Available Water Capacity Research Articles

EFFECT OF NEEM-BASED COMPOST RATE ON SOIL PHYSICOCHEMICAL PROPERTIES AND GROWTH RESPONSES OF AMARANTHUS VIRIDIS IN AWKA

A field experiment was conducted at the students’ research farm Faculty of Agriculture, Nnamdi Azikiwe University Awka to determine the effect of Neem-based compost rate on soil physicochemical properties and growth responses of Amaranthus viridis in Awka. Three treatments were used and a control was set out to monitor the effects of the applied treatments. The design was laid out in a Randomized Complete Block Design (RCBD), with 4 replication each. Where beds with 0 t/ha received 0kg of the compost, 3.5 t/ha received 2.1 kg/m² of the compost, 7 t/ha received 4.2 kg/m² of the compost and 10.5 t/ha received 6.3 kg/m² of the compost. The experiment lasted for 6 months and plant data was collected before harvesting. The treatments were applied in an experimental plot of 2m by 2m. The result obtained was subjected to a statistical analysis of variance using GENstat and least significant difference (LSD) to compare the mean. The mean were separated at 5% level of significance. Generally the applied treatments improved soil fertility as there was a significant increase in Moisture content (MC), Field capacity (FC), Plant Available water (PAW), Permanent wilting point (PWP), Bulk density (BD), and Total porosity (TP) of the soil. Also, potential hydrogen ion (pH), Available phosphorus (Av. P), Nitrogen (T.N), Organic carbon (OC), Calcium (Ca), Magnesium (Mg), Potassium (K), Sodium (Na), Exchangeable Acidity (EA), Effective Cation Exchange Capacity (ECEC), Base Saturation (BS) and exchangeable aluminum (Al3+) were all significantly differed. On the effects of the treatments on growth parameters, T3 (7 t/ha) gave the highest plant height and number of leaves with mean value of 25.8", and 30.9" respectively. The control gave the highest mean leaf width 3.43".

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.

Fluctation moisture properties in the application of soil dielectric measurement in the North Bengkulu District, Indonesia

Information about soil moisture in the root layer is very important in evaluating water availability for plants, erosion rates and various other hydrological characteristics. Previous research has found a technology for measuring soil dielectric properties as a soil moisture estimator that can be carried out quickly in the field. The purpose of this study was to apply dielectricity technology in estimating the characteristics of soil moisture in situ in the field at the North Bengkulu in Bengkulu Province. Five land units in North Bengkulu Regency, Indonesia, have been selected as experimental sites. At each location, the soil profile was excavated to a depth of 100 cm, the basic characteristics of the soil in each layer were described in the field and analyzed in detail in the laboratory. The variables measured in the field are the measurement of the dielectric properties of the soil, the effective depth of the soil, the horizon and the characteristics of each horizon. The variables analyzed in the laboratory were texture, organic matter in each layer, aggregate stability at 0-10 cm layer, field soil moisture at the time of measurement, and groundwater characteristics. The relationship between the data on the basic characteristics of the soil with the soil moisture balance variable in the laboratory analysis and measurements of dielectric properties in the field, was then determined using regression analysis. The results showed that the five locations studied had different profile characteristics and groundwater fluctuations. Of the four independent variables tested (percentage of sand, silt, clay and organic carbon) then the content of sand and clay can be used as predictors of the water content of field capacity. Because the four independent variables have a very weak correlation with permanent wilting point water, the available water content can only be predicted from the sand and clay content.

Untangling the complex mix of agronomic and economic uncertainties inherent in decisions on rainfed cotton

Context Production of rainfed (dryland) cotton (Gossypium hirsutum L.) occurs in many places globally, and is always burdened with greater uncertainties in outcomes than irrigated cotton. Assessing farm financial viability helps farmers to make clearer and more informed decisions with a fuller awareness of the potential risks to their business. Aim We aimed to highlight key points of uncertainty common in rainfed cotton production and quantify these variable conditions to facilitate clearer decision-making on sowing dates and row configurations. Methods The consequences of these decisions at six locations across two states in Australia, given estimates of plant-available water at sowing, are expressed in terms of comparable probability distributions of cotton lint yield (derived from crop modelling using historical weather data) and gross margin per hectare (derived from historical prices for inputs and cotton lint yield), using the copula approach. Examples of contrasting conditions and likely outcomes are summarised. Key results Sowing at the end of October with solid row configuration tended to provide the highest yield; however, single- and double-skip row configurations generally resulted in higher gross margins. Places associated with higher summer-dominant rainfall had greater chance of positive gross margins. Conclusion In order to maximise the probability of growing a profitable crop, farmers need to consider the variabilities and dependencies within and across price and yield before selecting the most appropriate agronomic decisions. Implications Given appropriate data on growing conditions and responses, our methodology can be applied in other locations around the world, and to other crops.

