Available Water Capacity Research Articles

An Ensemble Mean Method for Remote Sensing of Actual Evapotranspiration to Estimate Water Budget Response across a Restoration Landscape

Estimates of actual evapotranspiration (ETa) are valuable for effective monitoring and management of water resources. In areas that lack ground-based monitoring networks, remote sensing allows for accurate and consistent estimates of ETa across a broad scale—though each algorithm has limitations (i.e., ground-based validation, temporal consistency, spatial resolution). We developed an ensemble mean ETa (EMET) product to incorporate advancements and reduce uncertainty among algorithms (e.g., energy-balance, optical-only), which we use to estimate vegetative water use in response to restoration practices being implemented on the ground using management interventions (i.e., fencing pastures, erosion control structures) on a private ranch in Baja California Sur, Mexico. This paper describes the development of a monthly EMET product, the assessment of changes using EMET over time and across multiple land use/land cover types, and the evaluation of differences in vegetation and water distribution between watersheds treated by restoration and their controls. We found that in the absence of a ground-based monitoring network, the EMET product is more robust than using a single ETa data product and can augment the efficacy of ETa-based studies. We then found increased ETa within the restored watershed when compared to the control sites, which we attribute to increased plant water availability.

Interannual radial growth response of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) to severe droughts: an analysis along a gradient of soil properties and rooting characteristics

Key messageWe analyzed stem growth responses of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) to severe drought in 2003/04 and 2018. The results showed high drought tolerance in sandy, loamy, and most silty soils, with limitations on clayey soils. This study indicates the susceptibility of Douglas-firs with shallow root systems to extreme drought and the importance of deep rooting for high drought resilience.ContextAlthough Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) is considered a more drought-tolerant substitute for Norway spruce (Picea abies (L.) Karst.) in Europe, there is considerable uncertainty about the drought tolerance of Douglas-fir under climate change, specifically concerning soil properties.AimsThis study aimed to assess the influence of soil texture, plant-available water capacity, and rooting characteristics on the interannual stem growth response of Douglas-fir when exposed to severe drought.MethodsAlong a soil texture gradient from sand to clay, we selected seven closely spaced sites at elevations of approximately 500 m a.s.l. in southern Germany. Mixed-effects models were used to analyze the effects of soil physical and rooting characteristics on growth response indices (resistance, recovery, resilience) related to the severe to extreme droughts in 2003/04 and 2018.ResultsDouglas-fir showed high drought tolerance in sandy, loamy, and most silty soils. However, the results suggest a higher drought stress risk on clayey soils, as well as at specific silty sites with shallow root systems. A higher effective rooting depth increased the resilience of Douglas-fir during the extreme drought in 2018.ConclusionDouglas-fir demonstrated its drought tolerance in most soil textures. In addition, this study supports the need for combined above- and below-ground investigations on factors influencing drought tolerance and the importance of rooting for drought resilience.

Regional and farm level droughts characteristics for southwestern Uganda during 1981–2017

An increase in drought events associated with rising temperatures indicates that Uganda is facing a growing challenge from climate variability. Despite these challenges, there is a lack of comprehensive information on how climate variability affects soils, particularly drought characteristics. In an effort to address this limitation, this study utilised high-quality, in-situ climate data and soil Available Water Capacity (AWC) specific to south-western Uganda. The study employed the Palmer Drought Severity Index (PDSI) and the Standardised Precipitation-Evapotranspiration Index (SPEI) to assess drought occurrences over the period 1981–2017. Notably, the results from the 3-month SPEI indicated higher frequencies across all drought categories. Meanwhile, the 12-month SPEI exhibited more stabilised negative and positive truncations for drought and wet events, respectively. Analysing the temporal evolution of monthly PDSI values for five major soil mapping units revealed distinct patterns. Moderate droughts were observed over Lixic Ferralsols between 1981 and 1992 and between 1998 and 2008. Extreme drought events occurred during the first 5–7 months of 2017. Luvisols exhibited prolonged negative truncation levels, indicating a water deficit during several periods: 1982–1984, 1990–1994, 1998–2000, 2010, and 2012–2014. Histosols experienced drought conditions from 1982 to 1986, interspersed with wet events in 1988, 1997, 1999–2002, and 2005. The study emphasises the differential response of soil units to drought and wet conditions. As a result, the research recommends implementing water management practices such as irrigation, mulching, conservation tillage, zero tillage, and drainage for all soils to enhance resilience and sustainable agricultural practices in the region.

