High Moisture Treatment Research Articles

Intraspecific variation in Janzen-Connell effect is mediated by stress and plant-soil feedbacks.

Janzen-Connell (JC) effects, hypothesized to be partially driven by negative plant-soil feedbacks (PSFs), are considered to be a key mechanism that regulates tropical forest plant diversity and coexistence. However, intraspecific variation in JC effects may weaken this mechanism, with the strength of PSFs being a potentially key variable process. We conducted a manipulated experiment with seedlings from two populations of Pometia pinnata (Sapindaceae), a tropical tree species in southwest China. We aimed to measure the intraspecific difference in PSF magnitude caused by inoculating the soil from different P. pinnata source populations and growing seedlings under differing light intensity and water availability treatments, and at varying plant densities. We found negative PSFs for both populations with the inoculum soil originating from the same sites, but PSFs differed significantly with the inoculum soil from different sites. PSF strength responded differently to biotic and abiotic drivers; PSF strength was weaker in low moisture and high light treatments than in high moisture and low light treatments. Our study documents intraspecific variation in JC effects: specifically, P. pinnata have less defenses to their natively-sourced soil, but are more defensive to the soil feedbacks from soil sourced from other populations. Our results imply that drought and light intensity tended to weaken JC effects, which may result in loss of species diversity with climate change.

Characteristics of sorghum flour modified with physical and enzymatic treatments

This study evaluated the physicochemical and thermal properties of modified sorghum flour. The modified sorghum flour was obtained through extrusion -enzymatic treatment using thermostable-α amylase at various feed moisture levels. The results showed that unmodified sorghum flour had the average chemical composition of sample being 87.06% carbohydrate, 9.8% protein, 0.32% fat and 0.64% ash. The unmodified and modified sorghum flour differed in their properties. The swelling power and solubility changed from 16.21 (g/g) to 4.64(g/g) – 28.20 (g/g) and from 4.68% to 4.25%–83.81% respectively. A wide range of pasting properties were noticed, such as peak viscosity (54 cP-3028 cP), breakdown viscosity (59 cP-1029 cP), setback viscosity (-106.50–2351 cP). Peak viscosity was not detected when the modification was performed at high feed moisture (FM 35%) treatment combined with the addition of thermostable-αamylase. Additionally, the onset, peak, and conclusion temperatures of gelatinization, and the enthalpies of modified flours were lower than those of unmodified ones. Morphological changes in the surface of starch granules were noticed as shown by pore formation through SEM observation. This study provided insights into the future direction of extrusion combined with enzymatic treatment for the selective modification of sorghum flour functional properties.

Microwave-Supported Modulation of Functional Characteristics of Gluten-Free Breads

Currently, the market for gluten-free products is experiencing a significant growth due to, mainly, the increase in the number of gluten-intolerant patients diagnosed and to the merging of a new niche market for consumers who optionally avoid gluten. Native flours are perceived as viable alternatives for industrially used starch and hydrocolloids blends, which lack in the vitamins and minerals that are in abundance in non-refined raw materials. This study delves into the potential of microwave technology in enhancing the functional and nutritional attributes of gluten-free breads. The research was conducted by employing 900 W microwave power for 8 min for buckwheat and teff flours modification with an initial moisture content of 30%. The modified flours were blended with rice flour and baked to verify the potential of microwave high moisture treatment for adjusting the texture and nutritional quality of the bread. The results revealed that microwave treatment of flours helped in retaining a higher level of essential nutrients and bioactive compounds in gluten-free breads.

