Effect Of Soil Moisture Content Research Articles

Interactive effect of soil moisture content and phosphorus fertilizer form on chickpea growth, photosynthesis, and nutrient uptake

Water shortage and soil nutrient depletion are considered the main factors limiting crops productivity in the Mediterranean region characterized by longer and frequent drought episodes. In this study, we investigated the interactive effects of P fertilizer form and soil moisture conditions on chickpea photosynthetic activity, water and nutrient uptake, and their consequent effects on biomass accumulation and nutrient use efficiency. Two P fertilizer formulas based on orthophosphates (Ortho-P) and polyphosphates (Poly-P) were evaluated under three irrigation regimes (I1: 75% of field capacity, I2: 50% FC and I3: 25% FC), simulating three probable scenarios of soil water content in the Mediterranean climate (adequate water supply, medium, and severe drought stress), and compared to an unfertilized treatment. The experiment was conducted in a spilt-plot design under a drip fertigation system. The results showed significant changes in chickpea phenotypic and physiological traits in response to different P and water supply regimes. Compared with the unfertilized treatment, the stomata density and conductance, chlorophyll content, photosynthesis efficiency, biomass accumulation, and plant nutrient uptake were significantly improved under P drip fertigation. The obtained results suggested that the P fertilizer form and irrigation regime providing chickpea plants with enough P and water, at the early growth stage, increased the stomatal density and conductance, which significantly improved the photosynthetic performance index (PIABS) and P use efficiency (PUE), and consequently biomass accumulation and nutrient uptake. The significant correlations established between leaf stomatal density, PIABS, and PUE supported the above hypothesis. We concluded that the Poly-P fertilizers applied in well-watered conditions (I1) performed the best in terms of chickpea growth improvement, nutrient uptake and use efficiency. However, their effectiveness was greatly reduced under water stress conditions, unlike the Ortho-P form which kept stable positive effects on the studied parameters.

Influence of Organic Amendments and Moisture Regime on Soil CO2-C Efflux and Polycyclic Aromatic Hydrocarbons (PAHs) Degradation

In this study, a 30-day incubation experiment was performed to investigate the interactive effects of soil moisture content and two types of organic manure (animal manure: M and wheat straw: WS) on organic C mineralization and the degradation of PAH compounds. Specifically, washed sandy soil sample free from PAHs was treated with combined standard solution containing six different PAHs; pyrene (Pyr), fluoranthene (Flt), benzo[a]pyrene (BaP), benzo[g,h,i]perylene (BghiP), benzo[k]fluoranthene (BkF), and indeno[123-cd]pyrene (IP). The soil samples treated with PAHs were amended with M or WS and then, the soil samples were incubated and subjected to two levels of moisture content (50% and 100% field capacity, FC). The results indicate that CO2–C rates were the highest at day 1, but they tended to be decreased sharply when incubation time increased. The results showed that the higher rate of CO2-C efflux rate and cumulative were observed in M and WS treatments at 100% FC. Applying organic amendments at 50% FC increased the total cumulative CO2-C from 21.6 mg kg−1 to 228 mg kg−1 for M and to 216 mg kg−1 for WS. Meanwhile, applying organic amendments at 50% FC increased the total cumulative CO2-C from 30 mg kg−1 to 381 mg kg−1 for M and to 492 mg kg−1 for WS. The highest increases at 100% FC could be explained by the optimum water content at field capacity. PAHs concentrations decreased significantly in the presence of organic amendments in relation to enhance CO2-C efflux (soil respiration) and to decrease soil pH. It could be concluded that applying organic amendments might be a useful technique to remediate soil PAHs through mineralization.

