Plant Available Water Content Research Articles

Variable rate phosphorus fertilizer recommendations for rainfed wheat

A uniform application of phosphorus (P) fertilizers to spatially variable soils often results in under-fertilization in low P-localities and over-fertilization in high P-localities. This study aimed to evaluate the variable rate applicability of P fertilizers on a 300-ha sloping landscape under rainfed winter wheat cultivation for over 70 years. The soils were sampled (155 samples) using a random spatial sampling technique based on visual differences in soil color and topographic factors. Plant available soil P content (Pav) and other variables of soil samples were analyzed. The spatial variability of Pav was evaluated and the area was divided into three uniform zones (low, medium, high) for fertilizer P application based on the spatial variation of Pav. The values of Pav showed moderate variablity (CV= 21.3%). The fertilizer recommended by the Ministry of Agriculture and Forestry (MAF) was calculated for five identically-sized sub-regions. The results showed that P fertilizer rates calculated for all five sub-regions based on MAF were identical, suggesting that the MAF was insensitive to spatial variability of Pav in the study soils. Both semivariograms and surface maps of soil properties indicated a strong spatial association between Pav and each of plant available water content (PAWC) and aggregate stability index (ASI), suggesting that yield limitation casued by PAWC should be considered in a variable P-application program in the study area. A more comprehensive study is needed to evaluate the efficiency and cost-benefit economics of variable P application in the study soils.

Developing an environmental friendly approach for enhancing water retention with the amendment of water-absorbing polymer and fertilizers

The effect of climate/environmental change has resulted in adverse water stress conditions which necessitates the sustainable approaches for improving the water use efficiency to boost agricultural production in Central Asia. Water-absorbing polymer (WAP) has emerged as one of the amendments for soil water stress management. WAP are chemically cross-linked structure capable of absorbing and storing a large amount of water. The agricultural land has different levels of fertilizers which can influence the performance of WAP because of its sensitivity due to external ionic medium. Therefore, the combined or hybrid use of WAP and organic/ inorganic fertilizers may inhibit the functionality of WAP, which needs to be thoroughly investigated. This study demonstrates the performance of two different WAPs (a commercially WAP (crosslinked potassium polyacrylate) and a laboratory synthesized WAP (crosslinked fly ash-polyacrylate superabsorbent composite)) with varying combinations of fertilizers in silt loam (agrarian soil). The combined use of fertilizers and WAP have improved the water retention properties of soils due to modification in the soil pore volume for both the WAPs. Quantification from water retention properties revealed a significant increase in plant wilting time (PWT) and plant available water content (PAWC) under the combined influence of fertilizers and WAP amended soils, indicating the possibility of high-water availability to plant roots. The study suggests the potential of WAPs as an efficient soil conditioner even in the presence of fertilizer for countering the negative impacts of water stress conditions. WAPs might minimize the requirement for chemical fertilizers, which helps to enhance the climate/environmental change and agriculture sector in the Central Asian region.

Investigating soil properties and vegetation parameters in different biochar-amended vegetated soil at large suction for application in bioengineered structures

