Higher Soil Organic Matter Content Research Articles

Study on the mechanism of co-pyrolysed biochar on soil DOM evolution in short-term cabbage waste decomposition

Cabbage waste returned soil was studied to assess the short-term influences of the application of cabbage waste biochar (CB), pine wood biochar (PB), and co-pyrolysed biochar (PCB) on soil dissolved organic matter (DOM) evolution. The decrease in DOM and soil organic matter (SOM) content was greater in the biochar-added soils during 35 days of decomposition. The DOM and SOM content in PCB added group decreased by 26.96 mg L−1 and 4.48 g kg−1, respectively. The increase in relative abundance of humic acid-like substances in DOMs was higher in the biochar-added soils during decomposition, which increased by 4.29% in PCB added group. PCB addition also resulted in a high SOM content (initial content of 78.82 g kg−1), and mineral elements were introduced into the soil, thus increasing soil pH (7.81) and electrical conductivity (574.67 μs cm−1). Moreover, the addition of biochars attenuated the decrease in average relative abundance of Bacillaceae and promoted bacterial proliferation during decomposition. The application of biochars regulated the soil bacterial community and promoted organic matter conversion and soil DOM evolution.

Cadmium and zinc isotope compositions indicate metal sources and retention mechanisms in different soil particle size fractions

Soil particle size may significantly affect metal distribution and stable isotopic behavior. Here, two soils were separated into four particle size fractions, namely fine sand, silt, fine silt, and colloidal particles and used to determine cadmium (Cd) and zinc (Zn) concentrations and isotope compositions. Concentrations of Cd and Zn were generally enriched in the finer particles and positively correlated with the iron (Fe) and manganese (Mn) oxide contents. However, Cd concentration in the fine sand was higher than in the silt fraction due to the higher soil organic matter contents in the former particle fraction. The maximum δ114/110Cd value was found in the colloidal particles (−0.02 and 0.01‰) of both soils while the minimum was in the silt particles (−0.12 and 0.06‰). Incorporation into the mineral lattice of Fe and Mn oxides is suggested to explain the slight enrichment of heavy Cd isotopes in the colloidal fraction. The similar δ66Zn values of the four particle fractions (0.20–0.29‰ with a mean of 0.25‰) indicate similar Zn sources in different particle sizes. Metal isotopic fingerprint of different soil particle size fractions provides further insight into the underlying metal retention mechanisms within soil micro-zones and helps in tracing metal sources and biogeochemical processes.

Increase in cotton yield through improved leaf physiological functioning under the soil condition of reduced chemical fertilization compensated by the enhanced organic liquid fertilization.

Low agricultural nutrient input efficiency remains a significant impediment for crop production globally. To address this issue in cotton agroecosystems, there is a need to develop sustainable crop nutrient management strategies to achieve high crop yields. We hypothesized that organic liquid fertilizer (OF) combined with reduced chemical fertilizer (CF) would enhance cotton yield by improving leaf functioning and soil properties. However, the underlying mechanism and its related process is poorly understood. This study explored the effects of OF combined with reduced CF on cotton yield, physiology and soil properties. Treatments included a single application of CF (CF: N, P2O5 and K2O applied at 228, 131 and 95 kg ha-1) and combined applications of OF and CF (OF0.6-OF1.4) in the following ratios: OF0.6, OF+60% CF; OF0.8, OF+80% CF; OF1.0, OF+100% CF; OF1.2, OF+120% CF; OF1.4, OF+140% CF. The result showed that compared with CF, OF0.8, OF1.0 and OF1.2 increased soil organic matter (SOM) content by 9.9%, 16.3% and 23.7%, respectively. Compared with CF, the OF0.6, OF0.8, OF1.0, and OF1.2 treatments increased leaf area (LA) by 10.6-26.1%, chlorophyll content (Chl content) by 6.8-39.6%, and the efficiency of photosystem II (PSII) light energy (Y(II)), electron transfer rate of PSII (ETR) and photochemical quenching (qP) by 3.6-26.3%, 4.7-15.3% and 4.3-9.8%, respectively. The OF0.8 treatment increased net photosynthetic rate (P n), stomatal conductance (G s) and transpiration rate (E) by 22.0%, 27.4% and 26.8%, respectively, resulting in higher seed cotton yield. The seed cotton yield and economic coefficient were positively correlated with P n, E, G s and Y(II) from the full boll stage to the boll opening stage. In summary, the OF0.8 treatment can maintain a high SOM content and photosynthetic performance with reduced chemical fertilizer input without sacrificing yield. The integration of OF+80% CF (OF0.8) is a promising nutrient management strategy for highly efficient cotton production under mulch drip irrigation systems.

