Plant Available Water Capacity Research Articles

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.

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.

Effect of the incorporation of ashes from the Calbuco volcano on the porous function of an andosol

Soils derived from volcanic ashes represent >60% of the arable land in Chile. Permanent volcanic activity makes seeking solutions for the management of volcanic material deposited after an eruption essential. The aim of this research was to evaluate how incorporating ashes from the eruption of the Calbuco Volcano affected the structure of a volcanic soil in southern Chile. Undisturbed soil samples were collected in 2022, under three field conditions: soils from which the ashes were entirely removed after the eruption (c), soils in which the ashes were incorporated (c/i) and soils on which the ashes remained on the surface (s/i). The pore-size distribution and the air conductivity were determined based on the water retention curve (WRC), the coefficient of linear extensibility (COLE), the pore shrinkage index (PSI) and the air permeability (Ka). Under c/i field conditions, an increase in total porosity (TP) of 5.57 and 3.48% was found when compared to the control and s/i field conditions, respectively. The highest volume of plant available water capacity (PAWC) was observed in the s/i field conditions, which increased by 65% compared to the other soil conditions. The incorporation of ash into the first 20 cm of depth did not guarantee an increase in usable water for plants; nonetheless, changes in structure did generate a redistribution in the pore size. Therefore, it is essential to evaluate how volcanic ash deposits and their incorporation affect soil physical properties under field conditions.

Crop rotations influence soil hydraulic and physical quality under no-till on the Canadian prairies

Cropping system sustainability is dependent on the conservation of soil hydraulic and physical quality over time. This study examined the effects of crop rotations on soil hydraulic and physical quality on the Canadian prairies, emphasizing choices of crop species and sequence to preserve or improve soil quality under no-till management. Field experiments were initiated in spring 2018 at three sites: Lethbridge (Alberta), and Swift Current and Scott (Saskatchewan) to evaluate six crop rotations, consisting of (i) conventional (control), (ii) pulse/oilseed intensified, (iii) diversified, (iv) market-driven, (v) high-risk and high-reward, and (vi) soil health-enhanced. Undisturbed soil cores were collected from 5–10 and 15–20 cm soil depth increments in 2021 after crop harvest, to determine bulk density (BD), total (TP) and effective porosity (EP), pore size distribution, soil water retention, and unsaturated hydraulic conductivity. Results revealed that crop rotations did not significantly impact BD, TP, or EP in the 5–10 and 15–20 cm soil depth increments across the three sites. Depending on the site and soil layer, the pulse/oilseed intensified, diversified, high-risk and high-reward, and soil health-enhanced rotations improved macroporosity by 13−127% and mesoporosity by 1−36% compared to the conventional rotation, resulting in concomitant increases in large and medium unsaturated hydraulic conductivities. At Lethbridge, both conventional and high-risk and high-reward rotations resulted in increased water content at field capacity (FC) by 12–14%, permanent wilting point (PWP) by 7−12%, and plant available water capacity (PAWC) by 16−17%, accompanied by significant increases in microporosity (8%) and residual porosity (16%) in the 5−10 cm depth compared to the soil health-enhanced rotation. However, no significant differences were found at Swift Current or Scott in the 5−10 cm depth. The pulse/oilseed intensified rotation significantly improved FC by 22% and PAWC by 19% compared to the market-driven rotation. This rotation also showed an 18% increase in FC and a 32% increase in PWP when compared to the diversified rotation at Scott in the 15−20 cm depth, but did not differ significantly at Lethbridge or Swift Current. Overall, crop rotations with legumes and increased functional diversity have the potential to improve soil physical quality and plant available water but may require a period longer than the present study’s duration to become evident.

