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The combustion of low-grade solid fuels such as oil shale generates huge amounts of solid wastes such as fly ash. Use of oil shale combustion ash in granulated form for liming and amending peat soil has been suggested as a feasible recycling opportunity. However, the effect of granulated oil shale ash application on the characteristics of soil moisture and mobility of potentially toxic elements has not been thoroughly studied. The aim of the work was to study the environmental safety of the granulated oil shale fly ash when applied at peat soil in post-harvested peatlands. The oil shale ash was granulated using Na-alginate gel. The pH, EC and mobility of selected elements such as Al, As, Ba, Ca, Cd, Cr, Cu, Hg, K, Mo, Ni, Pb and Zn in amended peat soil was followed by analyzing soil water samples from the field. During vegetation period from April 2016 to September 2016 the pH value of the soil water samples in areas amended with granulated oil shale ash increased from 3 up to 6. The concentration of essential nutrients as well as other beneficial trace elements increased in soil water samples. The concentrations of potentially toxic microelements Cd, Hg and Pb were below detection limits in all collected soil water leachates. Granulated oil shale ash did not increased the mobility of other potentially hazard elements in amended peat soil during the study. [ABSTRACT FROM AUTHOR]

This study investigated the spatiotemporal variability and temporal stability of soil water at various depths in two croplands sown in corn and cotton during the 2018 growing season in the Tennessee Valley Region (TVR) of northern Alabama. Classical statistics and relative difference approaches were used to analyze soil water data in this study. In the corn field, the 30-60 cm depth showed the greatest variability, while the cotton field showed the greatest variability at 0-15 cm depth. A decreasing trend was noticed between mean soil water and coefficient of variation for all depths in the cotton field and at 30-60 cm depth in the corn field. However, convex upward, exponential decreasing, or no trends were found between mean soil water and standard deviation at different depths in both fields. The temporal stability analysis showed one representative sensor (S8 in corn and S1 in cotton) for the entire soil profile in both fields. Different statistical tests, i.e., Spearman's correlation (rs), Nash-Sutcliffe efficiency (NSE), coefficient of determination (R2), etc., were used to reduce uncertainty or increase confidence in the performance of representative sensors. Among various field attributes, topography in corn and soil properties in cotton were determined as significant factors responsible for soil water variability. Crop evapotranspiration (ETc) showed significant negative weak and moderate correlations with soil water in the corn and cotton fields, respectively. However, the mean air temperature showed a significant positive correlation with soil water in the corn field and a significant negative correlation in the cotton field. Solar radiation had a significant negative correlation with soil water in the cotton field and a non-significant correlation in the corn field. Accumulated growing degree days (accGDD) showed a significant negative correlation with soil water in the corn field and a positive correlation in the cotton field. This study gives insights into soil water variability, provides useful information about temporal stability, and identifies significant factors for precision uniform irrigation scheduling. [ABSTRACT FROM AUTHOR]

Dissolved organic matter (DOM) can serve as an indicator of watershed carbon cycling, and links terrestrial to aquatic ecosystems. The extent DOM is microbially processed before it enters aquatic ecosystems is expected to change with soil depth and landscape position, and as some research suggests, in response to recovery from chronic acidification. Here we examined DOM within freely flowing soil pore water and stream water collected from reference and calcium silicate‐treated watersheds at the Hubbard Brook Experimental Forest, New Hampshire, USA. Dissolved organic carbon (DOC) and nitrogen (DON) concentrations as well as, absorption and fluorescence properties were analyzed to assess patterns in DOM quantity and quality. Parallel factor analysis was used to identify three predominant fluorescing DOM components (C1‐3). All three components were terrestrial in origin, however C3 exhibited spectral properties previously linked to the microbial processing of humic material. Distinct horizonal patterns emerged between genetic soil horizons. DOC quantity decreased with soil depth, so too did, the plant derived lignin‐like fraction (C2), while the C3 fraction increased. High‐elevation coniferous zones with shallow bedrock contributed to higher DOC concentrations in soil and stream water, while high and low‐elevation mineral soils exhibited greater C3 fractions and fluorescence indicators of microbially processed DOM. This pattern suggests these mineral soils are important organic carbon sinks, due to greater rates of microbial DOM processing. DOC in forest floor solutions, C3 fractions, and indicators of smaller molecular size (E2:E3) were all higher in the calcium silicate‐treated watershed, suggesting greater microbial processing of DOM. Plain Language Summary: Northeast forests are recovering from decades of acid rain, while also impacted by a changing climate. Decaying organisms remains contribute highly variable forms of organic matter in soil, which can serve as an energy source for microbes and other decomposers. A fraction of this organic matter is dissolved and transported by water through the forest soils into streams affecting downstream water quality. Two decades ago, a small watershed at the Hubbard Brook Experimental Forest, in New Hampshire was treated with a calcium‐enriched mineral to accelerate recovery from acid rain. Since the application, chemical and biological indicators have seen a marked recovery. The goal of our current study was to examine patterns in dissolved organic matter quantity and quality within reference forest soil and stream water and the response to the calcium treatment. We used spectrofluorometric measurements and modeling to determine different organic matter fractions. One resulting fraction showed evidence of microbial processing, and its relative abundance increased with soil depth, especially at lower elevations in the calcium‐treated watershed where mineral soils are deeper and experience more vertical water flow. Greater fractions of unprocessed organic matter were transported through soils into streams at higher elevations in both watersheds. Key Points: Terrestrial sourced dissolved organic matter (DOM) dominates drainage waters in a northeast temperate forestTypical podzols at lower elevations produced higher fractions of microbially processed organic matterDOM within a calcium silicate‐treated watershed also exhibited more extensive microbial processing [ABSTRACT FROM AUTHOR]

Poor precipitation in the Loess Plateau area may significantly influence water uptake strategies of the plants growing there. The water sources of these trees have not been studied to date. We investigated the impacts of precipitation (before and after) on the water uptake strategies of typical broadleaf and coniferous trees in the Loess Plateau mountain area of northern China by using hydrogen and oxygen stable isotope techniques. Our results indicated that water sources of these two tree types varied before and after rainfall. Robinia pseudoacacia, a broadleaf tree, absorbed water mostly from the 30–40 cm (57.8%) soil layer before precipitation and from the 20–30 cm (58.5%) soil layer after precipitation. However, Pinus tabuliformis, a coniferous tree, mainly absorbed water from 20–30 cm (24.9%) and 10–20 cm (21.6%) soil layers before precipitation and from 0–10 cm (39.8%) and 10–20 cm (44%) soil layers after precipitation. Moreover, the herbaceous plants within the broadleaved forests had a higher community complexity according to filed investigation. Thus, R. pseudoacacia and P. tabuliformis exhibited peculiar difference in terms of water uptake, indicating that they are suitable to grow together as forest vegetation in arid and semi-arid areas. Overall, our results provided vital information for sustainable afforestation management in the Loess Plateau mountain area of northern China. [ABSTRACT FROM AUTHOR]