Effect of Land-Use Intensification on Soil Properties and Plant Species Diversity in the Mediterranean Agroecosystem

In recent decades, agriculture in Greece has undergone significant changes due to the intensification of land use. This intensification, contrary to the sustainable land management, has an impact on the healthiness of the environmental agroecosystem. This study aimed to investigate if these cultivation systems influence some of the main edaphic properties and plant species diversity and which are the main anthropogenic interventions which may have a decisive role in the changes of soil physicochemical properties and the reduction of plant species. To assess the environmental implications among different types of land-use, the most sensitive and reliable edaphic indicators were measured and plant species diversity was recorded. Three land-use types such as maize crops, alfalafa and abandoned land were selected and ten fields with an area of approximately 1 ha in each land use type were taken. The results indicate that among the edaphic parameters pH, sand, electrical conductivity (EC), soil organic matter (SOM), NO3- as well as Ca+2 and Cu+2 soil concentration presented statistically significant differences among thirty cultivated fields. Among three different land uses, the edaphic variables EC, SOM, BD, Cal & Na concentrations presented significant differences. A higher soil organic matter content was observed in abandoned land while bulk density and electric conductivity value as well as Na+ concentrations were lower compared to other land uses. In total 122 taxa belonging to 30 families were recorded, while the families with the greatest species diversity were Poaceae, Asteraceae and Fabaceae in all land uses. Therophytes was the dominant life-form, followed by the Hemicryptophytes and Geophytes. The findings of the present study imply that different agronomic practices influence soil quality parameters, which are likely to affect species diversity and the environmental implications among different land uses.

Potentially harmful elements pollute soil and vegetation around the Atrevida mine (Tarragona, NE Spain)

Mining activity is one of the main sources to pollute soil, water and plants. An analysis of soil and plant samples around the Atrevida mining area in Catalonia (NE Spain) was preformed to determine potentially harmful elements (PHEs). Soil and plant samples were taken at eight locations around the mining area. The topsoil (0–15 cm) samples were analysed for physico-chemical properties by standard methods, by ICP-MS for Cd, Co, Cr, Cu, Fe, Ni, Pb and Zn, and were microwave-digested. Plant, root and shoot samples were digested separately, and heavy metals were analysed by AAS. Translocation factor (TF), biological concentration factor (BCF) and biological accumulation factor (BAF) were determined to assess the tolerance strategies developed by native species and to evaluate their potential for phytoremediation purposes. Soil pH was generally acid (5.48–6.72), with high soil organic matter (SOM) content and a sandy loamy or loamy texture. According to the agricultural soil values in southern Europe, our PHEs concentrations exceeded the toxicity thresholds. The highest root content of the most studied PHEs appeared in Thymus vulgaris L. and Festuca ovina L., while Biscutella laevigata L. accumulated more PHEs in shoots. The TF values were > 1 in B. laevigata L., but BAF obtained < 1, except Pb. B. laevigata L., and can be considered potentially useful for phytoremediation for having the capacity to restrict the accumulation of large PHEs amounts in roots and Pb translocation to shoots.

Fractal Features of Soil Particles as an Index of Land Degradation under Different Land-Use Patterns and Slope-Aspects

This study examines the effects of land use and slope aspect on soil erodibility (K-factor) and the fractal dimension (D) of soil particle size distribution (PSD) in calcareous soils at the watershed scale in western Iran. The study analyzed 113 soil samples collected from four land uses (slope-farmland, farmland, pasture, and woodland) at a depth of 0–20 cm, measuring common soil properties such as soil texture, soil organic matter (SOM), calcium carbonate (CaCO3), pH, and cation exchange capacity (CEC). The PSD of soil samples was measured using the international system of soil size fractions, and the D for PSD was calculated. The K-factor was calculated using the RUSLE model. The results showed that the K-factor was highest in slope farmlands with SOM at 1.6% and lowest in woodlands at 0.02 Mg h MJ−1 mm−1 with SOM at 3.5%. The study also found that there were significant correlations between D and clay content (r = 0.52), sand content (r = −0.29), and CEC (r = 0.36). Woodland soils had the highest SOM content, with a mean D value of 2.895, significantly higher than the mean D value of slope farmland soils, which had the lowest SOM at 1.6%. The study concludes that woodland soils retain finer particles, particularly clay, resulting in lower soil loss and land degradation compared to other land uses. Finally, the study suggests that shady slope aspects (south aspect) contain more organic matter due to less solar radiation and higher soil water content, resulting in lower soil erodibility (0.02 Mg h MJ−1 mm−1) and higher D values compared to other slope aspects.

