Scott M. Holub, Glenn Cattnach, Kimberly M. Littke, Jeff A. Hatten
Forests around the world, and in the case of this study, the coastal Pacific Northwest United States, store large amounts of carbon, both above ground in the trees and below ground in soils. Understanding the effects of forest disturbance, including timber harvesting, is important in order to evaluate the role that forestry plays in the global carbon cycle. Soil carbon can be difficult to assess with enough precision to detect the kinds of changes that are expected, yet a series of small changes over time in the same direction could have important cumulative effects. In this study, eight randomly selected Douglas‐fir forest stands in Oregon and Washington were sampled at 300 points each using a fixed‐depth sampling approach to attempt to detect a 5% or higher change in soil carbon storage to 1 m, longitudinally from pre‐harvest to 10 years post‐harvest. There was moderate variability in results over time at individual sites, with some sites decreasing slightly and others increasing slightly. Only two sites achieved lower than the 5% minimum detectible difference target. The remaining six sites were able to detect 5.7%–10.7% differences. In one case, an unexpectedly large increase in mineral soil carbon 10 years post‐harvest occurred without clear explanation. On average, forest floor carbon stores were 20% larger 10 years post‐harvest than pre‐harvest. Even with the large increases excluded, both the fixed‐depth approach and equivalent soil mass correction showed there was no significant change in mineral soil carbon stores to 1 m at 10 years post‐harvest in the region.
{"title":"Forest soil carbon storage in 10‐year‐old Douglas‐fir plantations of western Oregon and Washington remains similar to pre‐harvest","authors":"Scott M. Holub, Glenn Cattnach, Kimberly M. Littke, Jeff A. Hatten","doi":"10.1002/saj2.20740","DOIUrl":"https://doi.org/10.1002/saj2.20740","url":null,"abstract":"Forests around the world, and in the case of this study, the coastal Pacific Northwest United States, store large amounts of carbon, both above ground in the trees and below ground in soils. Understanding the effects of forest disturbance, including timber harvesting, is important in order to evaluate the role that forestry plays in the global carbon cycle. Soil carbon can be difficult to assess with enough precision to detect the kinds of changes that are expected, yet a series of small changes over time in the same direction could have important cumulative effects. In this study, eight randomly selected Douglas‐fir forest stands in Oregon and Washington were sampled at 300 points each using a fixed‐depth sampling approach to attempt to detect a 5% or higher change in soil carbon storage to 1 m, longitudinally from pre‐harvest to 10 years post‐harvest. There was moderate variability in results over time at individual sites, with some sites decreasing slightly and others increasing slightly. Only two sites achieved lower than the 5% minimum detectible difference target. The remaining six sites were able to detect 5.7%–10.7% differences. In one case, an unexpectedly large increase in mineral soil carbon 10 years post‐harvest occurred without clear explanation. On average, forest floor carbon stores were 20% larger 10 years post‐harvest than pre‐harvest. Even with the large increases excluded, both the fixed‐depth approach and equivalent soil mass correction showed there was no significant change in mineral soil carbon stores to 1 m at 10 years post‐harvest in the region.","PeriodicalId":22142,"journal":{"name":"Soil Science Society of America Journal","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141931625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Isis S. P. C. Scott, Kossi Nouwakpo, Dave Bjorneberg, Christopher Rogers, Lauren Vitko
Optical methods including laser diffraction have been increasingly used to measure soil texture and particle size distribution. However, they have not been adopted yet as a routine methodology mainly due to the difficulties in comparing their results to more commonly used techniques (i.e., sedimentation methods). Many attempts exist in the literature to find an agreement between methodologies with relative success. In this work, we aim to improve the agreement between methodologies by adjusting parameters of the laser diffraction analysis, including sample treatment (chemical dispersion, carbonate removal, and sand separation), mode of sample addition (subsampling vs. transmittance matching), and analysis parameters (time of sonication and refractive index). Soil texture class determined by laser diffraction agreed with the sieve–hydrometer method in 78% of the runs when the following parameters were used: (1) Refractive index of 1.44 ‐ 0.100i, (2) 180 s of sonication, (3) sand sieving prior to analysis, and (4) sample dispersion by shaking the sample for 1 h with 5% sodium hexametaphosphate. We observed that adding the entire sample to the analyzer (1 g of soil in 100 mL of dispersant) while keeping the appropriate levels of transmittance through dilution (transmittance matching) is a better way of sample addition in comparison to subsampling, especially for coarser soil samples. This work proposes a standard operation procedure that may broaden the adoption of laser diffraction analysis as a routine soil texture methodology.