Quantitative evaluation of soil health based on a minimum dataset under various short-term crop rotations on the Canadian prairies

Maintaining and improving soil health (SH) is essential for the long-term sustainability and productivity of agriculture, notably in the face of climate change. This study addressed the challenge of selecting appropriate soil indicators, scoring methods, and indexing approaches for SH evaluation under no-till crop rotations. This study aimed to develop minimum datasets (MDS) and assess SH in six crop rotations (denoted as conventional, diversified, high-risk and high-reward, market-driven, pulse-oilseed intensified, and soil health-enhanced rotations) at three sites on the Canadian prairies. Fourteen soil indicators in the total dataset (TDS) were examined, encompassing both chemical (0–7.5 cm depth) and physical (5–10 cm depth) properties. Principal component analysis (PCA) identified MDSs from the TDS. Two scoring [linear (L) and non-linear (NL)] and two SH indexing approaches [additive (A) and weighted additive (WA)] were used to calculate the SH index (SHI). One-way ANOVA evaluated the SHI among crop rotations. The PCA revealed variations in the number of indicators in the MDS across sites, with soil organic carbon, bulk density, macroporosity, and plant-available water capacity as the common indicators for MDS across sites. Other indicators such as particulate organic matter carbon, aggregate stability, field capacity, and microporosity were found to be important, depending on the site. The non-linear weighted additive SH indexing (SHI.NLWA) proved to be the most sensitive and effective for differentiating among crop rotations in the short-term across study sites (R2 = 0.89–0.94, P < 0.05). Crop rotations significantly influenced SHI, with the diversified and high-risk and high-reward rotations having the highest SHI at Lethbridge and Scott, respectively. Overall, the diversified rotation at Lethbridge and Swift Current, along with the high-risk and high-reward rotation at Scott, exhibited better soil function than other rotations. Monitoring SHI over time and selecting crop rotations that improve SH can collectively enhance soil functions and agroecosystem productivity.

Improving stormwater infiltration and retention in compacted urban soils at impervious/pervious surface disconnections with biochar

Urban development often results in compacted soils, impairing soil structure and reducing the infiltration and retention of stormwater runoff from impervious features. Biochar is a promising organic soil amendment to improve infiltration and retention of stormwater runoff. Soil at the disconnection between impervious and pervious surfaces represents a critical biochar application point for stormwater management from urban impervious features. This study tested the hypothesis that biochar would significantly improve water retention and transmission at four sites, where varying percentages (0%, 2%, and 4% w/w) of biochar were amended to soils between impervious pavement, and pervious grassed slopes. Field-saturated hydraulic conductivity (Ksat) and easily drainable water storage capacity were monitored at these sites for five months (two sites) and 15 months (two sites). At the end of the monitoring periods, the physical, chemical, and biological properties of each site's soil were assessed to understand the impact of biochar on soil aggregation, which is critical for improved soil structure and water infiltration. Results indicated that the field Ksat, drainable water storage capacity, and plant available water content (AWC) were 7.1 ± 3.6 SE, 2.0 ± 0.3 SE, and 2.1 ± 0.3 SE times higher in soils amended with 4% biochar, respectively, compared to the undisturbed soil. Factor analysis elucidated that biochar amendment increased the organic matter content, aggregate mean weight diameter, organo-mineral content, and fungal hyphal length while decreasing the bulk density. Across the 12 biochar/soil combinations, the multiple linear regression models derived from factor analysis described the changes in Ksat and AWC reasonably well with R2 values of 0.51 and 0.71, respectively. Using soil and biochar properties measured before biochar addition, two recent models, developed from laboratory investigations, were found helpful as screening tools to predict biochar's effect on Ksat and AWC at the four field sites. Overall, the findings illustrate that biochar amendment to compacted urban soils can significantly improve soil structure and hydraulic function at impervious/pervious surface disconnections, and screening models help to predict biochar's effectiveness in this context.