Identification of factors controlling heavy metals/metalloid distribution in agricultural soils using multi-source data

Understanding the factors that controlling the agricultural soil heavy metals/metalloids distribution is vital for cropland soil remediation and management. For this objective, 227 agricultural soils were sampled in the Guanzhong Plain, China, to measure the concentration of five heavy metals (Pb, Cd, Ni, Zn, and Cu) and one metalloid (As) by X-ray fluorescence spectrometer, meanwhile, 24 possible influencing factors to agricultural soil heavy metals/metalloid distribution were collected and grouped into three categories. A sequential multivariate statistical analysis was carried out to provide insight into the controlling factors of soil heavy metals/metalloid distribution, then stepwise multiple linear regression (SMLR) and partial least squares regression (PLS) were used to predict heavy metals/metalloid concentrations in agricultural soil based on the result of soil heavy metals/metalloid controlling factors identification. The results demonstrated the types of soil and land use did not have a substantial effect on soil heavy metals/metalloid distribution, except Zn and Cu. The soil properties category played a major role in influencing the soil heavy metals/metalloid concentration. The concentrations of Mn and Fe, which are the main constitute elements of soil inorganic colloid, were the most significant factors, followed by the concentrations of P, K and Ca. Soil pH and soil organic matter (SOM) content, which are often considered as important factors for soil heavy metals/metalloid distribution, were not important in the present study. The SMLR was more effective than the PLS for predicting soil heavy metals/metalloid content. The results of this study enlighten that future soil heavy metals/metalloid contamination treatment in regions with high pH and low SOM content should concentrate on inorganic colloid particles, which have strong adsorption capacity for soil heavy metals/metalloid and are environmentally friendly. Moreover, the combination of successive multivariate statistical analysis and SMLR provide an effective tool to predict and monitor agricultural soil heavy metals/metalloid distribution, and facilitate the improvement of environmental and territorial management.

Are Ecosystem Engineering Traits Fixed or Flexible: A Study on Clonal Expansion Strategies in Co-occurring Dune Grasses

Many vegetated coastal ecosystems are formed through ecosystem engineering by clonal vegetation. Recent work highlights that the spatial shoot organization of the vegetation determines local sediment accretion and subsequently emerging landscape morphology. While this key engineering trait has been found to differ between species and prevailing environmental conditions, it remains unknown how the interplay of both factors drive shoot organization and therefore landscape morphology. Here, we compared the spatial shoot organization of young, clonally expanding plants of the two dominant European dune grass species: sand couch (Elytrigia juncea) and marram grass (Ammophila arenaria) across a range of coastal dune environments (from Denmark to France). Our results reveal that, on average, sand couch deployed a more dispersed shoot organization than marram grass, which has a patchy (Lévy-like) organization. Whereas sand couch exhibited the same expansion strategy independent of environmental conditions, marram grass demonstrated a large intraspecific variation which correlated to soil organic matter, temperature and grain size. Shoot patterns ranged from a clumped organization correlating to relatively high soil organic matter contents, temperature and small grain sizes, to a patchy configuration with intermediate conditions, and a dispersed organization with low soil organic matter, temperature and large grain size. We conclude that marram grass is flexible in adjusting its engineering capacity in response to environmental conditions, while sand couch instead follows a fixed expansion strategy, illustrating that shoot organization results from the interaction of both species-specific and environmental-specific trait expression.

