GrowGreen Performance Evaluation
Winter Strawberry Production in California, Ventura
County
Holden Research and Consulting
David Holden
11/22/2014
Objectives
Evaluation of GrowGreen in addition to grower standard program compared to grower
standard program for winter strawberry production in California.
Methods and Materials
Soil samples were collected in pre-plant, post plant to evaluate levels of all soil nutrients.
Leaf analysis samples were taken mid-growth and pre-harvest for analysis of all nutrients.
Growth ratings of plants and SPAD analysis of leaf chlorophyll production were taken over
the season. Yield at harvest was divided into marketable and unmarketable strawberries
for 30 pick-days in-season, replicated six times with extrapolation to total estimated yield
per acre.
The block of proprietary strawberries utilized for this trial were grown in a 20 acre field.
This trial was set up as a random block design trial of three treatments with completely
randomized data collection of six replicates maintained during the growing season. The
generalized treatment regimens can be found later in this report, but they were the grower
standard untreated check, a soil program of GrowGreen products, and a foliar program of
GrowGreen products, all applied on a schedule established by GrowGreen advisers. All
treatments received at planting controlled release fertilizer and regular in season
applications of nitrogen, phosphorus and potassium. All materials were applied in the
grower’s in ground drip system or as a foliar spray to the strawberry plants. No problems
with clogging or phytotoxicity were noted through the use of these material.
Plants were also visually analyzed for any adverse effects from the application of the
numbered products during the trial.
Results and Discussions
All data for this trial will be found in this report and represented in the attached charts,
along with nutrient analysis supplied by A&L Western Laboratory.
Charts track all marketable production for all picks commencing on January 13, 2014 and
ending March 31, 2014, with no statistically significant differences noted between
treatments, but some nice cumulative improvements in production for the two different
GrowGreen programs. Charts 5 and 6 show the marketable production in calibrated trays
per acre for all treatments for each pick day both on a daily and cumulative basis. As can be
seen in Chart 5, GrowGreen treatments 2 and 3 produced the most flats on average for the
pick period, with cumulative totals of 243 and 132 flats improvement over the untreated
check, shown in Chart 6.
A different perspective of how the rated production affected final grower returns is shown
in Chart 8 which shows the daily marketable returns based on USDA Shipping Point Market
Prices found at HTTP:\\marketnews.usda.gov/portal for each pick day. This data is
represented as the net back to grower after costs of approximately $6.00 per tray were
removed that would represent picking labor, carton and tray costs, transportation to the
cooler, and cooling costs associated with picking the strawberries. Based on this data
treatment 2 showed a $1609 improvement over the untreated check, while treatment 3
showed a $600 improvement in returns.
Chart 8 shows the daily market utilization for the berries picked during the season. This is
the percent of marketable berries to the total weight of berries picked. Treatment 2 shows
a 57.9% utilization while treatment 3 performed a bit less at 54%, which was better than
the untreated check at 50.8%.
Chart 6 shows the mean weight per marketable fruit during the season. In this case
treatment 2 had berries averaging 25.53 grams during the season followed by treatment 3
at 23.52 grams and the untreated check at 21.41 grams per berry. Both the size and quality
improvements contributed to better returns for treatments 2 and 3.
SPAD ratings taken on two occasions. These ratings showed any numerical improvements
for both treatments over the untreated check. SPAD is a number returned by a Minolta
SPAD meter which gives a relative rating of chlorophyll to be found in the leaves. The
higher the number the better the chlorophyll rating. Grower Standard program had an
average of 45.1 and 57.57 SPAD rating. GrowGreen Soil program showed an improved
SPAD rating of 47.33 and 58.72 SPAD rating and GrowGreen Foliar showed an
improvement of 46.88 and 59.6.
End of season soil and leaf nutrient values were also collected. A&L report 14-093-014
returns the soil nutrient values between the untreated check and the GrowGreen soil
program. For all major nutrients, the values were found to be higher (and lower soil pH) in
the GrowGreen treated soils. The nitrogen was so high that I am not sure that this was not
due to an error in collecting the soil with some residual fertilizer in it or for some other
reason. Could it possibly be that the GrowGreen stimulated biological activity since the
organic matter reading is much higher for the GrowGreen soil also?
The leaf report, 14-051-007 confirms much higher nitrogen and phosphorus values in the
GrowGreen soil program also, while the foliar program values for N-P-K are improved but
not at the level of the soil program. All leaf values would appear to be in the ample range
for this crop.
All data rated as significant was done so utilizing the New Duncan's Multiple Test Range at
a 90% confidence level.
Product
18-8-13
Controlled Release
Nitrogen (N) CAN
17
Phosphorous (P)
White Phos Acid
Potassium (K) KTS
Product
Grower Standard
Nutrimine
8-1-3
0-0-9
Product
Grower Standard
Nutrimine
8-1-3
0-0-9
8-1-3
Nutrimine
0-0-9
Xtend
Grower Standard Program
800lb/acre
In soil Bed
80 gal/acre
Drip Line
20 gal/acre
Drip Line
40-50 gal/acre
Drip Line
Soil Program
4 Quarts/Acre
4 Quarts/Acre
4 Quarts/Acre
Drip Line
Soil/Foliar Program
4 Quarts/Acre
4 Quarts/Acre
4 Quarts/Acre
42 OZ/Acre
32 OZ/Acre
42 OZ/Acre
22 OZ/Acre
Frequency
Pre-plant
In-Season
Frequency
Once a Month
Frequency
Drip Line
1 x 3 weeks
post plant
Foliar Application
Every 3 weeks
Conclusions
The addition of GrowGreen products, soil and foliar programs, to the Grower’s standard
NPK program showed significant improvements in strawberry weight and marketable
product collected. The GrowGreen soil program showed the largest improvement of
average weight at 25.53 grams compared to the Grower’s standard program of an average
weight of 21.41 grams. The marketable product was also increased. GrowGreen’s soil
program had the largest improvement of marketable product at 57.9% compared to the
Grower’s standard 50.8%.
The increased average weight and marketable product were contributing factors to the
overall improved profitability of Ventura strawberry production. The GrowGreen soil
improved profitability of $1609 over the Grower’s standard program.
The soil tests taken before and after production showed higher organic matter and residual
N in the soil. It was noted by Holden Research and Consulting that it may have been
contributed to an error in sampling or perhaps increased microbial activity for this finding.
The residual N can be attributed to both increased microbial and organic matter. It should
also be noted that GrowGreen has non-leaching technology that should be taken into
account in regards to the residual N in the soil.