Surface Soil Profile Research Articles

Machine learning-assisted risk evaluation of heavy metals in the Hainan gold mining region, China.

This study employed machine learning (ML) to thoroughly investigate the impact of informal mining activities on the distribution and pollution status of heavy metals in soils near private gold mines in Hainan Province, southern China, a region known for its ecological sensitivity and economic importance. By systematically collecting surface soil samples and samples at depths of 0.5-1m from 175 drilling sites, a comprehensive quantitative analysis was conducted on major heavy metal elements, including lead (Pb), copper (Cu), cadmium (Cd), nickel (Ni), mercury (Hg), chromium (Cr), arsenic (As), and zinc (Zn). Combined with evaluation methods such as the Pollution Load Index (PLI), Normalized Pollution Index (NIPI), and Ecological Risk Index (ERI), the study revealed a high level of soil pollution at informal mining sites. The findings indicated that the average concentrations of Pb, Cd, Hg, As, and Zn in surface soils significantly exceeded the background values for soils in China, with a pronounced positive correlation observed between these heavy metal elements in both surface and deep soil profiles (r > 0.5). Furthermore, leveraging the heavy metal content in surface soils and the constructed environmental indicators, the predictive accuracy for metal content in deep soils was found to range from R2 = 0.27 to 0.68, suggesting that informal mining activities have led to substantial variations in metal content across different soil profiles. Through the application of a random forest model for predictive analysis of the PLI, NIPI, and ERI, high prediction accuracy was achieved (R2 = 0.78, 0.86, and 0.60, respectively). The study demonstrates that informal mining activities not only elevate the risk of soil pollution but also alter the distribution patterns of heavy metals. Also, this study provides a crucial foundation for the scientific assessment of soil quality and potential environmental hazards, while also affirming the efficacy of ML techniques in forecasting soil quality parameters.

Оценка пространственно-временных изменений показателей радиоэкологического состояния почв зоны наблюдения Ростовской АЭС

The paper presents the results of a study of long-term (from 2003 to 2021) measurements of the specific activity of natural (226Ra, 232Th, 40K) radionuclides and artificial 137Cs in surface soil samples and soil profiles, including the dependence of the specific activity of radionuclides on some soil properties (content organic matter, pH level) in the observation zone of the Rostov NPP. In accordance with the requirements of radioecological monitoring, the study of the state of terrestrial ecosystems was carried out considering landscape-geochemical and climatic conditions in control plots with Haplic Kastanozems, Gleyic Kastanozems, Endosalic Kastanozems and Umbric Fluvisols soils laid out in the study region in 1999–2000 as part of pre-start monitoring of the Rostov NPP. It has been shown that there is a decrease in the specific activity of 226Ra in all studied soil types. A regular redistribution along the profile of artificial 137Cs in the Gleyic Kastanozems soil was revealed. There is no redistribution of natural radionuclides (226Ra, 232Th, 40K) in soil profiles over time. The minimum specific activity of radionuclides is recorded in Umbric Fluvisols soil located in the floodplain of the Don River. A linear dependence of the specific activity of 137Cs on pH and humus was established (r=0.62 and 0.88, respectively). Keywords: RADIOECOLOGICAL MONITORING, ROSTOV NPP, NATURAL AND ARTIFICIAL RADIONUCLIDES, ORGANIC MATTER, pH

Tolerance to waterlogging determines the effectiveness of biodrainage in mitigating runoff in hillslope-scale simulations

