Nitrogenous fertilizer effects on soil structural properties under switchgrass

作者：Jung Ji Young^*; Lal Rattan; Jastrow Julie D; Tyler Donald D

来源：Agriculture Ecosystems & Environment, 2011, 141(1-2): 215-220.

DOI：10.1016/j.agee.2011.01.016

• Switchgrass
• Nitrogen fertilizer
• Soil structure
• Aggregate stability
• Root
• Soil organic carbon (SOC)

Nitrogen (N) fertilization is needed to sustain the biomass yield of switchgrass (Panicum virgatum L, Poaceae) as a biofuel feedstock and, consequently, may influence the potential for soil quality improvements through soil organic carbon (SOC) sequestration. Therefore, the objective of this study was to assess how inorganic N application to switchgrass affects soil structural properties, which may feed back to affect the sustainability of biomass production. Soil was sampled at depths of 0-5, 5-10, and 10-15 cm in April and November 2008 during the fifth year of switchgrass growth in Milan, TN. Nitrogenous fertilizer was applied as NH(4)NO(3) at rates of 0, 67, and 202 kg N ha(-1) y(-1) beginning in the second year. Root weight density (RWD), root length density (RLD) and SOC concentration were measured under different N treatments as factors potentially influencing soil structural properties. Measured soil structural parameters included soil moisture characteristic curve (SMCC), and aggregate stability through wet-sieving. At 0-5 cm depth, spring RWD (3.8 mg cm(-3)) was significantly lower with 202 kg N ha(-1) application compared to 0 and 67 kg N ha(-1) (14.1 and 17.0 mg cm(-3), respectively). Although fall RWD did not vary among N treatments, RLD under 202 kg N ha(-1) (7.1 cm cm(-3)) was less than half of that at 0 kg N ha(-1) (15.7 cm cm(-3)). The SOC concentration was greater in both fertilized treatments than in the unfertilized treatment. Although SMCC varied somewhat between seasons, it did not exhibit any consistent trends attributable to N application. The proportion of macroaggregates for 0-10 cm depth were significantly greater in the 0 and 67 kg N ha(-1) treatments than in the 202 kg N ha(-1) treatment. These data suggest that excessive N application to switchgrass could have negative impacts on soil structural properties by reducing root biomass and length, crucial determinants of soil structure despite an increase in SOC.

• 出版日期2011-4
• 单位中国极地研究中心