{"title":"Establishing a standard protocol for soil texture analysis using the laser diffraction technique","authors":"Isis S. P. C. Scott, Kossi Nouwakpo, Dave Bjorneberg, Christopher Rogers, Lauren Vitko","doi":"10.1002/saj2.20738","DOIUrl":"https://doi.org/10.1002/saj2.20738","url":null,"abstract":"Optical methods including laser diffraction have been increasingly used to measure soil texture and particle size distribution. However, they have not been adopted yet as a routine methodology mainly due to the difficulties in comparing their results to more commonly used techniques (i.e., sedimentation methods). Many attempts exist in the literature to find an agreement between methodologies with relative success. In this work, we aim to improve the agreement between methodologies by adjusting parameters of the laser diffraction analysis, including sample treatment (chemical dispersion, carbonate removal, and sand separation), mode of sample addition (subsampling vs. transmittance matching), and analysis parameters (time of sonication and refractive index). Soil texture class determined by laser diffraction agreed with the sieve–hydrometer method in 78% of the runs when the following parameters were used: (1) Refractive index of 1.44 ‐ 0.100i, (2) 180 s of sonication, (3) sand sieving prior to analysis, and (4) sample dispersion by shaking the sample for 1 h with 5% sodium hexametaphosphate. We observed that adding the entire sample to the analyzer (1 g of soil in 100 mL of dispersant) while keeping the appropriate levels of transmittance through dilution (transmittance matching) is a better way of sample addition in comparison to subsampling, especially for coarser soil samples. This work proposes a standard operation procedure that may broaden the adoption of laser diffraction analysis as a routine soil texture methodology.","PeriodicalId":22142,"journal":{"name":"Soil Science Society of America Journal","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141931644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Field capacity is a dubious soil physical property, but its use continues because of its perceived value for representing a soil's capacity to store water. Appropriate field capacity estimates can be useful for interpreting data from soil moisture sensors, including those in large‐scale monitoring networks, but suitable methods for defining field capacity in this context are unclear. Motivated by the desire to determine optimal field capacity values for the Oklahoma Mesonet, our objectives were (1) to develop and apply an automated time series analysis algorithm to estimate volumetric soil water content at field capacity and corresponding matric potential and (2) to compare the resulting water contents to those calculated from traditional matric potential thresholds (−33 and −10 kPa). Across 118 Oklahoma Mesonet sites and three soil depths (5, 25, and 60 cm), a matric potential threshold of −10 kPa underestimated field capacity water content by 0.010–0.014 cm cm−3 (3–4%) on average, and a threshold of −33 kPa underestimated it for every site and depth by 0.055–0.078 cm cm−3 (16%−22%) on average. Median matric potentials corresponding to field capacity were −7.6 kPa at the 5‐cm depth, −7.2 kPa at the 25‐cm depth, and −7.3 kPa at the 60‐cm depth. The algorithm developed here can be used to estimate field capacity wherever adequate data are available, and for sites where soil water retention properties are known, matric potentials at field capacity can also be estimated. Using a matric potential of −33 kPa as a standard threshold to represent field capacity is not scientifically justified and should be discontinued.