Reversal of land degradation in agricultural systems through a wide range of natural resources management tailored to the specific climate, soil, and topography is crucial. This is especially critical for subsistence farming systems such as the Ethiopian Highlands, subject to some of the highest soil erosion rates in the world. Although biodrainage is widely and successfully used for waterlogging and erosion control in arid regions, it is not widely applied in sub-humid places like the Ethiopian Highlands. Beginning with field observations of the complex vertical soil profiles and variations in lithology and soil hydraulic properties along a hillslope ridge-channel transect in the Debre Mawi watershed of the Abay (Upper Blue Nile) Basin in the Ethiopian Highlands, we construct a synthetic model hillslope in HYRDUS-2D. For the growing season coinciding with the rainy season, known as Kiremt, we calibrated the hillslope water storage using observations of water table elevation. The synthetic hillslope is then used to test the feasibility of biodrainage to mitigate saturation, a major driver of gullying and soil loss in the area, and to identify plant traits to which such mitigation is sensitive. The simulation results using bare soil, eucalyptus and maize land covers revealed that in spite of low potential evapotranspiration during the Kiremt season, biodrainage with Eucalyptus can reduce the occurrence and duration of saturation of the top 0.6 m surface soil profile of the hillslope. Of the different plant traits explored, the maximum soil water potential at which the crop can transpire at potential rates, and the LAI, which controls potential evaporation rates via the crop coefficient, provide the most important controls on the effectiveness of biodrainage in desaturating the hillslope. We conclude that biodrainage strategies to mitigate soil erosion in sub humid locales merits further investigation through empirical trials. However, implementation of biodrainage strategies should be subject to thoughtful consideration of the implications for socio-economic outcomes and the local environment.

Evaluation of soil quality and land suitability in different management systems

ABSTRACT This study aimed to evaluate the effect of management systems on soil quality in rangeland and agricultural lands (smallholder, total owner, and Binaloud Company) in Neyshabur plain, northeastern Iran. Twenty-one soil profiles were described and sampled. The weighted and additive soil quality indices (SQI) of surface soil and soil profile (0–100 cm) were calculated. The minimum data set (MDS) was determined using principal component analysis (PCA) and expert opinion (EO) methods. The land index (LI) for alfalfa was calculated using the FAO method. In all management systems, the EO-weighted SQI was the highest for surface soil and soil profile. The relationship between the EO-weighted SQI and alfalfa yield was the strongest in the total owner and Binaloud Company. The LI showed a better relationship with the alfalfa yield than the SQI. The SQI of soil profile provides more comprehensive information regarding the different soil management systems. The LI, which considers crop requirements, could be useful in comparing the soil quality for a specific plant. The lower soil quality in smallholder system is an early warning sign of soil degradation in the area. Furthermore, the SQI has sufficient capability to reveal the effects of the land exploitation systems on soil quality.

Effect of grass cover and abandonment on soil surface changes and soil properties in traditional vineyards in Vráble viticultural region in southwestern Slovakia

Land use transition, related to the extensification of management and agricultural abandonment, is a widespread phenomenon across European landscapes. In this study, we examined the effects of protective grassing and abandonment on soil protection and regeneration in traditional vineyards of the Vráble viticultural region, located in the temperate climate zone of central Europe. We analysed changes in the soil surface level, soil profile, and soil properties at various slope positions: shoulder, backslope, and footslope. Variability in the soil surface level was assessed using the poles height method, which was developed to quantify soil erosion and deposition. The results showed that both measures positively affected soil development. In the abandoned vineyard, the soil surface level increased by 0.72 mm yr−1 on the slope shoulder, 0.26 mm yr−1 on the backslope, and 3.58 mm yr−1 on the footslope. In contrast, the cultivated vineyard exhibited minimal changes in the slope shoulder (0.02 mm yr−1), erosion on the backslope (4.52 mm yr−1), and deposition on the footslope (19.30 mm yr−1). The vineyard that was hoed for half of the analysed period and then grassed showed erosion rates of 0.25 mm yr−1 on the shoulder, 1.48 mm yr−1 on the backslope, and deposition of 3.42 mm yr−1 on the footslope. All slope profiles showed evidence of erosion-accumulation processes resulting from past management practices without protective vegetation cover; however, the development of a new humic layer was observed in grassed and abandoned vineyard. Grass cover and abandonment positively influenced soil organic carbon (SOC) content, bulk density, and porosity.

