U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Https

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

PubAg

Main content area

Nitrogen and harvest effects on soil properties under rainfed switchgrass and no-till corn over 9 years: implications for soil quality

Author:
Catherine E. Stewart, Ronald F. Follett, Elizabeth G. Pruessner, Gary E. Varvel, Kenneth P. Vogel, Robert B. Mitchell
Source:
Global change biology 2015 v.7 no.2 pp. 288-301
ISSN:
1354-1013
Subject:
Panicum virgatum, Zea mays, aggregate stability, bioenergy, bulk density, corn, corn stover, crop production, energy crops, fertilizer rates, harvesting, long term effects, microbial biomass, nitrogen, nitrogen fertilizers, no-tillage, pH, rainfed farming, soil aggregation, soil degradation, soil microorganisms, soil organic carbon, soil quality
Abstract:
Nitrogen fertilizer and harvest management will alter soils under bioenergy crop production and the long-term effects of harvest timing and residue removal remain relatively unknown. Compared to no-tilled corn (NT-C, Zea mays L.), switchgrass (Panicum virgatum L.) is predicted to improve soil properties [i.e. soil organic C (SOC), soil microbial biomass (SMB-C), and soil aggregation] due to its perennial nature and deep-rooted growth form, but few explicit field comparisons exist. We assessed soil properties over 9 years for a rainfed study of N fertilizer rate (0, 60, 120, and 180 kg N ha-1) and harvest management on switchgrass (harvested in August and postfrost) and NT-C (with and without 50% stover removal) in eastern NE. We measured SOC, aggregate stability, SMB-C, bulk density (BD), pH, P and K in the top 0-30 cm. Both NT-C and switchgrass increased SMB-C, SOC content, and aggregate stability over the 9 years, reflecting improvement from previous conventional management. However, the soils under switchgrass had double the percent aggregate stability, 1.3 times more microbial biomass, and a 5-8% decrease in bulk density in the 0-5 and 5-10 cm depths compared to NT-C. After 9 years, cumulative decrease in available P was significantly greater beneath NT-C (-24.0 kg P ha-1) compared to switchgrass (-5.4 kg P ha-1). When all measured soil parameters were included in the Soil Management Assessment Framework (SMAF), switchgrass improved soil quality index over time (Delta SQI) in all depths. NT-C without residue removal did not affect Delta SQI, but 50% residue removal decreased Delta SQI (0-30 cm) due to reduced aggregate stability and SMB-C. Even with best-management practices such as NT, corn stover removal will have to be carefully managed to prevent soil degradation. Long-term N and harvest management studies that include biological, chemical, and physical soil measurements are necessary to accurately assess bioenergy impacts on soils.
Agid:
62133
Handle:
10113/62133