Bioengineered structures, such as landfill cover, vegetated slopes or embankments, green roof and turf are comprised of soil and vegetation where vegetation imparts stability and protection through root reinforcement and hydrologic action. Soil in bioengineered structures often compacted and subjected to prolong drying due to irregular irrigation which necessitates the investigation of soil properties and vegetation growth in biochar-amended soil (BAS) under large suction range and it is scarce in the literature. In the present study, the effect of different biochar types on soil properties, and the vegetation growth in compacted soil and under large suction range was investigated for application in bioengineered structures. The results revealed that the biochar amendment decreased the dry density (5-32%) and increased the water retention capacity (θs by 15-104%, θ1500 by 82-445% and plant available water content (PAWC) by 22-55%), pH (28-77%) and cation exchange capacity (CEC, 16-723%) of the soil. Further, the vegetation growth i.e., vegetation density, dry root mass and shoot mass increased by 8-13%, 33-108% and 4-157% respectively after biochar amendment. The vegetation wilting was started at a higher suction (~ 900kPa) relative to bare soil (800kPa), the permanent wilting point (PWP) increased (by 3-35%) and the complete photosynthetic activity remained unchanged at a higher suction (1600kPa) relative to bare soil (1050kPa) after biochar amendment. Among the biochar types i.e., Sugarcane Bagasse biochar (SBB), Mesquite biochar (MB) and Water Hyacinth biochar (WHB) tested, the MB showed the best performance i.e., the suitable vegetation growth and health status. The improved water retention due to increased porosity, specific surface area (SSA) and presence of hydrophilic functional groups, and the higher pH, CEC and lower dry density in BAS attributed to the higher vegetation growth. The findings of the present study suggest the application of BAS in bioengineered structures.

Efficacy of novel water‐absorbing polymer amended soil for improving drought resilience of Solanum lycopersicum

AbstractClimate change has exacerbated the frequency and duration of droughts. To sustain food production in such conditions, water storage and retention capacity of soil must be enhanced. Development of water‐absorbing polymer (WAP) from coal carbon residue (fly ash) can provide an economical and environmentally friendly alternative to commercial WAP for enhancing water retention and crop yield. The main objective of this study is to evaluate the growth performance of tomato species (Solanum lycopersicum L.) under continued drought conditions in the presence of in‐house developed fly ash‐based WAP (FA‐WAP) against that of commercially available WAP (Com‐WAP). Quantification of the soil–water retention curve (SWRC) revealed an increase in plant wilting time and plant‐available water content (PAWC) in the order: control soil (no amendment) < Com‐WAP‐amended soil < FA‐WAP‐amended soil. Both the WAPs positively influenced the transpiration factors of crops in terms of stomatal conductance (SC) and photosynthetic yield under continued drought conditions. The yield parameters (i.e., the number of fruits, total weight, and shoot fresh biomass) increased by 82, 106, and 115%, respectively, in the case of FA‐WAP‐amended soil as compared with that of the control. Nevertheless, FA‐WAP provided 20% higher yield of tomato species during continued drought conditions than commercial WAP. The application of FA‐WAP can be an effective strategy to impart beneficial usage of FA waste by significantly reducing the irrigation frequency and irrigation water requirement without compromising the crop yield. It also ensures sustainable water stress management for a major food crop (tomato), thereby contributing towards United Nation's Sustainable Development Goals 2, 13, and 15.

Influence of inorganic and organic fertilizers on the performance of water-absorbing polymer amended soils from the perspective of sustainable water use efficiency

The frequent occurrence of unprecedented droughts has necessitated strategies for enhancing water use efficiency to boost agricultural production. Water-absorbing polymer (WAP) has emerged as a viable option for water stress management. However, the sensitivity of these hydrophilic WAP’s to the external ionic medium significantly affects their water absorption capacity. Therefore, the combined or hybrid use of WAP and organic/ inorganic fertilizers may inhibit the functionality of WAP, which needs to be thoroughly investigated. The objective of this study is to assess the performance of two different WAPs (a commercially available WAP and a laboratory synthesized WAP) with varying combinations of organic/ inorganic fertilizers in two different soil textures. The combined influence of fertilizers and WAP (a total of 13 combinations of treatment) on the soil-water retention curve (SWRC) of two agricultural soils (silt and silt loam) were quantified. The water-absorbing capacity (WAC) of both WAPs (Com-WAP and FA-WAP) was reduced under the influence of different fertilizers in the order of urea < organic < DAP. Despite the reduction in overall WAC, the combined use of fertilizers and WAP have improved the water retention in both the soils due to modification of the soil pore volume. The improvement in water retention was more significant in silt soil than the silt loam for both the WAPs. The sensitivity of FA-WAP to fertilizers was found to be less than Com-WAP. This opens up the possibility of engineering the WAP for better water use efficiency. Quantification from SWRC revealed a significant increase in plant wilting time and plant available water content (PAWC) under the combined influence of WAP and fertilizers. The study indicates the potential of WAP as an efficient soil conditioner even in the presence of fertilizer for countering the negative impacts of water stress conditions.