Soil water balance and wettability methods in soil treated with biochar and/or compost

The impacts of biochar application in combination with compost on soil hydrological conditions such as infiltration, water-storage capacity, and methods of soil wettability, are not well understood. The aim of this study was to fill this knowledge gap and propose the best composition proportion of compost and/or biochar to improve sand soil water balance. For this purpose, we examined three different mixtures of sand and compost and six different mixtures of sand, compost, and biochar with respect to their wettability and water infiltration using tree methods, (I) Water Droplet Penetration Time Test (WDPT test), (II) Wilhelmy Plate Method (WPM) and (III) Capillary Rise Method (CRM) applied at different soil water potential (pF) levels. The different mixtures were characterized by texture, bulk density, field capacity, and soil water holding capacity through measurement of the water content of soil columns. Increasing biochar plus compost or compost alone had contributed to increasing the soil water holding capacity and water available content. The best composition with the highest water storage capacity, plant-available water, and wettability was: 0.6% of biochar, 5.4% soil organic matter (SOM), and 93.99% of sand. According to the WDPT test, the increased content of biochar contributed to improving the soil wettability, this test was preferred since 1) WDPT appeared to allow the best estimates of wetting behavior of the different mixtures, 2) the column samples were the least disturbed, and 3) the test was particularly feasible at different water content levels. However, WDPT was strongly dependent on the conductor of the experiment and the accurate measurement of short infiltration times (0s - 2s) proved challenging. The WDPT results indicate that biochar might enhance the infiltration capacity under natural conditions and the combined results indicate that biochar-compost-applications are not expected to cause ecologically critical hydrophobicity or a critical lowering of the sandy soil infiltration capacity.Graphical abstract

Biochar applications to boreal podzol improve soil hydraulic properties and control nitrogen dynamics

The study aimed to investigate the effects of biochar (BC) application on hydraulic properties and nitrogen (N) transport in a podzolic soil profile. Soil samples were collected from an agricultural research field in Pasadena, Newfoundland, Canada. The following three types of leaching columns were prepared: ( i) topsoil, ( ii) top and E-horizon soil, and ( iii) mixed soil (2:1 ratio of topsoil and E-horizon soil). Granular biochar (GBC) and powder biochar (PBC) were mixed with soils at the rate of 0%, 1% and 2% (w/w). BC’s morphological structure and pore size distribution were examined using a scanning electron microscope, and the specific surface area was assessed by the Brunauer−Emmett−Teller method. Soil physical and hydraulic properties (bulk density, porosity, field capacity (FC), permanent wilting point, plant available water (PAW)), leaching concentration of nitrate (NO3 −) and ammonium (NH4 +), and volume of leachate were measured through a total of 378 experiments under laboratory conditions. GBC and PBC showed hydrophobic and hydrophilic characteristics, respectively. With the 2% PBC amendment, porosity increased by 3%, FC by 10%, and PAW by 13% in the mixed soil and reduced NO3 − leaching by 36% in top and E-horizon soil and NH4 + leaching by 72% in mixed soil. On the other hand, NO3 − and NH4 + leaching was reduced by 26% and 33% in mixed soil when treated with 2% GBC. A 2% application rate for both BC (GBC and PBC) showed the best performance to enhance soil hydraulic properties and retain significant amounts of NO3 − and NH4 + in the boreal podzol.

