Wetting and drying cycles in the maize rhizosphere under controlled conditions. Mechanics of the root-adhering soil
Wetting and drying cycles in the maize rhizosphere under controlled conditions. Mechanics of the root-adhering soil
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DOI：
10.1023/a:1004747323220
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发表时间：
2000-01-01
期刊：
影响因子：
4.9
通讯作者：
Bartoli, F
中科院分区：
文献类型：
--
作者：
Czarnes, S;Dexter, AR;Bartoli, F
对玉米(Zea Mays L.)上的表土(砂质泊德土和粉质Luvisol，FAO)的力学性质进行了研究。研究了土壤质地和收获时最终土壤吸力对根系和土壤质地的影响，三种土壤吸力分别为30、50和60kPa.还选择了两个尺度的观测：整个土壤：根系和根际土壤团聚体。用三种方法来表征土壤的稳定性：根系：在空气中机械振动，低功率超声波分散，有或没有初步浸泡土壤：在水中的根系。对土壤破坏动力学进行了分析和讨论，并用一级动力学方程进行了拟合。例如，在没有浸水的情况下，粉质土壤的超声动力学可以分为两个部分：第一个较快的部分，其平均速率K值为6.8-7.2MJ(-1)，归因于土壤的崩解；第二个较慢的部分，其特征为平均速率K值为1.5-1.6MJ(-1)，归因于“牢固粘根土壤”从根部破裂。根性粉质土的团聚体抗拉强度和脆性均表现出明显的植物效应，其团聚体强度(450-500kPa)高于其主体粉质土(410-420kPa)，而脆性(团聚体强度的变异系数)低于其主体粉质土(例如，在土壤吸力为30kPa时为67%)低于其主体粉质土(例如，在30kPa时为49%)。这些影响归因于根系分泌物，最干燥的粉质表土的根系分泌物显著高于湿润的表土。总之，粉质表土附着在玉米根际的力学性质归因于玉米根际发生的物理和生物相互作用。
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.