Vertisols shrink and swell with changes in soil moisture, influencing hydraulic properties. Vertisols are often in floodplains, yet the importance of flooding as a source of soil moisture remains poorly understood. We used blue dye and deuterated water as tracers to determine the role of the macropore network in matrix recharge under artificial flood durations of 3 and 31 days in large soil monoliths extracted from a forested soil. Gravimetric soil moisture content increased by 47% in the first three days, then increased only 3.5% from day 3–31. Post‐flood moisture content was greatest in the organic‐rich, top 10 cm and was lower at 10–75 cm where organic matter was less. Deuterium concentration revealed that soil moisture in the top 10 cm was quickly dominated by artificial flood water, but at depth remained <80% floodwater even after 31 days. Pervasive dye staining of ped surfaces in the top 4 cm indicated connectivity to flood waters but staining at depth was less and highly variable. The isotopic composition of soil water at depth continued to shift toward flood water despite no differences in dye staining between days 3 and 31. Results indicate flooding initially but incompletely recharges matrix water via macropores and suggest the importance of flooding as a source of matrix recharge in vertic floodplain soils may depend more on flood frequency than duration. Isotopic composition of matrix water in vertic soils depends on both advective and diffusional processes, with diffusion becoming more dominant as porosity decreases. Plain Language Summary: Shrink‐swell clay soils are common in floodplains but their behavior during flooding, particularly how much flood water they take up, is not well understood. We flooded large blocks of shrink‐swell soil with artificial floodwater spiked with dye and chemically labeled water, and found that water moved rapidly into soils via cracks and large soil pores, but swelling closed those pathways and prevented floodwater from spreading throughout the soil blocks. Only near the surface, where there is more organic matter, did floodwaters completely dominate soil moisture after flooding. Results indicate that flow into cracks in shrink‐swell soil is important early in a flood, but not enough water flows this way to allow floodwater to reach throughout the soil before the clays swell and close those pathways. Because the amount of water that the soil can take up is limited in each event, the importance of flooding for soil moisture in shrink‐swell clay soils in floodplains depends on how often flooding occurs rather than how long it persists. Key Points: Infiltration of floodwater via macropores ceased with swelling, but isotopic composition was heterogeneous even after 31 days of inundationSlow diffusion dominates isotopic evolution of soil matrix water in Vertisols as porosity decreasesThe importance of flooding as a source of matrix recharge in vertic floodplain soils may depend more on flood frequency than duration [ABSTRACT FROM AUTHOR]

A large gap between actual and potential herbage production of tall fescue is a major limitation for livestock production systems in Argentina. The objectives of this work were to (a) calibrate and test the ability of a published pasture–soil water model to represent herbage growth dynamics of tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] under different growing conditions, using data from controlled field experiments; (a) use the evaluated model to predict the magnitude and time of the year that N or soil water would constrain tall fescue from attaining its potential growth rate in the south‐eastern Pampas of Argentina; and (c) quantify herbage production gains and temporal variability for a proposed improved management practice (IMP) of N fertilizer under different meteorological and soils scenarios. After tall fescue‐specific calibration, the model accurately represented the response of tall fescue herbage mass to irrigation and N fertilization (root mean square error of prediction <550 kg DM ha−1, R2 >.70) observed in thirteen single‐season, controlled, field experiments. Results from a 40‐year simulation show that the gap between fertilized and unfertilized tall fescue pastures in Argentina can exceed 14 t DM ha−1 year−1. The proposed IMP maximized responses to N in autumn and early spring, reducing the annual herbage production gaps by 38%. The effect of IMP on annual herbage production was larger (4–5 t DM ha−1 year−1) than the effect due to variability in soils' ability to store water (2–4 t DM ha−1 year−1) or annual variability in meteorological conditions (±1–2 t DM ha−1 year−1). This work provides a sound modelling approach to identify, for a particular forage species and site, most of the main gaps of herbage production; and to quantify, without the need of long‐term, expensive field studies, some of the potential gains (and risks associated with temporal variability), that could be achieved by producers. In addition, our results clearly indicate that site‐specific calibration is required for the model to provide accurate predictions and sound management advice to farmers. [ABSTRACT FROM AUTHOR]

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• A karst cave monitoring work about δ18O with the designment of precipitation-soil water-drip water in Southern China. • Deep soil water is mainly supplied by the rainy season precipitation with light δ18O value. • The condition inside cave and overlying soil could affect the drip δ18O signature. Understanding the modern transport processes of δ18O between different waters in cave systems can provide a basis for the paleoenvironmental interpretation of records of stalagmite δ18O. We conducted monthly in-situ monitoring of local precipitation, soil water at three different soil depths, five drip water sites and environmental parameters in Remi cave, Western Hunan Province, Central China, from December 2020 to January 2024. During the monitoring period, due to differences in geological structure and ventilation effect at different locations within the cave, cave air temperature and relative humidity gradually remained constant from the cave entrance to the deep parts of the cave. On intra-annual timescales, precipitation δ18O p were depleted in the wet season and enriched in the dry season, which were mainly controlled by changes in moisture sources, upstream convective activity, and rainout effects. With the increasing thickness of the soil layer above the cave, soil water δ18O soil gradually became negative and leveled off, possibly because shallow soil water responded sensitively to local year-round precipitation, accompanied by surface evaporation. While, deep soil water with more negative δ18O, may be mainly replenished by heavy precipitation during the wet season, but the effect of water retained in the soil from preceding years couldn't be excluded and would be needed to verify by conducting more monitoring studies on the variation of δ18O soil covering the long period. The mean δ18O values of drip water at sites D1 and D2 near the cave entrance were heavier than that of shallow soil water and precipitation, possibly due to evaporation from the thin overlying soil layer, together with ventilation effect. There were seasonal variations of δ18O d values at site D5 in the deep parts of the cave, which may be associated with the seasonal variation of drip rate at this site. Due to the smoothing effect of soil layer and epikarst zone, there were no seasonality in δ18O d values at sites D3 and D4, in the middle and deep parts of the cave. The mean δ18O d at these two sites were lighter than amount-weighted annual mean δ18O p , and close to the deep δ18O soil and the wet-season amount-weighted mean δ18O p values. This suggests that the thick soil layer overlying the cave raises the precipitation threshold, causing these sites to be mainly recharged by heavy rainfall in the wet season. Therefore, the δ18O of stalagmites growing under these drip sites may mainly inherit the wet-season δ18O p signal. The short monitoring period of this study (three years) and the lack of modern calcite δ18O data, mean that caution is need in interpreting stalagmite δ18O on a timescale longer than that of this study. [ABSTRACT FROM AUTHOR]