THE SHORT TERM EFFECT OF TILLAGE SYSTEM ON SOIL MOISTURE RETENTION IN BAYELSA STATE, NIGERIA

The objective of the study was to determine the short time effect of tillage system on the water retention capacity of soils in the Niger Delta University Teaching and Research Farm, Bayelsa State. Five treatments (No-till, Digging, Hoeing, Hoeing+Digging once, and Hoeing+Digging twice) were considered. Plant Available Water Content (PAWC) and the Soil Water Holding Capacity (SWHC) were used to determine the soil water retention capacity. The results revealed that the crude tillage methods had a significant (P&lt;0.05) impact on some soil properties. The highest bulk density (1.18g/cm3) was found in the No-till zone, while the lowest (0.89g/cm3) was in the Hoe+Digging twice method. The tillage methods also affected the hydraulic conductivity as the highest value (4.67cm/hr) was found in the hoe+digging zone and the lowest (2.61cm/hr) in the no-till area. Furthermore, the PAWC and SWHC were highest (0.14cm3cm-3 and 2.03cm) at the No-till zone and lowest (0.06 cm3cm-3 and 0.95cm) at the Hoe+Digging twice zone. It is therefore recommended that, for unrestricted flow of water through the soils, compacted soils should be pulverized using tillage implements. Also, for optimal plant water availability, there should be less tillage on coarse-textured soils, as the disturbance promotes rapid leaching.

Testing numeric and logarithmic scales for hydraulic-energy indices and functions to assess physical earthworm effects on soil structure

Sufficient soil physical quality (SPQ) is needed to support the provision of multiple ecosystem services including food and fibre production, cycling of nutrients, cycling and storage of carbon, filtration of water and a habitat for biodiversity. Several SPQ indices are used to ascertain the SPQ of a soil and are often derived from the soil water retention curve (SWRC), built with multiple volumetric water content (θ) points across the pressure head (h) range, from saturation to oven-dried soil. The integral area under the SWRC has been used as an indicator for evaluating SPQ. The present study compared five hydraulic-energy SPQ indices and two cumulative hydraulic-energy functions based on the SWRC integral calculated on θ[log10(h)] basis and θ(h) in terms of their ability to track and refine soil structural information over time. For this, both approaches were applied to the SWRC data developed to examine the relationship between SPQ and earthworm abundance under dung pat and non-dung pat treatments from deposition to decay and beyond at a grassland field site in Ireland. Results showed that plant available water content (PAWC) and drainable porosity (DP) can be examined with either numeric (θ(h)) and logarithmic (θ[log10(h)]) scales and outcomes were not significantly different. Although the absolute hydraulic-energy SPQ indices of aeration and water retention presented distinct results, they both resulted in the same information with respect to soil structure status and this was consistent across numeric or logarithmic scales. However, the relative hydraulic-energy indices of aeration, water retention and air-water revealed more information with respect to water retention and drainage processes than when calculated on a logarithmic basis. Over the study duration, it was shown that more than 85% of the integral energy was used for storing water in the PAWC range and was dominant over the aeration process regardless of the treatment imposed. The results also indicate high and medium effect sizes for some parameters suggesting that a larger population or sample size could enhance the correlations and significance above those found in the present study.