GDGT distribution in tropical soils and its potential as a terrestrial paleothermometer revealed by Bayesian deep-learning models

Branched and isoprenoidal glycerol dialkyl glycerol tetraethers (br- and isoGDGTs) are membrane lipids produced by bacteria and archaea, respectively. These lipids form the basis of several frequently used paleoclimatic proxies. For example, the degree of methylation of brGDGTs (MBT’5Me) preserved in mineral soils (as well as peats and lakes) is one of the most important terrestrial paleothermometers, but features substantial variability that is so far insufficiently constrained. The distribution of isoGDGTs in mineral soils has received less attention and applications have focused on the use of the relative abundance of the isoGDGT crenarchaeol versus brGDGTs (BIT index) as an indicator of aridity. To expand our knowledge of the factors that can impact the br- and isoGDGT distribution in mineral soils, including the MBT’5Me index, and to improve isoGDGT-based precipitation reconstructions, we surveyed the GDGT distribution in a large collection of mineral surface soils (n = 229) and soil profiles (n = 22) across tropical South America. We find that the MBT’5Me index is significantly higher in grassland compared to forest soils, even among sites with the same mean annual air temperature. This is likely a result of a lack of shading in grasslands, leading to warmer soils. We also find a relationship between MBT’5Me and soil pH in tropical soils. Together with existing data from arid areas in mid-latitudes, we confirm the relationship between the BIT-index and aridity, but also find that the isoGDGT distribution alone is aridity dependent. The combined use of the BIT-index and isoGDGTs can strengthen reconstructions of past precipitation in terrestrial archives. In terms of site-specific variations, we find that the variability in BIT and MBT’5Me is larger at sites that show on average lower BIT and MBT’5Me values. In combination with modelling results, we suggest that this pattern arises from the mathematical formulation of these proxies that amplifies variability for intermediate values and mutes it for values close to saturation (value of 1). Soil profiles show relatively little variation with depth for the brGDGT indices. On the other hand, the isoGDGT distribution changes significantly with depth as does the relative abundance of br- versus isoGDGTs. This pattern is especially pronounced for the isoGDGTIsomerIndex where deeper soil horizons show a near absence of isoGDGT isomers. This might be driven by archaeal community changes in different soil horizons, potentially driven by the difference between aerobic and anaerobic archaeal communities. Finally, we use our extensive new dataset and Bayesian neural networks (BNNs) to establish new brGDGT-based temperature models. We provide a tropical soil calibration that removes the pH dependence of tropical soils (n = 404; RMSE = 2.0 °C) and global peat and soil models calibrated against the temperature of the months above freezing (n = 1740; RMSE = 2.4) and mean annual air temperature (n = 1740; RMSE = 3.6). All models correct for the bias found in arid samples. We also successfully test the new calibrations on Chinese loess records and tropical river sediments. Overall, the new calibrations provide improved temperature reconstructions for terrestrial archives.

Experimental and numerical analysis of the lateral response of full-scale bridge piers

This paper presents the results of in-situ testing of two integrated pile-columns of a partially demolished bridge located in Auckland, New Zealand. A series of tests involving lateral monotonic pushover and subsequent dynamic free vibration snapback tests were used to quantify the variation in the stiffness and damping behaviour of the pile-column specimens over a range of lateral load levels. Each testing sequence consisted of incrementally increasing peak monotonic loads followed by the dynamic snapback, with a series of varying peak loads at the end of the testing sequence to evaluate the influence of loading history on the monotonic and dynamic response. The secant stiffness between the monotonic pushover tests performed to the same loading levels before and after the maximum load was applied, reduced by up to 40% in both the pile-columns, primarily due to soil gapping effects, highlighting the significant potential softening of the system prior to pile or column yielding. Progressive reduction in the damping of the system during each snapback test was evident, due to the varying contributions of different energy dissipation mechanisms, and the level of damping varied depending on the peak load applied. These results highlighted the significant influence of soil gapping and nonlinearity on the dynamic response of the system. Numerical models were developed in the open source structural analysis software OpenSeesPy using a Nonlinear Beam on Winkler Foundation approach to further investigate the response of the pile-columns. Models of both the pile-columns using existing p-y curves for clay soils showed good agreement with the experimental data in load-displacement, period and snapback acceleration time histories. Sensitivity analysis showed that the surface soft clay layer had a significant effect on the lateral response and dynamic characteristics of the model, reinforcing the need for good characterisation of the near surface soil profile to capture the behaviour of the system.