Stable carbon isotope composition and intrinsic water use efficiency in plants along an altitudinal gradient on the eastern slope of Yulong Snow Mountain, China

BackgroundStable carbon isotope composition (δ13Cp) can be used to estimate the changes in intrinsic water use efficiency (iWUE) in plants, which helps us to better understand plants’ response strategies to climate change. This study focused on the variations in δ13Cp and iWUE for the different life-form plants (i.e., herbs, shrubs, and trees) along an altitudinal gradient (3300, 3600, 3900, 4100, 4300, and 4500 m) on the eastern slope of Yulong Snow Mountain, southeastern margin of the Qinghai-Tibet Plateau. The response mechanisms of δ13Cp and iWUE for different life-form plants to altitude were thoroughly analyzed in this mountain ecosystem.ResultsThe δ13Cp values of plants on the eastern slopes of Yulong Snow Mountain ranged from − 30.4‰ to − 26.55‰, with a mean of − 28.02‰, indicating a dominance of C3 plants. The δ13Cp and iWUE values varied among different life-form plants in the order of herbs > shrubs > trees, particularly in 3600, 3900, and 4300 m. The δ13Cp and iWUE values for herbs and shrubs increased with altitude and were mainly controlled by air temperature. The two parameters for trees exhibited a trend of initial decrease followed by an increase with altitude. Below 3900 m, the δ13Cp and iWUE values decreased with altitude, influenced by soil moisture. However, above 3900 m, the two parameters increased with altitude, mainly regulated by air temperature. In addition, iWUE was positively correlated with leaf P content but negatively correlated with leaf N:P ratio, especially for herbs and trees, suggesting that P plays a key role in modulating iWUE in this region.ConclusionsThe differentiated responses of water availability for different life-form plants to a higher altitudinal gradient are regulated by air temperature, soil moisture, and leaf P content in the Yulong Snow Mountain. These results provide valuable insights into understanding the water–carbon relationships in high-altitude ecosystems.

Effect of Humic Amendment on Selected Hydrophysical Properties of Sandy and Clayey Soils

In recent years, products containing humic acids have been increasingly used in agriculture to improve soil parameters. Quantifying their impact on soil quality is, therefore, of key importance. This study seeks to evaluate the impact of the commercial humic acid product (HA) on the hydrophysical parameters of sandy and clayey soils sampled from different sites in Slovakia. Specifically, the study hypothesizes that humic amendment will enhance particle density (ρs), dry bulk density (ρd), porosity (Φ), saturated hydraulic conductivity (Ks), soil water repellency (SWR), and water retention capacity in sandy and clayey soils. The results of the laboratory measurements were analyzed using NCSS statistical software at a statistical significance of p &lt; 0.05. In sandy soil, there was a statistically significant decrease in ρd and Ks and an increase in Φ and a contact angle (CA) after the application of 1 g/100 cm3 HA. At a dose of 6 g/100 cm3 HA, the values of ρs, ρd, and Ks decreased, and the Φ and CA values increased. In clayey soil, the Ks value significantly decreased by −35.5% only after the application of 6 g/100 cm3 HA. The addition of HA increased the full water capacity (FWC) and available water capacity (AWC) of clayey and sandy soils. The positive influence of HA on the studied soil parameters was experimentally confirmed, which can be beneficial, especially for their use in agricultural production.

