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Wetting and drying cycles, organic amendments, and gypsum play a key role in structure formation and stability of sodic Vertisols
Soil ( IF 5.8 ) Pub Date : 2023-03-03 , DOI: 10.5194/soil-9-141-2023
Sara Niaz , J. Bernhard Wehr , Ram C. Dalal , Peter M. Kopittke , Neal W. Menzies

Abstract. In the natural environment, soils undergo wetting and drying (WD) cycles due to precipitation and evapotranspiration. The WD cycles have a profound impact on soil physical, chemical, and biological properties and drive the development of structure in soils. Degraded soils are often lacking structure, and the effect of organic amendments and WD cycles on structure formation of these soils is poorly understood. The aim of this study was to evaluate the role of biotic and abiotic factors on aggregate formation and stabilization of sodic soils after the addition of gypsum and organic amendments (feedlot manure, chicken manure, lucerne pallets, and anionic poly acrylamide). Amended soils were incubated at 25 ∘C over four WD cycles, with assessment of soil microbial respiration, electrical conductivity, pH, sodium adsorption ratio (SAR), aggregate stability in water (ASWAT), aggregate size distribution, and mean weight diameter. Our results demonstrate that WD cycles can improve aggregate stability after the addition of amendments in sodic Vertisols, but this process depends on the type of organic amendment. Lucerne pellets resulted in highest soil microbial respiration, proportions of large macroaggregates (>2000 µm), and mean weight diameter. In contrast, dispersion was significantly reduced when soils were treated with chicken manure, whilst anionic polyacrylamide only had a transient effect on aggregate stability. When these organic amendments were applied together with gypsum, the stability of aggregates was further enhanced, and dispersion became negligible after the second WD cycle. The formation and stability of small macroaggregates (2000–250 µm) was less dependent on the type of organic amendments and more dependent on WD cycles as the proportion of small macroaggregates also increased in control soils after four WD cycles, highlighting the role of WD cycles as one of the key factors that improves aggregation and stability of sodic Vertisols.

中文翻译:

干湿循环、有机改良剂和石膏在钠变性土的结构形成和稳定性中起着关键作用

摘要。在自然环境中,由于降水和蒸散,土壤会经历干湿 (WD) 循环。WD 循环对土壤的物理、化学和生物特性具有深远的影响,并推动土壤结构的发展。退化的土壤通常缺乏结构,有机改良剂和 WD 循环对这些土壤结构形成的影响知之甚少。本研究的目的是评估添加石膏和有机改良剂(饲养场粪便、鸡粪、紫花苜蓿托盘和阴离子聚丙烯酰胺)后生物和非生物因素对团聚体形成和稳定的作用。改良土壤在 25 ∘C 下孵育四个 WD 循环,评估土壤微生物呼吸、电导率、pH 值、钠吸附率 (SAR)、水中的聚集体稳定性 (ASWAT)、聚集体尺寸分布和平均重量直径。我们的结果表明,WD 循环可以在添加含钠变性土的修正剂后提高聚集体稳定性,但这个过程取决于有机修正剂的类型。Lucerne 颗粒导致最高的土壤微生物呼吸、大型大团聚体(>2000 µm)的比例和平均重量直径。相比之下,当用鸡粪处理土壤时,分散性显着降低,而阴离子聚丙烯酰胺仅对聚集体稳定性产生短暂影响。当这些有机改良剂与石膏一起使用时,骨料的稳定性进一步增强,并且在第二次 WD 循环后分散变得可以忽略不计。
更新日期:2023-03-03
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