Competitive adsorption of lead and cadmium on soil aggregate at micro-interfaces: Multi-surface modeling and spectroscopic studies

Aggregates are the basic structural units of soils and play a crucial role in metal migration and transformation. Combined contamination of lead (Pb) and cadmium (Cd) is common in site soils, and the two metals may compete for the same adsorption sites and affect their environmental behavior. Herein, the adsorption behavior of Pb and Cd on aggregates of two soils and contributions of soil components in single and competitive systems were studied by combining cultivation experiments, batch adsorption, multi-surface models (MSMs), and spectroscopic techniques. The results demonstrated that < 2 µm size aggregate was the dominant sink for Pb and Cd competitive adsorption in both soils. Compared with Pb, the adsorption capacity and behavior of Cd were affected greatly under competition. MSMs prediction revealed that soil organic matter (SOM) contributed the most to Cd and Pb adsorption on aggregates (> 68.4%), but the dominant competitive effect occurred on different sites for Cd adsorption (primarily on SOM) and Pb adsorption (primarily on clay minerals). Further, 2 mM Pb coexistence caused 5.9 − 9.8% of soil Cd conversion to unstable species (Cd(OH)2). Thus, the competitive effect of Pb on Cd adsorption cannot be ignored in soils with high content of SOM and fine aggregates.

Low levels of arsenic and cadmium in rice grown in southern Florida Histosols - Impacts of water management and soil thickness

Rice is planted as a rotation crop in the sugarcane-dominant Everglades Agricultural Area (EAA) in southern Florida. The Histosols in this area are unlike other mineral soils used to grow rice due to the high organic content and land subsidence caused by rapid oxidation of organic matter upon drainage. It remains unknown if such soils pose a risk of arsenic (As) or cadmium (Cd) mobilization and uptake into rice grain. Both As and Cd are carcinogenic trace elements of concern in rice, and it is important to understand their soil-plant transfer into rice, a staple food of global importance. Here, a mesocosm pot study was conducted using two thicknesses of local soil, deep (D, 50 cm) and shallow (S, 25 cm), under three water managements, conventional flooding (FL), low water table (LWT), and alternating wetting and drying (AWD). Rice was grown to maturity and plant levels of As and Cd were determined. Regardless of treatments, rice grown in these Florida Histolsols has very low Cd concentrations in polished grain (1.5–5.6 μg kg−1) and relatively low total As (35–150 μg kg−1) and inorganic As (35–87 μg kg−1) concentrations in polished grain, which are below regulatory limits. This may be due to the low soil As and Cd levels, high soil cation exchange capacity due to high soil organic matter content, and slightly alkaline soil pH. Grain As was significantly affected by water management (AWD < FL = LWT) and its interaction effect with soil thickness (AWD-D ≤ AWD-S ≤ FL-D = LWT-S = LWT-D ≤ FL-S), resulting in as much as 62 % difference among treatments. Grain Cd was significantly affected by water management (AWD > FL > LWT) without any soil thickness impact. In conclusion, even though water management has more of an impact on rice As and Cd than soil thickness, the low concentrations of As and Cd in rice pose little health risk for consumers.

Aerification Strategies Affecting Golf Green Subsurface Properties

Golf greens often become compacted due to: 1. Construction of less-than-ideal soil containing high percentages of silt and clay. 2. Extensive traffic not only from daily play but continuous maintenance often with heavy machinery. 3. Traffic not being sufficiently curtailed during periods of excessive soil moisture. A two-year field experiment was conducted on a 14-year-old U.S. Golf Association (USGA)-specified Crenshaw creeping bentgrass [Agrostis stolonifera L. var palustris (Huds.)] research putting green in Clemson, SC, to evaluate the effects of varying spring HTA size and timing on turfgrass rooting, soil organic matter (OM) and soil properties. Spring HTA treatments included 1.2-cm i.d. tines spaced at 5.1 cm x 5.1 cm in March and May (standard); 1.2-cm i.d. tines spaced at 3.8 cm x 3.4 cm in March only (2x); 0.9-cm i.d. tines spaced at 3.8 cm x 3.4 cm in March and May; and 0.6-cm i.d. tines spaced at 3.8 cm x 3.4 cm in March, April, May and June. All aerification was to a depth of 7.6 cm, with cores removed. Plots aerified with 0.6-cm tines had the least 2-year reduction in dry root weight (DRW). Plots aerified with 1.2-cm tines in March only (2x) had the greatest reduction in DRW and had the deepest thatch mat depth (TMD) across both years. This “doubling up” treatment would not be advisable on greens where low root mass or thatch accumulation is a concern. Plots aerified with 1.2-cm tines had higher thatch OM content in Year 2. Plots aerified with 0.6-cm tines had higher soil OM content across both years. Repetitive equal depth aerification did not create a layer of increased compaction. Turf managers can vary their spring HTA size and timing to increase TQ during periods where this is important (e.g., for a tournament) with manageable effects on surface, OM, and soil properties.

