Soil Systems

12 pages, 1858 KiB

Open AccessCommunication

Seeding System Configuration Effects on Sunflower Seedling Emergence and Yield under No-Tillage

by Gustavo F. Nardón, Guido F. Botta, Kojo A. Aikins, David Rivero, Fernando Bienvenido and Diogenes L. Antille

Soil Syst. 2021, 5(4), 72; https://doi.org/10.3390/soilsystems5040072 - 15 Dec 2021

Cited by 3 | Viewed by 2165

Abstract

No-tillage farming can improve crop productivity and the reliability of cropping compared with conventional tillage. The effects of three different seeding system configurations on surface residue handling, sunflower emergence and stand establishment, yield, and gross income were investigated over three cropping seasons. The [...] Read more.

No-tillage farming can improve crop productivity and the reliability of cropping compared with conventional tillage. The effects of three different seeding system configurations on surface residue handling, sunflower emergence and stand establishment, yield, and gross income were investigated over three cropping seasons. The seeding system configurations comprised of (1) turbo coulter blade, (2) notched disc row cleaner before turbo coulter blade, and (3) no residue handling unit installed in front of a double-disc opener. For all three seeding system configurations, crop residue cover on sown rows (after seeding) was greater than the minimum recommended value of 30% for no-tillage. Residue cover was best with the notched disc row cleaner in front of the turbo coulter blade compared to the other two seeding systems. Furthermore, the notched disc row cleaner in front of the turbo coulter blade produced the highest plant emergence counts and the most uniform stand establishment. Sunflower yield and gross income were highest with the notched disc row cleaner in front of the turbo coulter blade (3.16 Mg·ha⁻¹ and 902 USD·ha⁻¹) compared to when only the turbo coulter blade (2.38 Mg·ha⁻¹ and 680 USD·ha⁻¹) or no residue handling unit (1.69 Mg·ha⁻¹ and 482 USD·ha⁻¹) was used. Full article

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16 pages, 3959 KiB

Open AccessArticle

Observations on Earthworm Communities and Soils in Various Natural and Man-Affected Ecosystems

by Christina Chalkia, Evangelia Vavoulidou, Csaba Csuzdi, Christina Emmanouil, Alexandros Dritsoulas and Anastasios Katsileros

Soil Syst. 2021, 5(4), 71; https://doi.org/10.3390/soilsystems5040071 - 10 Dec 2021

Cited by 1 | Viewed by 3173

Abstract

Earthworms are important members of the soil fauna since they regulate fundamental soil functions such as organic matter breakdown, fertility, structure and water balance. However, so far, their community assemblages have been poorly investigated in Greece. In this context, the earthworm communities of [...] Read more.

Earthworms are important members of the soil fauna since they regulate fundamental soil functions such as organic matter breakdown, fertility, structure and water balance. However, so far, their community assemblages have been poorly investigated in Greece. In this context, the earthworm communities of forty five sites in Greece, belonging to three types of ecosystems—terrestrial water bodies, undisturbed (natural) sites and cultivated (agricultural and urban) fields—were investigated using the combined method of digging and hand sorting followed by the application of a 0.4% formaldehyde solution. Specific soil parameters and various environmental characteristics were examined as potential factors affecting the abundance and species richness. The results showed no statistically significant difference between ecosystem densities. The species number was significantly different between ecosystems, with the cultivated fields exhibiting richer communities, with a mean of 5.3 ± 0.6 species per site compared to the natural areas with 2.4 ± 0.5 species per site, while the water bodies showed intermediate numbers (3.6 ± 0.5 species per site). Finally, earthworm densities were positively correlated with species number and percentage vegetation cover and negatively with clay. These results may contribute to understanding how different land uses affect earthworm communities. Full article

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3 pages, 165 KiB

Open AccessEditorial

Sorption Processes in Soils and Sediments

by Evert J. Elzinga and Yuji Arai

Soil Syst. 2021, 5(4), 70; https://doi.org/10.3390/soilsystems5040070 - 07 Dec 2021

Cited by 2 | Viewed by 2133

Abstract

Sorption processes at the mineral–water interface are fundamental to the chemical functioning of soils, and impact the biogeochemical cycling of both trace and major elements in soil and sediment environments [...] Full article