Effect of maternal environment on seed germination and seed yield components of Thlaspi arvense

Thlaspi arvense has attracted great attention due to its high oilseed content and potential use as biomass for biofuel production. However, seed dormancy and low seed yield of wild T. arvense difficulties its cultivation and efficient use. Knowledge on seed germination, seed yield (SY) and their response to maternal environmental conditions is needed for the development of less dormant, high yield accessions, but this information is limited. Here, fresh seeds of a low altitude population (LAP) from Xiahe, and a high altitude population (HAP) from Maqu, both located in central China, are compared for germination and dormancy characteristics, including germination percentage, germination rate and dormancy-release. In a pot experiment, the effect of soil moisture content and shading of maternal plants on seed germination, their response to gibberellin, SY and SY components were determined. Germination of freshly collected mature seeds from HAP (0.89%) was higher than that of LAP (7.33%). The difference in seed germination between the two populations also was reflected by the gibberellin requirement for dormancy-release, in which GA50 was 0.135 and 0.012 mmol/L for LAP and HAP seeds, respectively. In addition, drought stress and light decreased the sensitivity of dormancy-release to gibberellin (improved GA50). The GA50 of LAP was 0.123, 0.133, 1.781, and 0.069 mmol/L for seeds matured under low, moderate, and severe drought stress and shade conditions, respectively; while for HAP this values were of 0.034, 0.041, 0.056, and 0.016 mmol/L. Drought stress reduced SY of T. arvense through a direct and indirect negative effects on height, biomass, reproductive branches per plant, siliques per branch, seeds per silique and 1000-seed weight. However, shade treatment increased SY by improving height and biomass. These results suggest that T. arvense populations with different dormancy levels can be selected from wild germplasm resources for domestication, according to breeding objectives. On the other hand, results also indicate that different quality and yield of seeds can be obtained by adjusting the environmental conditions during plant growth. Moreover, reproductive branches per plant and siliques per reproductive branch contributed the most to seed yield of T. arvense both in drought stress and shade condition. Thus, reproductive branches per plant and siliques per reproductive branch should be prioritized in a breeding program to improve SY of T. arvense.

Effects of Soil Moisture Content on Germination and Physiological Characteristics of Rice Seeds with Different Specific Gravity

Soil relative water content and seed plumpness have been shown to be the key factors affecting seed germination and seedling growth of rice under direct drought cropping. It remains to be determined whether seed germination and seedling growth of water-saving and drought-resistant rice (WDR) and conventional rice with the same proportion of rice seed have the same response to soil moisture changes. The purpose of this study was to investigate the seed germination and physiological characteristics of the rice cultivars Guangliangyou 1813 (GLY-1813,indica hybrid rice) and Hanyou 73 ((HY-73), WDR) with four different specific gravities (T1, T2, T3, and T4; the rice seeds were divided into four specific gravity levels by weight using saline water, the representative specific gravities were <1.0, 1.0–1.1, 1.1–1.2 and >1.2 kg m−3, respectively), at five soil moisture content gradients (soil relative water contents of 10–20%, 20–40%, 40–60%, 60–80%, and 80–100%), under dry direct seeding conditions. The results showed that GLY-1813 had a higher germination potential, germination and seedling emergence rates, greater root dry weight, seedling dry weight, root oxidation activity, and chlorophyll content, and lower malondialdehyde (MDA) content when the soil relative water content was 20–40% or 40–60%. Cultivar HY-73 had the highest germination rate and seedling physiological activity at 20–40% relative water content; its growth vigor was better than that of GLY-1813 at the same soil moisture level. In conclusion, the soil relative water content for seed germination of HY-73 was 20–40%, which was less than that of GLY-1813. When soil relative water content was sufficient for seed germination and growth, the higher the plumpness of the rice seed, the easier it was to resist the negative effects of an adverse growth environment.

