Impact of management practices on water extractable organic carbon and nitrogen from 12-year poultry litter amended soils

Authors: He, Zhongqi; ZHANG, MINGCHU - University Of Alaska; ZHAO, AIQIN - Chinese Society Of Agricultural Engineering; Waldrip, Heidi; PAGLIARI, PAULO - University Of Minnesota; Harmel, Daren

Submitted to: Open Journal of Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/2017
Publication Date: 10/27/2017
Citation: He, Z., Zhang, M., Zhao, A., Waldrip, H.M., Pagliari, P.H., Harmel, R.D. 2017. Impact of management practices on water extractable organic carbon and nitrogen from 12-year poultry litter amended soils. Open Journal of Soil Science. 7:259-277.

Interpretive Summary: Animal manure contains essential plant nutrients and functional organic matter components. When used properly, recycling manure as a soil amendment enhances soil fertility, promotes crop growth, and reduces on-farm costs for chemical fertilizer. Understanding long-term effects of manure application on water extractable organic matter (WEOM) components in soils is one of the important steps towards achieving this balance. Water extractable organic carbon (WEOC) and organic N (WEON) in soil which are two key WEOM parameters. This work determined the impact of poultry litter (PL) application on WEOC and WEON in soils under different crops, tillage regimes, and grazing strategies. Data indicated that positive relationships existed with PL application rate and soil NO3-N and soil WEOC and WEON concentrations. PL application increased the proportion of decomposable fulvic-like organic matter in the cultivated soils. However, a similar increase was not observed in pasture soils where the content of humic-like portion was still greater than that of fulvic-like portions in the PL-applied pasture soils. This work increased the knowledge of forms and availability of soluble C and N in PL-amended soils.

Technical Abstract: Water extractable organic carbon (WEOC) and organic N (WEON) are two key parameters of soil water extractable organic matter (WEOM). Proper management of manure application rate in combination with tillage and cropping management could maintain appropriate WEOC and WEON concentrations in soils while decreasing the risk of their runoff from cropland and pastures. The objective of this research was to determine the impact of poultry litter (PL) application on WEOC and WEON in soils under different crops, tillage regimes, and grazing strategies. From 2001 to 2012, PL was applied at multiple rates to cultivated fields in a corn-oat/wheat-hay rotation or to pastures grazed by cattle or ungrazed. Soil samples (0-15 cm) were analyzed for KCl-extractable mineral N, and WEOC, and WEON contents. In addition, Ultraviolet-visible (UV-vis) and fluorescence spectroscopies were used to characterize WEOC stability. Organic N levels were higher at the high PL application rates. The soil C:N ratio narrowed as the PL application rate increased. However, the soil from pastures which received PL tended to have a wider range of C:N ratios than soil from the cultivated fields , despite identical PL application rates. The spectral analyses indicated that WEOC properties were responsive to management and PL application rate; therefore, this parameter may be used as a guide to provide best management strategy for manure application.