(This article belongs to the Special Issue Sorption Processes in Soils and Sediments)

15 pages, 1387 KiB

Open AccessArticle

Ensemble Modeling on Near-Infrared Spectra as Rapid Tool for Assessment of Soil Health Indicators for Sustainable Food Production Systems

by John Walker Recha, Kennedy O. Olale, Andrew Sila, Gebermedihin Ambaw, Maren Radeny and Dawit Solomon

Soil Syst. 2021, 5(4), 69; https://doi.org/10.3390/soilsystems5040069 - 12 Nov 2021

Cited by 3 | Viewed by 2894

Abstract

A novel total ensemble (TE) algorithm was developed and compared with random forest optimization (RFO), gradient boosted machines (GBM), partial least squares (PLS), Cubist and Bayesian additive regression tree (BART) algorithms to predict numerous soil health indicators in soils with diverse climate-smart land [...] Read more.

A novel total ensemble (TE) algorithm was developed and compared with random forest optimization (RFO), gradient boosted machines (GBM), partial least squares (PLS), Cubist and Bayesian additive regression tree (BART) algorithms to predict numerous soil health indicators in soils with diverse climate-smart land uses at different soil depths. The study investigated how land-use practices affect several soil health indicators. Good predictions using the ensemble method were obtained for total carbon (R² = 0.87; RMSE = 0.39; RPIQ = 1.36 and RPD = 1.51), total nitrogen (R² = 0.82; RMSE = 0.03; RPIQ = 2.00 and RPD = 1.60), and exchangeable bases, m3. Cu, m3. Fe, m3. B, m3. Mn, exchangeable Na, Ca (R² > 0.70). The performances of algorithms were in order of TE > Cubist > BART > PLS > GBM > RFO. Soil properties differed significantly among land uses and between soil depths. In Kenya, however, soil pH was not significant, except at depths of 45–100 cm, while the Fe levels in Tanzanian grassland were significantly high at all depths. Ugandan agroforestry had a substantially high concentration of ExCa at 0–15 cm. The total ensemble method showed better predictions as compared to other algorithms. Climate-smart land-use practices to preserve soil quality can be adopted for sustainable food production systems. Full article

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12 pages, 1093 KiB

Open AccessArticle

Short-Term Waterlogging Depresses Early Growth of Sunflower (Helianthus annuus L.) on Saline Soils with a Shallow Water Table in the Coastal Zone of Bangladesh

by Priya Lal Chandra Paul, Richard W. Bell, Edward G. Barrett-Lennard, Enamul Kabir, Mohammed Mainuddin and Khokan Kumer Sarker

Soil Syst. 2021, 5(4), 68; https://doi.org/10.3390/soilsystems5040068 - 06 Nov 2021

Cited by 9 | Viewed by 2492

Abstract

Sunflower (Helianthus annuus L.), which is widely grown globally for its high-quality edible oil, is reasonably salt and drought tolerant but it is susceptible to waterlogging. In the saline coastal zone of the Ganges delta, sunflower is often exposed to sudden heavy [...] Read more.

Sunflower (Helianthus annuus L.), which is widely grown globally for its high-quality edible oil, is reasonably salt and drought tolerant but it is susceptible to waterlogging. In the saline coastal zone of the Ganges delta, sunflower is often exposed to sudden heavy rainfall during early growth but plant tolerance to such events is not known. Hence, we evaluated the effect of short-term soil inundation (referred to as waterlogging) for 0, 24, 48 and 72 h on sunflower at emergence, 2-leaf, and 4-leaf stages in early- and late-sown crops under field conditions (saline, clay-textured soil, and shallow groundwater). Waterlogging for 24 h did not affect sunflower at any stage but waterlogging for 48 and 72 h suppressed emergence and growth at the 2 and 4-leaf stages. Waterlogging for 72 h completely prevented the emergence for early sowing, whereas emergence was less affected for later sowing. Shoot and root dry weight were most affected at the emergence and 2-leaf stage, not at the 4-leaf stage. In conclusion, waterlogging caused by more than 24 h soil inundation at up to the 4-leaf stage severely depressed emergence and growth, indicating the need for effective drainage at sowing of sunflower in the low-lying coastal saline zone of Bangladesh. Full article

