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Evaluating SMS for nutrient management of pumpkins.

Article Excerpt
OBJECTIVE: The objective of this study was to evaluate spent mushroom substrate (SMS) at varying application rates and two different timings of application in a pumpkin crop.

MATERIALS & METHODS

The study was conducted in 2007 and 2008 on a one-acre field consisting of a Hagerstown silt loam and located at the Horticulture Research Farm, Russell E. Larson Research Center, Rock Springs, PA.

Treatments consisted of SMS applied assuming varying rates of mineralization and at two timings of application (Table 1). Additionally three control treatments were included: ammonium nitrate at a rate of 80 lbs nitrogen per acre applied at two timings and an unamended control. Based on compost analysis (Table 2) conducted by the Agricultural Analytical Services Laboratory, Penn State, the amount of material to apply was calculated. Treatments were arranged in a randomized complete block design. Lach treatment was replicated four times on plots 1125 [ft.sup.2] in size. Treatments implemented two or three weeks before planting were applied on May 15, 2007 and May 24-26, 2008 and soil incorporated on May 22, 2007 and May 26, 2008 to a depth of about eight inches using an S-tine. The remaining treatments were implemented on May 29, 2007 and June 12-13, 2008 and soil incorporated on the same day.

Table 1: Treatments being used in this study. Nutrient Source, Mineralization Timing of Amount of Nitrogen Rate Rate (%) Application SMS Applied SMS, 80 lbs N/acre 10 2 or 3 weeks 26.7 preplant tons/acre SMS, 80 lbs N/acre 20 2 or 3 weeks 16.7 preplant tons/acre SMS, 80 lbs N/acre 40 2 or 3 weeks 9.5 preplant tons/acre SMS, 80 lbs N/acre 10 AT planting 26.7 tons/acre SMS, 80 lbs N/acre 20 At planting 16.7 tons/acre Control - Ammonium - 2 or 3 weeks 235 nitrate, 80 lbs preplant lbs/acre N/acre Control - Ammonium - At planting 235 nitrate, 80 lbs lbs/acre N/acre Control - unamended - - - Table 2: Analysis of the SMS used in this study. Analyte Results (as is) 2007 Results (as is) 2008 pH 7.9 7.1 Soluble Salts 16.02 mmhos/cm 14.61 mmhos/cm Solids 37.1% 39.1% Moisture 62.9% 60.9% Organic Matter 20.0% 23.5% Total Nitrogen 0.87% 1.0% Organic Nitrogen 0.80% 0.90% Ammonium N 687.2 mg/kg 6)4.1 mg/kg Carbon 10.7% 11.7% Corbon: Nitrogen Ratio 12.3 12.2 Phosphate 0.73% 0.57% Potash 1.25% 1.31% Calcium 2.59% 2.53% Magnesium 0.32% 0.33% Sulfur 0.81% 0.67% Sodium 1338 mg/kg 1108 mg/kg Aluminum 1811 mg/kg 1333 mg/kg Iron 1456 mg/kg 1460 mg/kg Manganese 147 mg/kg 128 mg/kg Copper 50 mg/kg 36.6 mg/kg Zinc 71 mg/kg 75.5 mg/kg

[ILLUSTRATION OMITTED]

Four-week-old Racer pumpkin plants were transplanted on May 30, 2007 and three-week-old plants were transplanted on June 16, 2008 using 3 ft in row spacing and 6 ft between rows. A drip irrigation system was installed to provide supplemental water to the plants when needed. Insect pests and diseases encountered included cucumber beetles, squash bugs, viruses and powdery mildew. These were managed with insecticide and fungicide sprays. Weeds were managed by periodic cultivation.

Soil samples were collected from each plot on May 21, 2007 and May 23, 2008 prior to applying treatments and on Sept. 29, 2007 and Sept. 26, 2008 after harvest. Samples were collected with a soil auger to a depth of 12 inches. Samples were submitted to the Agricultural Analytical Services Laboratory, Penn State for analysis of soil properties and nutrient levels.

Leaf samples for nutrient analysis were collected on July 11, 2007 and July 28; 42 days after planting, night recently fully expanded mature whole leaves (petioles were removed) were harvested from border plants in each plot. Leaf samples were submitted to the Agricultural Analytical Services Laboratory, Penn State for determination of micro and micro-nutrient contents.

Hand harvest occurred on Sept. 20, 2007 and Sept. 15, 2008. Yield parameters measured and recorded were the weight and number of marketable and unmarketable pumpkins. Unmarketable pumpkins were categorized as diseased, damaged by insects or under mature (less than 50 percent orange).

Data were analyzed with General Linear Model Analysis of Variance using Statistical Analysis System 9.1.3. When significant differences at P [less than or equal to] 0.05 were detected, Duncan's least significance difference test was used to separate means.

RESULTS & DISCUSSION

Total Yield

In both years, the lowest yields by weight were observed when no supplemental nutrients were supplied (Tables 3 and 4). This was expected as nutrients are applied to maximize yield potential.

In 2007, larger yields by weight were observed from plants where SMS was applied at planting assuming a 10 percent mineralization rate compared to applying SMS two weeks before planting using a 10 percent mineralization rate or applying inorganic fertilizer. Intermediate yields resulted from applying SMS with a 20 percent mineralization rate regardless of timing of application. Applying SMS using a 10 or...

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