{"title":"Traditional matric potential thresholds underestimate soil moisture at field capacity across Oklahoma","authors":"Erik S. Krueger, Tyson E. Ochsner","doi":"10.1002/saj2.20733","DOIUrl":"https://doi.org/10.1002/saj2.20733","url":null,"abstract":"Field capacity is a dubious soil physical property, but its use continues because of its perceived value for representing a soil's capacity to store water. Appropriate field capacity estimates can be useful for interpreting data from soil moisture sensors, including those in large‐scale monitoring networks, but suitable methods for defining field capacity in this context are unclear. Motivated by the desire to determine optimal field capacity values for the Oklahoma Mesonet, our objectives were (1) to develop and apply an automated time series analysis algorithm to estimate volumetric soil water content at field capacity and corresponding matric potential and (2) to compare the resulting water contents to those calculated from traditional matric potential thresholds (−33 and −10 kPa). Across 118 Oklahoma Mesonet sites and three soil depths (5, 25, and 60 cm), a matric potential threshold of −10 kPa underestimated field capacity water content by 0.010–0.014 cm cm<jats:sup>−3</jats:sup> (3–4%) on average, and a threshold of −33 kPa underestimated it for every site and depth by 0.055–0.078 cm cm<jats:sup>−3</jats:sup> (16%−22%) on average. Median matric potentials corresponding to field capacity were −7.6 kPa at the 5‐cm depth, −7.2 kPa at the 25‐cm depth, and −7.3 kPa at the 60‐cm depth. The algorithm developed here can be used to estimate field capacity wherever adequate data are available, and for sites where soil water retention properties are known, matric potentials at field capacity can also be estimated. Using a matric potential of −33 kPa as a standard threshold to represent field capacity is not scientifically justified and should be discontinued.","PeriodicalId":22142,"journal":{"name":"Soil Science Society of America Journal","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141931627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Johnathan D. Holman, Payton S. Mauler, Augustine K. Obour, Kraig L. Roozeboom, Logan M. Simon, Yared Assefa
Grazing annual forages in dryland cropping systems has been used to integrate crop and livestock systems, rejuvenate soils, enhance in‐field nutrient cycling and soil organic carbon (SOC), and increase net returns by eliminating harvest expenses and feed delivery. However, cattle (Bos taurus) could potentially degrade soil physical properties by increasing compaction and reducing water infiltration in no‐tillage (NT) systems. Minimum tillage (MT) may help correct some of these potential soil quality concerns. The objective of this study was to quantify MT effects on soil properties, forage mass, and weeds compared to NT in a grazed winter triticale [×Triticosecale Wittm. ex A. Camus (Secale × Triticum)] annual forage system from 2020 to 2022 near Jetmore, KS. The experiment had two tillage treatments, NT and MT (sweep plow to a depth of 5–13 cm twice during summer fallow), in a grazed continuous winter triticale cropping system. Bulk density was greater in June, pre‐till (1.31 g cm−3), compared to August, post‐till (1.23 g cm−3), across tillage treatments. The mean weight diameter of dry aggregates decreased, and wind‐erodible fraction increased with MT. Across years, the mean weight diameter of water‐stable aggregates was greater with NT compared to MT. The SOC stocks did not differ between tillage practices near the soil surface, but MT increased SOC at the 5‐ to 15‐cm depth. Nitrate (NO3‐N) concentration was 28% higher with MT compared to NT across depths at the August sampling time. Soil pH was slightly lower in NT (5.81) compared to MT (5.94). Penetration resistance was high due to frequently dry soil conditions, but there were no differences between tillage systems. Early‐season forage biomass was greater in MT compared to NT in one out of two seasons. Our findings suggest that MT could be used to mitigate adverse effects of grazing on soil bulk density in NT systems but could cause short‐term decreases in dry and wet aggregate stability and increased wind‐erodible fraction.
{"title":"Soil, forage, and weed attributes following tillage in grazed no‐tillage triticale pasture","authors":"Johnathan D. Holman, Payton S. Mauler, Augustine K. Obour, Kraig L. Roozeboom, Logan M. Simon, Yared Assefa","doi":"10.1002/saj2.20736","DOIUrl":"https://doi.org/10.1002/saj2.20736","url":null,"abstract":"Grazing annual forages in dryland cropping systems has been used to integrate crop and livestock systems, rejuvenate soils, enhance in‐field nutrient cycling and soil organic carbon (SOC), and increase net returns by eliminating harvest expenses and feed delivery. However, cattle (<jats:italic>Bos taurus</jats:italic>) could potentially degrade soil physical properties by increasing compaction and reducing water infiltration in no‐tillage (NT) systems. Minimum tillage (MT) may help correct some of these potential soil quality concerns. The objective of this study was to quantify MT effects on soil properties, forage mass, and weeds compared to NT in a grazed winter triticale [×<jats:italic>Triticosecale Wittm</jats:italic>. ex A. Camus (<jats:italic>Secale</jats:italic> × <jats:italic>Triticum</jats:italic>)] annual forage system from 2020 to 2022 near Jetmore, KS. The experiment had two tillage treatments, NT and MT (sweep plow to a depth of 5–13 cm twice during summer fallow), in a grazed continuous winter triticale cropping system. Bulk density was greater in June, pre‐till (1.31 g cm<jats:sup>−3</jats:sup>), compared to August, post‐till (1.23 g cm<jats:sup>−3</jats:sup>), across tillage treatments. The mean weight diameter of dry aggregates decreased, and wind‐erodible fraction increased with MT. Across years, the mean weight diameter of water‐stable aggregates was greater with NT compared to MT. The SOC stocks did not differ between tillage practices near the soil surface, but MT increased SOC at the 5‐ to 15‐cm depth. Nitrate (NO<jats:sub>3</jats:sub>‐N) concentration was 28% higher with MT compared to NT across depths at the August sampling time. Soil pH was slightly lower in NT (5.81) compared to MT (5.94). Penetration resistance was high due to frequently dry soil conditions, but there were no differences between tillage systems. Early‐season forage biomass was greater in MT compared to NT in one out of two seasons. Our findings suggest that MT could be used to mitigate adverse effects of grazing on soil bulk density in NT systems but could cause short‐term decreases in dry and wet aggregate stability and increased wind‐erodible fraction.","PeriodicalId":22142,"journal":{"name":"Soil Science Society of America Journal","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141886192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jennifer Fedenko, David D'Amore, Diogo Spinola, Raquel Portes, Ashlee Dere, Rebecca A. Lybrand
A dense concentration of old‐growth forest and a wet, cold climate promote mineral weathering and leaching in coastal temperate rainforest soils. Our objective was to assess soil development and soil organic carbon (SOC) distribution across 18 soil profiles in remote, upland terrain of southeast Alaska where pedon data are sparse. We made soil morphological observations, collected samples, and completed laboratory analyses to measure SOC content, pH, and particle size distribution. The survey of upland backslope soils included north‐ and south‐facing hillslopes derived from three lithologies (slate, metavolcanic, and phyllite). The soils across all sites were very gravelly (51.8 ± 20.4% coarse fragments), acidic (mineral soil pH 4.85 ± 0.45), and moderately deep (96.56 ± 37.80 cm); thin, broken E horizons were underlain by thick, carbon‐rich spodic horizons. Soil development was relatively consistent as demonstrated by the Profile Development Index with values from 15 to 26 and Podzolization Index values spanning 8 to 14. A mean pedon SOC stock of 198.02 ± 81.42 Mg C ha−1 (n = 18) was calculated using data collected for all upland organic and mineral soils from our work. The accumulation of SOC was similar among soils formed from contrasting lithologies with averages of 182 ± 15.70 Mg C ha−1 for slate, 188 ± 53.80 Mg C ha−1 for metavolcanic, and 218 ± 124 Mg C ha−1 for phyllite. Our work contributes to soil morphological observations, laboratory data, and SOC stock estimates required to better constrain and model pedogenic processes and SOC stock in remote forests where data sets are limited.
{"title":"Spodosol development and soil organic carbon distribution along a lithosequence in perhumid coastal temperate rainforest","authors":"Jennifer Fedenko, David D'Amore, Diogo Spinola, Raquel Portes, Ashlee Dere, Rebecca A. Lybrand","doi":"10.1002/saj2.20695","DOIUrl":"https://doi.org/10.1002/saj2.20695","url":null,"abstract":"A dense concentration of old‐growth forest and a wet, cold climate promote mineral weathering and leaching in coastal temperate rainforest soils. Our objective was to assess soil development and soil organic carbon (SOC) distribution across 18 soil profiles in remote, upland terrain of southeast Alaska where pedon data are sparse. We made soil morphological observations, collected samples, and completed laboratory analyses to measure SOC content, pH, and particle size distribution. The survey of upland backslope soils included north‐ and south‐facing hillslopes derived from three lithologies (slate, metavolcanic, and phyllite). The soils across all sites were very gravelly (51.8 ± 20.4% coarse fragments), acidic (mineral soil pH 4.85 ± 0.45), and moderately deep (96.56 ± 37.80 cm); thin, broken E horizons were underlain by thick, carbon‐rich spodic horizons. Soil development was relatively consistent as demonstrated by the Profile Development Index with values from 15 to 26 and Podzolization Index values spanning 8 to 14. A mean pedon SOC stock of 198.02 ± 81.42 Mg C ha<jats:sup>−1</jats:sup> (<jats:italic>n</jats:italic> = 18) was calculated using data collected for all upland organic and mineral soils from our work. The accumulation of SOC was similar among soils formed from contrasting lithologies with averages of 182 ± 15.70 Mg C ha<jats:sup>−1</jats:sup> for slate, 188 ± 53.80 Mg C ha<jats:sup>−1</jats:sup> for metavolcanic, and 218 ± 124 Mg C ha<jats:sup>−1</jats:sup> for phyllite. Our work contributes to soil morphological observations, laboratory data, and SOC stock estimates required to better constrain and model pedogenic processes and SOC stock in remote forests where data sets are limited.","PeriodicalId":22142,"journal":{"name":"Soil Science Society of America Journal","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Billi Jean Petermann, Katie Lewis, Veronica Acosta‐Martinez, Haydee E. Laza, Joshua J. Steffan, Lindsey C. Slaughter