Dry‐wet alternation and microplastics particle size effects on and contributions to soil water and soil pore properties

AbstractAgricultural soils always contain microplastics (MPs) residues and farmlands often undergo continuous drying‐wetting alternations. However, little is known about how the existing MPs and MPs particle size affect soil physical properties under drying‐wetting cycles; also their combined influences are not well understood. Hence, we completed measurements of hydraulic parameters and calculations of water characteristics and pore distributions in soil‐MPs mixtures subjecting to five drying‐wetting cycles and four MPs particle sizes. Quantitative findings indicated that both MPs and drying‐wetting cycles reduced saturated conductivity, which firstly decreased and then increased with the increase of MPs particle size and the progress of drying‐wetting cycles. The drying‐wetting cycles increased field capacity (FC) and permanent wilting coefficient (PWC), but reduced gravity water (GW) and available water content (AWC). Oppositely, the MPs reduced FC and PWC but increased GW and AWC; furthermore, the average FC and PWC overall firstly decreased and then increased with the increase in MPs particle size; however, the average GW and AWC firstly increased and then stabilized. The MPs reduced total porosity and the drying‐wetting cycle also reduced it in soil‐MPs mixtures, which whereas increased as the drying‐wetting cycles proceeded. Factors contribution analyses indicated that the drying‐wetting cycle made greater contributions than MPs particle size to the variation of soil physical properties, and their combined effects mainly made great contributions to the variation of soil hydraulic parameters. Our findings provide evidence for MPs influence on soil physical properties, which deserves attention with regard to the developments of sustainable agricultural practical managements in plastic‐polluted soil‐crop systems.

Análise espacial da produtividade da cenoura irrigada em função das propriedades físicas do solo

ABSTRACT Understanding soil, plant attributes, and carrot crop dynamics is vital for optimizing site-specific management practices and enhancing crop yield and soil quality. This study aimed to ascertain the dependence and spatial variability between irrigated carrot yield and soil physical attributes in a clayey Oxisol. The research took place during the 2021 growing season in a commercial carrot production area in Campos Altos, MG, Brazil. One hundred sampling points were established within the irrigated area, distributed across a square expanse of 40,000 m², positioned at the centers of 20 × 20 m grids. The study revealed high yield in the irrigated carrot crop (99.74 t ha-1) with moderate variability. Soil attributes displayed a range of heterogeneity, ranging from low to extremely high, contingent on the variable assessed, as determined by the coefficient of variation. Among the variables exhibiting spatial dependence, particle density exhibited a minimum range of 40 m, which is recommended for further studies on irrigated carrot cultivation in a clayey Oxisol. Total soil water availability demonstrated a positive spatial correlation and proved to be the recommended variable for estimating the spatial variability of carrot crop yield.

Individual vital rates respond differently to local‐scale environmental variation and neighbour removal

Abstract Understanding how plant fitness varies along natural gradients is critical for predicting responses to environmental change. However, individual vital rates are often used as fitness proxies without knowing how other vital rates vary along the same gradients. We investigated how canopy cover, plant–plant interactions, water availability and soil properties influenced the emergence, survival, seed production and population growth rates of eight annual plant species in semi‐arid Western Australia. We sowed seeds into sun‐exposed and shaded blocks across a reserve, removed all neighbouring plants from half of the interaction neighbourhoods, and used rainout shelters to reduce and increase precipitation relative to ambient plots. Canopy cover had strong negative effects on emergence, but few direct impacts on other vital rates and population growth rates. Direct competitive effects on survival and seed production were rare, although evident for population growth rate for 3/8 species. Competition was stronger in open than shaded plots for half of the species. Canopy cover also interacted with the watering treatment to influence survival of half of the species, but watering alone had few direct impacts on species' vital and population growth rates. We found only positive significant correlations between pairs of rates, and survival and seed production were far more frequently correlated with population growth rate than emergence. Synthesis. Our study illustrates that vital rates can respond to the same local‐scale environmental variation in different ways that are likely not driven by life history trade‐offs. We caution against using emergence as a proxy for population growth rate and emphasise that no single vital rate was a reliable fitness proxy overall. Interactions among abiotic and biotic factors were important drivers of vital and population growth rates for some species, highlighting the need to account for plant–plant interactions when predicting population responses to environmental change.