Water limitation reveals local adaptation and plasticity in the drought tolerance strategies of Bouteloua gracilis

AbstractAs the frequency and severity of drought increase in many regions around the globe, quantification of key drought tolerance traits and the intraspecific variability of these traits will improve predictions of the vulnerability of a species to novel drought conditions. The objective of this study was to quantify the variability in drought tolerance traits and correlate this to the sensitivity of plant growth to different soil moisture levels across populations of Bouteloua gracilis. Fourteen populations of B. gracilis were sampled along one local elevation‐aridity gradient in northern Colorado and one latitude‐aridity gradient from South Dakota to New Mexico. Individuals from each population were clonally propagated and subjected to high and low soil moisture treatments in a greenhouse and were measured for gas exchange, midday water potential (Ψmid), osmotic potential (Ψosm), biomass production, and morphological traits. Under water‐abundant conditions, plants from the most arid region produced more total biomass (67%) than plants from the most mesic system, yet experienced the greatest sensitivity (−34%) when subjected to water limitation. Productivity was strongly and negatively correlated with the magnitude of osmotic investment across all populations: each megapascal of osmotic potential was correlated with a decrease of 2.3 g of biomass under water‐limited conditions. Gas‐exchange and leaf morphological measurements did not explain these patterns. Unlike plants from the mesic regions, plants from the most arid regions did not adjust Ψosm. This lack of plasticity may be a local adaptation and the likely source of increased sensitivity in these populations.

Effect of Soil Moisture Level on the growth of the Giant African Land Snails, Archachatina marginata and Achatina achatina in different season.

This study focused on the evaluation of the effect of soil moisture on the feed intake and weight gain of the Giant African Land snails, Achatina achatina and Archachatina marginata in different seasons using a 2 x 2 x 4 factorial experiment with soil moisture at two levels (low 25ml of water/ week and high 100ml water/week), species at two levels (Achatina achatina and Archachatina marginata) and season at four levels (cold dry, hot dry, hot wet and cold wet) constituting the three factors. Result showed that there was a significant seasonal differences (P<0.001) for weekly feed intake of snails in which values of 3.85, 2.53, 3.88 and 4.44g were recorded in cold dry, hot dry, hot wet and cold wet seasons, respectively. Monthly weight gains of 5.41g recorded for Archachatina marginata was significantly higher (P<0.001) than the value of 1.94g recorded for Achatina achatina. There was significant interaction (P<0.001) between soil moisture level and species on monthly weight gains of the snails. The feed intake and weight gain of snails (4.28 g and 6.43 g) in the high soil moisture treatment was significantly (P<0.01) higher than those in the low soil moisture treatment (3.07 g and 5.30 g). In conclusion, it is evident that species, season and soil moisture level affected the feed intake and weight gain of the Giant African Land Snails

The potential for phosphorus benefits through root placement in the rhizosphere of phosphorus-mobilising neighbours.

Plants that produce specialised cluster roots, which mobilise large quantities of poorly available nutrients such as phosphorus (P), can provide a benefit to neighbouring plants that produce roots in the cluster rhizosphere, as demonstrated previously in pot studies. To be effective, such roots must be present within the short time of peak cluster activity. We tested if this requirement is met, and quantified potential P benefits, in a hyperdiverse Mediterranean woodland of southwest Australia where cluster-rooted species are prominent. Using minirhizotrons, we monitored root dynamics during the wet season in the natural habitat. We found non-cluster roots intermingling with all 57 of the observed cluster roots of the studied tree species, Banksia attenuata. Almost all (95%) of these cases were observed in a high-moisture treatment simulating the 45-year average, but not present when we intercepted some of the rainfall. We estimate that cluster-root activity can increase P availability to intermingling roots to a theoretical maximum of 80% of total P in the studied soil. Due to their high P-remobilisation efficiency (89%), which results from P rapidly being relocated from cluster roots within the plant, senesced Banksia cluster roots are a negligible P source for other roots. We conclude that, rather than serving as a P source, it is the cluster-root activity, particularly the exudation of carboxylates, that may improve the coexistence of interacting species that are capable of root intermingling, thus potentially promoting species diversity in nutrient-poor habitats, and that this mechanism will be less effective in a drying climate.

Nitrogen release rates from slow- and controlled-release fertilizers influenced by placement and temperature.

