INTRODUCTION

Reduced tillage on biosolids-amended land decreases runoff and erosion and increases infiltration and soil moisture. Little research has been conducted, however, on the effects of no-tillage on crop response nitrogen availability where biosolids are applied.

OBJECTIVE

To compare the interactive effects of land-applied biosolids types and tillage practices on soil and corn nitrogen availability in Coastal Plain agricultural soils.

METHODS

During 2009-2011, corn (Zea mays L.) was grown as test crop on an Orangeburg loamy sand (Fine-loamy, kaolinitic, thermic Typic Kandiudults), in Sussex County, VA.

• Experimental design:

Split-Plot Design

Main plot treatments: conventional tillage (CT) and no-tillage (NT).

Sub-plot treatments: commercial fertilizers (0x, 0.5x, 1x, 1.5x agronomic N rate), anaerobically digested biosolids (AD) and lime stabilized biosolids (LS) (1x agronomic N rate*).

Each treatment was replicated 4 times.

*1x agronomic N rate was based on estimated yield potential of 8.8 Mg ha-1 .

• Sampling and analysis:

Pre-Sidedress Nitrogen Test (PSNT)

Corn Ear Leaf Nitrogen (ELN)

Corn grain yield

End-of-season Corn Nitrate Test (CSNT)

Effects of Biosolids Types on Nitrogen Availability under Varying Tillage Practices

Jinling Li (jinling@vt.edu), Gregory K. Evanylo and Xunzhong Zhang Department of Crop and Soil Environmental Sciences, Virginia Tech

Properties of land-applied biosolids in 2009-2011

CONCLUSIONSTillage practices did not significantly influence biosolids Plant Available Nitrogen (PAN).Biosolids PAN was reduced by drought up to silking (as assessed by PSNT and ELN) and increased by drought at end of season (CSNT).

RESULTS AND DISCUSSIONPSNTBiosolids maintained higher level of inorganic N than fertilizers in 2009; lower level than fertilizers in 2010; and equal level to fertilizers in 2011; LS maintained higher level than AD.

ELNBiosolids maintained higher level of ear leaf N than fertilizers in 2009; lower level than fertilizers in 2010; and equal level to fertilizers in 2011; LS maintained higher level than AD.

CSNTBiosolids maintained equal level of corn stalk nitrate N to fertilizers in 2009; in 2010, LS maintained higher level than fertilizers, but AD maintained lower level than fertilizers; and higher level than fertilizers in 2011.

Grain YieldIn 2009-2011, both biosolids produced higher grain yields than fertilizers; LS produced higher or equal level than AD.

ELN

Biosolids pH Total

Kjeldahl N, g kg-1

Organic N, g kg-1

AmmoniaN, g kg-1

LS 12.3 37.3 35.5 1.8

AD 8.4 64.8 46.7 18.1

0 50 100 150 200 2500

30

60

90

120

f(x) = − 0.000948590381426203 x² + 0.450985249123465 x + 16.1986308003875R² = 0.999924156135197

f(x) = 0.000690021231422505 x² + 0.179414984259677 x + 16.115528096834R² = 0.975585064233167

f(x) = 0.0780796745686632 x + 10.9386260345069R² = 0.987658986517417

PSNT

N applied rate Kg ha-1

NH4+

NO3

mg

kg-1

0 100 200 3000

500

1000

1500

2000

2500

R² = 0.992195303109133

R² = 0.996257565134335

R² = 0.960769726977391

CSNT

N applied rate Kg ha-1NO3

mg

kg-1

0 50 100 150 200 2500

3

6

9

12

15

R² = 0.918948304690847

R² = 0.954318301085498

R² = 0.98045198486579

Grain Yield

N applied rate Kg ha-1Dry

matt

er M

g ha

-1

Lime Stabilized Biosolids

Anaerobically Digested Biosolids

CSNT

PSNT

Grain Yield

Biosolids Application

0 50 100 150 200 25010

15

20

25

30

R² = 0.98560642677126

R² = 0.993475051418577

R² = 0.940643067781971

ELN

N applied rate Kg ha-1

Tota

l N g

kg-

1