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The role of cover crops in the loss of protected and non-protected soil organic carbon fractions due to water erosion in a Mediterranean olive grove
Soil and Tillage Research ( IF 6.5 ) Pub Date : 2021-06-30 , DOI: 10.1016/j.still.2021.105119
M. López-Vicente , J.A. Gómez , G. Guzmán , J. Calero , R. García-Ruiz

Soil erosion plays an important role in C cycling at farm scale, especially in bare soil areas. In Mediterranean woody crops, temporary cover crops (CC) effectively reduce soil erosion and increase total and protected soil organic carbon (SOC) fractions. However, the effects of CC in olive groves on the preferential loss of organic carbon (Corg) fractions remains poorly understood. To address this issue, in four plots with seeded CC and two tilled plots (CT) in a Spanish olive grove, the unprotected and protected Corg fractions were measured in soil and sediments over the course of a hydrological year. The sediment/soil C enrichment ratios (ERSOC) were calculated, and results analysed considering the rainfall regimes of the site: dry (DS), heavy-rainy (HRS) and rainy (RS). Total, unprotected and protected Corg contents in the top 5 cm soil of CC plots were 46 %, 88.4 % and 28.5 %, respectively, higher than those of CT. 79.7 % and 70.3 % of the annual sediment yield (SY) was collected during December in CC and CT plots, respectively. Soil loss in CC plots (x¯ = 9.2 Mg ha–1 yr–1) was significantly lower (−55.6 %) than that in CT plots. Despite that the average eroded Corg was higher in the CT (x¯ = 222 kg C ha–1 yr–1) compared to CC (x¯ = 148 kg C ha–1 yr–1) plots differences were not significant due to the higher Corg concentration in the sediment from CC plots. The highest proportion of eroded Corg (44%–45%) corresponded to the physically protected fraction. The highest ERSOC (1.99 and 2.04 for CC and CT, respectively) was recorded in DS whereas the lowest was in the RS (0.90) and HRS (0.96) seasons. The mean ERSOC were of 1.00 and 0.92 in the CC and CT plots, with no significant difference. The fact that most of the SY was recorded in one month, when CC plants were not fully developed, might explain the ERSOC at 1, and why their presence did not modify it. This study demonstrates that CC favours greater total, unprotected and protected Corg fractions in the topsoil, promoting soil C sequestration. The asynchrony between the periods of full development of the CC plants and those with the highest rainfall erosivity prevented any selectiveness of the eroded Corg. Thus, fast-growing CC plant species with short life-cycles are recommended, as well as adequate management to promote self-seeding avoiding soil disturbance for seeding in erosion prone seasons.



中文翻译:

由于地中海橄榄林的水蚀,覆盖作物在受保护和非受保护土壤有机碳部分损失中的作用

土壤侵蚀在农场规模的碳循环中起着重要作用,尤其是在裸土地区。在地中海木本作物中,临时覆盖作物 (CC) 可有效减少土壤侵蚀并增加总和受保护的土壤有机碳 (SOC) 比例。然而,橄榄树中 CC 对有机碳 (C org ) 部分优先损失的影响仍然知之甚少。为了解决这个问题,在西班牙橄榄树林中的四个带种子 CC 的地块和两个耕地 (CT) 中,在一个水文年的过程中测量了土壤和沉积物中未受保护和受保护的 C有机组分。沉积物/土壤 C 富集比(ER SOC) 进行计算,并考虑该地点的降雨情况对结果进行分析:干燥 (DS)、大雨 (HRS) 和多雨 (RS)。CC样地表层5 cm土壤中总、未保护和保护C org含量分别比CT高46 %、88.4 %和28.5 %。12 月份在 CC 和 CT 地块中分别收集了 79.7% 和 70.3% 的年产沙量 (SY)。CC 地块中的土壤流失 (X¯= 9.2 Mg ha –1 yr –1 ) 明显低于 CT 图中的 (-55.6 %)。尽管平均侵蚀 C org在 CT 中较高(X¯= 222 kg C ha –1 yr –1 ) 与 CC (X¯= 148 kg C ha –1 yr –1 ) 地块差异不显着,因为来自 CC 地块的沉积物中的C org浓度较高。最高比例的侵蚀 C组织(44%–45%) 对应于物理保护的部分。最高 ER SOC(CC 和 CT 分别为 1.99 和 2.04)记录在 DS 中,而最低的是 RS (0.90) 和 HRS (0.96) 季节。CC 和 CT 图中的平均 ER SOC分别为 1.00 和 0.92,没有显着差异。大多数 SY 是在一个月内记录的,当 CC 植物没有完全发育时,这一事实可能解释了 ER SOC在 1,以及为什么他们的存在没有修改它。该研究表明,CC 有利于表层土壤中更多的总的、未受保护的和受保护的 C有机部分,促进土壤 C 封存。CC 植物的完全发育时期与降雨侵蚀性最高的时期之间的不同步阻止了对侵蚀的 C org 的任何选择性. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 因此,建议使用生命周期短的快速生长的 CC 植物物种,以及适当的管理,以促进自我播种,避免土壤干扰,以便在易受侵蚀的季节播种。 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

更新日期:2021-06-30
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