Drought Stress Affects the Reproductive Biology of Avena sterilis ssp. ludoviciana

Avena sterilis ssp. ludoviciana (hereafter, A. ludoviciana) is considered the most difficult-to-control winter weed in the Northern Grains Region (NGR) of Australia. The abundance of this weed has increased after the adoption of the no-tillage conservation agriculture (NTCA) approach, which does not bury seeds deep in the soil profile. In addition, the increasing frequency and intensity of drought stress events during the late winter to early spring period in the NGR may modify this weed’s persistence mechanisms, which may further impact crop production. The present study focused on plant maturity time and seed production, dormancy, and longevity of four NGR A. ludoviciana biotypes in relation to the severity of drought stress over 2 consecutive years. Plants of all four A. ludoviciana biotypes were grown under 100% plant available water capacity (PAWC) until panicle initiation. At panicle initiation, very mild (80% PAWC), mild (60% PAWC), moderate (40% PAWC), and severe (20% PAWC) drought stresses were imposed on plants and continued through to maturity; an additional subset of plants were maintained at 100% PAWC through to maturity (control). Plants exposed to severe drought stress matured 24 days earlier than control plants, and produced 34% fewer filled seeds, with seeds having a 42% lower mass, 70% less dormancy, and shorter predicted longevity of at least 2 years compared to the seeds produced on control plants. All reproductive traits were less affected when the severity of the drought stress was decreased. The increasing frequency of drought stress in combination with the widely adopted practice of NTCA favours seeds of A. ludoviciana to undergo rapid germination in the following autumn/winter NGR planting season. However, effective control of A. ludoviciana remains a challenge in the NGR due to this weed’s genetic variability with respect to its response toward the seasonal variability of the NGR.

No-tillage and rye cover crop systems improve soil water retention by increasing soil organic carbon in Andosols under humid subtropical climate

No-tillage (NT) combined with a cover crop is a climate-smart agricultural practice that eliminates nearly all physical disturbance of the soil surface and increases soil aggregation and soil organic carbon (SOC); however, the response of SOC and soil water retention (SWR) to long-term NT and cover crops systems in the volcanic ash Andosol soil of Japan has not been well addressed. This study aimed to evaluate the effect of NT and moldboard plow (MP) tillage systems combined with rye (RY) and fallow (FA) cover crop treatments on SOC, active carbon (AC), water-stable aggregates, aggregate stability index, mean weight diameter (MWD), bulk density, aggregate-associated carbon, and SWR. NT significantly increased the > 4 and 2 mm aggregates, aggregate-associated C at the 0–2.5 and 2.5–5 cm depths, field capacity, and SWR between 0 and 15 cm. RY cover crops significantly increased aggregate-associated carbon at the 2.5–5 and 5–10 cm depths in both NT and MP and SWR at the 10–15 cm depth. NT combined with RY significantly increased SOC and AC in the surface layer and volumetric water content at all soil depths. Path analysis revealed that SOC and MWD were correlated with easily plant-available water (EPAW) and field capacity under the NT system and is the primary reason for the observed increase in SWR. Thus, the NT system increased plant residue, reduced soil evaporation, increased SOC content and SWR, and bonded soil microaggregates into macroaggregates better than the MP system. The use of an RY-based NT system is an effective climate-smart agriculture practice that reduces the drought effects brought on by climate change.

Rapid beech decline under recurrent drought stress: Individual neighborhood structure and soil properties matter

During the summer of 2022, an acute drought once more afflicted central and southern Europe. This marked the third episode (after 2015 and 2018) of severe aridity in large parts of Germany within the last decade, leading to increased soil water depletion. Consequently, from July 2022 onward, European beech trees (Fagus sylvatica L.) exhibited early withering and pronounced premature defoliation. Nevertheless, crown defoliation exhibited substantial variation among trees within the same forest stands, prompting questions regarding the causal factors. In our study, we scrutinized twelve mature drought-impacted, beech-dominated forest stands in northern Bavaria, arranged along a gradient of different nutrient regime levels (base-rich, intermediate, base-poor), with co-occurring vital (≤40% crown defoliation) and declining (≥60% crown defoliation) trees. Within each stand, we selected an equal number of vital and declining trees, culminating in a total of 332 target trees. Dendrochronological patterns were analyzed to identify a potential timing of growth separation between vitality classes. Moreover, we used a Bayesian modelling framework to discern whether disparities in tree vitality hinged on competition, structure, small-scale differences in plant-available water capacity, and spatial clustering of declining competitors. We further explored the factors influencing the magnitude of growth decline post-2018 and how these were modulated by the site's nutrient regime. Our study unveiled that (i) low competition with increased size diversity bolstered tree vitality; (ii) declining trees were spatially aggregated; (iii) vital and declining trees exhibited strikingly similar growth trajectories in the past, which underwent a drastic shift following 2018, indicating a potential for a rapid vitality decline under recurrent severe drought stress; (iv) plant-available water capacity emerged as a crucial determinant of vitality and growth subsequent to 2018; (v) growth decline was most pronounced at base-poor and intermediate sites. Our findings underscore the importance of accommodating small-scale differences in soil and stand characteristics and advocate for silvicultural guidance towards reduced stand densities in combination with a more heterogenous structure to mitigate beech dieback in drought-prone forest stands.

