Semiarid Mediterranean agroecosyste

Semiarid Mediterranean agroecosystems need the implementation of sustainable land management
(SLM) practices in order to maintain acceptable levels of soil organic matter (SOM). The application of
SLM practices helps to maintain soil structure and physical-chemical protection of soil organic carbon
(SOC), hence improving soil carbon sequestration and mitigating CO2 emissions to the atmosphere. In an
organic, rain-fed almond (Prunus dulcis Mill., var. Ferragnes) orchard under reduced tillage (RT), as the
habitual management practice during the 14 years immediately preceding the experiment, we studied
the effect of two agricultural management practices on soil aggregate distribution and SOC stabilization
after four years of implementation. The implemented practices were (1) reduced tillage with a mix of
Vicia sativa L. and Avena sativa L. as green manure (RTG) and (2) no-tillage (NT). Four aggregate size classes
were differentiated by wet sieving (large and small macroaggregates, microaggregates, and the silt plus
clay fraction), and the microaggregates occluded within small macroaggregates (SMm) were isolated. In
addition, three organic C fractions were separated within the small macroaggregates and microaggregates,
using a density fractionation method: free light fraction (free LF-C), intra-aggregate
particulate OM (iPOM-C), and organic C associated with the mineral fraction (mineral-C). The results
show that the combination of reduced tillage plus green manure (RTG) was the most-efficient SLM
practice for SOC sequestration. The total SOC increased by about 14% in the surface layer (0–5 cm depth)
when compared to RT. Furthermore, green manure counteracted the effect of tillage on soil aggregate
rupture. The plant residue inputs from green manure and their incorporation into the soil by reduced
tillage promoted the formation of new aggregates and activated the subsequent physical-chemical
protection of OC. The latter mechanism occurred mainly in the fine iPOM-C occluded within
microaggregates and mineral-C occluded within small macroaggregates fractions, which together
contributed to an increase of up to 30% in the OC concentration in the bulk soil. No-tillage favored the OC
accumulation in the mineral-C within the small macroaggregates and in the fine iPOM-C occluded within
microaggregates in the surface layer, and in the mineral-C occluded within the small macroaggregates
and microaggregates at 5–15cm depth, but four years of cessation of tillage were not enough to
significantly increase the total OC in the bulk soil.

結果 (中文) 1:

半干旱地中海农田生态系统需要实施可持续土地管理(SLM) 的做法，以保持土壤有机质 (SOM) 的可接受的水平。中的应用SLM 做法有助于保持土壤结构和土壤有机碳的物理-化学保护(SOC)，因此改善土壤碳封存和减轻 CO2 排放到大气。在有机、 雨水灌溉杏仁 （李属椇轧机。，变种 Ferragnes） 果园下的作为减少耕作 (RT)习惯性的管理实践 14 年紧接实验，我们研究了两个农业管理实践对土壤集料的分布和 SOC 稳定的影响经过四年的执行情况。实施的做法是 (1) 减少的耕作的混合蚕豆根尖苜蓿草和燕麦苜蓿草作为绿肥 (RTG) 和 (2) 采用免耕 (NT)。四集料粒径节课用湿筛法 （大和小的 macroaggregates、 壤或加上淤泥分化粘土分数），和壤闭塞内小 macroaggregates (SMm) 被孤立。在另外，三个有机 C 组分分离小 macroaggregates 和壤内,使用密度分馏法︰ 免费轻馏分 (免费 LF-C)，内部聚合微粒 OM (iPOM-C) 和有机 C 与矿物组分 (矿物-C) 相关联。结果显示减少的耕 + 绿肥 (RTG) 的组合是最高效的运SOC 封存的实践。总的 SOC 增加了约 14%在表面层 (0 – 5 厘米深度)当相比，室温此外，绿肥抵消耕作对土壤聚合的影响破裂。从绿肥和其纳入由土壤植物残留投入减少耕作促进新聚集体的形成及激活后续的物理-化学保护的立案后者的机制主要发生在闭塞内细 iPOM C壤和矿物 C 闭塞内小 macroaggregates 分数，合在一起贡献大部分土壤业主立案法团浓度达 30%的升幅。免耕青睐业主立案法团积累在矿物 C 内小 macroaggregates 和精细的 iPOM C 闭塞内微团聚体的表面层，和矿物 C 闭塞内小 macroaggregates并在 5-15 厘米深度，但四年的耕作停止壤还不够给显著增加土体土壤总业主立案法团。

結果 (中文) 3:

地中海半干旱农业生态系统需要可持续土地管理实施（SLM）的做法，以维持可接受的土壤有机质（SOM）的水平。中的应用SLM的做法有助于保持土壤结构和土壤有机碳的物理保护（有机碳），从而提高土壤碳吸收和减轻二氧化碳排放到大气中。在一个有机旱作杏仁（扁桃磨。，var. Ferragnes）果园少耕（RT），作为在14年前的实验中，我们研究了习惯性的管理实践两种农业管理措施对土壤团聚体分布及土壤有机碳稳定性的影响经过四年的实施。实施的做法是（1）减少耕作的混合Vicia sativa L.和燕麦作为绿肥（RTG）和（2）免耕（NT）。四聚合大小类采用湿法筛分分化（大、小团聚体，团聚体，和粉+粘土分数），和微团聚体闭塞在小团聚体（SMM）进行分离。在此外，三的有机碳组分在小团聚体和微团聚体，采用密度分离法：免费的轻馏分（免费LF-C），内总颗粒有机质（ipom-c）、有机碳和矿物组分相关（mineral-c）。结果表明，减少翻耕绿肥（RTG）的组合是最有效的SLM土壤有机碳封存的实践。总SOC增加了约14%的表面层（0厘米5厘米的深度）相比，RT。此外，绿肥抵消耕作对土壤团聚体的影响破裂.从绿色肥料的植物残基输入到土壤中的减少耕作促进了新的聚集体的形成和随后的化学活性保护组织。主要从事精细ipom-c包藏在后者的发生机制微团聚体和mineral-c闭塞在小团聚体分数，一起导致多达30%在土体OC浓度增加。免耕有利于OC在mineral-c积累在小团聚体，在细ipom-c内闭塞在表面层的影响，并在mineral-c闭塞在小团聚体在5–15cm深度影响，但四年停止耕作是不够的显著增加土壤总有机碳。