The combination of crop diversification and no tillage enhances key soil quality parameters related to soil functioning without compromising crop yields in a low-input rainfed almond orchard under semiarid Mediterranean conditions

Soils provide key ecosystem services and are crucial to combat climate change. Agriculture provides important ecosystem services but also causes negative environmental effects depending on agricultural management. In this regard, crop diversification is a promising sustainable land management strategy to combat soil erosion and degradation, mitigate climate change and ensure food security. Here, we assess the combined short-term effects of crop diversification and no tillage on several key soil physico-chemical parameters related to soil functioning as well as on crop yields in a rainfed almond (Prunus dulcis Mill.) orchard under semiarid Mediterranean conditions. Almond trees were inter-cropped with Capparis spinosa L. (caper) or Thymus hyemalis Lange (winter thyme) and compared with the almond monocrop system. The experimental design consisted of three plots in a randomized-block design, with three replicates for each crop management treatment (almond monocrop, almond inter-cropped with caper, and almond inter-cropped with winter thyme). Along with crop yields, the combined effects of crop diversification and no tillage on a range of soil quality and health indicators including soil physical (bulk density, aggregate stability, water retention and availability) and chemical (total and particulate organic carbon and nitrogen, ammonium and nitrate content, available macro- and micro-nutrients) properties were monitored in the topsoil and subsoil (at 0–10 and 10–30 cm depth, respectively) one and three years from establishment. Resultsfrom this study indicate that soil water retention capacity and water availability for plants were enhanced in both crop diversification systems after three years from their implementation at 0–30 cm depth. Likewise, improvements in particulate organic carbon and available N were observed in the subsoil of both crop diversifications. Crop diversification did not significantly affect the main crop yields, highlighting that crop diversification can be a promising sustainable management practice for improving soil health without compromising food security under semiarid Mediterranean conditions. Indeed, land equivalent ratios (LER) of almond trees inter-cropped with winter thyme were higher than those of their respective monocrop systems for two consecutive years, indicating that inter-cropping with aromatics can improve the productivity of rainfed woody monocrop systems under semiarid conditions. Our results emphasize the importance of selecting an appropriate secondary crop that ensures a permanent soil cover while contributes to enhance the agroecosystem productivity from the first year of establishment onwards to off-set plausible lower yields from the main crop. In this regard, preliminary assessments on soil condition and crop nutrient requirements are encouraged before designing and implementing a crop diversification in these low-input cropping systems.Likewise, long-term studies are needed to provide evidence on the stability of the production of diversified crop management, particularly in these low-input cropping systems under harsh environmental conditions.

Responses of soil water-holding capacity to environmental changes in alpine ecosystems across the southern Tibetan Plateau in the past 35–40 years

Environmental changes on the Tibetan Plateau could affect not only the livelihoods of local people but also the food and environmental security of downstream people. Soil water-holding capacity (WHC) governs soil functioning in ecosystems, could be significantly altered by the accelerated climate change and vegetation degradation experienced by the Tibetan Plateau’s alpine ecosystem. However, it remains unclear regarding the direction and magnitude of this feedback. Here, we assessed the responses of WHC to the combined impacts of climate change and vegetation degradation across the Tibetan Plateau over the past decades based on a regional resampling campaign, including 148 well-matched sampling sites, conducted in the 1980s and 2020. We observed an overall decrease in the WHC in the study area in response to a warmer climate and increased soil erosion. The decrease in the topsoil (notably 0–20 cm) was more significant than that in the subsoil (notably 20–50 cm). Average soil available water content (AWC) decreased from 0.13 to 0.10 cm3 cm−3 (p < 0.0001) for topsoil, and from 0.10 to 0.09 cm3 cm−3 (p < 0.01) for subsoil. The changes in AWC were primarily explained by soil erosion (11.3 %) and climate change (9.2 %). Furthermore, the decline in AWC results in a significant decrease in soil productivity, which may exacerbate vegetation degradation and increase the susceptibility of alpine ecosystems to disturbances. These findings suggest that soil erosion control is still an urgent task for environmental protection on the Tibetan Plateau and that increasing WHC is an important goal of adaptation measures.

Effects of Soil Water Shortage on Seedling Shoot and Root Growth of Saragolle Lucana Tetraploid Wheat (Triticum durum Desf.) Landrace.