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15 pages, 3609 KiB

Open AccessArticle

Manure Application Timing and Tillage Influence on Nutrient Loss from Snowmelt Runoff

by Ammar B. Bhandari, Ronald Gelderman, David German and Dennis Todey

Soil Syst. 2021, 5(4), 67; https://doi.org/10.3390/soilsystems5040067 - 01 Nov 2021

Cited by 1 | Viewed by 2259

Abstract

Winter manure application contributes substantial nutrient loss during snowmelt and influences water quality. The goal of this study is to develop best management practices (BMPs) for winter manure management. We compared nutrient concentrations in snowmelt runoff from three dates of feedlot solid beef [...] Read more.

Winter manure application contributes substantial nutrient loss during snowmelt and influences water quality. The goal of this study is to develop best management practices (BMPs) for winter manure management. We compared nutrient concentrations in snowmelt runoff from three dates of feedlot solid beef manure application (November, January, and March) at 18 tons ha⁻¹ on untilled and fall-tilled plots. The manure was applied at a single rate. Sixteen 4 m² steel frames were installed in the fall to define individual plots. Treatments were randomly assigned so that each tillage area had two control plots, two that received manure during November, two in January, and two in March. Snowmelt runoff from each individual plot was collected in March and analyzed for runoff volume (RO), ammonium-nitrogen (NH₄-N), nitrate-nitrogen (NO₃-N), total suspended solids (TSS), total Kjeldahl nitrogen (TKN), total phosphorus (TP), and total dissolved phosphorus (TDP). Snowmelt runoff concentrations and loads of NH₄-N, TKN, TP, and TDP were significantly higher in runoff from manure application treatments compared to control. The concentration of NH₄-N and loads of NH₄-N and TDP were significantly (p = 0.05) greater (42%, 51%, and 47%, respectively) from untilled compared to fall-tilled plots. The November application significantly increased RO, NH₄-N, and TDP concentrations and loads in the snowmelt runoff compared to January and March applications. Results showed that nutrient losses in snowmelt runoff were reduced from manure applications on snow compared to non-snow applications. The fall tillage before winter manure application decreased nutrient losses compared to untilled fields. Full article

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18 pages, 3118 KiB

Open AccessArticle

Enrichment and Fractionation of Rare Earth Elements in an Estuarine Marsh Soil Receiving Acid Discharges from Legacy Sulfide Mine Wastes

by Juan Carlos Fernández-Caliani and Mihaela Mihaylova Grantcharova

Soil Syst. 2021, 5(4), 66; https://doi.org/10.3390/soilsystems5040066 - 26 Oct 2021

Cited by 5 | Viewed by 3277

Abstract

This paper provides new insights into the geochemical cycling of rare earth elements (REEs) in acid sulfate soils developed on salt marsh sediments of the Huelva estuary (Spain) as a result of sulfide mineral oxidation in abandoned ore stockpiles. The study was aimed [...] Read more.

This paper provides new insights into the geochemical cycling of rare earth elements (REEs) in acid sulfate soils developed on salt marsh sediments of the Huelva estuary (Spain) as a result of sulfide mineral oxidation in abandoned ore stockpiles. The study was aimed at determining the REE abundance, fractionation pattern and mineralogical control of the dispersal and retention of REEs in the soil system. Forty-one samples were collected at 13 core sampling sites along two transects extending across the degraded marshland, and they were subjected to XRD, ESEM-EDS and ICP-MS analyses. Measurements revealed that the soil receiving acid discharges has relatively high concentrations of ΣREEs (174.77 ± 19.77 mg kg⁻¹) compared to local baseline concentrations. Shale-normalized REE patterns are generally flat, but a slight middle REE (MREE) enrichment is consistently apparent in all soil samples, involving relatively low La_N/Gd_N ratios (0.83 ± 0.08) and Gd_N/Lu_N ratios up to 1.42. The convex-upward REE pattern supports the possibility that iron oxy-hydroxide minerals play an important role in MREE retention through adsorption and co-precipitation mechanisms. Efflorescent sulfate salts left on the topsoil by the evaporation of acid waters show a strong depletion of light REEs (La_N/Gd_N = 0.16 ± 0.10) and act as a temporary reservoir of labile MREEs and heavy REEs during dry periods. Full article