Techno-economic analysis reveals the untapped potential of wood biochar

The United Nations estimates the rate of deforestation over 10 million hectares per year, with additional infested wood available due to drought, bark beetle calamity and other damage vectors. Processing the hard-to-reach infested wood into biochar via mobile pyrolysis units seems to be a good option for fire prevention. However, since most biochar is currently produced mainly from biological waste, there is not enough experience with wood biochar on a large scale. Review of current knowledge, followed by techno-economic assessment reveals that following the chemical composition of the feedstock, wood biochar outperforms other types of biochar in terms of high porosity. Therefore, wood biochar shows excellent results in increasing the amount of plant-available water content in soil and appears to be an excellent tool for recycling nutrients (especially into plant-available forms of phosphorus and nitrogen). The overall positive effects of biochar application change from abiotic to biotic over time because as it decays, many of its physical properties disappear, but it can boost soil microbial communities on which soil fertility depends. As global climate change creates a wide range of factors that damage forest cover, wood biochar consequently represents untapped potential in the field of soil, nutrient, and energy management.

Investigating unsaturated hydraulic conductivity and water retention characteristics of compacted biochar-amended soils for potential application in bioengineered structures

This study investigates the influence of biochar amendment on the water retention and unsaturated hydraulic conductivity (Kunsat) of compacted soils focusing on its potential application in bioengineered structures. Physical properties, water retention characteristics and Kunsat of two different soils, such as silty sand and pure sand and amended with 5% and 10% (w/w) biochar made from mesquite were measured with the help of instantaneous profile method (IPM). The water retention capacity of the biochar-amended soil was characterised by plotting soil water retention curve (SWRC) and estimating the saturated volumetric water content (θs), residual water content (θr), shape parameter ‘n’ and plant available water content (PAWC). The results revealed that the amendment of biochar in the soils increased the θs (by 20–30%), θr (60–370%) and PAWC (7–60%), and decreased the n (by 5–18%) and Kunsat (one-two order). The microstructural observation showed that the hydrophilic surface functional groups and intra-pores in biochar contributed to the improved water retention, while the altered pore size distribution and porosity of the soils due to biochar amendment increased the tortuosity of the water flow path and hence reduced the Kunsat. Based on the findings, biochar-amended soil is proposed to be used in bioengineered structures that could promote the growth of vegetation and improve the performance.

Effect of Re-Used Lignite and Mineral Wool Growing Mats on Plant Growth, Yield and Fruit Quality of Cucumber and Physical Parameters of Substrates in Hydroponic Cultivation

In hydroponic cultivation of vegetables with a solid substrate, mineral wool predominates. The pro-ecological policy and consumers’ expectations cause an increase in interest in organic substrates, which, when properly used, are less harmful to the environment. The aim of this study was to determine the effect of reusing lignite substrate in hydroponic cultivation on the growth, yield and quality of cucumber fruit and on the physical parameters of the substrate. The greenhouse cucumber cultivar ‘Mewa F1’ with semi-long fruits and smooth skin was used for the study. The plants were grown in the ‘Carbomat’ lignite substrate and ‘Grotop Master’ rockwool in two cycles. In cycle 1, new growing mats were used, while in cycle 2 the same growing mats as in cycle 1 were used again. In the hydroponic cultivation carried out on mineral wool and in the lignite substrate, both in the new and the reused substrate, the cucumber obtained mostly similar plant growth parameters and fruit color. Cucumber grown on the new mineral wool had a higher number and weight of fruits, which were characterized by a higher content of β-carotene and lutein compared to fruits from plants grown in the new lignite substrate. On the other hand, the reused lignite substrate resulted in higher cucumber yields and fruits with higher firmness and higher carotenoid content compared to cucumber grown on reused mineral wool. At the same time, the content of dry matter and sugar extract in fruits obtained from plants growing in the new and reused lignite substrate was higher compared to fruits grown in mineral wool. Both new and reused lignite substrate were characterized by very low plant-available water content. In contrast; the air and water holding capacity of lignite after cultivation did not change as much as that of mineral wool.