Controlled-release and slow-release fertilizers can effectively supply nitrogen (N) while mitigating N loss. To determine the suitability of these fertilizers for plants in semi-arid environments, these fertilizers need to be evaluated under varying placement and temperature conditions. Several urea fertilizers were evaluated, including: uncoated, sulfur-coated (SCU), polymer-coated-sulfur-coated (PCSCU), and polymer-coated (PCU) with projected release timings between 45 and 180 d. Nitrogen release was measured under daily fluctuating or static temperatures applied either to the surface or buried in the soil. A second experiment consisted of two PCU sources and added a hanging bag placement comparison and low and high soil moisture treatments. For the first Experiment, the N in uncoated urea released shortly after application. The SCU and PCSCU treatments released > 80% of the N before the first sampling date. With fluctuating temperatures, the PCU 45, 75, 120, and 180 incorporated into the soil released N within +9, +9, -22, and -68 d of their expected timing. However, they released their N within 35 d when surface applied. Conversely, with static temperatures, PCU products released slowly, releasing under 80% for the entire study. The second experiment verified these results and showed no difference between low and high moisture and minimal release with fertilizer not in contact with soil. Each coated fertilizer in these studies exhibited slow/control release properties, but the PCU (surface applied) and SCU/PCSCU (surface applied or incorporated in soil) release was much more rapid than expected. Our research suggests that, although the SCU and PCSCU showed minimal slow-release properties (regardless of placement), the PCU fertilizers incorporated in the soil do have a controlled release approximate to what is expected, but have a much more rapid release when surface applied.

English

Sweet potato starch was subjected to cross-linking to achieve high content of resistant starch (RS) under heat-moisture treatment and the physicochemical properties of cross-linked sweet potato starches were investigated. The cross-linking agent was sodium trimetaphosphate and sodium tripolyphosphate (STMP/STPP). A maximum RS content (72.45%) was obtained after 10% STMP/STPP (99/1% w/w) at 120°C and pH 11.5 with a 20% moisture level. Through the analysis of 31P (phosphorus) nuclear magnetic resonance (31P NMR) spectroscopy, the RS-72.45% contained distarch monophosphate (DSMP) and monostarch monophosphate (MSMP) was not detected. Fourier-transform infrared spectroscopy (FTIR) presented the cross-linking reaction, confirmed by the comparison of native curves. After cross-linking, in the starches with high moisture treatment (≥25%) a loss of birefringence and surface erosion were observed. X-ray diffraction patterns showed that the crystal type was unchanged but with slight alteration in the relative crystallinity of cross-linked starches. Differential scanning calorimetry (DSC) showed gelatinization temperature increased as the moisture content increased, while gelatinization enthalpy apparently decreased.   Key words: Sweet potato starch, Heat-moisture treatment, 31P Nuclear magnetic resonance spectroscopy, optimization, X-ray difraction (XRD), scanning electron microscopy (SEM), polarized light microscopy. &nbsp

Effects of salinity and moisture on sediment net nitrogen mineralization in salt marshes of a Chinese estuary

The interactive effects of salinity and moisture on the net nitrogen mineralization were seldom studied in coastal wetlands. To reveal the phenomenons and mechanisms of salinity and moisture effects, we conducted a 30-days laboratory experiment with different salt addition levels (0, ppt, 5 ppt and 35 ppt) and moisture levels (10%, 50% and 100% of water holding capacity (WHC)), and the key N transformation rates and enzymes activities were measured. Our results showed that during the incubation, the rates of soil net nitrogen mineralization (Rmin) and nitrification (Rnit) under all treatments, increased during 0–1 day, decreased during 1–3 days, then increased and kept around zero. As incubation time increased, urease activities increased, arylamidase activities decreased and fluorescein diacetate activities increased first and then decreased. Increasing salinity under high moisture (100% WHC) treatments and increasing moisture under high salinity (35 ppt) treatments would promote Rmin and Rnit. Whereas, increasing salinity under low moisture (10% WHC) treatments, and increasing moisture under low salinity (0 ppt) treatments would suppress Rmin and Rnit. The responses of enzyme activities to salinity and moisture gradients almost correspond with Rmin, indicating salinity and moisture could affect N transformation by the regulation of related microbial enzyme activities.