Structural characteristics of the moss (bryophyte) layer and its underlying soil structure and water retention characteristics

The influence of the moss layer on soil structure and soil water retention is not well understood. Therefore, this study aims to investigate the changes in soil structure and soil water retention under moss layer and to reveal the influencing factors of these changes. 3D networks of moss layer and soil macropores were quantified using CT scanning and image analysis techniques, and soil water retention characteristics were explored through soil water retention curves (SWRCs) and VG model. The length densities of the soil macropores under the thin moss and thick moss layers were approximately 2.7 and 1.6 times higher than that under no moss cover. The soil water retention under the thin and thick moss layers were greater than those under no moss cover, with the highest plant-available water capacity under the thin moss layer. The maximum water-holding capacity of the moss layer was significantly positively correlated with the field water-holding capacity of the soil and negatively correlated with the equivalent diameter of the macropores, while the storage capacity of the moss layer was significantly and negatively correlated with the maximum effective water content of the soil. The field capacity (FC) and permanent wilting point (PWP) were significantly and positively correlated with the soil organic matter. The effect of the moss layer on water retention may be mainly realized by influencing the pore distribution and organic matter accumulation. The moss layer had a positive ecohydrological effect on soil water retention and even water conservation in forest soils.

Active plant biomass inputs influence pore system functioning in no-till soils

Available knowledge about the exact impact of plant growth on the properties and functioning of no-till soils is somewhat limited, especially in tropical and subtropical regions. The starting hypothesis for this work was that long-term active plant biomass Input-APBI (aboveground plant shoot biomass) would improve pore system functioning in surface and subsurface soil layers by playing different, complementary roles in a previously degraded subtropical Acrisol. The hypothesis was checked by examining the results of a 34-yr field experiment involving five different cropping systems, namely: bare soil (BS), perennial pasture (PAST), oat/maize (O/M), oat + vetch/maize (O + V/M) and oat + vetch/ maize + cowpea (O + V/M + C). The soil was supplied with APBIs varying from 0.13 to 1.48 kg dry matter ha−1 yr−1. The APBIs for each cropping system were very low (BS), low (O/M), medium (O + V/M), high (O + V/M + C), and very high (PAST). The surface (0–5 cm) and subsurface (5–15 cm) soil layer were analyzed for static and dynamic properties of the pore system including bulk density; total, macro, and microporosity; the ability of the system to conduct air and water; continuity in soil pores; and plant-available water capacity. Micromorphological images of the soil revealed a complex pore network whose structure and functioning were both improved by the action of plants. In the surface soil layer, very high APBIs from pasture and high inputs from O + V/M + C increased total porosity by 11 and 14 %, respectively; pore continuity (Ncont) by 11 and 40 %, respectively; and microporosity by 31 and 23 %, respectively —all relative to bare soil. In the subsurface soil layer, pasture, and O + V/M + C decreased Ncont by 44 and 40 %, respectively, but increased water permeability (kw) by a factor of 6.5 and 7, respectively. In addition, very high APBIs increased continuity and permeability to air in macropores relative to BS. Organized large macropores in the subsurface soil layer efficiently conducted water and air from the soil surface and acted as bridges between the surface and subsurface soil layer. Overall, our findings suggest that APBIs helped develop a pore system with differential properties and complementary functions that influenced water infiltration and air fluxes in the surface soil layer, and water availability to crops in the subsurface soil layer, through long-term self-organization in the system. Future research with a view to understanding the influence of species richness and roots on physical quality in no-till soils is recommended.

