Commercial Tomatoes

The Effect of Liquid and Conventional Fertigation Treatments on Commercial Tomato Production

Researchers compare liquid and conventional fertigation treatments for impact on yields of ‘Roma’ and ‘Beefsteak’ tomatoes.

Customized products work better for consumers because they meet their specific needs. Tomato nutrition is no different. Customized fertility programs are effective because they meet the specific nutrient requirements of the tomato crop. Fertigation is a good way to implement a customized nutrition program for commercial tomato production, especially when liquid fertilizers are used.

Many tomato growers use drip systems to provide plant nutrition through irrigation water, a process known as fertigation. Drip systems can accommodate both water-soluble granules and liquid fertilizers, but there are some definite advantages to using liquid over water-soluble granular formations. This article will discuss three of them.


According to a study performed by AgroLiquid, fertigation treatments using liquid fertilizer have a greater impact on tomato yields than conventional treatments. For the experiment, researchers compared the effects of liquid and conventional fertigation treatments on the yield of fresh market ‘Beefsteak’ and ‘Roma’ type tomatoes.

Materials and Methods

Soil preparation included banding liquid fertilizer down the center of the plots or broadcasting dry fertilizer into the area. A swath of plastic mulch covered the center 2 ft. of each 5 ft. wide plot.

Growers doused the soil around each transplant with approximately 4.2 oz. of transplant solution (~300 GPA) which contained the fertilizers described in Table MT1. The rest only had water. For early season disease and insect management, Ridomil and Admire were added to the transplant water.


Drip applications started at early bloom and continued until mid-September. Eight weekly treatments occurred during the season. Upon maturity, ripe fruits were counted and weighed to determine yields. Spring rains delayed planting and harvesting, so a majority of the yields for all treatments occurred during the final portion of the season. Six harvests took place throughout the season; the initial harvest occurred on Aug. 13 and the last on Oct. 18.



When 100% of the fertilizer was applied pre-plant, the AgroLiquid base program (Trt. #2, See Figure MT1) surpassed the conventional program (Trt. #1) for the yield of ‘Beefsteak’ and ‘Roma’ type tomatoes.

During the growing season, drip applications (Trt. #4-#6) supplied 40% of total nitrogen, and in some cases (Trt. #5 and #6), nearly half of the potassium. These changes in the application timing improved tomato yields without using any additional fertilizer when compared to the Agro-Liquid base program (Trt. #1). Table MT1 shows these changes in application timing and volumes.

Kalibrate, listed here as K-10 (Trt. #3 and #6), matched the performance of Sure-K® (Trt. #2 and #5) when it was used in a similar manner. Kalibrate has some winter storage advantages over Sure-K®.

Flexibility and Uniformity

Fertigation allows the grower to apply smaller applications on a frequent basis with greater uniformity. Conventional fertilizer programs can be hit or miss because they usually consist of two or three applications per season. Depending on a plant’s stage of development, it may receive too much or too little fertilizer, or it may not be able to utilize the nutrients at all.

Nutrient Uptake

Fertigation improves nutrient uptake because it targets the active root zone; plants have easy access to the nutrients they need. Application rates can also coincide with a crop’s nutrient needs at different growth stages. For instance, growers can start with smaller doses at planting, increase the dose during the vegetative stage, and then decrease the dose as the crop nears the fruiting stage and maintain crop health at the end of a plant’s lifecycle.


Key Stages For Fertilization In Fruit Production

Four of the critical stages of high nutrient demand for fruit trees are pollination, early development, mid to late season, and late season/postharvest. During these times, growers should be sure to maintain healthy fertilization levels.

Some tips for nutrient management during each stage of fruit production:

Stage 1: Pollination

Fertilizing for fruit set actually starts the season before during bud development. This year, you’ll feed the buds from the prior season for good fruit set for this season. Fertilization during bud development is important because you can always thin fruit off, but you can’t create blossoms and fruit set if you don’t have it at the beginning. Boron is critical during pollination and early fruit set. Many growers apply a foliar boron spray, particularly during early bloom. Foliar applications are the most efficient method of uptake, and a foliar spray applies nutrient right where it needs to be – on the buds themselves. The buds are a small target, so growers don’t need to apply much. In most cases, only a pound or two of boron per acre per season would be needed.