Life in interstitial space: Biocrusts inhibit exotic but not native plant establishment in semi‐arid grasslands

Abstract Exotic plant species commonly exploit disturbances more successfully than native plants. This outcome is widely attributed to the fact that disturbance reduces biotic resistance from native plant competitors. However, biocrusts, communities of mosses, lichens, and micro‐organisms, are a prominent component of semi‐arid grasslands occurring in the interstitial spaces between vascular plants. Biocrusts may provide an important source of biotic resistance to invaders, different from native plant competition, but poorly understood. We established a large‐scale field experiment to examine how intact versus disturbed biocrusts influenced the emergence and establishment of four native and four exotic plant species in intermountain bunchgrass systems over 2 years—one wet and one dry. We also conducted a complementary greenhouse experiment to explore how differences in moisture might influence biocrust effects on germination. In the greenhouse, biocrusts inhibited the germination of both native and exotic plants in the high moisture treatment only. In field experiments, biocrusts inhibited the overall emergence of exotic seedlings in the wetter of the 2 years and inhibited the establishment of exotic seedlings in both years, but they had no overall effect on the emergence or establishment of native seedlings. We found that intact biocrusts in intermountain grasslands can suppress the establishment of some exotic plants, but have much weaker effects on natives. They also suggest that water availability may influence biocrust effects on seed germination. Synthesis. Our results indicate that intact biocrusts may provide an important source of biotic resistance to exotic plant invasions in intermountain grasslands. Furthermore, precipitation inputs may mediate biocrust effects on plant establishment.

Cross-Life Stage Effects of Aquatic Larval Density and Terrestrial Moisture on Growth and Corticosterone in the Spotted Salamander

For organisms with complex life cycles, conditions experienced during early life stages may constrain later growth and survival. Conversely, compensatory mechanisms may attenuate negative effects from early life stages. We used the spotted salamander, Ambystoma maculatum, to test how aquatic larval density and terrestrial moisture influence juvenile growth, food intake, evaporative water loss and water reuptake rates, and corticosterone levels. We conducted an outdoor mesocosm experiment to manipulate larval density and transferred metamorphosed salamanders into low and high terrestrial moisture treatments in laboratory terrariums. After the larval stage, high-density salamanders were significantly smaller and had higher corticosterone release rates than those from low-density treatments. Salamanders in the low terrestrial moisture treatment consumed fewer roaches, had lower mass-specific growth rates, higher water reuptake, and higher corticosterone release rates than salamanders in high terrestrial moisture treatments. Across moisture treatments, smaller salamanders had higher mass-specific growth rates than larger salamanders. Our results suggest that salamanders can partially compensate for competition in the larval aquatic habitat with increased growth as juveniles, but this response is dependent on terrestrial habitat quality. Thus, the persistence of early life stage effects can be an important, yet context-dependent, component of amphibian life cycles.

Half-sibling loblolly pine clones exhibited intraspecific variation, a G × E interaction, and differences in stable isotope composition in response to soil moisture availability

We examined the response of three loblolly pine half-sibling clones (hereafter referred to as Clone 1, 2, and 3) to soil moisture availability in a greenhouse study. Three soil moisture treatments were imposed. Two were constant soil moisture treatments at either high (−0.3MPa) or low (−1.5MPa) soil water potential. The third was an alternating wet-dry treatment that alternated between one week at high (−0.3MPa) and three weeks at low (−1.5MPa) soil water potential, which simulated several natural wetting-drying cycles. At intervals throughout the experiment we measured biomass accumulation (via sequential harvesting), change in height, pre-dawn needle water potential, afternoon needle water potential, dark respiration, and morning and afternoon gas exchange (photosynthesis, stomatal conductance, intercellular CO2, and transpiration). Carbon allocation to root and shoot biomass, stomatal density, and carbon isotope composition were measured at the end of the experiment.All clones accumulated more biomass in the high soil moisture treatment than in the low soil moisture treatment, but there was a genetic by environment (G×E) interaction: Clone 1 accumulated more biomass than the other clones in the low soil moisture treatment and less than the others in the high soil moisture treatment. Stable carbon isotope composition, which we interpreted as a time-integrated index of water use efficiency, was significantly higher (indicating greater water use efficiency) in Clone 2, compared to Clones 1 and 3 across all soil moisture treatments except in the wet-dry treatment, where Clone 1 and 3 were not significantly different. A strong negative correlation was found between stable carbon isotope composition and biomass accumulation. Gas exchange parameters and needle water potential were higher in the high soil moisture treatment compared to the other treatments across all clones. Morning measurements of gas exchange were higher in Clones 2 and 3 than in Clone 1 across all treatments. Stomatal density varied significantly among clones but not among treatments. These results demonstrated that closely related clones differed in their growth and physiological responses to moisture availability, suggesting that clonal variation could be used to breed for increased drought resistance or to identify drought resistant genotypes for selective deployment.

