Runoff and Nutrient Losses from Constructed Soils Amended with Compost

Table 2

Effect of rates of compost and associated total N (TN) and P (TP) on TN, TP, soil-test P (STP), and water-extractable P (WEP) concentrations in soil on an 8.5% slope. Composted dairy manure (CDM) and municipal biosolids (CMB) were incorporated at volume-based rates in compost-manufactured topsoil (CMT) or mixed with wood chips in erosion-control compost (ECC) as specified by the Texas Department of Transportation. The control was established perennial grass.

Treatment

Compost

Rates applied as compost

Concentration within 5 cm sampling depth

Rate

Mass

TP

TN

TP

TN

STP

WEP

(m^3 m^−3)

(Mg ha^−1)

(kg ha^−1)

(kg ha^−1)

(mg kg^−1)

(mg kg^−1)

(mg kg^−1)

(mg kg^−1)

Control

NA

NA

254

e

1188

cd

80

e

17

d

CMT

CDM

0.125

62

d^‡

199

f

320

f

537

de

725

e

264

de

34

cd

CMT

CMB

0.125

28

f

408

d

468

e

875

cd

1035

de

439

cd

29

d

CMT

CDM

0.25

109

b

337

e

566

d

761

d

1059

de

496

cd

50

bc

CMT

CMB

0.25

50

e

810

b

865

c

1201

c

1515

c

623

c

33

cd

ECC

CDM

0.50

185

a

611

c

944

b

1773

b

2759

b

1115

b

77

a

ECC

CMB

0.50

100

c

1773

a

1712

a

5121

a

5212

a

2203

a

55

b

^†Different letters in columns represent significant differences using Fisher’s LSD means separation test.