Effect of soil moisture content on survival, growth, and physiological characteristics of wild cherry (Prunus avium L.) seedlings

Effect of soil moisture content on survival, growth, and physiological characteristics of wild cherry (Prunus avium L.) seedlings

Performance of in situ vs laboratory mid-infrared soil spectroscopy using local and regional calibration strategies

Comparison of in situ mid-infrared spectroscopy (MIRS) with laboratory MIRS is required to demonstrate the accuracy of field-scale prediction of soil properties. Application of MIRS to investigate soil management questions must also be tested. Our objectives were therefore to determine i) the accuracy of lab vs in situ calibrations using various numbers of local and/or regional soils for prediction of organic carbon (OC), total nitrogen (TN), clay and pH; ii) effects of soil moisture content and variability on model performance for coarser and finer soils; and iii) if the method of OC determination (dry combustion vs MIRS-estimation) affects evaluation of tillage effects. Surface field MIRS measurements were made at three loess sites in Germany, each featuring three tillage treatments. Material (0–2 cm) was collected for lab MIRS measurements on dried/ground (<0.2 mm) soil and determination of OC, TN, clay and pH. Spectral Principal Component Analysis (PCA) was conducted and partial least squares regression models were created for several calibration strategies: 1) local calibrations trained with n = 40 or 20 soils and tested with n = 110 soils from the same site; 2) regional calibrations trained with n = 150 or 38 soils from two sites and validated with n = 110 soils from the third site; 3) regional calibrations trained with n = 150 or 38 soils from two sites and n = 20 double- or n = 10 quadruple-weighted “spiked” soils selected from the spectral PCA to be representative of the third site, and validation with n = 110 soils also from the third site. Spiking regional calibrations with local soils generally improved accuracy and decreased performance variability, though there were typically diminishing marginal returns to accuracy from increasing the number of local soils. The first two principal components of the lab-MIRS PCA correlated with OC, TN, clay and pH, while the field-MIRS PCA was dominated by soil moisture effects. Lab outperformed field MIRS for all models and properties. Lab MIRS n = 38 regional models were highly accurate for OC (ratio of prediction to interquartile distance (RPIQ) = 4.3) and TN (RPIQ = 6.7), and estimates detected the same significant differences between tillage treatments as analysis conducted with measured values—thus, small regional models can be considered optimal (balancing accuracy and workload). For field MIRS prediction of OC and TN, calibrations with 150 regional or 38 regional plus 10 quadruple-weighted local soils achieved satisfactory accuracy (RPIQ ≥ 1.89). Although predicted changes to OC in response to tillage were more biased for field MIRS, agreement with measured effects was achieved with n = 40 local models or spiked regional models. Thus, the higher efficiency of field measurement is counterbalanced by a more arduous calibration process to achieve satisfactory accuracy. Accuracies for clay (RPIQ = 0.89–2.8) and pH (RPIQ = 0.60–3.2) were lower and more variable than OC and TN for both devices—thus, spiking calibrations and using more soils than OC/TN calibrations are recommended. Soil moisture more negatively affected OC prediction than clay prediction. No simple trend was established for the performances of soil subsets with low, high or variable moisture content, but accuracy was most negatively affected by moisture for the site with the highest sand content.

Producción y viviparidad de nogal pecanero (Carya illinoinensis [Wangenh.] K. Koch) en relación con la humedad del suelo

Introduction: Viviparity in pecan nut (Carya illinoinensis [Wangenh.] K. Koch) has increased considerably. This genetic-environmental phenomenon can be controlled with soil moisture management and other quality variables.Objective: To determine the effect of soil moisture content on yield, nut size, kernel percentage and germinated nut on the tree.Materials and methods: Forty-year-old pecan nut trees were irrigated by 40 emitters with an output of 3.2 L∙h-1. From the phenological stage of shell hardening, irrigation time was 4, 6 and 8 h, corresponding to moisture levels of 0.257, 0.327 and 0.380 m3 of water per m3 of soil, at depths of 40 to 80 cm. Yield per tree, germinated nut percentage, fruit size and kernel percentage were evaluated during the production cycles of 2016 and 2017 production cycles.Results and discussion: During the two production cycles, when soil moisture level increased from 0.257 to 0.380 m3∙m-3, nut yield per tree, fruit length and diameter, and kernel percentage increased on average 23.8 %, 25.3 and 10 %, and 1.8 %, respectively; however, vivipary increased 11.2 %, which was reflected in the decrease of commercial pecan nut percentage. Treatments 0.327 and 0.380 m3∙m-3 had a similar effect (P &gt; 0.05) on these variables.Conclusions: The lower moisture level (0.257 m3∙m-3), starting at the kernel filling stage, decreased vivipary and increased commercial kernel percentage.