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2 pages, 167 KiB

Open AccessEditorial

Challenges and Successes in Identifying the Transfer and Transformation of Phosphorus from Soils to Open Waters and Sediments

by Donald S. Ross, Eric O. Young and Deb P. Jaisi

Soil Syst. 2021, 5(4), 65; https://doi.org/10.3390/soilsystems5040065 - 19 Oct 2021

Viewed by 1947

Abstract

The anthropogenic loading of phosphorus (P) to water bodies continues to increase worldwide, in many cases leading to increased eutrophication and harmful algal blooms [...] Full article

(This article belongs to the Special Issue Challenges and Successes in Identifying the Transfer and Transformation of Phosphorus from Soils to Open Waters and Sediments)

18 pages, 3914 KiB

Open AccessArticle

A First Insight on the Interaction between Desiccation Cracking and Water Transfer in a Luvisol of Belgium

by Njaka Ralaizafisoloarivony, Aurore Degré, Benoît Mercatoris, Angélique Léonard, Dominique Toye and Robert Charlier

Soil Syst. 2021, 5(4), 64; https://doi.org/10.3390/soilsystems5040064 - 18 Oct 2021

Cited by 1 | Viewed by 2323

Abstract

The present paper presents the interactions between water retention/evaporation and cracking during the desiccation of intact and disturbed Belgian Luvisol. The disturbed (DS) and undisturbed (NDS) samples (reduced-tillage-residue-in (RTRI) and conventional-tillage-residue-out (CTRO)) were collected from an agricultural field in Gembloux, Wallonia, Belgium. The [...] Read more.

The present paper presents the interactions between water retention/evaporation and cracking during the desiccation of intact and disturbed Belgian Luvisol. The disturbed (DS) and undisturbed (NDS) samples (reduced-tillage-residue-in (RTRI) and conventional-tillage-residue-out (CTRO)) were collected from an agricultural field in Gembloux, Wallonia, Belgium. The drying experiment took place in controlled laboratory conditions at 25 °C. Moisture content, soil suction and surface cracks were monitored with a precision balance, a tensiometer and a digital camera, respectively. The image processing and analysis were performed using PCAS^® and ImageJ^® software. The results showed that crack formation was initiated at a stronger negative suction and a lower water content (Wc) in DS > CTRO > RTRI. The suction and the crack propagation were positively correlated until 300 kPa for the DS and far beyond the wilting point for the NDS. For the NDS, the cracking accelerated after reaching the critical water content (~20% Wc) which arrived at the end of the plateau of evaporation (40 h after crack initiation). The Krischer curve revealed that the soil pore size > 50 µm, and that it is likely that cracks are important parameters for soil permeability. The soil structure and soil fibre content could influence the crack formation dynamic during drying. The agricultural tillage management also influences the crack propagation. As retention and conductivity functions are affected by cracks, it is likely that the movement of fluids in the soil will also be affected by the cracks following a desiccation period (i.e., when the cracked soil is rewetted). Full article

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22 pages, 1476 KiB

Open AccessArticle

Evaluating Potential Ecological Risks of Heavy Metals of Textile Effluents and Soil Samples in Vicinity of Textile Industries

by Jaskaran Kaur, Sandip Singh Bhatti, Sartaj Ahmad Bhat, Avinash Kaur Nagpal, Varinder Kaur and Jatinder Kaur Katnoria

Soil Syst. 2021, 5(4), 63; https://doi.org/10.3390/soilsystems5040063 - 09 Oct 2021

Cited by 6 | Viewed by 3073

Abstract

The present study pertains to assessing the heavy metal (Cd, Cr, Co, Cu, Pb, and Zn) contents of untreated and treated effluents of two textile industries and agricultural soil samples in the vicinity of these industries located in Ludhiana, Punjab (India). The genotoxicity [...] Read more.