Heavy Metal Concentrations of Soil, Rock, and Coal Gangue in the Geological Profile of a Large Open-Pit Coal Mine in China

Risk assessment related to heavy metals in mining areas is crucial to ensuring the sustainable development of regional ecosystems and protecting human health. However, almost all research on the impact of mining activities on environmental quality entails field monitoring of surface soils or soil profiles. Here, to compare the variety of heavy metal concentrations in the geological profile, 39 samples (including soil, rock, and coal gangue) were collected and analyzed from hundreds of meters underground in the Pingshuo coal mine (Anjialing coal mine, Antaibao coal mine, and Donglutian coal mine), which is the largest open-pit coal mine in China. The mean heavy metal concentrations of Cd, Hg, As, Pb, Cr, Cu, Zn, and Ni in soils were 0.15 mg/kg, 0.02 mg/kg, 13.70 mg/kg, 27.12 mg/kg, 70.89 mg/kg, 26.10 mg/kg, 79.88 mg/kg, and 37.68 mg/kg, respectively; most of these metals were more concentrated in the soil samples than in the rock and coal gangue samples. A potential ecological risk assessment indicated that As, Pb, Cr, Cu, Zn, and Ni in all samples showed low risk, while the ecological risk degrees of Cd and Hg were higher and contributed most to the total risk index (RI). The highest E_r^i value (92.94) for Cd was found in rock samples, contributing to approximately 55.18% of the to tal RI. For Hg, four rock sampling sites had the highest E_r^i values (427.70, 270.78, 198.96, and 188.70), contributing approximately 68.36–88.07% of the total RI. Ranked after soil (0.15 mg/kg), limestone and shale showed high mean Cd concentrations (both 0.13 mg/kg). The highest mean concentration was found in coal gangue samples (0.1 mg/kg). Compared with the other types of samples, the mean concentrations of Cr, Cu, and Ni in soils, limestone, and mudstone were relatively higher. At different sites, heavy metal concentrations varied greatly at different depths, owing to diverse sample types and rock types. Correlations between heavy metals and soil nutrients indicated that N and P were closely correlated with heavy metals. Comparing the proportions of different heavy metals in various types of samples showed that heavy metals in soils were extremely similar to those in limestone, mudstone, and shale, implying that soils might indirectly inherit their features from their parent material.

Spatial Analysis of Soil Trace Element Contaminants in Urban Public Open Space, Perth, Western Australia

Public recreation areas in cities may be constructed on land which has been contaminated by various processes over the history of urbanisation. Charles Veryard and Smith’s Lake Reserves are adjacent parklands in Perth, Western Australia with a history of horticulture, waste disposal and other potential sources of contamination. Surface soil and soil profiles in the Reserves were sampled systematically and analysed for multiple major and trace elements. Spatial analysis was performed using interpolation and Local Moran’s I to define geochemical zones which were confirmed by means comparison and principal components analyses. The degree of contamination of surface soil in the Reserves with As, Cr, Cu, Ni, Pb, and Zn was low. Greater concentrations of As, Cu, Pb, and Zn were present at depth in some soil profiles, probably related to historical waste disposal in the Reserves. The results show distinct advantages to using spatial statistics at the site investigation scale, and for measuring multiple elements not just potential contaminants.

Evaluating quality of soils formed on basement complex rocks in Kaduna State, northern Guinea savanna of Nigeria.