Assessment of the Impacts of Climate and LULC Changes on the Water Yield in the Citarum River Basin, West Java Province, Indonesia

Changes in climate and land use land cover (LULC) are important factors that affect water yield (WY). This study explores which factors have more significant impact on changes in WY, spatially and temporally, within the Citarum River Basin Unit (RBU), West Java Province, Indonesia with an area of ±11.317 km2. The climate in the area of Citarum RBU belongs to the Am climate type, which is characterized by the presence of one or more dry months. The objectives of the study were: (1) To estimate a water yield model using integrated valuation of ecosystem services and tradeoffs (InVEST), and (2) to test the sensitivity of water yield (WY) to changes in climate variables (rainfall and evapotranspiration) and in LULC. The integration of remote sensing (RS), geographic information system (GIS), and the integrated valuation of ecosystem services and tradeoffs (InVEST) approach were used in this study. InVEST is a suite of models used to map and value the goods and services from nature that sustain and fulfill human life. The parameters used for determining the WY are LULC, precipitation, average annual potential evapotranspiration, soil depth, and plant available water content (PAWC). The results showed that the WY within the territory of Citarum RBU was 12.17 billion m3/year, with mean WY (MWY) of 935.26 mm/year. The results also show that the magnitude of MWY in Citarum RBU is lower than the results obtained in Lake Rawa Pening Catchment Areas, Semarang Regency and Salatiga City, Central Java (1.137 mm/year) and in the Patuha Mountain region, Bandung Regency, West Java (2.163 mm/year), which have the same climatic conditions. The WY volume decreased from 2006, to 2012, and 2018. Based on the results of the simulation, climatic parameters played a major role affecting WY compared to changes in LULC in the Citarum RBU. This model also shows that the effect of changes in rainfall (14.06–27.53%) is more dominant followed by the effect of evapotranspiration (10.97–23.86%) and LULC (10.29–12.96%). The InVEST model is very effective and robust for estimating WY in Citarum RBU, which was indicated by high coefficient of determination (R2) 0.9942 and the RSME value of 0.70.

Soil micromorphological and physical properties after application of composts with polyethylene and biocomponent-derived polymers added during composting

Composts are considered to be one of the best soil amendments. However, the effects of composts with added polymeric materials on soil physical, hydraulic, and micromorphological properties have not been widely discussed. Changes in soil physical properties influence the numerous services that soils provide. We studied the impacts of composts with the addition of three different polymers (F1–F3) produced from polyethylene and thermoplastic corn starch on the physical, hydraulic, and micromorphological properties of two soils, a Cambic Phaeozem and a Luvic Phaeozem. Applying composts with polymers had limited or no significant effect on soil bulk density and porosity, but increased the field water capacity by 18%–82% and 3%–6% and the plant-available water content by 15%–23% and 4%–17% for the Cambic Phaeozem and Luvic Phaeozem, respectively. The application of composts with polymers had a greater effect on the Cambic Phaeozem than on the Luvic Phaeozem. It was suggested that the use of modified composts led to changes in soil physical properties and micromorphological features and this effect was dependent on the compost application rate. Composts made with the addition of composite synthetic and natural material-derived polymers during composting were found to be a composite mixture that can be successfully used in agriculture.

Soil Water Characteristics of Gleysols in the Bamenda (Cameroon) Wetlands and Implications for Agricultural Management Strategies