The Effects of Soil Moisture on Harvesting Operations in Populus spp. Plantations: Specific Focus on Costs, Energy Balance and GHG Emissions

Background: Poplar tree plantations for wood production are part of a worldwide growing trend, especially in moist soil sites. Harvesting operations in moist sites such as poplar plantations require more study for detailed and increased knowledge on environmental and economic aspects and issues. Methods: In this study, the effects of soil moisture content (dry vs. moist) on productivity, cost, and emissions of greenhouse gases (GHG) caused by operations of different harvesting systems (chainsaw-skidder and harvester-forwarder) were evaluated in three poplar plantations (two in Italy and one in Iran). Results: The productivity (m3 h−1) of both systems in the dry sites were significantly higher (20% to 30%) than those in the moist sites. Production costs (€ m−3) and GHG emissions (g m−3) of both systems in the dry sites were also significantly lower than those in the moist sites. The productivity of the harvester-forwarder system was about four times higher, and its production cost was 25% to 30% lower than that of the chainsaw-skidder system, but the calculated GHG emissions by harvester-forwarder system was 50–60% higher than by the chainsaw-skidder system. Conclusions: Logging operations are to be avoided where there are conditions of high soil moisture content (&gt;20%). The result will be higher cost-effectiveness and a reduction in the emission of pollutants.

Reducing the Moisture Effect and Improving the Prediction of Soil Organic Matter With VIS-NIR Spectroscopy in Black Soil Area

Soil organic matter (SOM) is rich in black soil area. It has a significant effect on soil health and luxuriant vegetation. The agricultural production activities can thus be guided by measurements of SOM at different periods. Most of previous work estimated SOM using reflectance spectra measurements on dried soil samples, to remove the effect of soil moisture content (SMC). However, it is time-consuming and almost conduct-prohibitive in the field. In this study, we utilized the continuous wavelet transform (CWT) on visible (VIS) and near infrared (NIR) spectra to test its effect on eliminating the SMC influence, and proposed to use the PCA-RF method coupled with CWT to predict SOM from the wet samples. Multi-scale coefficients can amplify the response of spectra to SOM in varying degrees, while improving the correlation of characteristic wavebands and minimizing the moisture interference on SOM specific wavelength. By analysing the multi-scale coefficients, we found that wavelengths ranging around the peaks of $580nm$ , $820nm$ , and especially the narrow region around $1400nm$ are highly correlated regions to SOM. Furthermore, the accuracy of SOM estimation models illustrated the effectiveness of the CWT. Results of the validation model using the dataset of wet samples on CWT scale 6 ( $R^{2}$ = 0.84, $Mse$ = 0.23%, and $RPD$ = 2.53) can be statistically equivalent to dataset of dried samples ( $R^{2}$ = 0.86, $Mse$ = 0.20%, and $RPD$ = 2.68). Combined with the PCA-RF method, SOM estimation can be perfectly performed with fewer features as input variables and has a great improved. The best prediction of validation model was on scale 6 with features extracted from 4 PCs, compared with the EPO-PLSR method ( $R^{2}$ = 0.85, $Mse$ = 0.25%, and $RPD$ = 2.54), the proposed method has a better result ( $R^{2}$ = 0.94, $Mse$ = 0.09%, and $RPD$ = 4.08).