Changes in Physical and Water Retention Properties of Technosols by Agricultural Reclamation with Wheat–Rapeseed Rotation in a Post-Mining Area of Central Poland

During opencast lignite mining, the natural landscape is damaged, along with soils, and new anthropogenic landforms are created which require reclamation. Usually, the evaluation of the effects of reclamation (mostly forestry) is concerned with changes in chemical properties in the first years, mainly in the surface horizon. This study analyzed the effect of long-term agricultural reclamation (43 years) on the physical and water retention properties of Technosols. The experiment involved cultivation of winter wheat and winter oilseed rape under 3 fertilization variants. After 43 years, an Ap horizon (Ap1 and Ap2) developed in fertilized Technosols, but was not clearly formed in unfertilized minesoil. In Ap1, there was improvement in the physical quality (S), bulk density (BD), particle density (PD), structural stability index (SI), soil porosity (SP), air-filled porosity (AFP), field capacity (FC) and plant available water capacity (PAWC). In Ap2, properties were comparable to those in the surface horizon of unfertilized Technosols and to those observed before reclamation. Regardless of fertilization, there was deterioration in physical quality in parent materials. In general, the properties of fertilized Technosols have improved in the surface horizons, but increasing fertilization above plant requirements does not lead to their further enhancement.

Long-term impact of organic and conventional farming on soil physical properties under rice (Oryza sativa)-wheat (Triticum aestivum) cropping system in north-western Indo-Gangetic plains

Long-term (13 years) impact of organic and conventional farming on soil physical properties was evaluated under a rice (Oryza sativa L.) – wheat (Triticum aestivum L.) cropping system in a sandy clay loam soil at New Delhi. The treatments included unfertilized control (T1), conventionally managed (T2) and five organic treatments (T3: FYM @ 10 t/ha to rice and wheat, T4: SGM for rice and LGLM for wheat, T5: SGM + BGA for rice and LGLM + Azotobacter for wheat, T6: SGM + FYM for rice and LGLM + FYM for wheat, and T7: SGM + FYM + BGA for rice and LGLM + FYM + Azotobacter for wheat). The application of organic amendments had positive influence on soil physical properties such as saturated hydraulic conductivity (Ks), field capacity (FC) and permanent wilting point (PWP), plant-available water capacity (PAWC), water holding capacity (WHC), distribution of aggregate size fractions, bulk density (Db), and porosity in the 0-15 and 15-30 cm soil layer. A favourable effect of organic amendments was also found on soil strength (at depth 0-70 cm). Even, values related to these properties were significantly affected by the kinds of organic amendments. But, T1 and T2 had no improvement in soil physical properties over the organic ones. Value of Ks decreased with increase in soil depths. T7 and T3 were superior in Ks to other treatments for 0-15 and 15-30 cm soil depths. Volumetric moisture content at FC (θFC) and PWP (θWP) increased with addition of organic amendments and got varying response due to the kinds of organic amendments or their combinations. θFC and θWP were decreased substantially under T1 and T2, because of no addition of organic inputs. As a result of θFC and θWP, PAWC had also signified an improvement under the influence of different organic amendments over T1 and T2. Generally (for both depths), PAWC of T3, T6 and T7 were 17-26% more than T1, T2, T4 and T5. WHC of upper soil layer (0-15 cm) was greater for organic amended plots than plots devoid of organic inputs and lower values were recorded for 15-30 cm soil layer. WHC of T3, T7 and T6 was highest in comparison to plots amended only with (without FYM) green manure, BGA or Azotobacter as well as T1 and T2 for both depths (0-15 and 15-30 cm). A better soil aggregation was observed under organic amended plots for large and small macro-aggregates (LM - >2 and SM-0.25-2 mm) in both soil depths. Lowest value of Db with highest percentage of pore space was noted under T7 than other treatments in both soil layers. Soil strength was significantly lower in organic amended plots than T1 and T2. This study clearly indicated that application of organic inputs especially FYM, improved the soil physical properties, which resulted in better soil aggregation, porosity and soil moisture retention.