Water budgeting in agriculture requires local soil moisture information as crops depend mainly on moisture available at root level. The present paper aims to evaluate the soil moisture characteristics of Gleysols in the Bamenda (Cameroon) wetlands and to evaluate the link between soil moisture content and selected soil characteristics affecting crop production. The work was conducted in the field and laboratory, and data were analyzed by simple descriptive statistics. The main results showed that the soils had a silty clayey to clayey texture, high bulk density, high soil organic carbon content, and high soil organic carbon stocks. The big difference between moisture contents at wilting point and at field capacity testified to very high plant-available water content. Also, the soils displayed very high contents of readily available water and water storage contents. The soil moisture characteristics give sigmoid curves and enabled noting that the Gleysols attain their full water saturation at a range of 57.68 to 91.70% of dry soil. Clay and SOC contents show a significant positive correlation with most of the soil moisture characteristics, indicating that these soil properties are important for soil water retention. Particle density, coarse fragments, and sand contents correlated negatively with the soil moisture characteristics, suggesting that they decrease soil water-holding capacity. The principal component analysis (PCA) enabled reducing 17 variables described to only three principal components (PCs) explaining 73.73% of the total variance; the first PC alone expressed 45.12% of the total variance, associating clay, SOC, and six soil moisture characteristics, thus portraying a deep correlation between these eight variables. Construction of contoured ditches, deep tillage, and raised ridges management techniques during the rainy season while channeling water from nearby water bodies into the farmland, opportunity cropping, and usage of water cans and other irrigation strategies are used during the dry season to combat water constraints.

Updated European hydraulic pedotransfer functions with communicated uncertainties in the predicted variables (euptfv2)

Abstract. Soil hydraulic properties are often derived indirectly, i.e. computed from easily available soil properties with pedotransfer functions (PTFs), when those are needed for catchment, regional or continental scale applications. When predicted soil hydraulic parameters are used for the modelling of the state and flux of water in soils, uncertainty of the computed values can provide more detailed information when drawing conclusions. The aim of this study was to update the previously published European PTFs (Tóth et al., 2015, euptf v1.4.0) by providing prediction uncertainty calculation built into the transfer functions. The new set of algorithms was derived for point predictions of soil water content at saturation (0 cm matric potential head), field capacity (both −100 and −330 cm matric potential head), wilting point (−15 000 cm matric potential head), plant available water, and saturated hydraulic conductivity, as well as the Mualem–van Genuchten model parameters of the moisture retention and hydraulic conductivity curve. The minimum set of input properties for the prediction is soil depth and sand, silt and clay content. The effect of including additional information like soil organic carbon content, bulk density, calcium carbonate content, pH and cation exchange capacity were extensively analysed. The PTFs were derived adopting the random forest method. The advantage of the new PTFs is that they (i) provide information about prediction uncertainty, (ii) are significantly more accurate than the euptfv1, (iii) can be applied for more predictor variable combinations than the euptfv1, 32 instead of 5, and (iv) are now also derived for the prediction of water content at −100 cm matric potential head and plant available water content. A practical guidance on how to use the derived PTFs is provided.

Long-term effects of sustainable management practices on soil properties and crop yields in rainfed Mediterranean almond agroecosystems

The long-term effects of conservation agriculture on soil physical and chemical properties and their relationship with crop yields are still relatively poorly understood. In addition, the effects of those practices ranged widely depending on climatic and edaphic conditions and so they cannot be generalized for all agro-ecological regions and crop types. This study evaluates the effects of three conservation agriculture practices - reduced tillage (RT), reduced tillage plus incorporation of green manure (RTG), and no-tillage (NT) - on the soil quality on almond orchards under semiarid conditions and the soil factors explaining crop yield under these management practices. The soil physical indicators used were bulk density, resistance to penetration, total porosity, air capacity, relative field capacity, available water content, infiltration rate and field plant-available water content. The chemical parameters evaluated were soil organic carbon, total nitrogen, nitrate, and available phosphorus. Changes in the soil physical properties with the incorporation of green manure and with no-tillage, relative to RT were, mainly detected in the 5−15 cm soil layer, where improvements in soil water availability were observed. In addition, there was a positive effect of both green manure and no-tillage on the infiltration rate relative to RT. The shift from RT to RTG led to an improvement in total soil organic carbon and nitrogen, resulting in a positive effect on crop yield after six years of implementation. No-tillage led to a decline of about 70 % in crop yield with respect to the tillage treatments, despite the improvement in the soil available water content from the first year of its adoption. However, a strong decrease in the concentrations of available nitrogen was the factor mainly responsible for the crop yield reductions under NT.

