Performance of Dr. Earth^®, Premium Gold All Purpose Fertilizer
By: Milo Shammas, Founder & Formulator

OBJECTIVE: 
The objective of this field trial was to compare growth performance of Dr. Earth^® Premium Gold All Purpose Fertilizer with other commercially available, natural/organic all-purpose fertilizers during the spring and summer growing seasons. Performance was interpreted by measuring:
• Plant color
• Yield (by weight) of harvested fruit.

LOCATION:
The growth trials were conducted in Vacaville, California on agricultural land that had been fallow for three years. The soil was a sandy-loam soil. Soil samples from the top foot of soil in all plots yielded pH measurements ranging from 7.2 to 7.5.

EXPERIMENTAL PROCEDURE:
Randomly selected tomato plants were planted in the ground in seven separate test plots. Each plot measured 6 feet x 9 feet. The plants were equally spaced, separated by a distance of 36 inches measured from main stem to main stem. All plots were situated to receive equal sunlight exposure. All plots were irrigated using a timer-controlled, pressure-regulated, drip-irrigation emitter system. The system delivered equal amounts of water at identical times to all plots. Irrigation was increased periodically and equally for all plots as the plants increased in size.

Planting date: April 22, 2004
Harvest dates: Six harvests between August 17, 2004 and September 22, 2004.
Each plot contained six tomato plants (Big Boy variety). All plants were purchased in pony pack containers on April 21, 2004. Plants were randomly selected from the same source and were of similar size (20cm. high x 10cm. wide) and in similar (good) condition. Six of the seven plots were fertilized at the time of planting with the different organic fertilizer products identified as follows:
• Dr. Earth^® All Purpose Fertilizer 4-4-4
• WF (5-5-5)
• EBS (5-5-5)
• DTE (4-6-2)
• FF (5-5-5)
• GM (5-5-5)

The seventh plot was the control plot and received no fertilizer.

The rate of fertilizer application was based on each manufacturer’s recommendations as printed on the fertilizer package.

A second fertilizer application was made on June 27, 2004 at rates again based on each manufacturer’s recommendations as printed on the fertilizer package.

Plant color was measured using a digital 6.3 mega pixel camera. This camera was used to photograph the entire plant area. The photographs were quantified using a computer to count the actual number of pixels (points) by the degree of darkness for each plant.

Plant color was ranked from 1 to 9, with 9 being the darkest. Fertilizer effect curves measured how soon the different fertilizers improved plant color, and how long this effect persisted. Plant color was measured weekly.
Each plot’s production was measured by weighing the combined yield of ripe tomatoes as harvested from all the plants in each plot. Plants were harvested and weighed a total of 6 times during the field trial.

RESULTS:
Plant Color
The color of all plants treated with the different fertilizers is detailed in Table 1. Dr. Earth had the darkest overall average color rating at 7.4. The average color rating for plants treated with WF, EBS and DTE was 7.2. GM and FF had the lowest values, each measuring 7.0. The overall average color rating for the control group was 5.6.

Table 1. Darkness of color (values 1 to 9) in plants treated with different commercial organic plant fertilizers in Vacaville, California during April 22, 2004 through September 22, 2004.

Table 1, columns 1 through 6, illustrate the effect of the fertilizers on the color of the plant foliage.
The time required to achieve a color value of at least 7.5 after initial fertilization varied among the different fertilizers. Plants fertilized with EBS, WF, DTE each reached the 7.5 mark by the third weekly measurement. Dr. Earth, FF, and GM each surpassed the 7.5 mark, achieving a color value of 7.7, by the fourth weekly measurement.

Dr. Earth^® provided the longest-lasting color effect. Plants fertilized with Dr. Earth^® maintained a color value of 7.5 or higher for 13 out of 22 weekly measurements (59).

Plants fertilized with WF and DTE maintained a color rating of at least 7.5 for 10 out of 22 weekly measurements (45).
The plants fertilized with EBS maintained a color rating of 7.5 or more for 7 weekly measurements (32). Those plants fertilized with FF and GM surpassed the 7.5 mark for 4 weekly measurements (18).

PLANT YIELDS
Harvested tomato production of all plants in the plots is detailed in Table 2. The greatest overall yield occurred in Plot #1, treated with Dr. Earth^® fertilizer. 395.1 lbs. of tomatoes were harvested from this plot.
* Plot #2, fertilized with product WF, yielded 349.7 lbs.
* Plot #3, fertilized with product EBS, yielded 337.6 lbs.
* Plot #4, fertilized with product DTE, yielded 362.0 lbs.
* Plot #5, fertilized with product FF, yielded 328.0 lbs.
* Plot #6, fertilized with product GM, yielded 327.9 lbs.
* Plot #7, the untreated control, yielded 201.8 lbs.

Table 2. Total harvested weight of tomatoes in pounds. Six weekly harvests were conducted August 17, 2004 through September 22, 2004.

Assuming fruit production is an indicator of overall plant health, the results suggest plants fertilized with Dr. Earth^® were in the best health, strongly suggesting that the nutrients supplied were utilized at optimum levels as compared to the other fertilizers tested.