• Artificial restored shrub and grass aggravated soil deficit but they got replenished better under large rainfall. • The effects of revegetation and topography on SWS varied greatly with rainfall. • Water-intensive vegetation species should be used cautiously for revegetation. The Chinese Loess Plateau (CLP) rose to prominence for its fragmented terrain and fragile ecosystems. Large-scale revegetation was applied to control soil and water loss there. However, revegetation resulted in unexpected water shortages. In this study, we investigated the temporal-spatial distribution of soil water in the northern CLP based on 13-year soil water content (SWC) data of four different revegetation types on a loessial slope and 4-year data of a gully system to study the response of soil water to long-term revegetation, topography, and precipitation. Results showed that in the 0–400 cm soil depth under shrub, grass, natural fallow, and millet, soil water storage (SWS) was –102.8, –129.3, 54.9, and 39.3 mm higher after 13-year of restoration, respectively. Although soil water under shrubs- and grasslands became more replenished under high precipitation, planting these water-intensive vegetation types aggravated soil desiccation. The gully intensified soil water spatial heterogeneity, with mean SWS within 0–480 cm soil depth of 902, 712, and 746 mm at the gully bottom, edge, and bank, respectively. The deviation index among the four revegetation types and among gully bottom, edge, and bank were 0.43 and 0.26, respectively, which indicated that revegetation types had a more obvious effect on SWS. Given that more concentrated rainfall under global climate change, both revegetation type and topography should be considered during ecological restoration in semi-arid areas. These findings can deepen our comprehension of the hydrological processes on the CLP and provide a reference for the development of ecological restoration policies under future climate change. [ABSTRACT FROM AUTHOR]

This study indicated that the application of a novel Fe-Mn modified rice straw biochar (Fe/Mn-RS) as soil amendment facilitated the removal of sulfamonomethoxine (SMM) in soil water microcosms, primarily via activating degradation mechanism rather than adsorption. The similar enhancement on SMM removal did not occur using rice straw biochar (RS). Comparison of Fe/Mn-RS with RS showed that Fe/Mn-RS gains new physic-chemical properties such as abundant oxygenated C-centered persistent free radicals (PFRs). In the Fe/Mn-RS microcosms, the degradation contributed 79.5–83.8% of the total SMM removal, which was 1.28–1.70 times higher than that in the RS microcosms. Incubation experiments using sterilized and non-sterilized microcosms further revealed that Fe/Mn-RS triggered both the biodegradation and abiotic degradation of SMM. For abiotic degradation of SMM, the abundant •OH generation, induced by Fe/Mn-RS, was demonstrated to be the major contributor, according to EPR spectroscopy and free radical quenching experiments. Fenton-like bio-reaction occurred in this process where Fe (Ⅲ), Mn (Ⅲ) and Mn (Ⅳ) gained electrons, resulting in oxidative hydroxylation of SMM. This work provides new insights into the impacts of biochar on the fates of antibiotics in soil water and a potential solution for preventing antibiotic residues in agricultural soil becoming a non-point source pollutant. [Display omitted] • Fe-Mn modification leads to increased surface area and more abundant PFRs in biochar. • Fe/Mn-RS promotes the antibiotic removal in soil water via activating degradation. • Biotic and abiotic degradations of SMM are simultaneously enhanced by Fe/Mn-RS. • PFRs in biochar and Fenton-like bioreaction aid •OH formation to trigger degradation. • Potential degradation pathway, mechanism, and toxicological alteration are proposed. [ABSTRACT FROM AUTHOR]

• Disproportionate recharge from heavy rainfall is found with stable isotopes. • Evaporation is highlighted in the isotopic transmission to groundwater. • Groundwater buried depth is the dominant contributor to isotopic temporal variation. • Groundwater isotopes in paleoclimatic studies should be carefully considered. The use of stable isotopic composition in groundwater as a paleoclimatic proxy assumes that the isotopic values in groundwater are inherited from the corresponding values in the source precipitation. However, several studies have observed that groundwater δ18O (δ18O g) is not always in accordance with the average δ18O of precipitation (δ18O p). The cause of this inconsistency is still the subject of debate. Significant reduced isotopic variability and potential deviations from precipitation to groundwater because of the aquifer itself (e.g., groundwater buried depths and soil texture) and external precipitation characteristics (e.g., rainfall intensity and duration) have been poorly quantified in terms of identifying the dominant factors. To investigate the controls on the transmission of isotopic signals from precipitation to groundwater, we present new stable isotope data for precipitation and groundwater from an experimental site using eight soil cylinders of different soil textures and burial depths in a monsoon region. We collected data at inter-event sampling intervals (30 min) during and after two heavy precipitation events (daily amounts higher than 10 mm). Our results demonstrated a significant disparity between the average isotopic values of heavy rainfall and light rainfall, despite both exhibiting decreasing isotopic patterns throughout the course of the rainfall event. Various degrees of attenuation of isotopic variations were found in outflow waters with different groundwater burial depths (GBDs) and soil textures after rainfall events. The isotopic variations were not synchronized with the outflow changes. Specifically, there were evident outflow lags in response to heavy rainfall, especially in the lysimeters with GBDs deeper than 0.5 m, while the greatest isotopic variation was observed in the early infiltrating stage. Redundancy analysis indicated that precipitation amount was the most important contributor to the outflow variation (∼51 %, p < 0.05), while GBD was the key factor for isotopic temporal variation (∼52 %, p < 0.05). These results concurred with the clustering of principal component analysis results. The mixing of soil water and heavy rainfall event components was observed in four lysimeters with mixing proportions f P varying in the range of 7 %–51 %, indicating the effective recharge from heavy rainfall. Soil evaporation was highlighted with samples located parallel to the local meteoric water line. It is recommended that groundwater isotopes in paleoclimatic studies are used with additional constraints that consider disproportionate recharge from intense rainfall, past chaotic fluctuations in groundwater dynamics, and distortions introduced by evaporation. [ABSTRACT FROM AUTHOR]

ABSTRACT Potato (Solanum tuberosum L.) cultivation has a high demand for management and treatments during the vegetative cycle in the field. Among these requirements, water management is a limiting factor of tuber productivity and quality. This study aimed to determine the most appropriate soil water depletion depth for irrigation management in potato crops of Ágata cultivar, under the edaphoclimatic conditions of Guarapuava-PR, considering its influence on crop vegetative development. The study was conducted using four water depletion depths in the soil (12, 24, 36, and 48 mm). The different irrigation treatments promoted differences in shoot dry mass, leaf area index (LAI), number of tubers per plant, and productivity. The highest yield was observed for 27.62 mm depletion. When irrigation depth was increased to 48 mm, tubers showed individual mass reduction and hence productivity, affecting commercial classification. A cumulative depletion of about 27 mm between irrigations proved to be the most adequate management to supply the water demand of Ágata potato cultivar.