A few investigations have been done regarding the soil quality index (SQI) for various locations, soil types, and states. Still, little has been reported regarding SQI for both surface and control sections, especially for the Northern Guinea Savanna of Nigeria. Due to the subsurface property pedogenic influence on soil function, it is crucial to assess SQI using surface and subsurface properties as both properties influence soil productivity. We investigated the potentials of choosing a minimum data set for soil quality indicators and assess soil quality (SQ), using both surface and entire soil pedon data for the soils on the basement complexes. Both additive and weighted soil quality indices and different scoring methods (linear and non-linear) were used in evaluating SQ. Out of the twenty-three soil properties subjected to PCA, eight indicators (TEB, clay, silt, K, EA, EC, BD, and Fe) were selected as the minimum data set (MDS). There was not much difference in the calculated soil quality using the non-linear additive (SQI-NLA), linear additive (SQI-LA), linear weighted (SQI-LW), and non-linear weighted (SQI-NLW) for the soils as they were all rated low (SQI < 0.55). The estimated SQI for the control section had relatively higher values than the surface soil, thus suggesting the need to incorporate both surface and entire soil profile properties in assessing SQ as both are important in integrating the relationship between soil properties and management goals which eventually provides complete information that affects the production of crops.

Anthropogenic erosion-induced small-scale soil heterogeneity in South African rangelands

Land-use-induced soil erosion in semi-arid drylands induced by land-use changes creates patchworks of soils and vegetation different from those of natural conditions. Knowledge of the highly dynamic spatial heterogeneity in soil properties, not depicted in conventional soil maps, is important for managing land uses sustainably, and for understanding soil-climate interactions. This analysis of soil redistribution in a degraded rangeland in South Africa assessed the significance of anthropogenic soil heterogeneity within a small catchment with a silted reservoir. This study carries out analysis of soil redistribution in a degraded rangeland in South Africa, to assess the significance of anthropogenic soil heterogeneity within a small catchment with a silted-up reservoir. Surface soil (N = 51) and soil profile (N = 29) samples were collected from areas of various degrees of degradation and analysed for texture, pH, total nitrogen (TN), total organic carbon (TOC), available phosphorus (P), and potassium (K). Diverse vegetation cover is reflected in a high soil heterogeneity, showing differences in soil texture. Average surface soil nutrient content was significantly higher in vegetated areas (grassland: TOC 1.08 %, TN 0.10 %, P 20.12 mg kg −1 , mixed vegetation: TOC 0.93 %, TN 0.08 %, P 13.54 mg kg −1 , depositional: TOC 1.68 %, TN 0.18 %, P 34.67 mg kg −1 ) than at degraded sites (TOC 0.47 %, TN 0.06 %, P 7.52 mg kg −1 ). K content was low to moderate but did not show any significant difference between landscape units. Potential exists for the formation of distinct young anthropogenic soils on the silted-up reservoir where deposited sediments differed in TOC, TN, P, and profile depth from the shallow natural soils. Consequently, azonal soils on dam-deposits are different from those occurring naturally, and not depicted on conventional soil maps. Their different water and nutrient cycling may affect vegetation and biogeochemical fluxes. Land-use management should consider such soils, as they play an important role in rangeland ecology.

Characteristics of Atmospheric Dustfall and Soil Magnetic Susceptibility and Environmental Significance in Xining City

Magnetic susceptibility is an important means to quickly and economically monitor the enrichment of surrounding environmental elements. As a regional central city on the Qinghai-Tibet Plateau, the relationship between atmospheric dust magnetic susceptibility and heavy metal content in Xining area is relatively lacking. In this paper, the magnetic susceptibility and geochemical element content of the collected dust samples, loess samples, surface soil samples and soil profile samples obtained through long-term observations are analyzed. The results show that the magnetic susceptibility of the dust-fall samples is the highest, the soil samples are the second, and the loess samples are the lowest; the magnetic susceptibility of the dust-fall samples in Xining City has a significant correlation with the elements Cd, Cr, Ni, Cu, Pb, Zn and Hg, and the magnetic susceptibility can be used as an indicator of heavy metal in the soil; the elements Cr, Ni, Cu, Zn and As in the soil profile are enriched at 20 cm or 30 cm, which is related to the leaching of surface elements.