Ancient wheats may be a source of traits that are useful for the tolerance of climate change foreseen conditions of raising temperatures and low water availability. Previous research has shown a fine root system and a high mass of rhizosheath per unit root mass in the italian durum wheat (Triticum durum Desf) landrace Saragolle Lucana, and this may be relevant for successfully facing adverse conditions during seedling establishment. We investigated the effect of soil water shortage in Saragolle seedlings on root architecture, rhizosheath formation and biomass allocation. Pot experiments were conducted by comparing two levels of soil available water content (AWC): WW (100% of AWC) and DS (50% of AWC). Phenology was delayed by eight days in DS and above and belowground traits were measured at Zadoks 1.3 for each treatment. Biometric data collected at the same phenological stage show that DS plants did not reach the levels of biomass, surface area and space occupation of WW even after attaining the same developmental stage. Namely, plant dimensions were lower at low soil water availability, with the exception of rhizosheath production: DS yielded a 50% increase in rhizosheath mass and 32% increase in rhizosheath mass per unit root mass. The proportion of plant mass reduction in DS was 29.7% for aboveground parts and 34.7% for roots, while reductions in leaf and root surface areas exceeded 43%. The root/shoot mass and area ratios were not significantly different between treatments, and a higher impact on aboveground than on belowground traits at reduced available water was shown only by a lower ratio of shoot height to root depth in DS than in WW. Increases in rhizosheath in absolute and relative terms, which were observed in our experiment in spite of smaller root systems in the ancient durum wheat variety Saragolle lucana at DS, may provide an interesting trait for plant performance in conditions of low soil water availability both for water-related issue and for other effects on plant nutrition and relations with the rhizosphere.

A research agenda for nonvascular photoautotrophs under climate change.

Nonvascular photoautotrophs (NVP), including bryophytes, lichens, terrestrial algae, and cyanobacteria, are increasingly recognized as being essential to ecosystem functioning in many regions of the world. Current research suggests that climate change may pose a substantial threat to NVP, but the extent to which this will affect the associated ecosystem functions and services is highly uncertain. Here, we propose a research agenda to address this urgent question, focusing on physiological and ecological processes that link NVP to ecosystem functions while also taking into account the substantial taxonomic diversity across multiple ecosystem types. Accordingly, we developed a new categorization scheme, based on microclimatic gradients, which simplifies the high physiological and morphological diversity of NVP and world-wide distribution with respect to several broad habitat types. We found that habitat-specific ecosystem functions of NVP will likely be substantially affected by climate change, and more quantitative process understanding is required on (1) potential for acclimation, (2) response to elevated CO2 , (3) role of the microbiome, and (4) feedback to (micro)climate. We suggest an integrative approach of innovative, multimethod laboratory and field experiments and ecophysiological modelling, for which sustained scientific collaboration on NVP research will be essential.

Regolith water storage patterns determine vegetation productivity in global karst regions

Although the distribution of vegetation productivity is largely determined by temperature and precipitation variations, the influence of the substrate condition still requires further exploration, especially in karst regions characterized by extremely shallow soil underlain by weathered bedrock. In this study, we find that the regolith in karst landscapes can behave much like soil layer in many other terrestrial landscapes and the contribution of bedrock lithology to GPP by affecting water availability is significant, but dominant chemical elements have inconsistent impacts across the selected karst regions worldwide. In karst landscapes with tropical (Savannah, Aw) and temperate (without dry season, Cf) climates, more than 80% of the grids show a significant positive correlation between available water for plants and precipitation supply, and calcium-rich areas with lower average root length tend to form higher GPP. Conversely, in karst landscapes with arid (Steppe, Bs) and temperate (Dry winter, Cw) climates, more than 70% of the grids show decoupled water availability for plants from variability of precipitation, and silicon-rich regions with deeper average root lengths contribute to higher vegetation productivity. Instead of climate regimes, the effect of bedrock lithology on vegetation productivity is mediated by how precipitation is stored and released to plants. Our results highlight that the critical role of bedrock lithology-related water storage should not be ignored in the Earth system models.