Abstract Background The nonstructural carbohydrates (NSCs) of plants are posited to be crucial traits for the resistance and resilience of plants to climate change-induced drought and flooding. However, the potential effects of persistent drought and waterlogging on the dynamics of the NSCs and the underlying mechanisms are still poorly understood. Methods We measured the NSCs concentrations and pool size, photosynthetic rate and biomass of Robinia pseudoacacia L. seedlings for both 2015 and 2016 under five soil water treatments: 3%, 8%, 17%, 24% and 34% soil water content, representing extreme drought (ED), moderate drought (MD), the control group (CG), field capacity (FC) and waterlogging (WL) stresses, respectively. We observed the relationship between the pool size of NSCs and the survival of seedlings under water stress (drought and waterlogging) for 30 days in greenhouse. Results Compared with CG, the net photosynthetic rate decreased 91%, 67%, 34% and 71%, and the biomass decreased by 37%, 15%, 16% and 33% under ED, MD, FC and WL, respectively. The total NSC (TNSC) concentration was significantly increased by 154% under ED after 10 days and sharply decreased by 50% under ED after 30 days. The concentrations of soluble sugars (SS) were significantly increased by 100% under MD after 10 days and sharply decreased by 60% under ED after 30 days. Compared with GC, the response of NSCs, photosynthetic rate and biomass under ED were more dramatic than that under WL. The pool sizes of fructose and sucrose were larger under ED and WL, but the maximum pool size of starch occurred under the CG. The depletion of NSCs was not observed under ED at the end of the experiments in both 2015 and 2016. Conclusions Our results indicate that the dynamics of NSCs is an important physiological feature of plant adaptation and resistance to drought and waterlogging. In addition, high sugars concentrations are beneficial for the plants during the short-term extreme drought and the longer term mild drought or waterlogging.

This study assessed the strength of Sentinel-2 multispectral instrument (MSI) derived Red Edge (RE) bands in estimating Leaf Area Index (LAI) and mapping canopy storage capacity (CSC) for hydrological applications in wattle infested ecosystems. To accomplish this objective, this study compared the estimation strength of models derived, using standard bands (all bands excluding the RE band) with those including RE bands, as well as different vegetation indices. Sparse Partial Least Squares (SPLSR) and Partial Least Squares Regression (PLSR) ensembles were used in this study. Results showed that the RE spectrum covered by the Sentinel-2 MSI satellite reduced the estimation error by a magnitude of 0.125 based on simple ratio (RE SR) vegetation indices from 0.157 m2· m−2 based on standard bands, and by 0.078 m2· m−2 based on red edge normalised difference vegetation (NDVI-RE). The optimal models for estimating LAI to map CSC were obtained based on the RE bands centered at 705 nm (Band 5), 740 nm (Band 6), 783 nm (Band 7) as well as 865 nm (Band 8a). A root mean square error of prediction (RMSEP) of 0.507 m2· m−2 a relative root mean square error of prediction (RRMSEP) of 11.3% and R2 of 0.91 for LAI and a RMSEP of 0.246 m2/m2 (RRMSEP = 7.9%) and R2 of 0.91 for CSC were obtained. Overall, the findings of this study underscore the relevance of the new copernicus satellite product in rapid monitoring of ecosystems that are invaded by alien invasive species.

Forage radish is a unique winter cover crop that is relatively new but becoming rapidly adopted in temperate, humid North America. Little is known about how the use of this cover crop may influence subsequent nitrogen availability, soil water accumulation in the soil profile in corn silage production system. In this present work, the average nitrogen uptake by silage corn increased significantly by 11.6% in cover plots compared with the no-cover control plots. The recovery efficiency and agronomic efficiency of applied nitrogen in silage corn declined in cover plots compared to no-cover plots. The average soil water storage in cover plots was significantly higher than in the control after corn sowing and at the harvest stage. With increasing nitrogen application level, the average corn grain yield increased significantly at 56 and 112 kg N ha−1 by 13.1% and 39.8%, respectively. Planting a forage radish cover crop can facilitate growth of silage corn and markedly improve total nitrogen uptake of corn. Consideration should be given to nitrogen application rate and also to avoiding excessive nitrogen input in the subsequent crop following a cover crop, thereby truly improving subsequent fertiliser use efficiency.

Sowing date and seeding rate are critical for productivity of winter wheat (Triticum aestivum L.). A three-year field experiment was conducted with three sowing dates (20 September (SD1), 1 October (SD2), and 10 October (SD3)) and three seeding rates (SR67.5, SR90, and SR112.5) to determine suitable sowing date and seeding rate for high wheat yield. A large seasonal variation in accumulated temperature from sowing to winter dormancy was observed among three growing seasons. Suitable sowing dates for strong seedlings before winter varied with the seasons, that was SD2 in 2012–2013, SD3 in 2013–2014, and SD2 as well as SD1 in 2014–2015. Seasonal variation in precipitation during summer fallow also had substantial effects on soil water storage, and consequently influenced grain yield through soil water consumption from winter dormancy to maturity stages. Lower consumption of soil water from winter dormancy to booting stages could make more water available for productive growth from anthesis to maturity stages, leading to higher grain yield. SD2 combined with SR90 had the lowest soil water consumption from winter dormancy to booting stages in 2012–2013 and 2014–2015; while in 2013–2014, it was close to that with SR67.5 or SR112.5. For productive growth from anthesis to maturity stages, SD2 with SR90 had the highest soil water consumption in all three seasons. The highest water consumption in the productive growth period resulted in the best grain yield in both low and high rainfall years. Ear number largely contributed to the seasonal variation in grain yield, while grain number per ear and 1 000-grain weight also contributed to grain yield, especially when soil water storage was high. Our results indicate that sowing date and seeding rate affect grain yield through seedling development before winter and also affect soil water consumption in different growth periods. By selecting the suitable sowing date (1 October) in combination with the proper seeding rate of 90 kg ha–1, the best yield was achieved. Based on these results, we recommend that the current sowing date be delayed from 22 or 23 September to 1 October.

