Impact of Management Practices on Water Extractable Organic Carbon and Nitrogen from 12-Year Poultry Litter Amended Soils

Paulo H. Pagliari,Zhongqi He,Aiqing Zhao,R. Daren Harmel,Mingchu Zhang,Heidi M. Waldrip

doi:10.4236/ojss.2017.710019

Abstract

Water extractable organic carbon (WEOC) and nitrogen (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 effect 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.

Highlights

Animal manure contains essential plant nutrients and functional organic matter components
While numerous studies have focused on runoff N and P from manure, less attention has been paid to how manure impacts Water extractable organic carbon (WEOC) and WEON in soil which are two key water extractable organic matter (WEOM) components [10] [11] [12] [13] [14]
The soil WEOC and WEON concentrations varied from year to year, indicating dynamics of labile soil C (Figure 1) and N (Figure 2) and the spatial variability of these properties

Summary

Introduction

Animal manure contains essential plant nutrients and functional organic matter components. Improper management of manure can result in nutrient runoff from fertilized crop land and pastures, resulting in eutrophication of lakes, rivers and other surface waters [2]. It is crucial for livestock managers and crop producers to obtain a sustainable balance between beneficial manure use/recycling and negative environmental consequences [3]. Manure from poultry operations is in the form of poultry litter (PL), which is manure mixed with bedding material or litter (wood shavings or sawdust) and feathers Both poultry manure and PL are rich in plant nutrients, including nitrogen (N) and phosphorus (P). While numerous studies have focused on runoff N and P from manure, less attention has been paid to how manure impacts WEOC and WEON in soil which are two key WEOM components [10] [11] [12] [13] [14]

Objectives

Methods

Results

Conclusion