Glyphosate Effects on Earthworms: Active Ingredients vs. Commercial Herbicides at Different Temperature and Soil Organic Matter Levels

Little is known about the non-target effects of glyphosate active ingredients (GLY) versus glyphosate-based herbicide (GBH) formulations on soil organisms, and whether effects are influenced by environmental conditions. We investigated the avoidance behavior, biomass growth, and reproduction of earthworms (Eisenia fetida, E. andrei) in response to two GLYs (glyphosate ammonium and potassium salt), the corresponding GBHs (Touchdown Quattro, Roundup PowerFlex) containing these GLYs, and the “inert” co-formulant alkylpolyglycoside (APG) at two temperature (15 °C vs. 20 °C) and soil organic matter levels (3.2% vs. 4.3%). Earthworm avoidance was lower at high soil organic matter content, but remained unaffected by substances and temperature. Earthworm biomass growth and reproduction (cocoons and juveniles) were significantly affected by substances and temperature; reproduction was also affected by a substance and temperature interaction. Biomass growth was almost zero at higher temperature; reproduction was generally higher at higher temperature. More cocoons were produced under Roundup PowerFlex than under the corresponding AI, due to the impact of the co-formulant APG. No other differences were observed between GBH and the corresponding AIs. We conclude that the non-target effects of pesticides can only be fully assessed if all ingredients in a formulation are known and environmental parameters are included in environmental risk assessments.

Investigation of Factors Influencing on Ammonia Emission from Soils in Agricultural Land

Objectives : Major factors affecting ammonia emission from the soil and strategies to reduce ammonia emission were investigated through literature surveys.Methods : An academic search was conducted using keywords such as agriculture, ammonia, and fine dust, and the effects of soil characteristics on ammonia emission were summarized for each factor.Results and Discussion : Emissions of ammonia into the atmosphere can reduce economic returns for a farmer and negatively impact the atmospheric environment by acting as a precursor to PM2.5 formations. It is reported that agriculture accounts for 78% of the total ammonia emission sources in Korea. Ammonia emission from the soil is affected by the type of ammonia fertilizer, soil moisture, pH, temperature, cation exchange capacity, organic matter, and soil texture. An increase in soil moisture increases ammonia emissions. As soil pH increases, ammonia emissions increase, noticeably above 7.5. An increase in soil temperature increases the rate of hydrolysis of urea and the rate of conversion to ammonia gas, resulting in increased ammonia emissions. Soils with high cation exchange capacity adsorb ammonium to reduce ammonia emissions. Soils with a high clay content and soil organic matter content are more buffered to changes in soil pH, reducing ammonia emissions.Conclusion : Based on understanding the mechanisms and causes of ammonia emission from the soil, it is possible to establish soil and environmental management to reduce ammonia emissions into the atmosphere.

Fiddling with the blue carbon: Fiddler crab burrows enhance CO2 and CH4 efflux in saltmarsh

Saltmarshes are important global carbon (C) sinks, but the considerable uncertainty in the C budget and the underlying mechanisms limit the estimation of greenhouse gas emissions (GHG, e.g., CO2 and CH4) in the context of global climate change. To ascertain the mechanistic understanding, we assessed how crab burrows morphology and greenhouse gas effluxes changed in response to interactions of fiddler crab burrow density, soil organic matter content (high vs low), and presence/absence of Spartina alterniflora (vegetated saltmarsh vs nearby unvegetated mudflat) on the coast of New England (USA). The crab burrow volume in the vegetated saltmarsh was smaller than that in the mudflat, and crab burrow volume greatly correlated with soil CO2 efflux, indicating that crab activities could enhance coastal wetland CO2 efflux. Soil CO2 and CH4 effluxes rates were significantly positively correlated with crab burrow density, organic matter content, and vegetation types. Specifically, the higher soil organic matter content and crab burrow density greatly increased soil heterotrophic respiration in the saltmarsh. Overall, with crab disturbances, soil CO2 and CH4 efflux increased by 32.1% and 47.9%, respectively. This study highlights that fiddler crab burrowing activity plays an important role in the C sequestration of coastal blue C ecosystems (BCEs).