The present study pertains to assessing the heavy metal (Cd, Cr, Co, Cu, Pb, and Zn) contents of untreated and treated effluents of two textile industries and agricultural soil samples in the vicinity of these industries located in Ludhiana, Punjab (India). The genotoxicity of the effluents samples was estimated using Allium cepa root chromosomal aberration assay. The exposure of Allium cepa roots to untreated effluents from both industries resulted in the reduction of mitotic index (MI) and increase in chromosomal aberrations in the root tip meristematic cells when compared to those that were exposed to the treated effluents indicating the significant genotoxic potential of untreated effluents. Risk characterization of soil sample was carried out by calculating the potential ecological and human health risks of heavy metals. The hazard index was observed to be less than 1, indicating there was no potential health risk of heavy metals in soil samples. Furthermore, bioaccumulation potential studies on plant species grown in the vicinity of these industries have shown that bioaccumulation factor (BAF) varied as Ricinus communis L. > Chenopodium album L. > Cannabis sativa L. with Co and Pb having maximum and minimum values, respectively. Full article

(This article belongs to the Special Issue Assessment and Remediation of Soils Contaminated by Potentially Toxic Elements (PTE))

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12 pages, 1950 KiB

Open AccessArticle

Changes in Soil Prokaryotic Diversity in Response to Land-Use Changes in Sub-Saharan Africa

by Takamitsu Ohigashi, Michael Schloter, Stefanie Schulz, Kabenuka Munthali and Yoshitaka Uchida

Soil Syst. 2021, 5(4), 62; https://doi.org/10.3390/soilsystems5040062 - 04 Oct 2021

Cited by 1 | Viewed by 2917

Abstract

Sub-Saharan Africa is one of the most severely affected regions regarding soil degradation, a global issue with the loss of nutrients caused by inappropriate management, leading to low agricultural productivity. Here we asked the question of how soil prokaryotic communities are affected by [...] Read more.

Sub-Saharan Africa is one of the most severely affected regions regarding soil degradation, a global issue with the loss of nutrients caused by inappropriate management, leading to low agricultural productivity. Here we asked the question of how soil prokaryotic communities are affected by shifts in land use management and subsequent losses in soil organic carbon. We sampled soils from three sites in Zambia which have neighboring natural and managed sites. After the measurement of soil properties, soil DNA was sequenced, targeting the 16S rRNA gene. As expected, total carbon in soil was decreased in the managed sites, with significant reductions of bacterial biomass. However, the diversity indices in the managed soils were higher than in natural soils. Particularly, the relative abundance of nitrifiers was increased in the managed soils, most likely as a result of fertilization. However also other bacteria, e.g., those which formed tight interactions with the cultivated crops including the genera Balneimonas, and Bacillus, were increased in the managed soils. In contrast bacteria belonging to the family Chloroflexi, which were high in abundance in the natural soil were outcompeted by other prokaryotes in the managed soils most likely as a result of changes in the amount of soil organic carbon. Overall, our results suggest that we need to discuss the trends of prokaryotic diversity separately from those for prokaryotic abundance. Even when bacterial abundances were decreased in the managed soils, nitrifiers’ relative abundance and diversity increased in our experiment, suggesting the possible alteration of the nitrogen cycle in managed soils in sub-Saharan Africa. Full article

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20 pages, 3272 KiB

Open AccessReview

Soil Health Assessment and Management: Recent Development in Science and Practices

by Mingxin Guo

Soil Syst. 2021, 5(4), 61; https://doi.org/10.3390/soilsystems5040061 - 03 Oct 2021

Cited by 10 | Viewed by 11283

Abstract

In the past decade soil health has been intensively studied as a science and practiced as a means to help improve the global social, environmental, and economic sustainability. This paper reviews the recent advances of the scientific soil health system. The current understanding [...] Read more.

In the past decade soil health has been intensively studied as a science and practiced as a means to help improve the global social, environmental, and economic sustainability. This paper reviews the recent advances of the scientific soil health system. The current understanding and interpretation of soil health from the perspectives of soil functions, processes, and properties is summarized. Multi-tier soil health indicators were selected from relevant soil physical, chemical, and biological parameters. A suite of soil health assessment methods have been developed, such as soil health card, Solvita soil health tests, Haney soil health test, and comprehensive assessment of soil health. An array of soil health management practices have been recommended, including proper land use, crop rotation, cover crops, conservation tillage, soil organic amendment, crop-range-livestock integration, and rotational grazing. Overall, the recommended soil health indicators and assessment methods need further validation and improvement in relevance, scientific validity, practicality, and local adaptation. Continuous research, education, and outreach efforts are warranted to promote localized development, adoption, and implementation of soil health assessment and management. Full article