Uticaj sadržaja vlage zemljišta, dinamičkog opterećenja, klizanja točkova kod određivanja sile vuče u uslovima laboratorije

A study was conducted to determine the effect of soil moisture content, dynamic load and wheel slippage in measuring traction. A single wheel test rig was developed to enable fundamental research on traction studies on tropical soil at the department of Agricultural and Environmental Engineering of Federal University of Technology, Akure. This facility consists of a moving carriage with a trolley that moves in either forward or reverse directions on rails well above a soil bin powered by 2.2 kW, three phase induction motor. The present facility set up was able to operate in either towing test mode for tire motion resistance studies or driving test mode for tire net traction and tractive efficiency studies. The test tire on the moving carriage was powered to rotate by a motor with additional pull provided by a cable-pulley mechanism connected to a tower with hanging dead weights. All controls on the moving carriage were activated from the main control console. The developed facility was successfully tested to determine tractive efficiency for narrow wheels at a particular inflation pressure on clay soil. The single wheel test rig facility worked well and the research indicates that wheel load, wheel slippage, soil moisture content and inflation pressure has great effect on traction efficiency. Traction efficiency decreased as the wheel load and wheel slippage increased. The developed single wheel testing facility can perform traction tests in controlled soil conditions to study the effect of soil, tire and moisture parameters on the performance of the system.

Effect of soil moisture content on the bearing capacity of small bored piles in the unsaturated soil of Maringá, Paraná, Brazil

In this study, the influence of soil moisture on the bearing capacity of piles founded in an unsaturated clay soil was investigated. The soil studied, composing the upper soil layer in Maringá, Brazil, is lateritic, has degree of saturation between 37% and 70% and has collapsible behaviour when wet. The bearing capacity was determined by full-scale load tests following the Brazilian Standard for Static Load Test. Two pile lengths, 4 m and 8 m, were considered. To analyse the influence of soil moisture, two tests were performed for each pile length: one in soil in its natural moisture content and another in pre-moistened soil. Results show that for both pile lengths, an increase in water content caused a significant reduction in bearing capacity, which is attributed to the decrease in the matric suction of the soil. This is confirmed by the results of the initial evaluation made on the variation of matric suction and its contribution to the bearing capacity with changes in water content. In summary, this study confirms that the pile bearing capacity in unsaturated soil is dependent on soil water content, highlighting the fact that the approach of assuming full saturation condition in the evaluation of the pile bearing capacity in such soil may give erroneous results. Moreover, this study demonstrate that the empirical methods most commonly used in Brazil for pile bearing capacity determination, the Décourt &amp; Quaresma and Aoki &amp; Velloso methods, are overly conservative when applied to the Maringá soil.

Effect of soil moisture content and nitrogen fertilizer on survival, growth and some physiological characteristics of Platycladus orientalis seedlings

Given the important applications of oriental arborvitae (Platycladus orientalis /L./ Franco), we examined the interaction effects of soil moisture content (SMC) and urea fertilizer on survival, growth and some physiological characteristics of seedlings of this species. In this study, 270 uniform oriental arborvitae seedlings were transplanted in 2 kg containers filled with the top soil of the natural stand in Soorkesh forest reserve. After 2 months, 6 levels of SMC (100%, 75%, 50%, 25%, 15% and 10%) and 3 levels of urea [control: 0, low nitrogen (LN): 75 mg·kg&lt;sup&gt;–1&lt;/sup&gt;, and high nitrogen (HN): 150 mg·kg&lt;sup&gt;–1&lt;/sup&gt;] were used from June till the end of the first growing season in 3 replications and 5 seedlings per replication as subsamples. The results showed that all seedlings survived under SMC above 25% in control and urea fertilizer treatments. However, under 15% and 10% SMC, the seedling survival decreased significantly in control treatment, but adding urea fertilizer significantly increased the survival, especially in HN treatment. Growth and morphological properties of seedlings, including root and shoot length, number of first-order lateral roots and total biomass, showed a significant decrease at 75%. Seedling quality index gradually decreased with SMC reduction, but the addition of urea to the soil significantly increased it under all SMC treatments. The results also indicated that a decrease in SMC significantly decreased relative water content of leaves and total chlorophyll content, and urea fertilizer increased total chlorophyll under all SMC treatments, but it increased relative water content only at 100% to 25%. Moreover, water use efficiency of P. orientalis seedlings significantly increased under low soil moisture treatments, and urea significantly increased it, especially under HN treatment. In conclusion, urea fertilizer, especially in the higher amount (150 mg·kg&lt;sup&gt;–1&lt;/sup&gt;), improved growth and quality of seedlings under different soil moisture conditions, and increased their survival under severe drought.