Alkali Lignin-Based Hydrogel: Synthesis, Characterization, and Impact on Soil Water Retention From Near Saturation to Dryness

Highlights A lignin-based hydrogel was synthesized and shown to possess a swelling ratio of 2013%. The hydrogel contained important hydrophilic hydroxyl groups and macropores for water retention. The hydrogel improved soil water retention in silt loam soil at high matric potentials and in the dry soil range. Increasing hydrogel concentration increased water retention in a loamy fine sand soil at high and low matric potentials. Abstract. Superabsorbent polymers (hydrogels) have been proposed as soil amendments to increase the amount of plant-available water in the soil. Synthetic hydrogels have been widely investigated for use in agriculture. Due to increasing environmental concerns related to synthetic hydrogels, naturally sourced hydrogels are of interest because of their potential for increased biodegradability and biocompatibility. A lignin-based hydrogel was synthesized for this study, and its swelling properties and water absorption capacity were determined. The hydrogel was characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and gas pycnometry. A hanging water column, pressure plate apparatus, and dew point potentiometer were used to measure the soil water retention curve from saturation to oven-dryness for silt loam and loamy fine sand soils after amendment with the lignin-based hydrogel. Results showed a maximum swelling ratio in deionized water of 2013% of the hydrogel’s original mass, 1092% in tap water, and 825% in a 0.9% NaCl solution. The FTIR spectra of the hydrogel showed the presence of O-H bonds from the lignin structure, which renders the hydrogel reactive to a crosslinker and forms insoluble bonds, thereby allowing the hydrogel to swell when exposed to water. SEM images of the lignin hydrogels indicate large macropores, which allowed for water absorption. Applying hydrogels significantly increased the soil's water-holding capacity at 0.3% (w/w) treatment. Hydrogel treatment significantly increased water retention at saturation or near saturation by 0.12 cm3 cm-3 and at field capacity by 0.08 cm3 cm-3 for silt loam soil at 1% (w/w) treatment compared to the control treatment with no added lignin hydrogel. Hydrogel application increased water retention over the range of the soil water retention curve from -3 to -15,000 cm for the loamy fine sand soil at 1% (w/w) treatment. However, the application of lignin-based hydrogel did not affect plant available water capacity (PAWC) in either soil tested. These results serve as preliminary evidence upon which further lignin-based hydrogel amendment studies could be built by testing higher concentrations of hydrogel in the soil. Keywords: Lignin, Soil water retention curve, Super absorbent polymers, Swelling capacity, Water retention.

Seasonal and Soil Use Dependent Variability of Physical and Hydraulic Properties: An Assessment under Minimum Tillage and No-Tillage in a Long-Term Experiment in Southern Italy

Defining the optimal sampling time across the growing season is crucial to standardize sampling protocols for soil physical status monitoring and to achieve comparable results under different experimental conditions and on different sites. In this study, the seasonal variability of soil physical and hydraulic properties under two conservative soil management strategies, minimum tillage and no-tillage, was evaluated in a long-term field experiment. On two sampling dates, autumn 2021 and summer 2022, soil bulk density (BD) and volumetric soil water content at the time of the experiments (θi) were measured in each experimental unit and Beerkan infiltration experiments were performed. The soil water retention curve and the hydraulic conductivity function were then estimated using the Beerkan estimation of soil transfer parameters (BEST) methodology. In this way, the saturated hydraulic conductivity (Ks) and a set of capacitive indicators—plant available water capacity (PAWC), soil macroporosity (PMAC), air capacity (AC) and relative field capacity (RFC)—were obtained. Results underlined the role of soil moisture conditions as a main factor affecting variability in soil physical properties. Different soil moisture under autumn and summer samplings significantly affected BD (1.0093 and 1.1905 g cm−3, respectively, in autumn and summer) and Ks (0.0431 and 0.0492 mm s−1). Relationships observed between BEST-derived variables, such as PMAC (or AC) and RFC, and measured variables, such as BD, showed consistent results, with increases in PMAC to BD decreases. However, a comparison of capacity-based indicators obtained by BEST with those obtained from measured soil water retention curves, in a previous year but under comparable soil conditions, highlighted some discrepancies. This finding drives the focus towards the need to use more robust datasets deriving from experimental measurements or from coupling information obtained from measured and estimated data. Finally, this study provided further evidence that, in the long-term field experiment investigated, the two soil management systems allowed keeping the values of key soil physical quality indicators, such as bulk density and saturated hydraulic conductivity, within the optimal or near- optimal reference ranges.