Surfactant-enhanced reduction of soil-adsorbed nitrobenzene by carbon-coated nZVI: Enhanced desorption and mechanism

The reduction process of pollutants by nano zero-valent iron (nZVI) is limited by mass transfer and its effective utilization, and previous studies have ignored the electron loss caused by its oxidative passivation. The carbon-coated structure can effectively inhibit the oxidation of nZVI, but the effectiveness of carbon-coated nZVI (Fe0@C) as a reducing agent in soil remediation is unclear. Therefore, in this study, the Fe0@C/surfactant system was used to remove soil-adsorbed nitrobenzene (NB) to simultaneously enhance the mass transfer process and effective utilization of nZVI. The results showed that the use of surfactants effectively promoted the desorption of NB adsorbed by the soil, and the desorption process was affected by factors such as the type and concentration of surfactants, water-soil ratio, and soil organic matter (SOM) content. The enhanced desorption of NB by the surfactant in the soil system promoted the effective contact between the composite and NB, thereby enhancing the reduction of NB by the composite. In addition, Fe0@C exhibited excellent performance for the reduction of soil-adsorbed NB compared with the conventional nZVI, and this advantage was more obvious in the potting soil system. However, the composite will be gradually passivated due to the alkaline environment during the reduction process, and this phenomenon was especially obvious in the campus soil system. When the pH value decreased from 9 to 3, the proportion of aniline (AN) generated in the campus soil system increased from 19.37 % to 69.29 %. In addition, in potting soil systems with high SOM content, the adsorption of soil particles to the composite and the high dissolved organic matter (DOM) content resulting from the high SOM content also negatively affected the reduction process. The conclusions of this study demonstrate the great potential of the Fe0@C/surfactant system for in-situ contaminated site remediation applications.

Three-dimensional mapping of carbon, nitrogen, and phosphorus in soil microbial biomass and their stoichiometry at the global scale.

Soil microbial biomass and microbial stoichiometric ratios are important for understanding carbon and nutrient cycling in terrestrial ecosystems. Here, we compiled data from 12245 observations of soil microbial biomass from 1626 published studies to map global patterns of microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial biomass phosphorus (MBP), and their stoichiometry using a random forest model. Concentrations of MBC, MBN, and MBP were most closely linked to soil organic carbon, while climatic factors were most important for stoichiometry in microbial biomass ratios. Modeled seasonal MBC concentrations peaked in summer in tundra and in boreal forests, but in autumn in subtropical and in tropical biomes. The global mean MBC/MBN, MBC/MBP, and MBN/MBP ratios were estimated to be 10, 48, and 6.7, respectively, at 0-30 cm soil depth. The highest concentrations, stocks, and microbial C/N/P ratios were found at high latitudes in tundra and boreal forests, probably due to the higher soil organic matter content, greater fungal abundance, and lower nutrient availability in colder than in warmer biomes. At 30-100 cm soil depth, concentrations of MBC, MBN, and MBP were highest in temperate forests. The MBC/MBP ratio showed greater flexibility at the global scale than did the MBC/MBN ratio, possibly reflecting physiological adaptations and microbial community shifts with latitude. The results of this study are important for understanding C, N, and P cycling at the global scale, as well as for developing soil C-cycling models including soil microbial C, N, and P as important parameters.

Exploring the Critical Role of Water in Regenerative Agriculture; Building Promises and Avoiding Pitfalls

This article seeks greater clarity in the connections between water and regenerative agriculture (RA). We first review existing soil/water knowledge and argue that desired “RA and water” outcomes depend on the management and optimal levels of two key soil properties; readily available moisture and infiltration rate. Secondly, we hypothesize these help define a range of RA beneficial outcomes or “promises,” such as improved vegetative growth, reduced risk of erosive runoff, higher soil organic matter content and biological fertility, easier irrigation management, resilience to drought, better water filtration and less variable streamflow hydrology. Thirdly we show that by not fully understanding water's multiple roles for achieving desired RA outcomes, risks, contradictions and “pitfalls” can arise. With these three parts we observe that carefully explained and quantified roles of water in the existing RA literature are often missing, neglected, over-generalized or poorly explained. We also suggest that narratives and terms (e.g., “net zero” or “net positive”) for describing the benefits and aims of RA and water can lack context and situational fit, or are misleading and incorrect. Cautions also apply to water quantities additionally required for soil regeneration activities, recognizing stiff competition for scarce river basin water and its allocation. How necessary quantities overlap with local and catchment policies for water allocations and hydrology, incorporating farmers' views and choices and informed by field, farm and system water accounting, are critical to successful agricultural practices including those that are “regenerative.” Accordingly, we suggest that scientists and decisions-makers should more thoroughly interrogate how “RA and water” is being analyzed so that relevant policies develop its promises whilst avoiding pitfalls.

