Strawberry Fertility Trial Results 2015-2016

Testing Biostimulants: AgroThrive and O-MEGA

The standard practices required for strawberry production in Ventura County deplete soil organic matter and disturb beneficial microbial populations. Liquid biostimulant fertilizers offer a safe and practical means to restore organic matter and microbial communities. In a recent trial, I tested the effects of applying two biostimulant products, AgroThrive and O-MEGA, provided by Tri-Tech. AgroThrive, a progressively digested fish based fertilizer, supplies macro and micro nutrients as well as a rich carbon source to feed soil microbiota. O-MEGA contributes a high dose of beneficial microorganisms and stimulatory herbs. Both products have potential to increase soil microbial activity in the root zone and enhance plant health. I tested the effects of applying AgroThrive and O-MEGA on strawberries grown in pots under a hoop house from October 2015 to June 2016.

Experimental Design:

Fifty University of California variety strawberry transplants and 50 Wel Pict transplants were grown in 5 gallon pots arranged in five experimental rows in a hoop house outside the Tri-Tech/TriCal office. Each row included 10 plants from each variety. The five fertilizer treatments included:

Control: No Fertilizer

Grower’s Standard fertilizer only

Grower’s Standard + O-MEGA

Grower’s Standard + AgroThrive

Grower’s Standard + O-MEGA + AgroThrive

I irrigated all treatments at the same rate using a drip system and applied fertilizer by hand with a pipette.

 

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Plant Weight

In December, I destructively harvested four plants from each treatment to measure early plant growth. I weighed the roots separately from the above groundstems and leaves. I measured all plant parts while fresh and again after oven drying. I harvested and weighed the remaining plants in June using the same methods. Overall, the Well Pict variety responded positively to O-MEGA and AgroThrive, while the university variety had highest biomass with grower’s standard fertilizer alone.

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pH and Nutrient Availability

Throughout the trial, I used lysimeters from AGQ Labs to extract soil solution and measure pH, EC, and nutrient availability. Treatment 3, OMEGA, maintained a relatively low pH, likely increasing nutrient availability compared with the other fertilizer treatments. Although Treatment 5, Grower’s Standard + O-MEGA + AgroThrive, did not have the lowest soil pH, it had high phosphate and moderate potassium availability throughout the trial. Treatment 5 also displayed a steady nitrate concentration, avoiding the extreme changes in availability observed in the other treatments. When used together, AgroThrive and O-MEGA likely increased microbial growth leading to temporary nitrogen immobilization, thus inducing a buffered nitrogen release. Microbial communities provided a low but steady supply of nitrate as their populations died and recovered. Plant growth and environmental quality benefit from maintaining a steady nitrate concentration, since plants avoid the stress associated with abrupt nitrogen spikes and crashes, and increased microbial communities prevent nitrogen leaching to groundwater.

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Strawberry Harvest

Throughout the trial, I counted and weighed all ripe, undamaged strawberries. Treatment 3, O-MEGA, produced the highest number of berries in both varieties. Amongst the Well Pict plants, Treatment 3 also had the highest cumulative berry weight while Treatment 2, Grower’s Standard Fertilizer only, produced the highest cumulative berry weight in the university variety. In both varieties, applying O-MEGA increased early berry production.

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Impeding Factors

The trial results were likely influenced by the amount and timing of sunlight hitting the plants each day. Treatment 2, Grower’s Standard Fertilizer Only, received the most early morning sun, followed by Treatment 3, Grower’s Standard + O-MEGA. Treatment 4, Grower’s Standard + AgroThrive, and Treatment 5 Grower’s Standard + O-MEGA + AgroThrive, remained shaded for longer in the day. The high biomass and yield observed in Treatments 2 and 3 may have been driven more by sunlight than fertilizer treatment.

 

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Conclusion

In future trials, I will adjust the experimental design to account for differences in sunlight under the hoop house. The results of this trial show that O-MEGA and AgroThrive have potential to influence soil dynamics and benefit plant growth. With my team at Tri-Tech, I will continue to test these products to find their optimal application rates and timing for strawberries.

For more information about the trial, download the official AgroThrive/OMEGA Trial Report