High capacity of integrated crop–pasture systems to preserve old soil carbon evaluated in a 60-year-old experiment

Author:

González-Sosa MaximilianoORCID,Sierra Carlos A.ORCID,Quincke J. AndrésORCID,Baethgen Walter E.ORCID,Trumbore SusanORCID,Pravia M. Virginia

Abstract

Abstract. Integrated crop–pasture rotational systems can store larger soil organic carbon (SOC) stocks in the topsoil (0–20 cm) than continuous grain cropping. The aim of this study was to identify if the main determinant for this difference may be the avoidance of old C losses in integrated systems or the higher rate of new C incorporation associated with higher C input rates. We analyzed the temporal changes of 0–20 cm SOC stocks in two agricultural treatments of different intensity (continuous annual grain cropping and crop–pasture rotational system) in a 60-year experiment in Colonia, Uruguay. We incorporated this information into a process of building and parameterizing SOC compartmental dynamical models, including data from SOC physical fractionation (particulate organic matter, POM > 53 µm > mineral-associated organic matter, MAOM), radiocarbon in bulk soil, and CO2 incubation efflux. This modeling process provided information about C outflow rates from pools of different stability, C stabilization dynamics, and the age distribution and transit times of C. The differences between the two agricultural systems were mainly determined by the dynamics of the slow-cycling pool (∼MAOM). The outflow rate from this compartment was between 3.68 and 5.19 times higher in continuous cropping than in the integrated system, varying according to the historical period of the experiment considered. The avoidance of old C losses in the integrated crop–pasture rotational system resulted in a mean age of the slow-cycling pool (∼MAOM) of over 600 years, with only 8.8 % of the C in this compartment incorporated during the experiment period (after 1963) and more than 85 % older than 100 years old in this agricultural system. Moreover, half of the C inputs to both agricultural systems leave the soil in approximately 1 year due to high decomposition rates of the fast-cycling pool (∼POM). Our results show that the high capacity to preserve old C of integrated crop–pasture systems is the key for SOC preservation of this sustainable intensification strategy, while their high capacity to incorporate new C into the soil may play a second role. Maintaining high rates of C inputs and relatively high stocks of labile C appear to be a prerequisite for maintaining low outflow rates of the MAOM pool.

Publisher

Copernicus GmbH

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3