Fase2 growth nutrients during this phase will stimulate growth in perennial crops such as orchards and vineyards. Fase2 promotes fruit set and bud retention and is intended for foliar applications.

Stage 2: Early Development

Early development is largely about nitrogen and phosphorus, applied to produce a good canopy and for the energy to get and hold fruit set. Overall, fertilizer rates will be based on what’s appropriate for the age of the tree and the results of a soil test.

Stage 3: Mid To Late Season

Calcium and potassium are the nutrients to monitor mid- to late-season. While every variety will need more potassium during this time, calcium is especially important for Honeycrisp apples.

Foliar applications are the way to fine tune a crop, fill in certain growth stages, or deal with a dry period of little water uptake – but start with the soil to get the right balance. As trees will also be setting buds for next season during this phase, micronutrients can be important to apply at this time.

Stage 4: Late Season/Post Harvest

Some of the very early season apple varieties and all types of cherries will have a fair bit of growing to do, even into the late season. For these, maintaining insecticide and fungicide applications, even after harvest, will maintain leaves as long as possible and give trees more energy going into winter. Some growers have also been looking into late-season nitrogen as a way to improve spring flush and vigor.

Throughout the entire growing season, Pro-Germinator and Sure-K are two main nutrition products that support a balanced fertilizer program. Pro-Germinator is primarily used as a soil application, but it can also be applied as a foliar nutrient. It provides season-long phosphorus availability. Sure-K provides potassium for foliar or fertigation applications, which allows flexible use depending on crop or variety. For those varieties that need additional calcium, Liberate Ca from AgroLiquid can be tank mixed with many other products for efficient source of calcium applications.

Use Liquid Fertilizer for Long-Lasting Strip-Till Applications

Strip-till applications are the perfect time to place liquid fertility where the crop needs it, with the assurance that nutrients will be available when and where you need them.

Strip-till combines the best features of no-till and conventional tillage systems. Tilled strips that will house the seed row reside alongside undisturbed bands of crop residue that shelter the soil and conserve moisture. Growers who want to practice Responsible Nutrient Management, have poorly drained soils or are apprehensive about areas with poor soil structure can benefit from using strip-till in their operations.

Strip-till accelerates the warming and drying of the soil in the spring, which stimulates earlier and deeper root growth in field crops such as corn. It can also increase air circulation and improve aerobic conditions.

One of the biggest advantages of strip-till is that nutrients can be placed into the root zone where there is less potential they will be diverted or immobilized by crop residue. Dual placement of phosphorus (P), potassium (K) and micronutrients near the seed zone and placement of nitrogen beneath the seed zone, improves the proximity of nutrients to the roots as they grow and develop.

Successful strip-till applications match the right nutrients with the right timing, according to geographic area. For example, it isn’t advisable to apply nitrogen in the fall in areas that have large amounts of rainfall because of the potential for leaching. However, in arid areas growers can successfully apply nitrogen in the fall.

An effective combination for strip-till applications is Pro-Germinator for phosphorus and Sure-K for potassium, along with microLink for balanced micronutrient application. For nitrogen applications, AgroLiquid offers a number of choices from their N-Suite to meet the needs of any strip-till situation.

Agronomists at the North Central Research Station in St. Johns, Mich., conducted a two-year trial that assessed the effect of fertilizer timing and placement on strip-till corn (2012 Research Report, Effect of Fertilizer Timing and Nutrient Placement in Nutri-Till/Strip-Till Corn).

Strip-Till 2012-Research-Report-18_GraphResearchers found that deep fall placement was only slightly lower in yield than shallow fall placement. And both spring and fall placement of P, K and micronutrients resulted in similar yields. The study also established that the highest yield for both years was where all of the fertilizer was applied in the spring with the strip-till operation. This treatment resulted in corn that was noticeably ahead of the other treatments.