Subsoiling and mechanical hole-drilling tillage effects on soil physical properties and initial growth of eucalyptus after eucalyptus on steeplands

The re-establishment of trees after previous forest harvesting (so-called second rotation) requires soil structure amelioration, since the tree harvest with heavy machinery usually causes soil compaction and deformation, mostly at the surface, but also in deeper layers. Efficient soil tillage methods are necessary to create a physical environment suitable for the next generation of trees to grow and develop successfully. The aim of this study was to evaluate the effect of four different soil tillage methods on soil physical properties and the initial growth of eucalyptus (Eucalyptus saligna) after eucalyptus on a gravelly Ultisol in southern Brazil with a compacted layer in 0.3 m depth. Tree seedlings were planted in randomized blocks in three replications after applying the following soil tillage methods: intermittent (every 4 m) downslope subsoiling (DSS), cross-slope subsoiling after above-ground stump cutting (C + CSS), cross-slope subsoiling plus ridging after above-ground stump cutting (C + CSS + R), and hole drilling (HD). Before as well as 122 and 391 days after planting, undisturbed and disturbed soil samples were collected in each tillage treatment in five layers down to 1.00 m to evaluate soil bulk density, macroporosity, microporosity, plant-available water content, and penetration resistance, along with chemical analyses. Operational costs and, where applicable, product costs of each method were compared, while the initial growth of E. saligna was evaluated by means of tree survival rate and height, diameter at breast height and wood volume 90, 180 and 330 days after planting. The tillage method did not affect soil chemical properties, but positively influenced physical properties by means of lower bulk density and penetration resistance. The most intensive and expensive method C + CSS + R provided the best conditions for tree growth, while HD was the cheapest method, but the least efficient due to low productivity. Per volume of produced wood, DSS was the most efficient method with lowest total costs and the second highest wood production.

Effect of Liquid Organic Fertilizer and Zeolite on Plant Available Water Content of Sand and Growth of Perennial Ryegrass (Lolium perenne)

The use of high permeability soils with low plant available water content (PAWC) for cultivation of plants in the greenhouses, green roofs, and urban green spaces requires frequent irrigation, which leads to high water consumption. This paper presents an innovative method consisting of combined use of sustainably produced liquid organic fertilizer (LOF) extracted from landscape grass waste and clinoptilolite zeolite for improving PAWC of sand. The study included four substrates, namely sand (S), sand with 20% zeolite (SZ), sand treated with LOF (SLOF), and sand with 20% zeolite treated with LOF (SZLOF), to evaluate the effect of LOF and zeolite on PAWC of sand. The effect of three growth medium treatments, sand that received LOF fertilizer (LOF1), sand with 20% zeolite that received LOF fertilizer (ZLOF), and sand that received inorganic fertilizer (CF1), through a greenhouse experiment during two growing seasons (fall and summer) on productivity of perennial ryegrass (Lolium perenne) and properties of its growth medium was also evaluated. Combined use of LOF and zeolite increased the volumetric water content of sand by 29, 154, and 220% at 0, 30, and 100 centibar (CB) suctions compared to S substrate, respectively, and increased the dry biomass yield (DBY) of perennial ryegrass by 42% in ZLOF during the summer season compared to CF1 growth medium. Additionally, the content of organic matter, nitrogen, and phosphorus increased by 25, 120, and 84%, respectively, for ZLOF treatment compared to 33, 40, and 53% for LOF1 treatment. The outcomes of the experiments demonstrate the feasibility of using LOF and zeolite to improve the PAWC of sand and DBY of perennial ryegrass.

Spatial and Temporal Heterogeneity Analysis of Water Conservation in Beijing-Tianjin-Hebei Urban Agglomeration Based on the Geodetector and Spatial Elastic Coefficient Trajectory Models.