No-till and carbon stocks: Is deep soil sampling necessary? Insights from long-term experiments

Confusion persists regarding the potential for no-till (NT) farming to accumulate soil organic C (SOC) and mitigate climate change. This uncertainty could be partly due to shallow sampling (<40 cm soil depth) employed in most previous SOC publications. The specific objective of this study was to gain additional knowledge of SOC accumulated by a wide range of tillage systems in surface and deeper soil profiles in the long term (> 34 yr). We quantified SOC stock (Mg ha−1) on an equivalent mass basis for the 0–60 or 100 cm soil depths for NT, disk, double disk, chisel plow, and moldboard plow under continuous corn and corn-soybean on silt clay loams after 34 yr and 39 yr in the western US Corn Belt. Results showed that NT did not increase SOC stocks near the surface but it did with cumulative depth relative to moldboard plow. No-till accumulated SOC at a rate of 0.68 Mg ha−1 yr-1 relative to inversion tillage (moldboard plow). However, NT did not store more SOC than common conventional (chisel plow) or reduced (disk) till practices for the whole soil profile. Results indicate that depth of soil sampling can affect conclusions about tillage system impacts on SOC stocks. For example, if we had sampled to 20 cm soil depth only, we would have incompletely concluded that NT does not significantly accumulate more SOC than moldboard plow. Results after 34 and 39 yr of tillage management also indicate that non-inversion tillage, particularly disk, can be as effective as NT for accumulating SOC. Overall, deep soil sampling can tell a different story about NT impacts on SOC stocks from shallow sampling.

POTENTIAL MOBILITY AND TOXICITY RISK OF METAL POLLUTANTS IN SOILS FROM A TROPICAL AREA AFFECTED BY INDUSTRIAL WASTES

The potential mobility of Cd, Cr, Cu, Ni, Pb and Zn in soils severely impacted by inadequate storage of industrial wastes in Rio de Janeiro State (Brazil) was evaluated by applying the Toxicity Characteristic Leaching Procedure (TCLP). This procedure allowed the estimation of toxicity risks for Cd, Cr and Pb. In a contamination hotspot within the study area, the following order of metal concentrations was observed: Pb > Zn > Cu > Ni > Cd > Cr, with significantly higher values than observed for a control site. Decades of soil exposure to wastes implied TCLP results for Pb above 300 mg/L in this hotspot, which exceed the TCLP regulatory threshold in two orders of magnitude, while Cd (up to 0.8 mg/L) and Cr (up to 0.3 mg/L) results were below the respective TCLP thresholds. Surface soil profile analysis (0-30 cm depth) indicates that Pb vertical migration occurs in the hotspot. TCLP concentrations of Pb were up to four orders of magnitude higher than the groundwater quality threshold preconized by Brazilian regulations for this metal (0.01 mg/L), suggesting that downward dispersion of large loadings of anthropogenic Pb is a major concern.

Dynamic variations in soil moisture in an epikarst fissure in the karst rocky desertification area

Epikarst fissures filled with soil (EFS) are important factors controlling karst hydrological processes and ecological hydrological functions. The EFS are common in karst rocky desertification areas, and it is important to understand the hydraulic properties and hydrological characteristics of EFS for vegetation restoration. In this study, we analysed the soil moisture content dynamics of surface soil and EFS in a rocky desertification environment to explore the influencing factors of soil moisture variation. A typical epikarst fissure was selected as the sample site in the rocky desertification area of the Karst Plateau Gorge (Beipanjiang catchment, Guizhou Province) in Southwest China, and surface soil was used as the control site. From May 12, 2018 to January 10, 2020, soil moisture content data for the EFS profile (20, 80, 140, 200, and 260 cm) and the surface soil profile (20 and 40 cm) were monitored synchronously at 30-min intervals. Simultaneously, soil samples were collected to measure the physical properties. The results show that the difference in vegetation cover and soil physical properties is the main reason for the difference in soil water dynamics between the shallow EFS and surface soil. The shallow EFS hydraulic connectivity is better, and the mean values of total porosity and saturated hydraulic conductivity of shallow EFS are 15.6% and 69.5% higher than those of the surface soil, respectively. The seasonal variations in soil moisture in the shallow EFS are obvious, the soil moisture rainfall response and dry-wet alternation are fast, the seasonal variations in soil moisture in the surface soil are relatively stable, and the soil water retention time is long. In the EFS profile, the hydraulic connectivity of the shallow soil (0–40 cm) are obviously better than those in the middle and lower layers (40–280 cm), which affected the response speed and retention time of soil water at different depths. In conclusion, the vertical hydraulic connectivity of the EFS profile is quite different and is shown to be significantly different from the surface soil hydrology. These results are helpful for understanding the ecohydrological process of epikarst.

