Nutrient Availability and Quality Assessment of

Exceptional Quality Biosolids Products

Odiney Alvarez and Greg EvanyloCrop and Soil Environmental Sciences

Virginia Tech

Mid-Atlantic Biosolids AssociationAnnual Symposium and Meeting 2016

Introduction

• World population and urbanization increase

• Cities faced with challenge of sustainable development

• Urban agriculture can provide ecosystem services

Urban Soils

Introduction

• Generation of Exceptional Quality (EQ) biosolids products is increasing

• Assess crop and soil benefits, and environmental impact

Objective • Assess the quality of various EQ biosolids products

designed for urban soil use with a soybeangermination and growth bioassay.

• Quantify plant available nitrogen (PAN) of various EQbiosolids products with a tall fescue N uptake bioassay.

• Evaluate bioavailable phosphorus (BAP) of EQ biosolidsproducts with various chemical tests.

Methods: EQ biosolids products studied

1. BSS = 1.5 Blue Plains DC EQ biosolids: 1 sawdust: 1 sand

2. BM = 0.75 Blue Plains DC EQ biosolids: 1 mulch

3. TSS = Tagro blended biosolids-sand-sawdust from Tacoma, WA.

4. TM = Tagro blended biosolids with mulch-based potting soil Tacoma, WA.

5. AREM = Biosolids blended with woody mulch from Alexandria Renew Enterprises, Alexandria, VA

6. SBC = Composted biosolids from Spotsylvania County, VA

7. OCHDB = Heat treated-biosolids from Ocean County, NJ

Greenhouse Soybean Bioassay: Product Quality

Amendment Application RateInorganic Fertilizer 75 mg PAN/kg soilBMBSSTMTSSAREMSBCOCHDBBM 100% growth medium

BSSTMTSS

Greenhouse Tall Fescue Bioassay: Plant Available N (PAN) and Bioavailable P (BAP)

Amendment Application rate (mg PAN/kg soil)Fertilizer 0, 37.5, 75, 150, and 300BM 75 and 150BSS 75 and 150TM 75 and 150TSS 75 and 150AREM 75SCB 75OCHDB 75

Results: EQ biosolids properties

BM BSS TM TSS AREM OCHDB SCB

pH 6.52 6.07 7.77 9.00 7.44 7.30 7.98

Total Solids (g/kg) 666 699 666 625 591 949 606

TKN (g/kg) 26.9 22.3 10.0 9.8 17.2 49.1 23.1

NH4-N (g/kg) 3.6 2.8 2.6 3.1 6.2 5.7 7.8

Organic N (g/kg) 23.3 19.5 7.4 6.7 11.0 43.4 15.3

C:N 14.4 11.1 26.5 18.4 18.5 7.8 15.8

TP (g/kg) 17.0 14.5 5.1 6.9 11.4 26.6 9.9

K (g/kg) 2.0 0.9 1.5 1.3 3.0 1.4 4.0

Fe (g/kg) 58.3 52.5 15.5 16.2 30.7 32.8 17.5

Results: Soybean Dry Weight

b

a a

a a

a

a a

b

b

b

a

0

0.5

1

1.5

2

2.5

Soyb

ean

Dry

Wei

ght

(g)

Results: Soybean Soil EC

c

cd cdd

d dd cd

a

a

b

b

0

1

2

3

4

5

6

7

8

9

EC (

dS/

m)

Results: Soybean Bioassay

100% BM – 100% TM – Fertilizer 1x 100% BSS – 100% TSS – Fertilizer 1x

Results: Soybean Bioassay

BM1x – TM1x – Fertilizer 1x BSS1x – TSS1x – Fertilizer 1x

Results: Tall Fescue N Uptake

gh

efgh def

defg

h

cde

a

def

ab

bcd

a

fgh

abc

defg

def cde

0

20

40

60

80

100

120

140

N u

pta

ke (

mg

/kg)

BM1x BM2x

BSS1x BSS2x

Plant Available N (PAN) Standard Curve

TreatmentActual PAN applied

(mg/kg)BSS1x 90BM1x 83TSS1x 108TM1x 26AREM1x 50SBC1x 87OCHDB1x 94

y = 0.3094x + 49.392R² = 0.9911

0

10

20

30

40

50

60

70

80

0 20 40 60 80

N u

pta

ke (

mgk

g)

N applied (mg/kg)

Results: Tall Fescue Soil Mehlich-1 Phosphorus

0

10

20

30

40

50

60

70

80

90

100

Soil

Meh

lich

1-P

(m

g/k

g)

Results: Tall Fescue Soil Phosphorus Saturation

0

5

10

15

20

25

30

35

40

P s

atu

rati

on

(%

)

Conclusion

• The use of blended EQ biosolids products as an entire root zone mix should be done with caution to ensure salt is not high and products are properly cured.

• We validated that Blue Plains EQ biosolids blended products have approximately 20% organic N availability.

• All other estimations of organic N availability were close, except for TM1x and AREM1x which were underestimated.

• EQ biosolids products increased M1-P, but the presence of Fe and Al reduces the risk of P loss as shown with the soil P saturation ratio.

Future Research

THANK YOU

Questions???