Rubber cultivation is primarily rainfed agriculture, which means that water supplies are not stable in most rubber cultivated areas. Therefore, improving the water use of rubber trees through fertilization management seems to be a breakthrough for enhancing the growth and latex yield of rubber trees and carrying out the intensive management of rubber agriculture. However, the relationships among the nutrient status of rubber trees, their water uptake, and soil resources, including water and nutrients, remain unclear. To address this issue, we measured C, N, P, K, Ca, and Mg concentrations in soil and leaves, stems, and roots in a monoculture rubber plantation and distinguished the water uptake depths based on stable isotope analysis throughout the year. We found that the rubber trees primarily absorbed water from the 5–50 cm depth layer, and soil water and nutrients (usually N, P, K) decreased with depth. In addition, the water uptake depth of rubber trees exhibited positive correlations with the nutrient status of their tissues. The more water the rubber trees absorb from the intermediate soil layer, the more nutrients they contain. Therefore, applying fertilizer to intermediate soil layers, especially those rich in C content, could greatly promote rubber tree growth.

Berberine (BBR), a Chinese herbal medicine used in intestinal infection, has been applied as a botanical pesticide in the prevention of fungal disease in recent years. However, its degradation in the environment remains poorly understood. Here, we investigated BBR’s degradation in soil water from different sources accompanied by its effect on bacterial diversity. Our results indicated that BBR was only degraded in soil water, while it was stable in tap water, river water and aquaculture water. Bacterial amplicon results of these samples suggested that the degradation of BBR was closely related to the enrichment of Methylotenera. To reveal this special relationship, we used bioinformatics tools to make alignments between the whole genome of Methylotenera and the pathway of BBR’s degradation. An ortholog of Tetrahydroisoquinoline N-methyltransferase from plant was discovered only in Methylotenera that catalyzed a crucial step in BBR’s degradation pathway. In summary, our work indicated that Methylotenera was an essential bacterial genus in the degradation of BBR in the environment because of its Tetrahydroisoquinoline N-methyltransferase. This study provided new insights into BBR’s degradation in the environment, laying foundations for its application as a botanical pesticide.

Thorough knowledge of soil lithology and its properties are of considerable importance to agriculture. These parameters have a direct impact on water permeability and the content of the water in soil, which represent significant factors in crop yield, decisively determining the design of irrigation systems and farming processes. In the framework of this study, and considering the inevitable impacts of climate change, the rational management of water resources and the optimization of irrigation through innovative technologies become of significant importance. Thus, we propose an interdisciplinary approach based on robust techniques from the allied fields of earth (geological mapping, geophysical methods) and soil sciences (sampling, mechanical analysis) assisted by statistics and GIS techniques. Clay or the sum of clay and silt soil content is successfully determined from the normalized chargeability using induced polarization and electrical resistivity techniques. Finally, we distinguished three classes (S1, S2 and S3) considering the clay or the sum of clay and silt soil content in the study area (a) based on the dry period geophysical data and (b) using as classification criterion the spatial distribution of the geological formations.

Water is considered the most important natural resource utilized on managed amenity grasslands, and water conservation is an integral part of an overall program in environmental stewardship and best management practices. Measuring and monitoring the soil water content of turfgrass root zones has become an important and routinely accepted practice of golf courses and sports pitches. In recent years, portable hand-held soil moisture meters or sensors have become commercially available and affordable, and therefore have become a valuable and often relied-upon tool for the turfgrass industry practitioner. To maximize or optimize the time and resources needed to measure the root zone volumetric water content of a turf site, a field experiment was conducted to determine the minimum number of soil moisture readings needed per 93 m2 of a sand-based root zone. Of note, 93 m2 is equivalent to 1000 ft2, which is the common form of area measurement utilized by the turfgrass industry in the USA. The standard error of the mean calculated from sampling data revealed that three to four measurements per 93 m2 were the minimum number required. Soil moisture meters should be utilized in a structured, purposeful, and site-specific manner along with traditional soil moisture evaluation methods of diligent scouting for visual signs of turfgrass wilt and drought stress, as well as examining soil root zone cores, to support prudent irrigation water management practices. Knowledge of the soil moisture status will support best practices for water conservation and environmental stewardship while optimizing turfgrass quality, function, and performance.

[Objectives] To study the relationship between soil water, groundwater burial depth, and precipitation for summer maize in Huaibei Plain. [Methods] The atmospheric precipitation, soil water and groundwater for the growth period of summer maize in Huaibei Plain were analyzed using the 26-year long series of data from the Wudaogou Hydrological Experimental Station, combined with the hydrogen and oxygen stable isotope tracing method. [Results] The average soil moisture content of summer maize in different growth periods showed a trend of first decreasing, then increasing and then decreasing with the increase of soil depth. The average soil moisture content was the lowest at the surface soil layer. From the characteristic values of hydrogen and oxygen isotopes of atmospheric precipitation, soil water and groundwater, it can be known that the average values of δ18O and δD of soil water decreased with the increase of soil depth, indicating that soil moisture evaporation leads to the enrichment of soil heavy isotopes, and the degree of enrichment decreased from the surface layer to the deep layer of the soil. The seasonal variation of the stable isotope of hydrogen and oxygen in soil water declined with the increase of soil depth. The soil water changes at 30 cm and 50 cm soil depths were the most obvious. The soil was easily recharged by precipitation, and soil evaporation was relatively strong. [Conclusions] The research results are favorable for in-depth understanding of the regional water cycle process, and are expected to provide a certain scientific basis for realizing the efficient and sustainable use of regional groundwater. [ABSTRACT FROM AUTHOR]

Applying physically based models that include preferential flow (PF) is still very challenging at the catchment scale. A gravity‐driven film flow approach could be a promising concept for modeling PF as it only requires a small number of parameters. We tested if this approach can be used for different soils and land covers within a 247 km2 catchment and if we can find generalizable relationships of the film flow parameters to site or rainfall properties. We used a unique data set from a soil moisture sensor network with 135 instrumented soil profiles in three different geologies (slate, marl, and sandstone) and two land covers (forest and grassland) and fitted the film flow model to around 1,700 infiltration events. The results demonstrate that the physical relationship of film flow was capable to predict wetting front velocity (v) and flow parameters from rainfall input (qs) alone. This relationship was pronounced in grassland sites but weaker for forest sites, probably due to heterogeneity of the rainfall input underneath the canopy. Incorporating the water content into the v‐qs relationship did not improve the quality, but showed that for the film flow the rainfall input and hence gravity is in fact the dominant driver and not capillarity. Furthermore, abstraction of water into the soil matrix during film flow is an important process to be included into the framework with reasonable agreements for marl and sandstone using a multiple linear regression. Film flow and corresponding functional parameter relationships for other regions could improve catchment wide PF modeling in the future. Key Points: Gravity‐driven film flow has a large potential to describe preferential flow during natural infiltration events at a diversity of sitesParameters can be determined from the rainfall input, which has a stronger effect on the flow velocity than initial soil water contentAbstraction of water from film flow in macropores into the soil matrix is a process that has to be included in more detail [ABSTRACT FROM AUTHOR]