In Situ Rainwater Collection and Infiltration System Alleviates the Negative Effects of Drought on Plant-Available Water, Fine Root Distribution and Plant Hydraulic Conductivity

Soil water status and fine-root characteristics are the foundation for implementing forest water-management strategies in semiarid forest plantations, where rainwater is always the sole source of water for plant growth. Rainwater management and utilization are effective strategies to alleviate water scarcity in semiarid areas as ground water is always inaccessible there. Through the implementation of an in situ rainwater collection and infiltration system (IRCIS), we investigated the effects of IRCIS on soil water and fine-root distributions in the 0–5 m soil profile in a wet (2015, 815 mm) and a dry year (2016, 468 mm) in rainfed Robinia pseudoacacia forests in the Loess Plateau region of China. The results showed drought significantly decreased plant water availability and hydraulic conductivity of roots and branches, but strongly increased soil moisture deficits and fine-root (&lt;2 mm diameter) biomass. With the implementation of IRCIS, soil profile available water and plant hydraulic conductivity can be significantly increased, but soil moisture deficits and fine-root (&lt;2 mm diameter) biomass can be significantly decreased. Drought also significantly influenced the root distribution of Robinia pseudoacacia. The maximum depth of Robinia pseudoacacia roots in the dry year was significantly greater than in the wet year. Therefore, Robinia pseudoacacia can absorb shallow (0–1.5 m) soil water in wet years, while utilizing deep (&gt;1.5 m) soil water in dry years to maintain normal growth and resist drought stress. The results of this study will contribute to the formulation of appropriate strategies for planning and managing rainwater resources in forest plantations.

Water availability and plant-herbivore interactions.

Water is essential to plant growth and drives plant evolution and interactions with other organisms such as herbivores. However, water availability fluctuates, and these fluctuations are intensified by climate change. How plant water availability influences plant-herbivore interactions in the future is an important question in basic and applied ecology. Here we summarize and synthesize the recent discoveries on the impact of water availability on plant antiherbivore defense ecology and the underlying physiological processes. Water deficit tends to enhance plant resistance and escape traits (i.e. early phenology) against herbivory but negatively affects other defense strategies, including indirect defense and tolerance. However, exceptions are sometimes observed in specific plant-herbivore species pairs. We discuss the effect of water availability on species interactions associated with plants and herbivores from individual to community levels and how these interactions drive plant evolution. Although water stress and many other abiotic stresses are predicted to increase in intensity and frequency due to climate change, we identify a significant lack of study on the interactive impact of additional abiotic stressors on water-plant-herbivore interactions. This review summarizes critical knowledge gaps and informs possible future research directions in water-plant-herbivore interactions.

Growth and yield of tomato on soil amended with waste paper based hydrogels

Increased water and nitrogen use efficiency enhances crop production and reduces environmental degradation. Cellulosic hydrogels derived from paper waste can retain and gradually release water and nitrogen for plant growth. This study assessed tomato response to water and NO3− − N in soils amended with hydrogels. The experiment was conducted in a greenhouse on a tomato crop, comprising of following treatments: freeze-dried hydrogels (FDH), oven-dried hydrogels (ODH), control (CO) (without hydrogels) as well as two irrigation treatments (95% and 75% available water content (AWC)). The results indicated that FDH- 95% AWC treatment produced the highest average crop yield of 0.88 kg plant−1, compared to the ODH (0.32 kg plant−1) and control treatments (0.40 kg plant−1). The hydrogel and AWC combinations did not significantly (p > 0.05) impact plant height and stem diameter, while these treatment combinations significantly enhanced crop yield, leaf area index and plant biomass (p < 0.05). FDH and ODH produced higher yields and saved 15 % and 20% of irrigation water (225mm), respectively, compared to the control treatment. There was a noticeably higher water use efficiency in the FDH-95 (3.9 kg m−1 plant−1) treatment compared to the ODH-95 (1.46 kg m−1 plant−1) and control (1.5 kg m−1 plant−1) treatments. The results that under FDH and ODH treatments, excess nitrate was stored in the soil vacuoles and was remobilized for uptake by the plant roots. Moreover, the re-swelling ratio of freeze-dried beads (415.62 ± 18.13%) was recognizably higher than that of oven-dried beads (224.16 ± 5.51%), as freeze-dried beads could re-swell 185.4% times more in water than the oven-dried beads. Therefore, this research demonstrates a clean technology whereby wastepaper can be recycled into biodegradable hydrogels to increase crop productivity.