Evaluating the particle densities of subarctic soils using pedotransfer functions and vis–NIR spectroscopy

AbstractThe particle density (ρs) is a fundamental physical property needed for calculating the soil porosity and phase distributions. While ρs is often estimated using soil organic matter (SOM) content and particle size distribution, the specific densities of each soil component remain unclear in a subarctic agricultural setting. This study aimed to evaluate the ρs of soils from Southwest Greenland using a three‐compartment model (3CM) based on the mixing ratio of SOM derived from loss‐on‐ignition, mineral particles &lt;20 μm (FC), and mineral particles ≥20 μm (CC). We further evaluated the accuracy of the 3CM against pedotransfer functions (PTFs) and visible near‐infrared (vis–NIR) spectroscopic models. A total of 324 soil samples from 16 Greenlandic agricultural fields were investigated, covering a wide range in SOM content (0.021–0.602 kg kg–1) and clay content (0.020–0.185 kg kg–1). Despite their high SOM content, the Greenlandic soils exhibited relatively high ρs (1.936–3.044 Mg m–3), which together with a large SOM/organic carbon ratio of 2.16 indicated a high SOM density of 1.493 Mg m–3. The 3CM fit on all soils indicated FC and CC densities of 3.047 and 2.713 Mg m–3, respectively, while a subset of soils (n = 203) from the same geological setting resulted in FC and CC densities of 2.738 and 2.731 Mg m–3. Prediction accuracy of the 3CM (RMSE = 0.067 Mg m–3) was similar to PTFs (RMSE = 0.068–0.070 Mg m–3) and better than vis–NIR spectroscopic models (RMSE = 0.091 Mg m–3).

Analysis of Possible Eucheuma Cottonii Seaweed Cultivation Based on Aspects of Soil Substrate on Barombong Beach, Makassar, Indonesia

This research aims to determine the possibility of Eucheuma cottonii seaweed cultivation based on soil substrate aspects at Barombong Beach, Makassar, Indonesia. The research was carried out for 2 (two) months, namely from February to March 2021 by conducting 2 (two) sampling times, namely at the beginning and end of the research by taking 3 observation stations, namely- Station 1 (ST 1), which is located around community settlements, Station 2 (ST 2), which is located around the Barombong Sports Building and Station 3 (ST 3), which is located around the Jeneberang River Estuary. The data obtained were collected, and then processed and analyzed by descriptive analysis. The results showed that based on the aspect of the soil substrate, the research location was still able to cultivate Eucheuma cottonii seaweed with the value of each parameter, namely - the highest phosphate content obtained at Station (ST 2) with a value of 8.69 ppm. The highest soil substrate pH value was obtained at Station (ST 3) with a pH value of 8. The highest nitrogen content of soil substrate was obtained at Station (ST 1) which was 0.106 ppm. Furthermore, the highest soil organic matter content was obtained at Station (ST 2) with a value of 0.36 ppm.

Comparison of natural and technogenic soils developed on volcanic ash by Vis-NIR spectroscopy

Soil biological properties and carbon storage of three young Technosols deriving from volcanic soil of Campi Flegrei, Italy, were compared with two natural volcanic soils, sampled from two forest ecosystem sites (chestnut and Mediterranean maquis). The soil properties were examined with Vis-NIR spectroscopy and portable XRF, along the soil profile. The results showed that the average soil organic matter (SOM) amount in Technosols profiles were lower than in natural volcanic soils. The differences in SOM content between the two investigated natural volcanic soils probably resulted from their land-use histories and different plant cover. Indeed, the chestnut soil profile, which has a higher SOM content, was covered by an old chestnut grove, while the second soil profile, after a severe burning, showed a change in natural Oak forest vegetation towards the typical Mediterranean maquis. The microbial biomass can be predicted with Vis-NIR spectroscopy coupled with PLS Regression. Our results showed that 6-year natural incorporation of organic residue in Technosols significantly increased the C storage on the top soils due to the increase in C input with rhizodeposition. The forest soils show higher TOC content also with the depth that indicate a greater capacity of C storage in response to litter incorporation, whereas the Technosols accumulated about half the amount of TOC, compared to the chestnut grove. Indeed, after six years of natural vegetation, the Technosols showed a large potential to sequester C and to sustain biological activity. Overall, the emerging knowledge on Technosols make them highly promising for the regeneration of urban area.