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The Northeast China Plain (NECP) is one of the main maize (Zea mays L.) production regions in China but is now subject to drought because of climate change and a rain-fed cultivation system. A two-year experiment was conducted in a typical maize cultivation region in the NECP to investigate the responses of plant physiological factors and evapotranspiration (ET) to water stresses at different growth stages. Results show that the responses of plant physiological factors to water stress can be divided into three levels based on soil water content (SWC) in the main root zone: when SWC was greater than 0.22 cm3/cm3 (equivalent to 62% field capacity (FC)), stomatal conductivity (gs) and ET reached their highest values, and the canopy temperature (Tc) was close to the air temperature; when SWC was within 0.15-0.22 cm³/cm³ (43%-62% FC), the gs and ET decreased, and Tc increased as SWC decreased; and when SWC was lower than 0.15 cm³/cm³ (<43% FC), gs and ET reached their lowest values and Tc was greater than 1.2 times the air temperature. The ratio of canopy temperature to air temperature (RT), is closely related to stomatal conductivity and soil water content, and especially linearly related to crop water stress index (CWSI), and can be used as an alternative to CWSI for evaluating maize water stress because of easily data achieving and simple calculation processes. In a conclusion, RT of 1.2 can be used as an index to identify a severe water stress status, and maintaining SWC greater than 60% FC at the heading and grain-filling stages is important for supporting maize normal ET and growth in the study region. [ABSTRACT FROM AUTHOR]

Catchment‐scale response functions, such as transit time distribution (TTD) and evapotranspiration time distribution (ETTD), are considered fundamental descriptors of a catchment's hydrologic and ecohydrologic responses to spatially and temporally varying precipitation inputs. Yet, estimating these functions is challenging, especially in headwater catchments where data collection is complicated by rugged terrain, or in semi‐arid or sub‐humid areas where precipitation is infrequent. Hence, we developed practical approaches for estimating both TTD and ETTD from commonly available tracer flux data in hydrologic inflows and outflows without requiring continuous observations. Using the weighted wavelet spectral analysis method of Kirchner and Neal [2013] for δ18O in precipitation and stream water, we calculated TTDs that contribute to streamflow via spatially and temporally variable flow paths in a sub‐humid mountain headwater catchment in Arizona, United States. Our results indicate that composite TTDs (a combination of Piston Flow and Gamma TTDs) most accurately represented this system for periods up to approximately 1 month, and that a Gamma TTD was most appropriate thereafter during both winter and summer seasons and for the overall time‐weighted TTD; a Gamma TTD type was applicable for all periods during the dry season. The TTD results also suggested that old waters, i.e., beyond the applicable tracer range, represented approximately 3% of subsurface contributions to streamflow. For ETTD and using δ18O as a tracer in precipitation and xylem waters, a Gamma ETTD type best matched the observations for all seasons and for the overall time‐weighted pattern, and stable water isotopes were effective tracers for the majority of vegetation source waters. This study addresses a fundamental question in mountain catchment hydrology; namely, how do the spatially and temporally varying subsurface flow paths that support catchment evapotranspiration and streamflow modulate water quantity and quality over space and time. [ABSTRACT FROM AUTHOR]

Soil water dynamics are central in linking and regulating natural cycles in ecohydrology, however, mathematical representation of soil water processes in models is challenging given the complexity of these interactions. To assess the impacts of soil water simulation approaches on various model outputs, the Soil and Water Assessment Tool was modified to accommodate an alternative soil water percolation method and tested at two geographically and climatically distinct, instrumented watersheds in the United States. Soil water was evaluated at the site scale via measured observations, and hydrologic and biophysical outputs were analysed at the watershed scale. Results demonstrated an improved Kling–Gupta Efficiency of up to 0.3 and a reduction in percent bias from 5 to 25% at the site scale, when soil water percolation was changed from a threshold, bucket‐based approach to an alternative approach based on variable hydraulic conductivity. The primary difference between the approaches was attributed to the ability to simulate soil water content above field capacity for successive days; however, regardless of the approach, a lack of site‐specific characterization of soil properties by the soils database at the site scale was found to severely limit the analysis. Differences in approach led to a regime shift in percolation from a few, high magnitude events to frequent, low magnitude events. At the watershed scale, the variable hydraulic conductivity‐based approach reduced average annual percolation by 20–50 mm, directly impacting the water balance and subsequently biophysical predictions. For instance, annual denitrification increased by 14–24 kg/ha for the new approach. Overall, the study demonstrates the need for continued efforts to enhance soil water model representation for improving biophysical process simulations. [ABSTRACT FROM AUTHOR]

Dryland Sorghum, which is the fifth most important cereal crop in the world, is grown in Zimbabwe typically as a rain-fed crop in areas receiving low, erratic and highly variable rainfall. A two-season field trial was carried out at Save Experiment Station (20°24′S; 28°29′E) in Zimbabwe to establish soil water storage, selected biometric parameters of dryland grain sorghum responses to in-field rainwater harvesting tillage methods. Deep basin tillage method significantly increased the soil moisture content by 14.6% (62.5 mm); 6.2 % (26.5 mm) above that on the ridges and in furrows of open and closed end tied ridges, respectively. Soil moisture storage in deep basins, on ridges and in furrows of open and closed end tied ridges exceeded that in conventional tillage plots by 98.0 mm (29.8%); 35.5 mm (10.8%) and 69.5 mm (21.1%), respectively. Consequently, sorghum plant biometric growth parameters in deep basin tillage treatments were significantly higher than those in conventional, open- and close-ended tied ridges tillage plots. However, the use of conservation tillage methods where tied end ridges are opened introduces homogeneous soil water build-ups in furrows and ridges as those observed in tied end ridges with closed ends. As a consequence, biometric growth parameters of sorghum are not altered by substituting open with closed end tied ridges.

Snowmelt water in spring is an important source of soil water, which is critical to supporting crop growth. Quantifying the contribution of snowmelt water to soil water and its dynamic changes is essential for evaluating soil moisture and allocating agricultural water resources. In this paper, through controlled outdoor experiments, different snow depths and soil depth gradients were set; and snow, precipitation, and soil samples were collected regularly. To analyze the contribution of snowmelt water to soil water and its dynamic changes, the MAT-253 stable isotope ratio mass spectrometer was adopted for hydrogen and oxygen isotope analyses. The results showed that the snowmelt water for snow depths of 10 cm, 30 cm, and 50 cm all contributed to the 0–30 cm soil layer. The contribution increased with soil depth, contributing 8.13%, 8.55%, and 11.24%, respectively. The contribution of the snow cover at the same depth to the soil moisture at different depths also varied, i.e., the contribution increased with increasing soil depth. The snowmelt water retention time at depths of 10 cm, 30 cm, and 50 cm was inconsistent, i.e., it was the longest at 0–10 cm (average of 69 days), followed by 20–30 cm (average of 59 days), and the shortest at 10–20 cm (average of 54 days). The greater the snow depth, the shorter the retention time of the snowmelt water in the different soil layers. For surface soil, the contribution of the snowmelt water at greater depths was significantly different; while for deep soil, the contribution was more sensitive to the snow depth. Regardless of snow depth, soil contributions at different depths were significantly different. Precipitation also affected the contribution of the snowmelt water to the soil water, exhibiting different effects at different depths.