Study on Erosion Status of Typical Small Watershed in Yanghe River Basin

A typical small-scale watershed in the Yanghe River Basin is selected as the research area, and the regional digital elevation model map (DEM) is studied by using the aerial photography of the drone. Based on the arcgis10.4 platform, the SWAT model was used to extract the water system and determine the boundary of the study area. The meteorological data of the SWAT model comes from the automatic weather station at the study area center. The physicochemical properties of soil surface samples and soil profiles were determined in the study area in July each year. The results were used as parameters of the SWAT soil model, and determine other parameters of the SWAT model by Sensitivity analysis. The soil erosion status of the study area was obtained, and the soil erosion in the study area was studied. It is more serious and the erosion channel has a tendency to expand further. According to the erosion status and development trend simulated by the SWAT model, it provides reference for soil and water conservation control measures.

Pre-Sowing Irrigation Plus Surface Fertilization Improves Morpho-Physiological Traits and Sustaining Water-Nitrogen Productivity of Cotton

The changing climatic conditions are causing erratic rains and frequent episodes of moisture stress; these impose a great challenge to cotton productivity by negatively affecting plant physiological, biochemical and molecular processes. This situation requires an efficient management of water-nutrient to achieve optimal crop production. Wise use of water-nutrient in cotton production and improved water use-efficiency may help to produce more crop per drop. We hypothesized that the application of nitrogen into deep soil layers can improve water-nitrogen productivity by promoting root growth and functional attributes of cotton crop. To test this hypothesis, a two-year pot experiment under field conditions was conducted to explore the effects of two irrigation levels (i.e., pre-sowing irrigation (W80) and no pre-sowing irrigation (W0)) combined with different fertilization methods (i.e., surface application (F10) and deep application (F30)) on soil water content, soil available nitrogen, roots morpho-physiological attributes, dry mass and water-nitrogen productivity of cotton. W80 treatment increased root length by 3.1%–17.5% in the 0–40 cm soil layer compared with W0. W80 had 11.3%–52.9% higher root nitrate reductase activity in the 10–30 cm soil layer and 18.8%–67.9% in the 60–80 cm soil layer compared with W0. The W80F10 resulted in 4.3%–44.1% greater root nitrate reductase activity compared with other treatments in the 0–30 cm soil layer at 54–84 days after emergence. Water-nitrogen productivity was positively associated with dry mass, water consumption, root length and root nitrate reductase activity. Our data highlighted that pre-sowing irrigation coupled with basal surface fertilization is a promising option in terms of improved cotton root growth. Functioning in the surface soil profile led to a higher reproductive organ biomass production and water-nitrogen productivity.

Spring safflower water use patterns in response to preseason and in-season irrigation applications

The deep root system of safflower (Carthamus tinctorius L.) is an important adaptive trait under rainfed conditions in semi-arid agriculture. Lower water requirements and ability to tolerate abiotic stresses make safflower a potential alternative crop for the Southern High Plains (SHP). However, information on water extraction patterns of safflower and its role in oil yield formation under center pivot irrigation system that keeps only the surface soil profile wet with frequent irrigations is limited. Therefore, a field experiment was conducted in a split-plot design at Clovis, New Mexico during 2012 and 2013 growing seasons to assess the soil water use patterns, evapotranspiration, and oil yield of two spring safflower cultivars under different preseason and in-season irrigation levels. Half of the experimental units received 164 and 153 mm of preseason irrigation in 2012 and 2013, respectively, while the other half remained unirrigated. Five in-season irrigation levels (I1–I5) ranging from 88 to 392 mm in 2012 and from 83 to 373 mm in 2013 were applied to preseason and no-preseason irrigation blocks. On average, safflower extracted 70 and 28 mm of stored soil moisture in the preseason and no-preseason irrigation treatments, which significantly increased evapotranspiration (ET), water use efficiency (WUE), and oil yield in preseason compared to no-preseason irrigation treatment. Average water extraction decreased with increasing level of in-season irrigation and a decline of 32, 27, and 25% in soil moisture at the end of the season compared to initial soil moisture were observed in I1, I3, and I5, respectively. Since, WUE was not much affected by in-season irrigation treatment in both years, limiting the in-season irrigation level to I4 can save 17% of irrigation with a corresponding 9% reduction in oil yield. The relatively smaller differences were observed for water extraction and WUE among the cultivars. Overall, safflower was able to use preseason irrigation water more efficiently in semi-arid SHP. Growers can pre-irrigate safflower and reduce its in-season irrigation to allocate more water to high water requirement traditional-crops such as corn.

