TY - JOUR
T1 - Additive effects of organic and inorganic amendments can significantly improve structural stability of a sodic dispersive subsoil
AU - Fang, Yunying
AU - Singh, Bhupinder Pal
AU - Van Zwieten, Lukas
AU - Collins, Damian
AU - Pitt, Wayne
AU - Armstrong, Roger
AU - Tavakkoli, Ehsan
N1 - Funding Information:
This research is supported by Grains Research and Development Corporation in Australia (project number: DAV00149). We thank Graeme Schwenke from New South Wales Department of Primary Industries (NSW DPI) and Lawrence Di Bella (Herbert Cane Productivity Services Limited) for providing organic amendments. We are thankful to Graeme Poile, Yan Jia, and Promil Mehra from NSW DPI for their technical assistance, and the help from Ashlea Webster and Francesca Galea for setting up the experiment. We acknowledge Michael Mclean and Jessica L. Rigg for the internal review and comments provided.
Funding Information:
This research is supported by Grains Research and Development Corporation in Australia (project number: DAV00149). We thank Graeme Schwenke from New South Wales Department of Primary Industries (NSW DPI) and Lawrence Di Bella (Herbert Cane Productivity Services Limited) for providing organic amendments. We are thankful to Graeme Poile, Yan Jia, and Promil Mehra from NSW DPI for their technical assistance, and the help from Ashlea Webster and Francesca Galea for setting up the experiment. We acknowledge Michael Mclean and Jessica L. Rigg for the internal review and comments provided.
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/12/15
Y1 - 2021/12/15
N2 - Sodic dispersive subsoils pose significant constraints to agricultural productivity and sustainability in arid and semiarid regions. Gypsum and organic amendments (OAs) have shown the potential to improve soil structure and fertility and may address constraints associated with these dispersive soils. However, the mechanistic linkages between the quality of OAs, and the dynamics of soil structural stability (i.e., soil aggregates), particularly under the interactive impacts of gypsum and exogenous nutrients, remain elusive. We quantified aggregate stability (i.e., wet mean weight diameter, WMWD) and the accumulation of OA-carbon (C) in different aggregate-classes in a dispersive clay subsoil (δ13C −24.5‰) with or without the application of OAs (δ13C −12.8 to −14.3‰), gypsum and/or exogenous nutrients (nitrogen (N) and phosphorus (P)) over the 270 days incubation period. The OAs include sorghum stubble and sugarcane bagasse that were low C quality (e.g., C:N:P ratio of 328:6.2:1 and 850:17.3:1, respectively) and less decomposed (e.g., low alkyl-C/o-alkyl-C ratio), and sugarcane mill mud that was high C quality (C:N:P ratio of 17:1.4:1) and more decomposed status. The results suggest that the quality of OAs is likely to control the dominant mechanisms of soil aggregation: (i) a quick top-down formation of aggregate hierarchy (~31 days) in the low C quality and less decomposed OAs; and (ii) a slow bottom-up formation of aggregate hierarchy (≥90 days) in the high C-quality and more decomposed OA. Over time, lowering the C-nutrient stoichiometric ratio of OAs (via exogenous nutrients) decreased aggregate stability by 30%, owing to accelerated breakdown/loss of OAs (i.e., by 16%). The exchangeable Ca2+ (from gypsum) was positively correlated to WMWD and water stable aggregates (>0.05 mm), which were not influenced by OAs or nutrients. In this dispersive clay subsoil, a long-term positive effect on soil aggregation occurred when improving either biochemical properties (e.g., microbial biomass and soil organic C) or chemical properties (e.g., soil dispersion, exchangeable sodium percentage, and pH), and an additive effect appeared when both properties were changed. This study provides critical information on the effects of OAs with variable C qualities, gypsum, and nutrients on structural stability with insights into strategies of sodic subsoil amelioration and soil C storage.
AB - Sodic dispersive subsoils pose significant constraints to agricultural productivity and sustainability in arid and semiarid regions. Gypsum and organic amendments (OAs) have shown the potential to improve soil structure and fertility and may address constraints associated with these dispersive soils. However, the mechanistic linkages between the quality of OAs, and the dynamics of soil structural stability (i.e., soil aggregates), particularly under the interactive impacts of gypsum and exogenous nutrients, remain elusive. We quantified aggregate stability (i.e., wet mean weight diameter, WMWD) and the accumulation of OA-carbon (C) in different aggregate-classes in a dispersive clay subsoil (δ13C −24.5‰) with or without the application of OAs (δ13C −12.8 to −14.3‰), gypsum and/or exogenous nutrients (nitrogen (N) and phosphorus (P)) over the 270 days incubation period. The OAs include sorghum stubble and sugarcane bagasse that were low C quality (e.g., C:N:P ratio of 328:6.2:1 and 850:17.3:1, respectively) and less decomposed (e.g., low alkyl-C/o-alkyl-C ratio), and sugarcane mill mud that was high C quality (C:N:P ratio of 17:1.4:1) and more decomposed status. The results suggest that the quality of OAs is likely to control the dominant mechanisms of soil aggregation: (i) a quick top-down formation of aggregate hierarchy (~31 days) in the low C quality and less decomposed OAs; and (ii) a slow bottom-up formation of aggregate hierarchy (≥90 days) in the high C-quality and more decomposed OA. Over time, lowering the C-nutrient stoichiometric ratio of OAs (via exogenous nutrients) decreased aggregate stability by 30%, owing to accelerated breakdown/loss of OAs (i.e., by 16%). The exchangeable Ca2+ (from gypsum) was positively correlated to WMWD and water stable aggregates (>0.05 mm), which were not influenced by OAs or nutrients. In this dispersive clay subsoil, a long-term positive effect on soil aggregation occurred when improving either biochemical properties (e.g., microbial biomass and soil organic C) or chemical properties (e.g., soil dispersion, exchangeable sodium percentage, and pH), and an additive effect appeared when both properties were changed. This study provides critical information on the effects of OAs with variable C qualities, gypsum, and nutrients on structural stability with insights into strategies of sodic subsoil amelioration and soil C storage.
KW - Alkaline soil
KW - Amelioration
KW - Gypsum
KW - Isotope
KW - Soil constraints
KW - Solonetz
UR - http://www.scopus.com/inward/record.url?scp=85107730631&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85107730631&partnerID=8YFLogxK
U2 - 10.1016/j.geoderma.2021.115281
DO - 10.1016/j.geoderma.2021.115281
M3 - Article
AN - SCOPUS:85107730631
VL - 404
SP - 1
EP - 13
JO - Geoderma
JF - Geoderma
SN - 0016-7061
M1 - 115281
ER -