Cropping systems in semiarid regions have frequently relied on continuous tillage and irrigation, but declining groundwater resources have prompted a greater focus on conservation practices to improve soil health and water storage. We compared soil health responses from cotton production systems in semiarid, coarse‐textured soils with different crop management strategies under high or low irrigation levels. Management systems included continuous cotton with conventional tillage (CCCT) compared to no‐till cotton with a rye cover crop (NTCR) and no‐till cotton with a wheat‐fallow rotation (NTCW), including high or low irrigation zones within each system. Samples were collected annually from two bulk soil depths (0–10 cm and 10–20 cm) and root‐associated soils 7 years after systems were established and continued for 2 years. We found that cropping system, but not irrigation level, altered soil microbial communities and other soil health indicators. Despite variation between study years and sampling zones, the conservation systems had greater soil microbial community size via ester‐linked fatty acid methyl ester (EL‐FAME or FAME) analysis, extracellular enzyme activities, and soil organic matter than the CCCT system. The NTCW system also had greater arbuscular mycorrhizal fungi FAME abundance. Our study suggests that no‐till and conservation strategies such as cover cropping and rotation can improve biological soil health indicators in these sandy semiarid soils even with limited irrigation.
{"title":"Soil health influenced more by conservation tillage and cropping practice than irrigation level in a sandy semiarid cotton system","authors":"Billi Jean Petermann, Katie Lewis, Veronica Acosta‐Martinez, Haydee E. Laza, Joshua J. Steffan, Lindsey C. Slaughter","doi":"10.1002/saj2.20737","DOIUrl":"https://doi.org/10.1002/saj2.20737","url":null,"abstract":"Cropping systems in semiarid regions have frequently relied on continuous tillage and irrigation, but declining groundwater resources have prompted a greater focus on conservation practices to improve soil health and water storage. We compared soil health responses from cotton production systems in semiarid, coarse‐textured soils with different crop management strategies under high or low irrigation levels. Management systems included continuous cotton with conventional tillage (CCCT) compared to no‐till cotton with a rye cover crop (NTCR) and no‐till cotton with a wheat‐fallow rotation (NTCW), including high or low irrigation zones within each system. Samples were collected annually from two bulk soil depths (0–10 cm and 10–20 cm) and root‐associated soils 7 years after systems were established and continued for 2 years. We found that cropping system, but not irrigation level, altered soil microbial communities and other soil health indicators. Despite variation between study years and sampling zones, the conservation systems had greater soil microbial community size via ester‐linked fatty acid methyl ester (EL‐FAME or FAME) analysis, extracellular enzyme activities, and soil organic matter than the CCCT system. The NTCW system also had greater arbuscular mycorrhizal fungi FAME abundance. Our study suggests that no‐till and conservation strategies such as cover cropping and rotation can improve biological soil health indicators in these sandy semiarid soils even with limited irrigation.","PeriodicalId":22142,"journal":{"name":"Soil Science Society of America Journal","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141772330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Raquel Portes, Diogo Spinola, Michael E. Ketterer, Markus Egli, Rebecca A. Lybrand, Jennifer Fedenko, Frances Biles, Thomas P. Trainor, Ashlee Dere, David V. D'Amore
Quantifying soil redistribution rates, including both erosion and deposition, is critical for understanding erosion processes, landscape evolution, land management strategies, and the carbon cycle. In the Northeast Pacific coastal temperate rainforest, the interaction of perhumid climate and dense coniferous forest tends to form Spodosols which are soils characterized by a subsurface accumulation of organic matter and iron and aluminum oxides, across a range of contrasting lithologies. Deep Spodosols are frequently found on steep backslopes (up to 60%) of colluvial deposits, where shallower soils would typically be expected. We hypothesized that deep Spodosols in Southeast Alaska indicate slope stability, exhibiting negligible soil redistribution rates and stable surfaces regardless of the lithology. Our objective was to quantify soil redistribution rates for Spodosols formed on steep slopes across a range of lithologies in hilly and mountainous areas of Juneau, AK. We used 239+240Pu isotopes to quantify soil erosion and deposition rates in Spodosols formed on colluvial deposits from tonalite, slate, metavolcanic rock, and phyllite. 239+240Pu measurements revealed negligible soil redistribution rates for all studied pedons, ranging from erosion rates of 0.51 t/ha/year to deposition rates up to 0.43 t/ha/year. No difference was detected between the hill and mountain landforms, further supporting the idea that Spodosols could indicate slope stability over decadal timescales across the region. Understanding the resilience of Spodosols to erosion processes in varied lithologies and landforms on steep slopes is paramount for making informed decisions regarding sustainable land use, landslide risk mitigation, and effective carbon sequestration strategies.
