Enke Liu1,2, Changrong Yan1,2*, Xurong Mei1,2, Yanqing Zhang1,2*, Tinglu Fan3

1 Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, China, 2 Key Laboratory of Dryland Farming g

Agriculture, Ministry of Agriculture of the People’s Republic of China (MOA), Beijing, China, 3 Dryland Agricultural Institute, Gansu Academy of Agricultural Sciences,

Lanzhou, Gansu, China

ABSTRACT

An understanding of the dynamics of soil organic carbon (SOC) as affected by farming practices is imperative for maintaining soil productivity and mitigating global warming. The objectives of this study were to investigate the effects of long-term fertilization on SOC and SOC fractions for the whole soil profile (0–100 cm) in northwest China. The study was initiated in 1979 in Gansu, China and included six treatments: unfertilized control (CK), nitrogen fertilizer (N), nitrogen and

phosphorus (P) fertilizers (NP), straw plus N and P fertilizers (NP+S), farmyard manure (FYM), and farmyard manure plus Nand P fertilizers (NP+FYM). Results showed that SOC concentration in the 0–20 cm soil layer increased with time except in the CK and N treatments. Long-term fertilization significantly influenced SOC concentrations and storage to 60 cm depth.

Below 60 cm, SOC concentrations and storages were statistically not significant between all treatments. The concentration of SOC at different depths in 0–60 cm soil profile was higher under NP+FYM follow by under NP+S, compared to under CK.

The SOC storage in 0–60 cm in NP+FYM, NP+S, FYM and NP treatments were increased by 41.3%, 32.9%, 28.1% and 17.9%, respectively, as compared to the CK treatment. Organic manure plus inorganic fertilizer application also increased labile soil organic carbon pools in 0–60 cm depth. The average concentration of particulate organic carbon (POC), dissolved organic carbon (DOC) and microbial biomass carbon (MBC) in organic manure plus inorganic fertilizer treatments (NP+S and NP+FYM) in 0–60 cm depth were increased by 64.9–91.9%, 42.5–56.9%, and 74.7–99.4%, respectively, over the CK treatment. The POC, MBC and DOC concentrations increased linearly with increasing SOC content.

These results indicate that long-term additions of organic manure have the most beneficial effects in building carbon pools among theinvestigated types of fertilization.

Citation: Liu E, Yan C, Mei X, Zhang Y, Fan T (2013) Long-Term Effect of Manure and Fertilizer on Soil Organic Carbon Pools in Dryland Farming in Northwest China. PLoS ONE 8(2): e56536. doi:10.1371/journal.pone.0056536

Editor: Vishal Shah, Dowling College, United States of America

Received November 4, 2012; Accepted January 10, 2013; Published February 20, 2013

Copyright: _ 2013 Liu et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted

use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: This study was supported by the National Basic Research Program of China (973 Program) (No.2012CB955904), the Chinese National Scientific Foundation (No. 31000253, 31170490), the 12th five-year plan of the National Key Technologies R&D Program (No. 2012BAD09B01). The authors declare that no external funding was received for this study.The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests: The authors have declared that no competing interests exist.

PLOS ONE | www.plosone.org 9 February 2013 | Volume 8 | Issue 2 | e56536: