Particulate Organic Matter Affects Soil Nitrogen Mineralization under Two Crop Rotation Systems.

Rongyan Bu,Bo Liu,Xiaokun Li,Rihuan Cong,Jianwei Lu,Tao Ren,Manuel Reigosa

doi:10.1371/journal.pone.0143835

Rongyan Bu, Bo Liu + Show 5 more

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https://doi.org/10.1371/journal.pone.0143835

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Journal: PloS one	Publication Date: Dec 8, 2015
Citations: 29	License type: CC BY 4.0

Affiliation: Huazhong Agricultural University

Abstract

Changes in the quantity and/or quality of soil labile organic matter between and after different types of cultivation system could play a dominant role in soil nitrogen (N) mineralization. The quantity and quality of particulate organic matter (POM) and potentially mineralizable-N (PMN) contents were measured in soils from 16 paired rice-rapeseed (RR)/cotton-rapeseed (CR) rotations sites in Hubei province, central China. Then four paired soils encompassing low (10th percentile), intermediate (25th and 75th percentiles), and high (90th percentile) levels of soil PMN were selected to further study the effects of POM on soil N mineralization by quantifying the net N mineralization in original soils and soils from which POM was removed. Both soil POM carbon (POM-C) and N (POM-N) contents were 45.8% and 55.8% higher under the RR rotation compared to the CR rotation, respectively. The PMN contents were highly correlated with the POM contents. The PMN and microbial biomass N (MBN) contents concurrently and significantly decreased when POM was removed. The reduction rate of PMN was positively correlated with changes in MBN after the removal of POM. The reduction rates of PMN and MBN after POM removal are lower under RR rotations (38.0% and 16.3%, respectively) than CR rotations (45.6% and 19.5%, respectively). Furthermore, infrared spectroscopy indicated that compounds with low-bioavailability accumulated (e.g., aromatic recalcitrant materials) in the soil POM fraction under the RR rotation but not under the CR rotation. The results of the present study demonstrated that POM plays a vital role in soil N mineralization under different rotation systems. The discrepancy between POM content and composition resulting from different crop rotation systems caused differences in N mineralization in soils.

Highlights

IntroductionSoil organic matter (SOM) mineralization can account for 50–80% of N accumulation by crops [1]
Given favorable growth conditions, soil organic matter (SOM) mineralization can account for 50–80% of N accumulation by crops [1]
The potentially mineralizable-N (PMN) contents were closely related to the particulate organic matter (POM) contents and appeared to be governed by intrinsic biochemical differences in the POM between the different rotation systems

Summary

Introduction

Soil organic matter (SOM) mineralization can account for 50–80% of N accumulation by crops [1]. Mineralization of SOM is a complex biochemical process that is affected by many factors, including environmental conditions [4], indigenous soil properties [5], soil microbial communities [6] and agricultural practices [7]. Especially labile SOM fraction, plays a dominant role in N mineralization because it serves as an accessible energy source for microorganisms and results in greater soil N mineralization [9]. Ros et al [13] reported that labile SOM fractions acted as the source of soil mineralizable N. The role of labile SOM in N mineralization is remains obscure

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