在潮湿的夏季,通过土壤水分控制景观位置对有机物分解的影响

IF 6.1 1区 农林科学 Q1 SOIL SCIENCE Soil & Tillage Research Pub Date : 2024-08-28 DOI:10.1016/j.still.2024.106277
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引用次数: 0

摘要

可持续的耕地管理需要保护土壤有机质(SOM)。尽管从大量的实地和实验室研究中获得了深入的了解,但我们对新鲜有机质(OM)分解及其转化为土壤有机碳(SOC)的景观尺度空间变化了解甚少。特别是,当地的地形位置可能会通过土壤水文来共同控制这些过程。在这项研究中,我们试图通过在 10 块缓坡耕地上设置两个对比位置的田间试验来确定这种控制是否显著,这些耕地覆盖了三种不同的土壤质地组,即壤土、(沙)壤土和粉砂壤土。我们希望将 OM 分解与田间土壤湿度差异联系起来,同时尽量减少其他土壤和管理因素的变化。具体地说,我们在田间放置了富含 13C 的黑麦草(OM 来源)的中置样器十周,然后将土壤分成 500 微米、53 - 500 微米和 53 微米三个大小的部分。总体而言,我们发现,壤质砂土、(砂质)壤土和粉质壤土的低洼位置比高洼位置湿润,充满水的孔隙空间平均差异分别为 11%、20% 和 16%。令人惊讶的是,添加的 OM 的矿化与地貌位置无关,尽管在地势低的地方水分条件似乎比最佳条件湿润,但在地势高的地方则不然。剩余的黑麦草残留物 > 500 µm 确实遵循当地地形导致的土壤湿度梯度,在地势低的地方含量较高。换句话说,地势高处更干燥的条件改善了粗OM的分解,因此有更多的黑麦草碳(C)最终进入更细的土壤组分(< 500 µm)。此外,土壤质地也会影响最小部分(53 微米)的分解,对质地较细(粉砂壤土)的土壤有稳定作用。我们的结论是,尽管不同景观位置之间的湿度条件存在显著差异,但在观测到的夏季潮湿时期,田间 OM 矿化的空间变异性总体上是有限的。然而,地貌位置会影响残余未矿化碳的质量,在较干燥的高地,新加入的 OM 转化为与淤泥和粘土相关的 OM 的情况相对较多,这可能会提高 SOM 的长期稳定性。同样,还需要在不同天气条件下进行观测,以评估是否有必要建立当地土壤水文的精确模型,从而预测景观尺度上 SOC 储量的演变。
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Control of landscape position on organic matter decomposition via soil moisture during a wet summer

Sustainable cropland management requires preservation of soil organic matter (SOM). In spite of in depth understanding gained from ample field and laboratory studies, we have a poor understanding of landscape scale spatial variation of fresh organic matter (OM) decomposition and its conversion into soil organic carbon (SOC). Particularly, local topographic position may be expected to co-control these processes via soil hydrology. In this study, we sought to identify if such control is significant by setting up a field experiment with two contrasting positions across 10 gently sloping cropland fields covering three different soil texture groups, i.e. loamy sand, (sandy) loam and silt loam. We wanted to link OM decomposition to within-field differences in soil moisture, whilst keeping variation in other soil and management factors minimal. Specifically, mesocosms with 13C enriched ryegrass (the OM source) were incorporated in the fields for ten weeks and afterwards, soil was separated into > 500 µm, 53 – 500 µm and < 53 µm sized fractions. Overall, we found that lower located positions were wetter than higher positions with average differences of 11 %, 20 % and 16 % in water-filled pore space for the loamy sand, (sandy) loam and silt loam soil, respectively. Mineralization of added OM was surprisingly independent of landscape position, even though moisture conditions appeared wetter than optimal at the low but not at the high landscape positions. Remaining ryegrass residues > 500 µm did follow local topography-driven gradients in soil moisture with higher amounts in low landscape positions. In other words, drier conditions at high landscape positions improved coarse OM decomposition, with consequently more ryegrass-carbon (C) ending up in finer soil fractions (< 500 µm). Additionally, soil texture affected decomposition of the smallest fraction (< 53 µm) with a stabilizing effect for finer-textured (silt loam) soils. We conclude that, despite significant contrasts in moisture conditions between landscape positions, within-field spatial variability of OM mineralization was overall limited during the observed wet summer period. Nevertheless, landscape position affected the quality of remnant unmineralized C, with relatively more conversion of freshly added OM into OM associated with silt and clay at the drier higher positions, potentially improving the long-term stability of SOM. Likewise observations under different weather conditions are needed to evaluate the necessity of precise modelling of local soil hydrology for predicting SOC stock evolution on the landscape scale.

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来源期刊
Soil & Tillage Research
Soil & Tillage Research 农林科学-土壤科学
CiteScore
13.00
自引率
6.20%
发文量
266
审稿时长
5 months
期刊介绍: Soil & Tillage Research examines the physical, chemical and biological changes in the soil caused by tillage and field traffic. Manuscripts will be considered on aspects of soil science, physics, technology, mechanization and applied engineering for a sustainable balance among productivity, environmental quality and profitability. The following are examples of suitable topics within the scope of the journal of Soil and Tillage Research: The agricultural and biosystems engineering associated with tillage (including no-tillage, reduced-tillage and direct drilling), irrigation and drainage, crops and crop rotations, fertilization, rehabilitation of mine spoils and processes used to modify soils. Soil change effects on establishment and yield of crops, growth of plants and roots, structure and erosion of soil, cycling of carbon and nutrients, greenhouse gas emissions, leaching, runoff and other processes that affect environmental quality. Characterization or modeling of tillage and field traffic responses, soil, climate, or topographic effects, soil deformation processes, tillage tools, traction devices, energy requirements, economics, surface and subsurface water quality effects, tillage effects on weed, pest and disease control, and their interactions.
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