Growers are often apprehensive about nutrient applications during fall strip-till because they worry nutrients will not be available for crops the next year. AgroLiquid product formulations promote stability and protect nutrients from tie-up and loss. They are a great fit for conservation tillage cropping systems. Best of all, growers can apply fertilizer with confidence during strip-till, having the peace of mind that nutrients will be available at the right time and in the right place.


Micro 500

Without the proper balance of nutrients fertilizers are not as efficient as they could be. Balance your nutrients and use less to produce more. Micro 500 is the place to start.

Sure-K Video

Learn about AgroLiquid’s Potassium product Sure-K.


Balance is critical in plant nutrition. Justus von Liebig propounded the “Law of the Minimum”. It states that if one of the nutritive elements is deficient or lacking, plant growth will be poor even when all other elements are abundant. A crop will only produce to the potential of the least usable nutrient.

Phosphorus in Plants

There is no substitute for phosphorus in high-value crop production.

Phosphorus may not be first in the N-P-K lineup, but don’t underestimate its importance to plant growth and development. Many essential plant processes would not occur without it. There is no substitute for phosphorus if your primary goal is to maintain first-rate crops and high yields.

Every living plant cell contains phosphorus as part of the substances that carry the DNA code of living things. Phosphorus directly influences reproduction, photosynthesis, cell division, root development and energy storage. Some flowers and fruit also contain high concentrations of phosphorus.

Correct placement of phosphorus near the root zone is crucial because of its low mobility in the soil. The greater the distance the root must cover to reach the phosphorus, the greater the chance it will be unavailable when the plant needs it. Most plant roots only explore about 3% of the soil around them. Stunted growth, spindly stalks, distorted leaves and purpling are all signs of a phosphorus deficiency, as well as reduced blooms and/or onset of fruit.

In any given year, crops take up a combination of phosphorus applied in the current cropping year and phosphorus applied in previous years. Soil pH or acidity influence phosphorus reactivity and determines the speed and type(s) of insoluble phosphorus that is most likely to form. Phosphorus fertilizers are generally very inefficient and only a small portion of what is applied typically gets into the crop.

What’s new on the phosphorus front at Agro-Culture Liquid Fertilizers?

Pro-Germinator™ utilizes carbon as a building block to form long phosphorus chains that provide protection for the nutrient until the plant is ready to absorb it. The phosphorus compound isn’t subject to movement from the cropping environment because it reaches its intended destination the first time. This creates an optimum situation and leads to greater use efficiency.

Pro-Germinator™ performance is one of the standards that AgroLiquid uses to evaluate experimental phosphorus products. In 2012, researchers evaluated two experimental phosphorus fertilizers, SP-12 and ZP-12, on corn, soybeans and various vegetable crops. Both products, in addition to being N-P-K products, have added sulfur to help meet more complete crop requirements. This presented an increased risk for injury if the product comes into contact with the seed, unlike Pro-Germinator™, which is safe for in-furrow applications up to 10 gal/A on field corn.

Experimental Phosphorus Placement Options for Corn

This trial evaluated in-furrow and 2×2 placement options for effects on establishment, yield and stand. Pro-Germinator yields were similar for both application methods (197.2 vs. 194.5 bu/A). When comparing 2×2 applications, SP-12 and ZP-12 yields were numerically higher, but this did not hold true for in-furrow applications. Testing will continue to verify the conclusion that SP-12 and ZP-12 cause yield loss when applied in-furrow. (See Corn Planter Program Additives)


Experimental Phosphorus Applications on Soybeans

In-furrow and 2×2 applications of Pro-Germinator, SP-12 and ZP-12 were made with rebounders or tubes in the bottom of the furrow. Averages on all locations show SP-12 increased soybean yield 2 bu/A over that of Pro-Germinator. This may be enough of an increase to continue further testing during the 2013 growing season.


For the full research results see “Experimental Phosphorus Placement Options (NCRS 12-309, 719)” and “Experimental Phosphorus Fertilizers on Soybeans (NCRS 12-709, 1002, 1101)” in the 2012 Research Report.