Potato (Solanum tuberosum L.) is a very sensitive crop to water stress and timely irrigation water management improves tuber yield and quality. The objectives of this study were to (1) investigate soil water dynamics under potato crops across their root zone and (2) estimate potato crop evapotranspiration (ETa) under sprinkler irrigation on the sandy loam soil. The field experiment was conducted during the 2018 and 2019 growing seasons at the Navajo Farms within the Navajo Agricultural Products Industry, Farmington, NM. Two irrigation scheduling methods were evaluated as FAO-56 approach evapotranspiration-based scheduling and soil moisture sensing irrigation scheduling. Sentek capacitance soil moisture probe was used across four commercial potato fields in each year after calibration to the soil texture just after installation. Crop Evapotranspiration values estimated by the water balance method and the two-step approach were compared to the satellite-based models used in OpenET. The results showed that the potato’s effective rooting zone is the upper 40 cm soil layer. Potato plants extracted more than 50% of total water from the upper 15 cm of the soil profile and about 85% from the upper 40 cm of the soil profile. Little water amount was extracted from the 40–60 cm soil water. Potato crop seasonal evapotranspiration averaged 580 to 645 mm in 2018 and 2019, respectively. The Two-step approach ETa values of 795.5 and 832.7 mm in 2018 and 2019, respectively, were higher than the soil water balance estimated ETa. The satellite modeled ETa varied with field and years and ranged from 437 to 759 mm and averaged 570.4 mm for the 2016–2020 period. Soil moisture probe-based irrigation scheduling improved irrigation water management and the irrigation water use of potatoes in the semiarid climate.

Soybeans [Glycine max (L.) Merrill] have great economic prominence in the world, and soil management systems can directly interfere with their yield through changes in soil physical-hydric properties. Thus, the aim of this research was to verify the relationship between yield components, physiological traits, root development, and soil physical-hydric properties in soybean yields grown under conventional tillage and no-tillage systems. The experiment was carried out in Botucatu, SP, Brazil, with two treatments: soybeans grown under conventional tillage and no tillage. It is a long-term experiment, conducted since 1986. The main variables that influenced soybean yield were plant height, relative leaf water content, root dry matter, soil penetration resistance, and soil accumulated water infiltration. Physiological components of the plant and soil water showed a significant and negative correlation with soybean yield. On the other hand, the root development and soil physical components were positively correlated with soybean yield. However, the yield components were not significant. The no-tillage system resulted in 7.8% more soybean productivity compared to conventional tillage. Soybean yield depends on the physical properties and the water storage capacity of the soil, as well as on the physiological traits and the root development of the plant.

Soil water and temperature are important factors to reflect variations in soil heat and water flows especially for tillage systems. The objective of this study was to evaluate the performance of the CoupModel in predicting the effect of tillage practices on soil water and heat processes for conventional tillage (CT) and no-tillage (NT) systems with straw mulching on semi-arid and high-latitude Mollisols of northeast China. This model was calibrated and evaluated in a three-year tillage experiment from 2009 to 2011 in a field experiment station, using field measurements of daily soil temperature and water storage in profiles for CT and NT separately. The results showed that under the model, soil temperatures were well simulated at 0–90 cm soil depths for CT, as indicated by R2 ≥ 0.97, the nRMSE = 27.5–38.7% and −1.02 °C ≤ ME ≤ −0.31 °C, and soil water storage at 0–130 cm soil depth (R2 = 0.01–0.06, the nRMSE = 19.6–37.1%, 13.3 mm ≤ ME ≤ 28.2 mm) was simulated with more uncertainty. “Moderate to good agreements” were achieved for NT. In general, the temporal and spatial variations of soil temperature and water for NT were well simulated by CoupModel. Although NT decreased soil evaporation—thus improving soil water content, especially in the root zone soil—and lowered the soil frozen depths, it reduced the soil temperatures, which could influence crop growth. It was concluded that the CoupModel proved to be a functional tool to predict soil heat and water processes for CT and NT systems in high-latitude seasonal frost conditions of Mollisols in China to estimate the soil temperature, water, energy balance, and frost depth dynamics in relatively complex systems that combined plant dynamics with tillage and/or no tillage covered with straw mulching in the soil surface.

Biochar is considered to sequester C and deliver other soil ecosystem services, but an overview that synthesizes the current knowledge of biochar implications on all essential soil ecosystem services is difficult to find in the ample biochar literature. Most previous research and review articles on this topic focused on a single ecosystem service and did not integrate all essential soil ecosystem services. This overview paper (1) synthesizes the impacts of biochar on water and wind erosion, C sequestration, soil water, nutrient leaching, soil fertility, crop yields, and other soil ecosystem services based on published literature and (2) highlights remaining research areas. Literature indicates that, in addition to sequestering C, biochar can reduce N2O emissions, nitrate leaching, and runoff; increase soil microbial biomass, plant available water, and crop yields (particularly in tropical regions), and CO2 emissions; and have small or no effects on water and wind erosion. Biochar benefits can be in this order: C sequestration > N2O emissions > Nitrate leaching > Available water > Soil biology > Soil fertility > Crop yields > Runoff. However, literature also indicates that biochar does not always improve all ecosystem services. Its benefits depend on biochar feedstock, pyrolysis temperature, application rate, biochar properties, soil properties, climate, and other factors. For example, biochar can enhance crop yields more in degraded and low fertility soils than in highly fertile and fine‐textured soils. Long‐term (>3 years) field‐scale studies under different soil types, management conditions, and climates are needed for a determination of optimum levels of application, comprehensive life‐cycle analysis, and assessment of agronomic and environmental tradeoffs. Overall, biochar can improve most soil ecosystem services, but the extent of such improvement is highly dependent on biochar properties and soil and climatic conditions. [ABSTRACT FROM AUTHOR]