{"title":"Assessing decadal soil redistribution rates using 239+240Pu across diverse lithologies in Southeast Alaska","authors":"Raquel Portes, Diogo Spinola, Michael E. Ketterer, Markus Egli, Rebecca A. Lybrand, Jennifer Fedenko, Frances Biles, Thomas P. Trainor, Ashlee Dere, David V. D'Amore","doi":"10.1002/saj2.20732","DOIUrl":"https://doi.org/10.1002/saj2.20732","url":null,"abstract":"Quantifying soil redistribution rates, including both erosion and deposition, is critical for understanding erosion processes, landscape evolution, land management strategies, and the carbon cycle. In the Northeast Pacific coastal temperate rainforest, the interaction of perhumid climate and dense coniferous forest tends to form Spodosols which are soils characterized by a subsurface accumulation of organic matter and iron and aluminum oxides, across a range of contrasting lithologies. Deep Spodosols are frequently found on steep backslopes (up to 60%) of colluvial deposits, where shallower soils would typically be expected. We hypothesized that deep Spodosols in Southeast Alaska indicate slope stability, exhibiting negligible soil redistribution rates and stable surfaces regardless of the lithology. Our objective was to quantify soil redistribution rates for Spodosols formed on steep slopes across a range of lithologies in hilly and mountainous areas of Juneau, AK. We used <jats:sup>239+240</jats:sup>Pu isotopes to quantify soil erosion and deposition rates in Spodosols formed on colluvial deposits from tonalite, slate, metavolcanic rock, and phyllite. <jats:sup>239+240</jats:sup>Pu measurements revealed negligible soil redistribution rates for all studied pedons, ranging from erosion rates of 0.51 t/ha/year to deposition rates up to 0.43 t/ha/year. No difference was detected between the hill and mountain landforms, further supporting the idea that Spodosols could indicate slope stability over decadal timescales across the region. Understanding the resilience of Spodosols to erosion processes in varied lithologies and landforms on steep slopes is paramount for making informed decisions regarding sustainable land use, landslide risk mitigation, and effective carbon sequestration strategies.","PeriodicalId":22142,"journal":{"name":"Soil Science Society of America Journal","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141772332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Corey Palmer, Arthur Siller, Raina Naylor, Masoud Hashemi, Ashley Keiser
Implementing soil conservation practices can begin to restore degraded soils, improve soil health, and increase overall ecosystem services. Cover cropping is an effective strategy to rebuild soil quality through decreased erosion and increased residue inputs, which can help build soil organic matter. Cover crop seeding rate may have a positive relationship with ecosystem services; however, it is unknown whether this is realized at or below the recommended cover crop seeding rate. The goal of this study was to identify the relationship between cover crop seeding rate and soil health biogeochemical measures across the growing season using five oat (Avena sativa L.)–pea (Pisum sativum L.) cover crop treatments of 0%, 25%, 50%, 75%, and 100% the industry standard seeding rate at the University of Massachusetts Amherst Research Farm. Soils were tested for soil carbon (C), nitrogen (N), and microbial measures at winter kill, spring thaw, post‐planting, and succeeding cash crop harvest. Soil measures did not vary among seeding rates, but total ground cover was consistent among treatments due to weed growth. Soil health measures vary seasonally reflecting soil microbial activity. Our study provides initial evidence that soil biogeochemical responses do not respond to increased seeding rate within one growing season when the resulting groundcover—cover crop biomass plus weeds—is consistent across seeding rates, but sampling date can influence the magnitude of soil biological and chemical soil health metrics.
