Different fall/winter cover crop root patterns induce contrasting red soil (Ultisols) mechanical resistance through aggregate properties,Plant and Soil

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Different fall/winter cover crop root patterns induce contrasting red soil (Ultisols) mechanical resistance through aggregate properties
Plant and Soil ( IF 3.9 ) Pub Date : 2022-04-20 , DOI: 10.1007/s11104-022-05430-4
Waqar Ali ₁ , Mingxuan Yang ₁ , Qi Long ₁ , Sadeed Hussain ₁ , Jiazhou Chen ₁ , Yangbo He ₁ , David Clay ₂

Affiliation

Purpose

Red soil (Ultisol) with high clay content and low aggregation results in high soil mechanical resistance and often suppresses crop root growth and productivity. Bio-tillage can be an effective tillage method to reduce the high soil mechanical resistance. This study aims to investigate different bio-tillage plants' root effects on soil mechanical resistance through soil aggregates properties.

Methods

The experiment designed 5 fall/winter cover crops (2 raps cultivars, lucerne, one-year vetiver (Vet_1Y) and six-year vetiver (Vet_6Y) as bio-tillage before summer maize and one control treatment. Plant root morphological and chemical traits, soil organic carbon (SOC), soil aggregate properties and soil mechanical resistance (measured and fitted values using model) were determined.

Results

The fibrous-rooted vetiver showed the largest root length density (RLD) (ranging from 2.71 to 4.82 cm cm⁻³), highest root diameter (RD) in deep soil depth, highest percentage of fine roots (0.2–0.5 mm), while lowest root lignin/cellulose ratio than tap-rooted lucerne and rapes. These root properties resulted in the highest improvement in the macroaggregate (> 5 mm and 5–2 mm) percentage for vetiver and especially for perennial Vet_6Y compared to other crops and control. Finally, fibrous-rooted vetiver contributed to the least soil mechanical resistance values followed by lucerne and two rapes compared to fallow. This was attributed to their positive root effect on improvement in macroaggregate and decrease in soil bulk density.

Conclusion

Our finding suggested that fibrous-rooted vetiver can be selected as a bio-tillage plant to improve soil physical properties, especially to reduce high mechanical resistance in clayey red soil.

中文翻译：

不同的秋季/冬季覆盖作物根系模式通过聚合特性诱导对比红土（Ultisol）机械阻力

目的

具有高粘土含量和低聚集性的红土 (Ultisol) 会导致高土壤机械阻力，并经常抑制作物根系生长和生产力。生物耕作是降低土壤高机械阻力的有效耕作方法。本研究旨在通过土壤团聚体特性研究不同生物耕作植物根系对土壤机械阻力的影响。

方法

本试验设计了 5 种秋冬覆盖作物（2 种 raps 品种、苜蓿、一年香根草（Vet_1Y）和六年香根草（Vet_6Y）作为夏玉米前的生物耕作和一种对照处理。植物根系形态和化学性状，测定了土壤有机碳（SOC）、土壤团聚体特性和土壤机械阻力（使用模型测量和拟合的值）。

结果

须根香根草显示出最大的根长密度（RLD）（范围为 2.71 至 4.82 cm cm ^-3），在深层土壤深度中根直径（RD）最大，细根百分比最高（0.2-0.5 mm），而根木质素/纤维素比低于直根苜蓿和油菜。与其他作物和对照相比，这些根特性导致香根草，尤其是多年生植物 Vet_6Y 的大聚集体（> 5 毫米和 5-2 毫米）百分比的最大改善。最后，与休耕相比，纤维根香根草对土壤机械阻力的贡献最小，其次是苜蓿和两种油菜。这归因于它们对改善大团聚体和降低土壤容重的积极根系效应。