The research assessed water storage in a dry dipterocarp forest (DDF) with enriched 34-year-old pine planting and the role of pine. Plant surveys were carried out using 10, 40×40 m2 plots, and data were obtained by measuring tree stem girths and heights. Plant features, biomass, and stored water amounts were measured. Fresh plant samples of abundant species were taken one time per month from January to December 2018. Three soil pits were made in three plots, and soil samples along 100 cm depth were taken on the same days of collecting plant samples for studying fied capacity, water content and water amount. The DDF was divided into three stands based on the most dominant tree species; Shorea obtusa, Dipterocarpus tuberculatus, and Dipterocarpus obtusifolius. The forest was composed of 86 species with biomass at 101.62 Mg/ha and contained an average water amount of 88.01 m³/ha. The water amount in biomass varied with sampling times from 58.74 to 111.83 m³/ha. The average MWHC of 100 cm soil was estimated to be 5,113.74 m³/ha. The water amount in soil also varied with sampling times from 3,651.50 to 4,481.06 m³/ha. As a result, the total water amount in plant biomass and soil (ecosystem) of the DDF varied in a range from 3,735.0 to 4,558.67 m³/ha. The pine contributed to 30.87 m³/ha (35.07% of the total) and could increase by 64.92% the water storage potential of the forest, and thus these results support the concept of pine enrichment planting in the poor DDF. [ABSTRACT FROM AUTHOR]

Developing improved water management strategies and on-farm cultural practices are important in reducing pomegranate (Punica granatum L. cv Wonderful) production costs. A pomegranate orchard established in 2010 was irrigated at water replacement rates of 35, 50 and 100% of crop evapotranspiration from 2013 to 2016. A durable white plastic tarp was installed in one half of each water replacement plot to evaluate the added benefits to soil moisture retention, weed control, and plant growth and yield. Edaphic orchard floor conditions such as light reflectance into the lower tree canopy, mid-day soil surface temperature, soil water content, and average daily soil temperatures were moderated or improved by the plastic cover. Phenological changes such as leaf greenness, trunk basal suckering, and trunk diameter were generally enhanced by increased water application rates and plastic use. Marketable and total fruit yields increased by an average of 20 to 29% from 2013 to 2016 with the use of plastic cover compared to bare soil. Total fruit yield increased linearly with increasing water replacement rates. Neither the white plastic nor irrigation rates improved external fruit color. Fruit raw product attributes were little changed by treatments. The research clearly demonstrated the benefit of plastic cover on improving pomegranate production. [ABSTRACT FROM AUTHOR]

Language simplification in scientific works that use electromagnetic induction (EMI) will promote this technique in soil and water-related research and applications. One way of fostering easy understanding and communication of ideas is by omitting the usage of the term "apparent electrical conductivity" (ECa) when dealing with EMI techniques. Herein we justify that the use of ECa terminology in many EMI sensor applications is unnecessary and can create confusion due to issues on units and dimensions of ECa. While the concept of a relative electrical conductivity within a soil system may have merit, it is our opinion that the use of the term ECa is not of primary importance in many applications of EMI to the pedosphere and hydrosphere, thus, omission of the term is warranted. [ABSTRACT FROM AUTHOR]

Soil moisture is an essential variable for both the agricultural production and the functioning of natural ecosystems, as well as one of the main variables regulating the climate system. Like precipitation, soil moisture has a marked annual cycle that depends mainly on the behaviour of precipitation and evapotranspiration. In this study, we developed a methodology that allows describing and characterizing the annual cycle of soil moisture in Argentina. For this purpose, we estimated soil moisture at 121 sites of Argentina by means of a simple hydrological balance (the BHOA, an acronym for its name in Spanish: "Balance Hidrológico Operativo para el Agro") and analysed its intra‐annual variability by means of different indices. This methodology allowed recognizing five different annual behaviours, with a consistent geographical pattern throughout Argentina. The characterization was based mainly on the time of occurrence of the annual maximum and minimum values of soil moisture, and secondly by the annual soil moisture content and seasonality. The northwest and part of the centre of Argentina present the minimum soil moisture values in spring and the maximum ones in autumn, while the east and south present the minimum values in summer and the maximum ones in winter. In general, sites with higher soil water content were found to have lower seasonality and vice‐versa. [ABSTRACT FROM AUTHOR]

Black pod disease of cacao caused by Phytophthora palmivora and Phytophthora megakarya in Ghana take heavy toll of cacao production in the field. Intensive research has been carried out worldwide on these pathogens. However, viability of the cultures during prolonged storage has remained a major challenge in the research. This paper reports findings of assessment of six storage media viz sterilised distilled water (SDW), sterilised and unsterilized soil suspension (SSS and USS), vegetable 8 juice broth (V8JB), Oat Meal Agar slant under mineral oil (at 4°C) and empty tube. Viability of the cultures was assessed on V8JA and in tetrazolium chloride test. Ability of zoospores of the cultures to infect cacao leaf discs was used to assess growth vigour and pathogenicity. Phytophthora cultures stored in SDW (26 ± 2°C; alternating day light and night) were preserved for 60 days (5 years). Both P. palmivora and P. megakarya performed better on SDW and SSS than on USS due to removal of staling substances in the soil medium by the sterilisation. Vigour of growth and pathogenicity of the stored cultures required re-inoculation of host tissue (cacao pod) in order to maintain potency to continually infect host. [ABSTRACT FROM AUTHOR]

To explore the impact of land- use change on the long- term soil water balance in Northern China's Loess Plateau, we used the H ydrus-1 D model to simulate the soil water dynamics at depths of 0--4 m under the scenario of arable land-alfalfa land-natural grassland located in the Liudaogou watershed. The evolution characteristics of hydro logical variables including soil water storage, deep seepage and evapotranspiration were quantified from 1981 to 2050. The results showed that soil water fluctuated with rainfall levels during arable land periods, with 88% of the annual precipitation consumed through evapotranspiration, and 11 % was lost to deep seepage. The first stage of soil water change during the alfalfa land period was 1--6 years after plantation, during this period, evapotranspiration accoun ted for 108 % of the annual rainfall, leaving the soil water in a negative balance. And the soil water storage of 0--4 m decreased at a rate of 52 mm/a. The second stage was 7- 13 years after plantation, almost all rainfall was consumed by evapotranspiration. Eight years after alfalfa land transitioned into natural grassland, annual evapotranspiration de creased by 31 %, and soil water storage gradually recharged at 45 mm/ a. Subsequently, 92% of the annual rainfall was used for evapotranspiration, with the remaining 8% was lost to deep seepage. The soil water remained in a rela tively stable state. These indicated that the soil water balance modes varied under different vegetation types. Planting vegetation with high-water-consumption could cause negative balance of soil water and led to serious soil desiccation, which then had a negative effect on soil water supply. However, the formed dry soil layer could be completely re stored by changing the vegetation type. [ABSTRACT FROM AUTHOR]