Inclusion of bedrock vadose zone in dynamic global vegetation models is key for simulating vegetation structure and function

Abstract. Across many upland environments, soils are thin and plant roots extend into fractured and weathered bedrock where moisture and nutrients can be obtained. Root water extraction from unsaturated weathered bedrock is widespread and, in many environments, can explain gradients in vegetation community composition, transpiration, and plant sensitivity to climate. Despite increasing recognition of its importance, the “rock moisture” reservoir is rarely incorporated into vegetation and Earth system models. Here, we address this weakness in a widely used dynamic global vegetation model (DGVM; LPJ-GUESS). First, we use a water flux-tracking deficit approach to more accurately parameterize plant-accessible water storage capacity across the contiguous United States, which critically includes the water in bedrock below depths typically prescribed by soil databases. Secondly, we exploit field-based knowledge of contrasting plant-available water storage capacity in weathered bedrock across two bedrock types in the Northern California Coast Ranges as a detailed case study. For the case study in Northern California, climate and soil water storage capacity are similar at the two study areas, but the site with thick weathered bedrock and ample rock moisture supports a temperate mixed broadleaf–needleleaf evergreen forest, whereas the site with thin weathered bedrock and limited rock moisture supports an oak savanna. The distinct biomes, seasonality and magnitude of transpiration and primary productivity, and baseflow magnitudes only emerge from the DGVM when a new and simple subsurface storage structure and hydrology scheme is parameterized with storage capacities extending beyond the soil into the bedrock. Across the contiguous United States, the updated hydrology and subsurface storage improve annual evapotranspiration estimates as compared to satellite-derived products, particularly in seasonally dry regions. Specifically, the updated hydrology and subsurface storage allow for enhanced evapotranspiration through the dry season that better matches actual evapotranspiration patterns. While we made changes to both the subsurface water storage capacity and the hydrology, the most important impacts on model performance derive from changes to the subsurface water storage capacity. Our findings highlight the importance of rock moisture in explaining and predicting vegetation structure and function, particularly in seasonally dry climates. These findings motivate efforts to better incorporate the rock moisture reservoir into vegetation, climate, and landscape evolution models.

Estimating fracture characteristics and hydraulic conductivity from slug tests in epikarst of southwest China

Study regionGuizhou Province, Southwest China Study focusThis study aims to estimate the hydraulic conductivity (Kh) of the weathered rock fractures (epikarst) based on the best fitting of observed water head in 105 slug tests in the study sites. Specifically, comparisons of the estimated results from the analytical and numerical methods reveal the effects of changes in fracture flow conditions (e.g., steady and non-steady) on Kh for various fracture apertures and soil fillings. New hydrological insights for the regionThe results comparatively show that Kh from the analytical solution of steady flow was significantly underestimated, and the numerical modeling of the non-linear and unsteady flow can improve the water head fitting when the Reynolds number (Re) > 17.27. The optimized Kh ranges 0.014–2673 m/d and the mean value of Kh is about 100 times the median value, suggesting that epikarst flow might be controlled by a limited number of larger fractures. Moreover, the soil filling in large fractures (>10 mm) creates a turning point of the exponential increase of Kh with d. Comparatively, the naturally full-filling fractures resemble the soil matrix with a low Kh, and the partial-filling fractures can create preferential flow around the soil-rock interfaces with a high Kh. These results fundamentally improve our understanding of water infiltration, retention, and availability for plant uses in the karst areas of southwest China.