Sustained productivity and agronomic potential of perennial rice

There is an urgent need for agricultural systems to intensify sustainably, increasing crop productivity, farmer livelihoods and soil health while using fewer resources. Crop perennialization, the conversion of especially annual grains to perennial forms, has shown such possibility. Here we report the successful breeding of perennial rice and assess its performance and potential. Domesticated, annual Asian rice (Oryza sativa) was hybridized with its perennial African relative Oryza longistaminata. From a single planting, irrigated perennial rice produced grain for eight consecutive harvests over four years, averaging 6.8 Mg ha−1 harvest−1 versus the 6.7 Mg of replanted annual rice, which required additional labour and seed. Four years of cropping with perennial rice resulted in soils accumulating 0.95 Mg ha–1 yr–1 organic carbon and 0.11 Mg ha−1 yr−1 nitrogen, along with increases in soil pH (0.3–0.4) and plant-available water capacity (7.2 mm). Perennial cultivars are strongly preferred by farmers; growing them saves 58.1% of labour and 49.2% of input costs in each regrowth cycle. In 2021, perennial rice was grown on 15,333 ha by 44,752 smallholder farmers in southern China. Suited to a broad range of frost-free environments between 40° N and 40° S, perennial rice is a step change with potential to improve livelihoods, enhance soil quality and inspire research on other perennial grains.

Plant available water capacity of soils at regional scale: Analysis of fixed and dynamic field capacity

Estimation of the plant available water capacity (PAWC) of soils at a regional scale helps in adopting better land use planning, developing suitable irrigation schedules for crops, and optimising the use of scarce water resources. In the current study, 72 soil profiles were sampled from the Barossa Region of South Australia to estimate pedo-transfer functions deduced from easily estimated soil properties. These functions were then used to estimate the fixed (10, 33 kPa) and dynamic pressure head ( h fc ) water content at field capacity (FC) for minimum drainage flux ( q = 0.01 and 0.001 cm/day), which serves as the upper boundary for plant-available water in the soils. The estimated crop lower limit (CLL, θ wp ) was corrected for subsoil constraints, especially the exchangeable sodium percentage (ESP). The data showed that the mean values of h fc in sand-dominated light and medium textures (i.e. sand, loamy sand, sandy loam, and loam) varied in a narrow range (15.8–18.2 kPa), while in the clay-dominated heavy textured soils (i.e. clay loam) showed the widest range of h fc (11.3–49.3 kPa). The data showed wide variability in the PAWC for dynamic FC (PAWC fc ) and fixed FC at 10 kPa (PAWC 10 ), 33 kPa (PAWC 33 ), and a mix of 10 and 33 kPa (PAWC 10,33 ) pressure heads depending on soil texture. Normally, the difference between PAWC at h fc and 10 kPa (ΔPAWC 10 ) was positive, whereas the corresponding difference between PAWC at 33 kPa and h fc (ΔPAWC 33 ) was negative across all sites. Nevertheless, the estimation of PAWC assuming a fixed FC at 10 and 33 kPa pressures (PAWC 10,33 ) for sandy, clay, and silty soils reduced the deviation between dynamic and fixed pressure PAWC < 10% across the region. The estimation of PAWC was improved by incorporating the impact of subsoil constraints, such as high ESP in the soil, which was more pronounced for clay and silty texture soils occurring at lower depths. These findings demonstrate the inherent inconsistencies between static pressure and flux-based dynamic field-capacity estimations in soils. Soil heterogeneity, intra-texture variability, subsoil constraints, and swell–shrink clays can have great impacts on the water retention capacity in response to dynamic and fixed pressure FC values.