Yield, mineral content and root growth response of jute mallow (Corchorus olitorius L.) to planting density and water availability

Current trends in agriculture dictate an urgent need for the reduction of input resources while maintaining high biomass yield of good quality. The overall aim of the study was to investigate the interactive effects of planting density and water availability on growth, development, total biomass yield and quality of jute mallow. It was hypothesized that up to 20% of the crop irrigation water requirement could be saved through deficit irrigation without compromising biomass production and nutritional value. To achieve the stated aim, three planting densities: low (100 000 plants.ha −1 ); medium (167 000 plants.ha −1 ); and high (330 000 plants.ha −1 ) were tested in a two-year field trial. Each of these planting densities received three irrigation strategies: full irrigation (irrigation to field capacity (FC)); medium stressed (irrigation to 80% plant available water (PAW)); and stressed (irrigation to 60% PAW). All treatments were replicated three times in a randomized complete block design layout. Irrigation was applied every fifth day for all treatments under nitrogen non-limiting conditions. Results showed that high leaf area index (LAI), stomatal conductance (gs), total fresh yield, and mineral content (Zn and K) were attained at the medium planting density of 167 000 plants.ha −1 under the medium stress (irrigation to 80% PAW) strategy. Consequently, 20% less than is needed to fill the root zone to FC was saved. Hence, the hypothesis was accepted. On the other hand, the irrigation strategy of irrigation to FC increased the length and dry mass of the roots. • Jute mallow crop strive well under semi-arid climatic conditions. • Irrigation and appropriate plant population provide optimum biomass yield. • High nutritional value depends soil fertility and water availability. • Root growth and architecture is highly influenced by drought stress.

Soil preparation systems and type of fertilization as affecting physical attributes of cohesive soil under eucalyptus in Northeastern Brazil

Cohesive Oxisols are widely used for cultivating eucalyptus in the Coastal Tablelands of the northeastern region of Brazil. However, mechanization and plant cultivation in these soils are difficult because of their cohesive layers. Therefore, the objective of this study was to identify better combinations between tillage systems and types of fertilization to improve the physical attributes of cohesive soil, with the aim of improving eucalyptus growth. The experimental design was completely randomized in a 4 × 2 factorial scheme (soil preparation × fertilization). The tillage systems tested were: i) conventional tillage (CT) - one plowing combined with two harrowings, ii) minimum tillage (MT) - subsoiling down until 0.57 m depths in the planting line, iii) no-tillage type 1 (NT1) - planting in 0.3 m-deep pits, and iv) no-tillage type 2 (NT2) - planting in 0.6 m-deep pits. The types of fertilization tested were mineral (MF) and organic fertilization (OF). The diameter of the soil aggregates was reduced after being subjected to any combination of cohesive soils. Furthermore, OF provided the best levels of plant-available water, attenuating the adverse conditions of the cohesive layer. MT, NT1, and NT2 improved the soil physical attributes when compared to CT. Therefore, the combination of either NT1 or NT2 with OF, followed by the combination of either NT1 or NT2 with MF, was determined to be the best way to cultivate eucalyptus on cohesive soils.

Atmospheric dryness impacts on crop yields are buffered in soils with higher available water capacity

Atmospheric dryness has been recognized as a dominant driver for agroecosystem functioning due to its limiting controls on stomatal behavior, even under sufficient soil moisture. Due to its relative importance in influencing carbon and water fluxes, atmospheric dryness has emerged as an important element of global change, jeopardizing food security and agricultural profitability via negative impacts on crop yields. Although negative impacts of atmospheric dryness are well recognized at various scales, it is unknown how heterogeneity in soils’ ability to retain water for plant uptake affects crop yields’ response to increasing atmospheric dryness. To address this, we analyzed how soil available water capacity (AWC) affects the response of crop yields to space and time variation in summer (June-July-August) vapor pressure deficit (VPDJJA) across the conterminous U.S. (CONUS) during 1980–2020 using 77,701 and 51,190 county-year records for maize and soybean, respectively. A distinct co-distribution of VPDJJA and AWC regimes is experienced by maize and soybean acreage and is subject to significant yield variation. Accounting for entire AWC heterogeneity in CONUS, both crops showed a positive yield response to increasing VPDJJA until 0.8 kPa, thereafter showing a gradually increasing negative response to VPDJJA increase. Upon soil-specific investigation of yield response to VPD, the yield sensitivity parameter to VPDJJA became less negative as soil AWC increased, implying buffering of dryness impacts on yields as the ability of soils to retain water increased. For VPDJJA increase between 1.0 kPa and 1.4 kPa, mean VPDJJA impacts on maize yields in soils with 10 %<AWC < 12.5 % were buffered by one-half (50.6 %) as compared with 7.5 %<AWC < 10 % soils. Increasing AWC from 10 to 12.5 % class to 12.5–15 % class further buffered VPDJJA impacts on maize yields by 26.2 %. VPDJJA impacts on soybean yields in soils with 15 %<AWC < 17.5 % were buffered by 40 % as compared with 12.5 %<AWC < 15 % soils. Further increase in AWC (17.5–20 %) resulted in additional 15.5 % buffering of VPDJJA impacts on soybean as compared to impacts recorded for 15 %<AWC < 17.5 % soils. The greatest buffering of negative impacts from VPDJJA were found when AWC is>10 % and 15 % for maize and soybean, respectively. Possible physical mechanisms responsible for this buffering are improved plant physiological function and fulfilment of evaporative demand due to additional soil water resulting from higher AWC, given sufficient water supply. This empirical large-scale evidence of mediating role of AWC for crop yield impacts from a dryer atmosphere underscores the critical nature of soils to support climate-smart agricultural practices via building soil organic matter as well as providing co-benefits for improved crop performance to meet current and future population’s food and fiber needs.