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18 pages, 2915 KiB

Open AccessArticle

Effect of Municipal Solid Waste Compost on Antimony Mobility, Phytotoxicity and Bioavailability in Polluted Soils

by Stefania Diquattro, Giovanni Garau, Matteo Garau, Gian Paolo Lauro, Maria Vittoria Pinna and Paola Castaldi

Soil Syst. 2021, 5(4), 60; https://doi.org/10.3390/soilsystems5040060 - 01 Oct 2021

Cited by 5 | Viewed by 2365

Abstract

The effect of a municipal solid waste compost (MSWC), added at 1 and 2% rates, on the mobility, phytotoxicity, and bioavailability of antimony (Sb) was investigated in two soils (SA: acidic soil; SB: alkaline soil), spiked with two Sb concentrations (100 and 1000 [...] Read more.

The effect of a municipal solid waste compost (MSWC), added at 1 and 2% rates, on the mobility, phytotoxicity, and bioavailability of antimony (Sb) was investigated in two soils (SA: acidic soil; SB: alkaline soil), spiked with two Sb concentrations (100 and 1000 mg kg⁻¹). The impact of MSWC on microbial activity and biochemical functioning within the Sb-polluted soils was also considered. MSWC addition reduced water-soluble Sb and favored an increase in residual Sb (e.g., by 1.45- and 1.14-fold in SA-100 and SA-1000 treated with 2% MSWC, respectively). Significant increases in dehydrogenase activity were recorded in both the amended soils, as well as a clear positive effect of MSWC on the metabolic activity and catabolic diversity of respective microbial communities. MSWC alleviated Sb phytotoxicity in triticale plants and decreased Sb uptake by roots. However, increased Sb translocation from roots to shoots was recorded in the amended soils, according to the compost rate. Overall, the results obtained indicated that MSWC, particularly at a 2% rate, can be used for the recovery of Sb-polluted soils. It also emerged that using MSWC in combination with triticale plants can be an option for the remediation of Sb-polluted soils, by means of assisted phytoextraction. Full article

(This article belongs to the Special Issue Assessment and Remediation of Soils Contaminated by Potentially Toxic Elements (PTE))

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25 pages, 2797 KiB

Open AccessArticle

Long-Term Effects of Forest Plantation Species on Chemical Soil Properties in Southern Rwanda

by Peter Rwibasira, Francois Xavier Naramabuye, Donat Nsabimana and Monique Carnol

Soil Syst. 2021, 5(4), 59; https://doi.org/10.3390/soilsystems5040059 - 26 Sep 2021

Cited by 4 | Viewed by 3332

Abstract

Understanding the long-term effects of tree species on soil properties is crucial for the development of forest restoration policies in relation to the choice of species that meet both environmental and local livelihood needs. This study was performed in the Arboretum of Ruhande, [...] Read more.

Understanding the long-term effects of tree species on soil properties is crucial for the development of forest restoration policies in relation to the choice of species that meet both environmental and local livelihood needs. This study was performed in the Arboretum of Ruhande, Southern Rwanda, where monocultures of 148 deciduous and 56 conifer species have been established in 0.25 ha replicated plots from 1933 onwards. We investigated the effects of six exotic and two native tree species planted in monoculture plots and native species mixed within one self-regenerated plot on soil properties in two layers (0–5 cm and 5–10 cm depth). We measured general soil properties (pH, SOM, exchangeable base cations) and water-soluble C and N as a proxy for soil functioning. Changes in soil properties were observed in the upper soil layer for all tree species. Planting Eucalyptus species caused soil acidification, whereas soil exchangeable cations and pH were higher under native species (Entandrophragma excelsum and Polyschias fulva) and mixed native species. The effects of tree species were more pronounced for hot water-extractable C and N than for other soil properties. Their analyses could be used for detecting changes in soil functioning linked to vegetation types. Full article

(This article belongs to the Special Issue Forest Soils: Functions, Threats, Management)