Pedotransfer Functions for Field Capacity, Permanent Wilting Point, and Available Water Capacity Based on Random Forest Models for Routine Soil Health Analysis

ABSTRACT Available water capacity (AWC), field capacity (θFC), and permanent wilting point (θPWP) are regarded as key physical soil health indicators that directly capture the soil’s capacity to store plant available water but are expensive components of a comprehensive soil health analysis. To reduce costs, pedotransfer functions for θFC, θPWP, and AWC were developed from a dataset of 7,232 soil samples with texture, soil organic matter (SOM), permanganate-oxidizable carbon, soil respiration, AWC, θFC, θPWP, wet aggregate stability, and extractable potassium, magnesium, iron, and manganese. Three functions were developed for each property: a full random forest (RF) model containing all variables, a reduced RF model and a multiple linear regression model containing texture and SOM. Pedotransfer functions were validated with an independent dataset that contained 1,406 samples. The full RF models for θFC, θPWP, and AWC reduced the root mean square error (RMSE) by 16.3, 13.3, and 12.8%, compared to multiple linear regression models, respectively. Furthermore, the full RF models for θFC, θPWP, and AWC reduced RMSE by 11.6, 6.7, and 12.8%, compared to the reduced RF model, respectively. Permanganate-oxidizable carbon, wet aggregate stability, and extractable magnesium, potassium, and iron were useful novel predictor variables for improving prediction of θFC and AWC. AWC was sensitive in 20/57 long-term experiments, and full RF models were able to replicate 5/20 of those significant results. New RF pedotransfer functions for θFC, θPWP, and AWC can enhance prediction compared to traditional modeling techniques, fits into existing interpretative frameworks, and improves cost-effectiveness of comprehensive assessments of soil health.

Silicon Combined with Trichoderma harzianum and Organic Matter as an Environmental Friendly Strategy for Mitigating Salt Stress in Quinoa (Chenopodium quinoa Willd.)

Silicon is known to be an effective salt stress attenuator for crops, and evaluating its application effectiveness in combination with other salt stress attenuators is essential for crops and soils. This work aimed to assess whether applying organic matter (OM) and Trichoderma (T) potentiates silicon (Si) in mitigating soil salinization and promoting quinoa growth under salt stress. Quinoa plants were grown in pots under saline irrigation (3.12 dS m−1) and subjected to the following treatments: quinoa only; quinoa + Si; quinoa + Si + OM; quinoa + Si + T; and quinoa + Si + OM + T, at two levels of soil moisture—30 and 80% of the available water content (AWC). Sixty days after transplanting, soil and quinoa plants were collected from the pots. At 80% AWC, Si + OM and Si + OM + T promoted the highest fresh mass for quinoa—301.54 and 247.26 g, respectively. Si + OM + T significantly mitigated saline parameters (EC = 9.82 dS m−1; ESP = 32.27%). Si combined with OM and T was the most effective way to attenuate salt stress in quinoa and soil salinization and promote a more sustainable way to manage saline irrigation in semiarid regions.

Crop-livestock integration influenced soil profile organic carbon and hydro-physical properties in converted grasslands to row crops

