Date

Location

Cultural System

Vitazyme/Fertilization

Results

1999

Crossville, Tennessee (The University of Tennessee)

Variety:  "Carib" sweet potato

Planting date:  early November, 1996

Planting rate:  17,400 plants/acre

Row spacing:  30 inch between row spacing, 12 inch in-row spacing

Harvest date:  February 7, 1997 (about 12 weeks of growth)

Vitazyme application:  About seven days after planting, a solution of Vitazyme (15 cc/gal) was applied over the plants and soil.

Marketable tuber yield:

Control: 4,864 lb/acre x 1,000
Vitazyme: 5,949 lb/acre x 1,000 (+22%)
 

Unmarketable tuber yield:

Control: 4,928 lb/acre x 1,000
Vitazyme: 10,237 lb/acre x 1,000 (+108%)

Total tuber yield:

Control: 9,792 lb/acre x 1,000
Vitazyme: 16,186 lb/acre x 1,000 (+65%)

Income increase:

+$1,881.64/acre (+48%)

Fertilization:  unknown

Date

Location

Cultural System

Vitazyme/Fertilization

Results

2003

Quivican, Havana Province, Cuba

(Republic of Cuba, Ministry of Agriculture, Soils Institute)

Variety:  CEMSA 78-354

Planting date:  April 3, 2003

Row spacing:  1.6 meters

Soil type:  rhodic ferralsol

Harvest date:  September 8, 2003, just over 5 months after planting

Vitazyme application: 

(1) Sweet potato plants were submerged in a 1% solution at planting; 

(2) Vitazyme was aprayed on the leaves and soil at 1 l/ha at 25 days; 

(3) Vitazyme was sprayed on the leaves and soil at 50 days.

Sweet potato yield:

100% fertilizer: 27.20 tons/ha
100% fertilizer + Vitazyme: 34.00 tons/ha* (+25%)

75% fertilizer + Vitazyme: 32.33 tons/ha* (+19%)

50% fertilizer + Vitazyme: 26.73 tons/ha (-2%)

*Significantly greater than the control at P=0.010 according to Duncan's Multiple Range Test.  Standard error=1.11 tons/ha.
 

Sweet potato number per plant:

100% fertilizer: 2.80
100% fertilizer + Vitazyme: 3.98* (+42%)

75% fertilizer + Vitazyme: 3.63* (+30%)

50% fertilizer + Vitazyme: 2.78 (-1%)

*Significantly greater than the control at P=0.010 according to Duncan's Multiple Range Test.  Standard error=0.21 tubers/plant.

Sweet potato dry matter and starch:  Vitazyme in all three treatments increased dry matter by 4%, and the 75% and 50% fertilizer treatments increased starch by 5%.

Income increase:

+109 pesos/ha

Fertilization:  The 100% fertilizer rate received 100 kg/ha P₂O₅, and 75 kg/ha K₂O as a "complete formula" and urea.  This is the "optimum economic dosage" for chemical fertilization according to the Cultivation Technical Institute.