Effect of Soil Moisture Content and Rate of Potassium Fertilizer on Soil Potassium Content and Growth of Cowpea (Vigna unguiculata l.) Grown in Sandy Regosol in Sri Lanka

A research study was conducted to identify the effect of potassium rate and drought stress on the post-harvest soil potassium content and growth parameters of cowpea (Vigna unguiculata L.). The experiment was arranged in a Completely Randomized Design (CRD) in a factorial manner with 8 treatments (4 different rates of fertilizer potassium as muriate of potash (MOP (i) 100% of recommended level (75 kgha-1), (ii) 125% of recommended level (93.75.kgha-1), (iii) 150% of recommended level (112.5 kgha-1), and (iv) 175% of recommended level (131.25.kgha-1) at 2 different soil moisture conditions as 25% depletion and 75% depletion of available soil moisture as optimal and sub-optimal moisture condition respectively and was replicated 3 times. The post-harvest soil potassium content, chlorophyll content of leaves and cowpea growth parameters such as, dry weight of root and dry weight of shoot were recorded at vegetative and harvesting stages. The results reveal that there was a significant influence (p<0.05) of potassium rate and soil moisture on the growth parameters, leaf chlorophyll content and available soil potassium content after harvest. In overall terms potassium promoted growth of cowpea when subject to sub-optimal soil moisture. Further, it was found that the increased application of potassium fertilizer up to 175% of recommended level can be considered as a significant factor in overcoming soil moisture stress in cowpea.

Influence of soil moisture content on pullout properties of Hippophae rhamnoides Linn. roots

Plant root system plays an important role in preventing soil erosion and improving slope stability. However, its performance is significantly affected by soil moisture content, and the role of soil moisture in root reinforcement is not fully understood. In this study, the influence of soil moisture on root pullout properties was studied by experiments. Vertical in-situ pullout tests under four different levels of soil matric suction (12 kPa, 18 kPa, 24 kPa, 30 kPa) were carried out on roots of sea buckthorn plants (Hippophae rhamnoides Linn.) which were artificially cultivated for 7 months. Diameter and length of the root system of sea buckthorn were investigated. The results showed that a very significant correlation was observed between root diameter (D) and root length (L) (P<0.01), and root diameter decreased with soil depth. When soil bulk density was constant, peak pullout force (F) and friction coefficient of root-soil interface (μ) decreased with increasing gravimetric soil moisture content in power functions. Soil moisture content significantly affected root pullout resistance because the increase of soil moisture content decreased the friction coefficient between the roots and soil. Root diameter at breakage point (Db) and length of root segment left in soil (Lb) were increased with soil moisture content. In addition, peak pullout force of the roots increased in a power function with root diameter at the soil surface (Do) and in a linear function with total root length (L). The results provided an experimental basis for quantifying the effects of soil moisture content on soil reinforcement by plant roots.

Evaluation of 11 soil thermal conductivity schemes for the permafrost region of the central Qinghai-Tibet Plateau

Soil thermal conductivity (λ), which describes the ability of the soil to transfer heat, is critical to understand the thermal regime of ground surfaces. In this study, in situ measurements of λ were conducted at two field sites in the permafrost region of the central Qinghai-Tibet Plateau (QTP) and the results were used to evaluate 11 schemes of λ at depths of 10–50 cm during the freeze-thaw cycle period. Our analyses revealed that λ had a remarkable seasonal variation, due to the significant effects of soil moisture content and ice-water phase changes as temperature changed during the freeze-thaw cycle period. Among the selected schemes, the Johansen scheme, its three derivatives (i.e., the He scheme, Yang scheme and Zhao scheme), and the Campbell scheme were significantly superior to others. Moreover, the Johansen scheme ranked among the top schemes for frozen soil, while the Campbell scheme gave the most accurate values for unfrozen soil. The effects of different estimation methods of quartz content (q), dry λ and the Kersten number (Ke) on the predicted schemes results were also evaluated. The results showed that, the methods used for the estimation of q and Ke had the greatest influence on the calculation results for the permafrost region. Overall, this research provides insights for the development of a λ scheme for the permafrost region of the central QTP.