Mechanical Intervention in Compacted No-Till Soil in Southern Brazil: Soil Physical Quality and Maize Yield

The intense and successive use of mechanization in modern cropping systems has increased soil compaction under no-till areas. In this study, we aimed to assess the performance of a fixed shank coupled with a seeder for the mitigation of soil compaction induced by machinery traffic as an efficient alternative to replacing the chiseling and subsoiling operations in no-till areas. We evaluated a long-term experiment conducted in clay loam (Rhodic Haplustox) soil in southern Brazil. The experiment was conducted under a randomized block design, whose treatments consisted of three wheel-traffic intensities: 0 wheel-traffic (0 WT), 14 wheel-traffic (14 WT), and 28 wheel-traffic (28 WT), combined with four soil tillage mechanical interventions under a no-till field: no-till (NT), no-till with a fixed shank (NT + FS), soil chiseling (SC), and soil subsoiling (SS). The soil physical attributes evaluated were the soil penetration resistance (SPR), macroporosity (MaP), microporosity (MiP), total porosity (TP), bulk density (BD), field-saturated hydraulic conductivity (Kfs), S index, and plant-available water capacity (PAWC). In addition, three critical soil physical functions were evaluated by using a soil physical quality index (SPQI). The results showed that SPR was sensitive to soil compaction and captured differences among the mechanical intervention methods. Machinery traffic caused soil compaction, increasing SPR and reducing PAWC. Soil chiseling and subsoiling promoted lower BD, a higher TP, MaP, Kfs, and higher S index at the 0.05–0.15 m soil layer. Based on the SPQI, no changes were detected in the soil physical functions between NT and NT + FS. On the other hand, SC and SS enhanced soil physical functioning by 10%. We concluded that a 15-cm deep fixed shank could not mitigate the soil compaction induced by machinery traffic at the seeder operation. Therefore, this method is less effective in improving the soil’s physical environment than chiseling and subsoiling operations. Finally, we encourage monitoring the persistence of these benefits on the soil over the subsequent crop seasons and in years with an intense water deficit along with the crop cycle.

Influence of land-use systems on hydraulic properties of soils in Yenagoa and Amassoma, Bayelsa State, Nigeria

This research aimed to determine the effect of different land-use systems on the matric potential, and hydraulic conductivity of the soils of Yenagoa and Amassoma communities. Soil samples were collected from four respective land-use types namely: Fallow land, Oil Palm Plantation, Plantain Plantation, and Virgin land. A total of 12 samples were bulked from three replicates at each land use type and were collected at depths of 0-15cm, 15-30cm, and 30-45cm respectively. The samples were taken to the laboratory to analyze their physical, chemical, and hydrological properties. The result showed that the different land use had a significant effect (P&lt;0.05) on some soil physical, chemical, and hydraulic characteristics. The different land-use systems had a significant effect on the soil hydraulic conductivity with the highest in virgin (13.6 cm/hr) and lowest in the plantain plantation (7.6 cm/hr). The virgin land recorded the highest Soil Water Holding Capacity (SWHC) of 2.85 cm with a range of 1.55 – 2.85cm and Plant Available Water Capacity (PAWC) of 0.19 cm3cm-3, with a range of 0.10 - 0.19 cm3cm-3, while the plantain plantation recorded the lowest (1.55 cm and 0.10 cm3cm3). Based on the study, it is recommended that soils with high Plant Available Water Capacity (PAWC) and Soil Water Holding Capacity (SWHC) be used to cultivate crops that are non-tolerant to water stress while organic amendments are used on soils with low fertility.

Plant available water capacity (PAWC) of soils predicted from crop yields better reflects within-field soil physicochemical variations

Within field variations of plant available water capacity (PAWC) of soil is one of the major causes of spatial yield variability in dryland agriculture systems, as PAWC interacts with pre-season and in-season rainfall and other climatic variables to determine crop growth and final yield. Quantification of such variations helps to better understand the changes in soil texture and subsoil constraints to inform spatially explicit management practice. An inverse modelling approach to estimate PAWC from crop yields was developed as a more cost-effective alternative to traditional soil sampling methods. In this study, we further extend this approach to predict and map in-field variations of PAWC from yield maps of single and multiple crops. Soil PAWC maps were produced based on inversely predicted PAWC using crop yield maps together with in-field management information, and compared with: 1) available water capacity derived using laboratory-measured soil properties, and 2) soil types derived from proximally sensed soil spectra and ground geophysics for four representative farms in Australia. The results show that the predicted PAWC maps matched well with within-field spatial variation of soil types, and well reflected the impact of soil constraints (e.g. salinity), and soil classifications from soil survey and local experience. This demonstrates that the predicted PAWC from crop yield using inverse modelling can reflect the soil physicochemical variations within-field. The generated PAWC maps can be combined with process-based modelling to predict crop yield and yield zones and to inform spatial field management and soil sampling.