Geochemical and mineralogical processes leading to variation of soil characteristics on calcareous toposequence in semiarid ecosystem condition

Soils are under the influence of their formation processes at varying rates. Determining the variability and characteristics of soils due to the formation processes’ effects is vital for sustainable soil management. This study aimed to investigate soils formed on limestone and on different physiographic units (summit, shoulder, backslope and footslope) under semiarid climatic condition. That is why, the present study assessed clay mineralogy, weathering indices, mass loss/gain states, and physic-chemical properties of different profiles. It is concluded that smectite clay mineral is dominant in the profile IV located on footslope position with differences in clay mineralogy due to physiographical change. The summit physiographic unit includes the highest aggregate stability (63.74%). The soil’s field capacity and wilting point contents showed statistically significant variation with the increase in smectite clay minerals in the PIV profile on the footslope unit (p < 0.01). In addition, a positive (0.506; p < 0.05) directional relationship was found between the variability in physiographic units (from summit to footslope) and the available water content (AWC). In addition, bulk density and porosity characteristics varied depending on the particle size distribution and land use type. The soils formed on shoulder and backslope units classified as Entisol soil order are described as “not decomposed” according to the Chemical Alteration Index (CIA), Chemical Weathering Index (CIW), and Plagioclase Alteration Index (PIA) values. On the other hand, in the Inceptisol and Vertisol soils, it was determined leaching process for basic cations in the PI and PIV profiles located on the summit and footslope. As for mass balance system, the highest losses from the soil formed on the backslope whereas, the PI and PIV formed on the footslope position gains. As a result of this study, it has been revealed that soil formation process in the summit and footslope is more effective than in other physiographic units. Therefore, physico-chemical properties are mainly affected by these processes.

Plant available water predicted by a flux-based approach

Plant available water (PAW) is an important indicator of soil suitability for crop growth and biomass production. Total available water (TAW) is defined as the difference between the water content at field capacity (FC) and at wilting point (WP). The readily available water (RAW) is a fraction of TAW defined as the water content between FC and the limiting point (LP). The challenge in determining TAW and RAW lies in the correct determination of FC, WP, and LP. We propose a process-based approach to address the issue, referenced as flux-based method (FBM). Five scenarios were used to assess the FBM: (1) generic soil-plant-atmosphere conditions, from which sensitivity analyses were performed; (2) a maize crop on several soils to compare the predictions of the FBM and the traditional FAO method; (3) mean plant-atmosphere conditions to map PAW from soil texture using the FBM and the FAO method; (4) a field experiment with a fully irrigated soybean crop; and (5) a field experiment with a common bean crop under water deficit. Resulting flux-based TAW and RAW showed high sensitivity to root length density and soil hydraulic parameters. The FBM tended to predict higher water contents at FC than the FAO method for maize crop scenarios. Texture triangles to predict TAW and RAW showed that the differences between the predictions of FBM and FAO are mostly due to the distinct values for FC, and for the LP, respectively. For both observed scenarios of soybean and common bean crops, the predictions of the FBM were plausible with time series of observed data. The FBM allows predicting PAW in Van Genuchten – Mualem type soils for different FC flux criteria, soil depths, root densities, and dynamic potential transpiration rates.

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.