Integrated crop-livestock systems (ICLS) can mitigate the impacts of cropping intensification by improving soil organic carbon (SOC) and associated hydro-physical properties. This study was conducted on three on-farm long-term (≥30 years) sites (Site 1, 2, and 3) and one short-term (4 years) experimental site (Site 4) to compare the SOC and hydro-physical properties to a depth of 40 cm for an intensive-cropland (CL), a native-grassland (NG) and cropland managed with ICLS. Data showed higher SOC, soil water retention (SWR), macroporosity, available water capacity (AWC), and saturated hydraulic conductivity (Ksat) for the NG than the CL indicating the degradation of soil physical quality because of intensive agriculture. However, for sites 1 and 2, the ICLS had 27% and 46% more SOC than the CL in the 0–10 cm depth. In addition, the ICLS decreased bulk density (ρb) (sites 1 and 3) and increased the Ksat (sites 1, 2, and 3) at 0–10 cm depth as compared to the CL. No differences in SOC or hydro-physical properties were observed for the short-term ICLS (site 4) when compared to the CL. The impacts of ICLS were most prominent at the surface soil (0–10 cm) and no difference was observed for the deeper soil. The AWC showed a linear increase with the increase in SOC, however, soils under ICLS and CL showed a higher increase in AWC with an increase in SOC as compared to the NG. This study highlighted the negative impacts of grassland to cropland conversion and suggested the implementation of ICLS to improve organic carbon and other associated hydro-physical properties of soils.

Cactus pear pruning residue in agriculture: Unveiling soil-specific responses to enhance water retention

This study examines the effects of incorporating powdered cactus pear pruning waste (PCPPW) on the hydraulic properties of benchmark soils, in line with circular economy principles. The cultivation of cactus pear generates substantial amounts of pruning residues, which offer the potential for nutrient recovery and reuse. Our findings reveal that amending soils with this material has a positive impact on water retention, but it requires a substantial volume, exceeding 20%, which may not be practical for open-field applications. However, this presents promise for the horticultural and floricultural sectors. These results challenge previous assumptions about soil density, plant-available water capacity, and swelling potential, contributing to our understanding of agronomic applications. Notably, the enhancement of drainable water capacity is most significant in less clayey soils, while highly clayey soils experience fewer benefits. These results highlight the importance of considering specific soil conditions when implementing circular economy principles, particularly in soil amendment practices.

Effects of Biochar and Municipal Solid Waste Compost on Soil Physical Quality and Productivity Index Under Sorghum Cultivation Irrigated with Saline Water

ABSTRACT Amending soil with different materials is gaining acceptance as an effective and inexpensive technique for reclamation of salt-affected soils. The main idea of this study was to investigate the effects of biochar, compost of municipal solid waste and different water salinities level on soil physical quality (SDexter) and soil productivity index (SPI). The treatments were as followed: Control: Soil without biochar or compost and irrigated with tap water, S1: Soil without biochar or compost and irrigated with saline water (EC = 4.5 dS m−1), S2: Soil without biochar or compost and irrigated with saline water (EC = 9 dS m−1), B: Soil amended with 1.5%w/w biochar and irrigated with tap water, B+S1: Soil amended with 1.5%w/w biochar and irrigated with saline water (EC = 4.5 dS m−1), B+S2: Soil amended with 1.5%w/w biochar and irrigated with saline water (EC = 9 dS m−1), C: Soil amended with 1.5%w/w compost and irrigated with tap water, C+S1: Soil amended with 1.5%w/w compost and irrigated with saline water (EC = 4.5 dS m−1), C+S2: Soil amended with 1.5%w/w compost and irrigated with saline water (EC = 9 dS m−1). Soil water characteristic curve (SWCC), Field capacity (FC), Plant wilting point (PWP), Plant available water (PAW), Dexter’s index of soil physical quality (SDexter) and SPI were examined in a greenhouse experiment. The SPI was calculated by integrating the effects of six soil quality indices: plant available water, organic matter (OM), Electrical conductivity (EC), pH, Bulk density (BD) and Root weighting factor (RF) for all treatments were calculated. The results showed that the B treatment had a slightly higher effect on SWCC. The applied B and C treatments caused insignificant increase in PAW relative to the control. In addition, application of biochar or compost to soil significantly increased the SDexter. The application of C treatment had insignificantly higher value of SDexter compared to other treatments. Compared with the control, SPI was significantly higher for the B and C treatments. Overall, the application of biochar/compost minimized the destructive effects of saline irrigation water and improved the quality of the salt-affected fine-textured soil.