{"title":"Increased winter‐killed cover crop seeding rate may not increase soil health outcomes","authors":"Corey Palmer, Arthur Siller, Raina Naylor, Masoud Hashemi, Ashley Keiser","doi":"10.1002/saj2.20735","DOIUrl":"https://doi.org/10.1002/saj2.20735","url":null,"abstract":"Implementing soil conservation practices can begin to restore degraded soils, improve soil health, and increase overall ecosystem services. Cover cropping is an effective strategy to rebuild soil quality through decreased erosion and increased residue inputs, which can help build soil organic matter. Cover crop seeding rate may have a positive relationship with ecosystem services; however, it is unknown whether this is realized at or below the recommended cover crop seeding rate. The goal of this study was to identify the relationship between cover crop seeding rate and soil health biogeochemical measures across the growing season using five oat (<jats:italic>Avena sativa</jats:italic> L.)–pea (<jats:italic>Pisum sativum</jats:italic> L.) cover crop treatments of 0%, 25%, 50%, 75%, and 100% the industry standard seeding rate at the University of Massachusetts Amherst Research Farm. Soils were tested for soil carbon (C), nitrogen (N), and microbial measures at winter kill, spring thaw, post‐planting, and succeeding cash crop harvest. Soil measures did not vary among seeding rates, but total ground cover was consistent among treatments due to weed growth. Soil health measures vary seasonally reflecting soil microbial activity. Our study provides initial evidence that soil biogeochemical responses do not respond to increased seeding rate within one growing season when the resulting groundcover—cover crop biomass plus weeds—is consistent across seeding rates, but sampling date can influence the magnitude of soil biological and chemical soil health metrics.","PeriodicalId":22142,"journal":{"name":"Soil Science Society of America Journal","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141772382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Enhancing fertilizer nitrogen use efficiency (NUE) in corn (Zea mays L.) production is critical for closing yield gaps, increasing producer profitability, and promoting environmental stewardship. In 2014 and 2015, a field experiment was conducted to determine the potential for fertilizer N stabilizer products to improve NUE of granular urea and urea ammonium nitrate (UAN) solution applied to strip‐till corn. A urease inhibitor (UI) or nitrification inhibitor (NI) or both were added at labeled rates to urea or UAN solution for a target rate of 180 kg N ha−1. At V3, a single application of broadcast granular urea and subsurface banded UAN solution with and without fertilizer N stabilizers was made. A split application (50% at V3; 50% at V6) of subsurface banded UAN solution served as a control representing a standard grower practice. Fertilizer N stabilizers improved components of NUE, such as grain N recovery efficiency (GNRE) and partial factor productivity (PFP). A single full rate UAN application did not differ in terms of grain yield each year but did result in less PFP and GNRE in 2015 as compared to the grower standard practice. A timely one‐time full season N rate subsurface banded application of UAN treated with UI and NI to improve NUE could be a viable substitute for the practice of multiple fertilizations. Untreated broadcast urea was inferior to UAN as a N source for corn, but when treated with both a UI and NI, NUE was improved.
