Prior S A, Torbert H A, Runion G B, Rogers H H, Kimball B A
National Soil Dynamics Laboratory, U.S. Department of Agriculture-Agricultural Research Service, 411 South Donahue Drive, Auburn, AL 36832, USA.
J Environ Qual. 2008 May 2;37(3):753-8. doi: 10.2134/jeq2007.0276. Print 2008 May-Jun.
The positive impact of elevated atmospheric CO(2) concentration on crop biomass production suggests more carbon inputs to soil. Further study on the effect of elevated CO(2) on soil carbon and nitrogen dynamics is key to understanding the potential for long-term carbon storage in soil. Soil samples (0- to 5-, 5- to 10-, and 10- to 20-cm depths) were collected after 2 yr of grain sorghum [Sorghum bicolor (L.) Moench.] production under two atmospheric CO(2) levels: (370 [ambient] and 550 muL L(-1) [free-air CO(2) enrichment; FACE]) and two water treatments (ample water and limited water) on a Trix clay loam (fine, loamy, mixed [calcareous], hyperthermic Typic Torrifluvents) at Maricopa, AZ. In addition to assessing treatment effects on soil organic C and total N, potential C and N mineralization and C turnover were determined in a 60-d laboratory incubation study. After 2 yr of FACE, soil C and N were significantly increased at all soil depths. Water regime had no effect on these measures. Increased total N in the soil was associated with reduced N mineralization under FACE. Results indicated that potential C turnover was reduced under water deficit conditions at the top soil depth. Carbon turnover was not affected under FACE, implying that the observed increase in soil C with elevated CO(2) may be stable relative to ambient CO(2) conditions. Results suggest that, over the short-term, a small increase in soil C storage could occur under elevated atmospheric CO(2) conditions in sorghum production systems with differing water regimes.
大气中二氧化碳浓度升高对作物生物量生产有积极影响，这意味着有更多碳输入土壤。进一步研究二氧化碳浓度升高对土壤碳氮动态的影响，是理解土壤长期碳储存潜力的关键。在亚利桑那州马里科帕的一种特里克斯黏壤土（细壤质、壤质、混合[石灰性]、热性典型干热雏形土）上，在两种大气二氧化碳水平（370[环境浓度]和550μL L⁻¹[自由空气二氧化碳浓度升高；FACE]）以及两种水分处理（充足水分和有限水分）条件下，种植了两年的粒用高粱[Sorghum bicolor (L.) Moench.]后，采集了土壤样本（深度为0至5厘米、5至10厘米和10至20厘米）。除了评估处理对土壤有机碳和全氮的影响外，还通过一项为期60天的实验室培养研究测定了潜在的碳氮矿化和碳周转。FACE处理两年后，所有土壤深度的土壤碳和氮均显著增加。水分状况对这些指标没有影响。FACE处理下土壤全氮增加与氮矿化减少有关。结果表明，在表层土壤深度，水分亏缺条件下潜在碳周转降低。FACE处理下碳周转不受影响，这意味着在二氧化碳浓度升高条件下观测到的土壤碳增加相对于环境二氧化碳条件可能是稳定的。结果表明，短期内，在不同水分状况的高粱生产系统中，大气二氧化碳浓度升高条件下土壤碳储存可能会有小幅增加。