To regulate regional water resources, it is essential to identify the relationships among the elements that influence water conservation. Taking the Beijing‐Tianjin‐Hebei urban agglomeration as the study area, the authors applied a new method in combination with a geodetector model and spatial elastic coefficient trajectory model to reveal factors controlling water conservation and to identify relationships among the elements driving water conservation, in which the water conservation capacity and its spatial distribution were achieved using an Integrated Valuation of Ecosystem Services and Tradeoffs model. The authors selected precipitation, potential evapotranspiration, temperature, land use, maximum burial depth of soil, plant‐available water content, soil‐saturated hydraulic conductivity, percentage slope, gross domestic product, and population as the spatial driving factors, which measured the influence on the distribution of water conservation capacity on the whole region, plateaus, mountains, and plains, respectively. On the basis of previous research results, the authors selected precipitation, potential evapotranspiration, and land use as time‐driven factors. The results indicated that the strong water conservation capacity was reflected primarily in the Yanshan and Taihang Mountains and the eastern coastal areas. The water conservation capacity of the entire region, mountains, plateaus, and plains was affected mainly by the soil‐saturated hydraulic conductivity, plant‐available water content, precipitation, and precipitation, respectively. Each driving factor exhibited a clearly interactive influence on the spatial distribution of water conservation in terms of space and time.

Influence of soil water holding and transport capacity on glyphosate dynamics in two agricultural soils from Pampas Region

Water dynamics is one of the most important regulating factors on glyphosate fate in agricultural soils. The objectives of this work were: i- to determine static and dynamic soil physical quality (SPQ) indicators during the crop cycle in two different textured soils from Argentinean Pampas Region, under no tillage (NT) and conventional tillage (CT); ii- to quantify glyphosate accumulation during the crop cycle in two different textured soils of Argentinean Pampas Region under NT and CT; and iii- to determine the relationship between glyphosate accumulation and vertical transport during the crop cycle with the static and dynamic SPQ indicators. Static and dynamic SPQ indicators and Total Extractable Glyphosate (TEG) were determined in a silty loam typic Argiudoll (Pergamino site, PER) and in a sandy loam Entic Haplustoll (Dorila site, DOR) at the beginning and the end of the crop cycle. In general, soils under NT showed higher values of plant available water content (PAWC) and lower values of saturated hydraulic conductivity (K0) as compared with CT. PER showed higher values of water content at wilting point (θWP), as compared with DOR. High values of θWP, along with low values of K0 were correlated to glyphosate accumulation, especially in the top soil. On the other hand, high values of K0 may favor vertical transport, as was observed under CT for PER. Our results show that repeated glyphosate application could lead to its accumulation in agricultural soils, depending of the soil type and tillage systems, implying a potential risk of soil pollution.

A Model to Predict Plant-available Water Content of Soils at Different Land Units in Bengkulu, Indonesia

Soil water availability to the plants is a very important physical property of soil that controls water and nutrient absorption by the plant. It is defined as the difference between the maximum amount of water the soil can hold and the minimum condition that the plant can no longer extract water from the soil. However, soil factors that control the plant available water content (PAWC) in the soil have not been fully understood. The present study aims to analyze the relations between particle-size distributions and organic carbon with the available water of the soil and to develop a model of predicting PAWC. Five soil profiles at different land units were described up to the depth of 100 cm. Ten undisturbed soil samples were taken using the stainless-made core sampler from 10 cm increments for the soil water holding capacity analysis. A similar number of disturbed samples were also provided from the same depths for soil texture and organic carbon analysis. Results showed that the variance in PAWC could be explained by sand and clay fractions (R2&gt;0.35) but not by silt and organic carbon contents. Therefore, we were able to develop a model for the prediction of available water content in the soil from the sand and clay parameters. The model will help decision-makers be able to propose conservation and management strategies for PAWC in agricultural practices as well as for the soil moisture retention at civil works.