{"title":"Efficacy of fertilizer nitrogen source, stabilizer, and application timing for corn nitrogen nutrition","authors":"Michael Nattrass, Jac J. Varco, Jagman Dhillon","doi":"10.1002/saj2.20727","DOIUrl":"https://doi.org/10.1002/saj2.20727","url":null,"abstract":"Enhancing fertilizer nitrogen use efficiency (NUE) in corn (<jats:italic>Zea mays</jats:italic> L.) production is critical for closing yield gaps, increasing producer profitability, and promoting environmental stewardship. In 2014 and 2015, a field experiment was conducted to determine the potential for fertilizer N stabilizer products to improve NUE of granular urea and urea ammonium nitrate (UAN) solution applied to strip‐till corn. A urease inhibitor (UI) or nitrification inhibitor (NI) or both were added at labeled rates to urea or UAN solution for a target rate of 180 kg N ha<jats:sup>−1</jats:sup>. At V3, a single application of broadcast granular urea and subsurface banded UAN solution with and without fertilizer N stabilizers was made. A split application (50% at V3; 50% at V6) of subsurface banded UAN solution served as a control representing a standard grower practice. Fertilizer N stabilizers improved components of NUE, such as grain N recovery efficiency (GNRE) and partial factor productivity (PFP). A single full rate UAN application did not differ in terms of grain yield each year but did result in less PFP and GNRE in 2015 as compared to the grower standard practice. A timely one‐time full season N rate subsurface banded application of UAN treated with UI and NI to improve NUE could be a viable substitute for the practice of multiple fertilizations. Untreated broadcast urea was inferior to UAN as a N source for corn, but when treated with both a UI and NI, NUE was improved.","PeriodicalId":22142,"journal":{"name":"Soil Science Society of America Journal","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141740022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Conservation management practices often produced positive but limited desirable outcomes in US Southeast sandy soils, likely due to their intrinsically low clay contents that constrain the soil's capacity to preserve organic carbon (C) and nutrients. In the field, we tested the effectiveness of a novel approach, that is, clay soil amendment, to improve sandy soils. In October 2017, clay‐rich soils (25% clay) were spread at 25 metric tons ha−1 and tilled onto a sandy soil (1.9% clay) in the field, which was further mixed by light tillage at 0‐ to 15‐cm depth, followed by planting winter cover crop mixtures (cereal rye, crimson clover, and winter pea). The crop rotation was cotton and corn with cover crop mixtures planted in the winter fallow season. Soils (0–15 cm) were collected in August 2021 and subjected to physio‐biochemical analyses. Clay amendment increased soil clay content to 3.4%, which improved nitrogen (N) availability by 51% but inhibited the activities of C (β‐d‐cellubiosidase [CB]; β‐xylosidase [BX]; N‐acetyl‐β‐glucosaminidase [NAG]) and N (leucine aminopeptidase [LAP]) cycling enzymes, resulting in up to 78% reduction in microbial respiration. A follow‐up kinetic study on BG and LAP enzymes suggested that clay addition can have different impacts on enzymes with diverse biological origins through distinct mechanisms. Clay addition can potentially improve sandy soils by stabilizing the organic inputs in soils. However, more research is required to understand its long‐term impacts making this approach practical.
{"title":"Clay soil amendment suppressed microbial enzymatic activities while increasing nitrogen availability in sandy soils","authors":"P. Poudel, Rongzhong Ye, Binaya Parajuli","doi":"10.1002/saj2.20731","DOIUrl":"https://doi.org/10.1002/saj2.20731","url":null,"abstract":"Conservation management practices often produced positive but limited desirable outcomes in US Southeast sandy soils, likely due to their intrinsically low clay contents that constrain the soil's capacity to preserve organic carbon (C) and nutrients. In the field, we tested the effectiveness of a novel approach, that is, clay soil amendment, to improve sandy soils. In October 2017, clay‐rich soils (25% clay) were spread at 25 metric tons ha−1 and tilled onto a sandy soil (1.9% clay) in the field, which was further mixed by light tillage at 0‐ to 15‐cm depth, followed by planting winter cover crop mixtures (cereal rye, crimson clover, and winter pea). The crop rotation was cotton and corn with cover crop mixtures planted in the winter fallow season. Soils (0–15 cm) were collected in August 2021 and subjected to physio‐biochemical analyses. Clay amendment increased soil clay content to 3.4%, which improved nitrogen (N) availability by 51% but inhibited the activities of C (β‐d‐cellubiosidase [CB]; β‐xylosidase [BX]; N‐acetyl‐β‐glucosaminidase [NAG]) and N (leucine aminopeptidase [LAP]) cycling enzymes, resulting in up to 78% reduction in microbial respiration. A follow‐up kinetic study on BG and LAP enzymes suggested that clay addition can have different impacts on enzymes with diverse biological origins through distinct mechanisms. Clay addition can potentially improve sandy soils by stabilizing the organic inputs in soils. However, more research is required to understand its long‐term impacts making this approach practical.","PeriodicalId":22142,"journal":{"name":"Soil Science Society of America Journal","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141641233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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