Environmental degradation and efficacy of a sprayable, biodegradable polymeric mulch

Polyethylene (PE) and other non-degradable plastics are used in vast quantities as agriculture mulch to help protect the soil surface, conserve water, and improve soil microclimatic factors. Unfortunately, their continued use poses several environmental problems, so an environmentally friendly solution needs to be found. The use of biodegradable plastics in place of conventional PE is one well studied solution, and here we investigate how different controlled environmental conditions affect the water conservation efficacy, and rate of biodegradation of a novel, biodegradable, sprayable polycaprolactone based polyurethane mulch. The effect of soil moisture content, sunlight, soil type, and polymer pigmentation are investigated using several different characterization techniques and measurements. It was found that the polymer studied is effective at conserving soil moisture, and that it biodegrades at different rates via a bulk erosion mechanism. The rate at which it degrades mostly depends on the soil type to which it is applied, and the moisture content of that soil. This was confirmed using soil CO2 emissions, polymer mass loss, polymer molecular weight reduction, and scanning electron microscopy. Results are discussed.

Effects of soil moisture content on CO2 triggered soil physicochemical properties in a near-surface environment

Carbon capture and storage (CCS) has been frequently discussed as a strategy for meeting CO2 emission reduction and its targets. However, some critical issues have been raised with regard to the potential hazards to near-surface environments by CO2 leakage. Hence, this study was conducted to examine the effects of soil moisture content on the potential risks associated with a high concentration of CO2 to change physicochemical properties of a near-surface soil. Soil samples for a batch experiment were collected from an abandoned gold mine, South Korea. Batch experiments were conducted in a specially designed CO2 glove box (95–99 vol.% CO2) at four different moisture contents (0, 15, 27.5 wt.%, and a suspension of soil to water ratio 1:10) and different reaction times up to 30 days. A control experiment was conducted at the ambient conditions open to the atmosphere otherwise the same conditions. Physicochemical properties of the soil samples (i.e., pH, mineralogy, organic matter (OM), inorganic carbon (IC), and cation exchange capacity (CEC)) as well as leachability of metal(loid)s were examined before and after the CO2 incubation. Results showed that the pH of the CO2-incubated partially wet (15 and 27.5 wt.%) and suspension samples rapidly decreased by about one unit (P < 0.01) in 2 h and gradually recovered in 10 days. It was noteworthy that CO2 was adsorbed to the dry soil (0 wt.%) and led to acidification as the soil pH dropped from 5.56 ± 0.02 to 4.5 ± 0.03. Soil organic matter content and cation exchange capacity decreased with increasing moisture content in the CO2-incubated samples. A noticeable increase in the leachability of Fe, Al, Ca, Mg, Mn, K, and Zn were observed in the CO2-incubated soil suspensions. In contrast, the leachability of metal(loid)s in the dry and partially wet samples were not remarkable, although the soil pH decreased significantly. Our findings highlighted the effect of CO2 exposure on the soil acidification, even to soils in unsaturated zones, and stressed to monitor simultaneously soil physicochemical properties and metal(loid)s leaching induced by CO2 exposure in the near-surface environment.

