INTRODUCTION

1. 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 • 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 (ZeamaysL.) was grown as test crop on an Orangeburg loamy sand (Fine-loamy, kaolinitic, thermicTypicKandiudults), 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) Lime Stabilized Biosolids Biosolids Application Anaerobically Digested Biosolids PSNT Grain Yield CSNT • RESULTS AND DISCUSSION • PSNT • Biosolids 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. • ELN • Biosolids 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. • CSNT • Biosolids 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 Yield • In 2009-2011, both biosolids produced higher grain yields than fertilizers; LS produced higher or equal level than AD. ELN Properties of land-applied biosolids in 2009-2011 • CONCLUSIONS • Tillage 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).