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20 pages, 4797 KiB

Open AccessArticle

Impact of Drought and Changing Water Sources on Water Use and Soil Salinity of Almond and Pistachio Orchards: 2. Modeling

by Sarah A. Helalia, Ray G. Anderson, Todd H. Skaggs and Jirka Šimůnek

Soil Syst. 2021, 5(4), 58; https://doi.org/10.3390/soilsystems5040058 - 24 Sep 2021

Cited by 5 | Viewed by 3167

Abstract

California is increasingly experiencing drought conditions that restrict irrigation deliveries to perennial nut crops such as almonds and pistachios. During drought, poorer quality groundwater is often used to maintain these crops, but this use often results in secondary salinization that requires skilled management. [...] Read more.

California is increasingly experiencing drought conditions that restrict irrigation deliveries to perennial nut crops such as almonds and pistachios. During drought, poorer quality groundwater is often used to maintain these crops, but this use often results in secondary salinization that requires skilled management. Process-based models can help improve management guidelines under these challenging circumstances. The main objective of this work was to assess seasonal soil salinity and root water uptake as a function of irrigation water salinity and annual rain amounts. The manuscript presents a comparison of three-year experimental and numerically simulated root zone salinities in and below the root zone of almond and pistachio drip-irrigated orchards at multiple locations in the San Joaquin Valley (SJV), California, with different meteorological characteristics. The HYDRUS-1D numerical model was calibrated and validated using field measurements of soil water contents and soil solute bulk electrical conductivities at four root zone depths and measured soil hydraulic conductivities. The remaining soil hydraulic parameters were estimated inversely. Observations and simulations showed that the effects of rain on root zone salinity were higher in fields with initially low salinities than in fields with high salinities. The maximum reduction in simulated root water uptake (7%) occurred in response to initially high soil salinity conditions and saline irrigation water. The minimum reduction in simulated water uptake (2.5%) occurred in response to initially low soil salinity conditions and a wet rain year. Simulated water uptake reductions and leaching fractions varied at early and late times of the growing season, depending on irrigation water salinity. Root water uptake reduction was highly correlated with the cumulative effects of using saline waters in prior years, more than salt leaching during a particular season, even when rain was sufficient to leach salts during a wet year. Full article

(This article belongs to the Special Issue Advances in the Prediction and Remediation of Soil Salinization)

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19 pages, 2647 KiB

Open AccessArticle

Machine Learning for Predicting Field Soil Moisture Using Soil, Crop, and Nearby Weather Station Data in the Red River Valley of the North

by Umesh Acharya, Aaron L. M. Daigh and Peter G. Oduor

Soil Syst. 2021, 5(4), 57; https://doi.org/10.3390/soilsystems5040057 - 23 Sep 2021

Cited by 22 | Viewed by 5297

Abstract

Precise soil moisture prediction is important for water management and logistics of on-farm operations. However, soil moisture is affected by various soil, crop, and meteorological factors, and it is difficult to establish ideal mathematical models for moisture prediction. We investigated various machine learning [...] Read more.

Precise soil moisture prediction is important for water management and logistics of on-farm operations. However, soil moisture is affected by various soil, crop, and meteorological factors, and it is difficult to establish ideal mathematical models for moisture prediction. We investigated various machine learning techniques for predicting soil moisture in the Red River Valley of the North (RRVN). Specifically, the evaluated machine learning techniques included classification and regression trees (CART), random forest regression (RFR), boosted regression trees (BRT), multiple linear regression (MLR), support vector regression (SVR), and artificial neural networks (ANN). The objective of this study was to determine the effectiveness of these machine learning techniques and evaluate the importance of predictor variables. The RFR and BRT algorithms performed the best, with mean absolute errors (MAE) of <0.040 m³ m⁻³ and root mean square errors (RMSE) of 0.045 and 0.048 m³ m⁻³, respectively. Similarly, RFR, SVR, and BRT showed high correlations (r² of 0.72, 0.65 and 0.67 respectively) between predicted and measured soil moisture. The CART, RFR, and BRT models showed that soil moisture at nearby weather stations had the highest relative influence on moisture prediction, followed by 4-day cumulative rainfall and PET, subsequently followed by bulk density and Ksat. Full article

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Soil Syst., Volume 5, Issue 4 (December 2021) – 16 articles

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