Salmonella Survival in Soil and Transfer Onto Produce via Splash Events

Nearly one-half of foodborne illnesses in the United States can be attributed to fresh produce consumption. The preharvest stage of production presents a critical opportunity to prevent produce contamination in the field from contaminating postharvest operations and exposing consumers to foodborne pathogens. One produce-contamination route that is not often explored is the transfer of pathogens in the soil to edible portions of crops via splash water. We report here on the results from multiple field and microcosm experiments examining the potential for Salmonella contamination of produce crops via splash water, and the effect of soil moisture content on Salmonella survival in soil and concentration in splash water. In field and microcosm experiments, we detected Salmonella for up to 8 to 10 days after inoculation in soil and on produce. Salmonella and suspended solids were detected in splash water at heights of up to 80 cm from the soil surface. Soil-moisture conditions before the splash event influenced the detection of Salmonella on crops after the splash events-Salmonella concentrations on produce after rainfall were significantly higher in wet plots than in dry plots (geometric mean difference = 0.43 CFU/g; P = 0.03). Similarly, concentrations of Salmonella in splash water in wet plots trended higher than concentrations from dry plots (geometric mean difference = 0.67 CFU/100 mL; P = 0.04). These results indicate that splash transfer of Salmonella from soil onto crops can occur and that antecedent soil-moisture content may mediate the efficiency of microbial transfer. Splash transfer of Salmonella may, therefore, pose a hazard to produce safety. The potential for the risk of splash should be further explored in agricultural regions in which Salmonella and other pathogens are present in soil. These results will help inform the assessment of produce safety risk and the development of management practices for the mitigation of produce contamination.

Growth and Flavonoid Content of Gynura procumbens (Lour) Merr. in Different Soil Water Content

Gynura procumbens contains tannins, saponins, steroids, triterpenoids, essential oils and flavonoids which have bioactivity as a medicine for various diseases. One effort to obtain the quality of medicinal plants uses management of soil water content. The opti-mum of soil water content will support optimal growth of a plant. Whereas in conditions of low soil water content resulted in the induc-tion of the production of secondary metabolites as a self-defense sys-tem. This study aimed to determine the effect of soil moisture content on the growth and total content of plant flavonoids G. procumbens. This study was carried out experimentally using a one-factor com-plete randomized design (CRD) consisting of 4 treatments with five replications. The treatment used is the difference in soil water content of 40%, 60%, 80% and 100% field capacity. The data obtained in the form of quantitative data will be analyzed by One Way ANOVA Test. Measurement of the content of total flavonoid compounds was car-ried out using UV-Vis spectrophotometer analysis. The results of the study indicate the influence of soil moisture level on the growth and total content of G. procumbens. Parameter growth of fresh weight, dry weight, and root G. procumbens showed an increase in 40% soil water content. The flavonoid content showed the highest total flavo-noid content 18.884 mg/g in the 40% field capacity soil water content

Effect of Soil Moisture Content and End-Effector Speed on Pick-up Force and Lump Damage for Seedling Transplanting

Efficient transplanting has been identified as one of the essential steps towards achieving an increased yield in the farm. However, many factors are affecting these processes such as soil moisture content and the speed of pickup. This study was carried out to investigate the effect of different soil moisture content and pickup speeds on pickup force, balance, resistance, and lump damage during transplanting of seedlings. The results showed that penetration resistance was inversely proportional to the speed and soil moisture content. The highest penetration resistance (38 N) values were recorded under the lowest speed (0.5 mm/s) at the low moisture content; whereas, the lowest penetration resistance was obtained at highest speed (10 mm/s) under high moisture content. The highest pick-up force resistance values were recorded under the lowest speed (0.5 mm/s) at low moisture content than the lowest pick-up force resistance of 1.4 N at (10 mm/s) under the high moisture content. On the other hand, an increase of pick-up force led to a decrease in the pick-up force resistance. The pick-up damage and the pick-up speed are directly proportional—nevertheless, the former increased with a decreasing soil moisture content. The highest pick-up damage values (82%) were observed under the top-most speed (10 mm/s) at high moisture content. It can be concluded that for successful auto-transplanting of seedling the soil condition, the force applied and speed should be taken into consideration. This work will implement an effective seedling-picking performance and basis for the optimal design of end-effectors.