Reclamation of Coastal Saline Wasteland Using Drip Irrigation and Embedded Subsurface Pipes

A 3‐yr field experiment investigated the impact of drip irrigation and embedded subsurface drain pipes on salt leaching and Chinese rose (Rosa chinensis Jacq.) growth in a severely degraded saline soil located in north China. The experiment consisted of five soil matric potential (SMP) treatments where the soil matric potential at 0.2 m below the emitter was −5, −10, −15, −20 and −25 kPa in 2014 and 2015 and then decreased to −15, −20, −25, −30 and −35 kPa in 2016. With time, the size of the low salinity zone increased and the soil extract electrical conductivity (ECe) in surface 40 cm decreased from 27.32 to &lt;1.5 dS m−1. Soil water content increased with increasing SMP threshold values in the surface soil profile, but there were no significant differences among treatments in the deep layer. Soil pH values increased and then decreased for all treatments and obvious alkalization occurred, especially in the root zone. High survival rates of Chinese rose with values &gt;96% were obtained in 2014 for all treatments and these decreased with time, especially in the lower SMP treatments in 2016. An SMP higher than −5 kPa in the first year, −10 kPa in the second year and −20 kPa in the third year, combined with an irrigation water event of 10 mm, can be used for rose drip‐irrigation scheduling, which can maintain survival rates of &gt;85% on reclamation of coastal saline sandy loam soil with embedded subsurface pipes.Core Ideas Chinese roses were grown on coastal saline soils under drip irrigation and embedded subsurface pipe. Five soil matric potential thresholds were set for drip irrigation. The drip irrigation scheduling for rose grown in coastal saline soils was determined.

Determining the depth of mixing layer in which soil solute releasing from soil to surface runoff on the unsaturated loess slope under artificial rainfall condition

The mixing zone depth is a critical parameter in many popular agricultural non-point source pollution (NPS) models. Its variation for some special soil conditions and easily erosive region was limitedly studied. This study dealt with the extent of Br− releasing from soil to surface runoff, the actual mixing depth and the calculated one on the unsaturated loess slope, and the influences of soil initial moistures. Br− was placed as a tracer at different soil depths in the loess slope with three soil initial moistures. Br− concentration in surface runoff and soil profiles was monitored under simulated rainfall condition. The actual mixing layer depth was determined by whether Br− in that layer could be detected in surface runoff during the whole rainfall process. The average effective depth of interaction (EDI) was calculated by the confirmation method reported before. The shallower the application depth, the higher the Br− concentration and loss risk in surface runoff. The net loss rate had an exponential decreasing correlation with the solute-applied depth. The depth of Br− peak content in soil profile after the rainfall ended increased with the application depth. Br− concentration in the surface soil was more than that in the runoff at the end of rainfall, which indicated an incomplete mixing between runoff water and soil water in the mixing layer. Under this experimental condition, the actual mixing layer depth for 3.5% soil moisture slope was about 3 cm, that for 10% soil moisture was 6 cm or so, and that for 20% soil moisture was more than 7 cm. The average EDI calculated for 3.5, 10, and 20% soil moisture was 2.31, 3.76 and 4.95 cm, respectively, which were less than the actual mixing layer depth and more than some former studies. The traditional 1.0-cm mixing depth in many agricultural NPS models might not be so exact for some special region.