Photosynthetic responses of Larix kaempferi and Pinus densiflora seedlings are affected by summer extreme heat rather than by extreme precipitation

The frequency and intensity of summer extreme climate events are increasing over time, and have a substantial negative effect on plants, which may be evident in their impact on photosynthesis. Here, we examined the photosynthetic responses of Larix kaempferi and Pinus densiflora seedlings to extreme heat (+ 3 °C and + 6 °C), drought, and heavy rainfall by conducting an open-field multifactor experiment. Leaf gas exchange in L. kaempferi showed a decreasing trend under increasing temperature, showing a reduction in the stomatal conductance, transpiration rate, and net photosynthetic rate by 135.2%, 102.3%, and 24.8%, respectively, in the + 6 °C treatment compared to those in the control. In contrast, P. densiflora exhibited a peak function in the stomatal conductance and transpiration rate under + 3 °C treatment. Furthermore, both species exhibited increased total chlorophyll contents under extreme heat conditions. However, extreme precipitation had no marked effect on photosynthetic activities, given the overall favorable water availability for plants. These results indicate that while extreme heat generally reduces photosynthesis by triggering stomatal closure under high vapor pressure deficit, plants employ diverse stomatal strategies in response to increasing temperature, which vary among species. Our findings contribute to the understanding of mechanisms underlying the photosynthetic responses of conifer seedlings to summer extreme climate events.

High‐resolution mapping of available water content in Senegal using iSDA Africa dataset and USDA Rosetta3 model

AbstractThis data article presents a high‐resolution map of available water content (AWC) for Senegal, derived from the iSDA Africa dataset and the USDA Rosetta3 model, as well as the method used for its production. The map covers the entire country at a resolution of 30 m and provides a valuable resource for hydrological studies and spatialized crop model simulations in the region where water is a limiting factor for crop production. The dataset is based on existing soil properties data and leverages pedotransfer functions (PTFs) to estimate water retention capabilities from soil properties. This AWC map derived from datasets with enhanced accuracy offers a more precise estimate of soil water retention capacity, which can be instrumental in informing water and agricultural management, policy decisions and investments. The dataset, including intermediate variables, is available in geotiff format at Cirad Dataverse under the DOI 10.18167/DVN1/SGNSII and complies with FAIR data principles, allowing its broad reuse. The code used to produce this dataset is also made available under the DOI 10.5281/zenodo.10078399, so that AWC maps can be produced for any territory covered by the iSDA Africa product.

Temporal variability of physical quality of a sandy loam soil amended with compost

AbstractCompost can enhance the soil's ability to retain water, resulting in an overall improvement of soil physical quality (SPQ). The purpose of this study was to evaluate the temporal variability of physical and hydraulic properties of a sandy loam soil amended with a compost obtained from orange juice processing wastes and garden cleaning. The soil water retention curve of repacked soil samples at varying compost to soil ratios, r, was determined at the time of compost embedding (M0) and after six months (M6), and twelve months (M12). Indicators of SPQ linked to soil water retention curve such as air capacity (AC), macroporosity (Pmac), plant available water capacity (PAWC), relative field capacity (RFC) and Dexter S-index (S), were estimated. The effect of compost addiction of the pore volume distribution function was also evaluated.The elapsed time from compost application influenced all SPQ indicators but the maximum beneficial effects of compost amendment were achieved within approximately the first six months. Indicators linked the macro- and mesoporosity (Pmac and AC) decreased with r whereas indicators linked to plant water availability (PAWC and RFC) increased with r. The combined effect of time and rate was statistically observed only for Pmac, PAWC and S.Compost addiction reduced the soil compaction and modified the pore system, as the fraction of structural porosity (i.e., macropores) decreased and the fraction of textural porosity (i.e., micropores) increased. It was concluded that even a single application of compost could have a significant impact on soil water retention and microstructure with positive implications for soil health, precision agriculture and crop productivity.