or manure side of the fields. This may allow an additional cutting for the season. Dairy producers who participated in these trials noted not only the faster regrowth but more and larger leaves and less of the typical leaf yellowing below the canopy.

The question is how do AgroLiquid’s plant nutrient products achieve these remarkable tonnage and digestibility improvements in alfalfa? The answer is likely their unique Flavonol Polymer TechnologyTM. The flavonol organic polymer facilitates better nutrient uptake and utilization within the plants with less metabolic energy expended. Review the individual alfalfa trials at

lucerne alfalfa
The beautiful backdrop of Lucerne (alfalfa)

Calcium on Apples

Why is calcium important?

Calcium is the third most important element in a plant. And, calcium is the fifth most abundant element on the planet. It makes sense that traditionally, growers don’t apply much calcium, because they assume the plant will get what they need from the soil. But, calcium is usually found in a form that is not easily taken up by plants.

In an apple tree, the leaves, new shoots, and fruit all take calcium and the nutrient will be found in the tissues and the root, but, the fruit cannot compete with the other parts of the plant hence why the fruit often doesn’t get enough calcium. That is why calcium deficiencies are evidenced on the fruit, rather than the rest of the tree. In apples, a calcium deficiency causes a disorder known as bitter pit. Bitter pit is a physiological breakdown of the cell walls in the fruit that occur below the skin of the fruit. For that reason, when scouting for calcium deficiencies, it is important to test the fruit, rather than relying solely on leaf or soil tests.bitter pit in apples

In this particular trial, Horticulturists were testing for fruit firmness, how many apples produced on each tree, and how much the fruit weighs. At the North Central Research Station High-Density Apple Orchard, researchers test approximately 10 apples per experimental plot for firmness. They use a pentameter, which measures the pressure needed to break the cell part inside the apple. They test four spots on each apple, as research has shown there is a difference in firmness between the side of the apple exposed to sun, versus the shade-side. The average fruit firmness is reported.

A trial of the effects of LiberateCa™ in 2015 at the NCRS High-density Apple Orchard in Michigan showed that the apples treated with LiberateCa™ fall close to the preferred range of 14.5 lb – 17.5 lb for fruit firmness, while the untreated trees’ fruit firmness was significantly higher than desired. In addition, the treated trees had more apples per tree, and overall yield per tree increased as well. These trees were planted at 3 ½ feet between trees, 11 feet between rows, with a planting density of 1,100 trees per acre.Ca on apples

“If you can hang two more apples per tree, with 1,100 trees, you have 2,200 more apples – and that means more money in your pocket.” Horticulturist Jacob Emling