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首页> 外文期刊>Plant and Soil >Wetting and drying cycles in the maize rhizosphere under controlledconditions. Mechanics of the root-adhering soil
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Wetting and drying cycles in the maize rhizosphere under controlledconditions. Mechanics of the root-adhering soil

机译：受控条件下玉米根际的干湿循环。固根土的力学

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Mechanical properties of the topsoil (sandy Podsol and silty Luvisol, FAO) adhering to maize (Zea mays L.) roots and its bulk soil counterpart were studied as a function of soil texture and final soil water suction at harvest, with three soil water suction values of approximately 30, 50 and 60 kPa. Two scales of observation were also selected: the whole soil:root system and the root-adhering soil aggregates. Three methods were used to characterize the stability of the soil:root system: mechanical shaking in air, and dispersion by low-power ultrasonication, with or without preliminary immersion of the soil:root system in water. Soil disruption kinetics, which were fitted with first-order kinetics equations, were analyzed and discussed. For example, silty soil ultrasonication kinetics, without preliminary water-immersion, could be divided into two parts: the first faster part, which was characterized by a mean rate K value of 6.8-7.2 mJ(-1), is attributed to soil slaking, whereas the second slower part, which was characterized by a mean rate K value of 1.5-1.6 mJ(-1), was attributed to the rupture of the 'firmly root-adhering soil' from the roots. A clear plant effect was observed for both aggregate tensile strength and friability, with higher aggregate strength for the root-adhering silty soil (450-500 kPa) than for its bulk silty soil counterpart (410-420 kPa), and lower friability (coefficient of variation of the aggregate strength) for the root-adhering silty soil (e.g. 67% at a soil water suction value of 30 kPa) than for its bulk silty soil counterpart (e.g. 49% at asoil water suction value of 30 kPa). These effects were attributed to root exudation, which was significantly higher for the driest silty topsoil than for the wetter ones. In conclusion, the mechanical properties of the silty topsoil adhering to the maize roots are attributed to both physical and biological interactions occurring in the maize rhizosphere.
机译：研究了粘附于玉米根（Zea mays L.）及其表层土壤的表土（桑迪·波德索尔和粉质Luvisol，粮农组织）的机械特性与收获时土壤质地和最终土壤吸水率的关系，其中三个土壤吸水率值约为30、50和60 kPa。还选择了两个观测尺度：整个土壤：根系和附着根的土壤团聚体。三种方法用于表征土壤：根系：在空气中的机械摇晃，以及通过低功率超声进行分散（无论是否将土壤：根系预先浸入水中）的稳定性。分析和讨论了拟合一级动力学方程的土壤破坏动力学。例如，粉质土的超声动力学，无需预先浸水，可分为两部分：第一个较快的部分，其特征是平均速率K值为6.8-7.2 mJ（-1），这归因于土壤结块。 ，而第二个较慢的部分的特征是平均速率K值为1.5-1.6 mJ（-1），这归因于从根部“牢固地附着土壤”的破裂。观察到明显的植物效应，即骨料抗张强度和脆性，与根部粉质土壤的团聚强度（450-500 kPa）相比，块状粉质土壤的团聚强度（410-420 kPa）高，脆性（系数）低。粘附根的粉质土壤的总强度变化（例如，在30 kPa的土壤吸水值下为67％）比其粉质土壤相应的（例如，在30 kPa的土壤水分吸水值下为49％）。这些影响归因于根系渗出，最干燥的粉质表层土比湿润的表土高得多。总之，粘附于玉米根部的粉质表土的机械特性归因于玉米根际中发生的物理和生物相互作用。

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