Downscaling of climate change scenarios for a high-resolution, site-specific assessment of drought stress risk for two viticultural regions with heterogeneous landscapes

Abstract. Extended periods without precipitation, observed for example in central Europe including Germany during the seasons from 2018 to 2020, can lead to water deficit and yield and quality losses for grape and wine production. Irrigation infrastructure in these regions to possibly overcome negative effects is largely non-existent. Regional climate models project changes in precipitation amounts and patterns, indicating an increase in frequency of the occurrence of comparable situations in the future. In order to assess possible impacts of climate change on the water budget of grapevines, a water balance model was developed, which accounts for the large heterogeneity of vineyards with respect to their soil water storage capacity, evapotranspiration as a function of slope and aspect, and viticultural management practices. The model was fed with data from soil maps (soil type and plant-available water capacity), a digital elevation model, the European Union (EU) vineyard-register, observed weather data, and future weather data simulated by regional climate models and downscaled by a stochastic weather generator. This allowed conducting a risk assessment of the drought stress occurrence for the wine-producing regions Rheingau and Hessische Bergstraße in Germany on the scale of individual vineyard plots. The simulations showed that the risk for drought stress varies substantially between vineyard sites but might increase for steep-slope regions in the future. Possible adaptation measures depend highly on local conditions and are needed to make targeted use of water resources, while an intense interplay of different wine-industry stakeholders, research, knowledge transfer, and local authorities will be required.

One-time omission of puddling improves soil structure and post-rice soybean yield in clay-rich fields within paddy–soybean rotation systems in central Hokkaido, Japan

A one-time omission of puddling was noted to increase post-rice soybean yields within the paddy–soybean rotation systems in central Hokkaido, Japan. We analyzed the physical, chemical, and biological properties of soil via an onsite survey in 47 farmers’ soybean fields where either puddled transplanted rice (PT), nonpuddled transplanted rice (NT), or dry direct-seeded rice (DS) was cultivated in the previous year (referred to as one-time PT, NT, and DS treatments, respectively). The objective of the study was to determine the key soil parameters that could explain the higher post-rice soybean yield following the one-time omission of puddling (NT and DS treatments). In addition, soybean yield and soil properties were surveyed in an experimental field experiment where PT and NT treatments were applied for 3 consecutive years with the expectation that the increases in post-rice soybean yield caused by the omission of puddling (NT treatment) would be more pronounced. In the survey of farmers’ field, soybean yields were comparable among the one-time PT, NT, and DS treatments when the clay content was < 40%. However, soybean yield decreased as the clay content increased only under the one-time PT treatment. The adverse effects of puddling (PT treatment) on clay-rich soil appeared in a few soil physical parameters but not on any soil chemical and biological parameters. In the 34 selected clay-rich farmers’ fields (clay content >40%), narrow macropore and mesopore volumes, which indicate total available water capacity, were significantly (P < 0.05) lower under the one-time PT treatment than under the other two treatments. At the same time, the narrow macropore volume was significantly (P < 0.05) correlated with soybean yield. The one-time omission of puddling (NT and DS treatments) adopted in the surveyed farmers’ fields did not affect the wide macropore volume. Three consecutive years of NT treatment improved several soil physical properties as well as soybean root development in the experimental field. However, these improvements did not significantly increase soybean yield in the experimental field where the clay content was < 40%. These findings suggest that the one-time omission of puddling (NT and DS treatments) prevents the decreasing in the yields of post-rice soybean in clay-rich soils in central Hokkaido. The stable soybean yield, irrespective of the clay content, after the one-time omission of puddling (NT and DS treatments) in fields was attributed to the increased plant-available water capacity owing to the increased narrow macropore and mesopore volumes without clear changes in the wide macropore volume. By contrast, the effects of the one-time and three-time omission of puddling (NT and DS treatments) were not obvious in non–clay-rich field conditions in central Hokkaido.