Impact of pyrolysis and hydrothermal biochar on gas-emitting activity of soil microorganisms and bacterial and archaeal community composition

Most biochar studies are focusing on the usage of char produced by pyrolysis (pyrochar). However, only dry biomass can be subjected to pyrolysis. It is beneficial to produce biochar by hydrothermal carbonization (hydrochar) from wet biomass to avoid energy use for drying. The objective of this study was to compare the effects of pyrochar and hydrochar on greenhouse gas-emitting activity, abundance and composition of the soil bacterial and archaeal community. Three different moisture contents (40%, 60% and 80% of water holding capacity) and two N fertilization steps (with and without N addition) were investigated. The microcosm study was conducted in 120mL glass bottles with septum caps for periodic headspace gas analysis. N2O and CO2 emissions from pyrochar were in the same range as the char-free control. Hydrochar, however, caused high N2O emissions in the fertilized high moisture treatment and significantly higher CO2 emissions in all treatments compared to the control. Pyrochar increased CH4 emission in the unfertilized treatments, whereas hydrochar had no effect except a small reduction in the fertilized and highest moisture treatment. Enzyme activity in all pyrochar microcosms was in the same range as the char-free control, but lower in unfertilized hydrochar microcosms. Pyrochar soil amendment did not change bacterial and archaeal abundance. Hydrochar decreased archaeal abundance in the majority of the treatments. T-RFLP analysis revealed that pyrochar, hydrochar and control each developed a distinct bacterial community. Pyrochar had no effect on archaeal communities, whereas hydrochar induced the formation of significantly different communities compared to the control. Furthermore, hydrochar reduced the abundance of Acidobacteria and Firmicutes, while it remarkably increased the abundance of Bacteroidetes and Proteobacteria. The results suggest that the addition of hydrochar induces considerably stronger effects on soil microbial communities than the addition pyrochar.

Effects of Soil Moisture and Fertilization Treatments on the Agronomic Traits of Teff (<i>Eragrosis tef</i>) in Southern Kyushu, Japan

This study investigated the agronomic characteristics of pot-cultured teff (Eragrostis tef) under soil moisture and fertilization treatments in southern Kyushu, Japan. In experiments examining the effects of soil moisture and fertilization, growth of teff and Setaria (Setaria sphacelata) as a reference species was compared under six treatments combining two soil moisture regimes, control (C) and high moisture (H) treatment, and three fertilizer applications, chemical fertilizer with manure (CF + M), chemical fertilizer (CF) and doubled level of manure (DM). H treatment did not decrease dry matter yield in teff two months after transplanting, except when combined with CF + M, compared with a decreasing tendency in Setaria. Top and underground dry matter yields and harvest index in teff increased significantly (P 0.05) at CF application levels above 6.2 gN m-2 two months after sowing, suggesting that the optimum CF level of teff in southern Kyushu was comparable with that in the USA, and that teff had potential as an early-harvest forage crop two months after planting to replace summer forage in paddy fields of this region.

EFFECT OF DIFFERENT THERMAL TREATMENTS AND STORAGE ON STARCH DIGESTIBILITY AND PHYSICOCHEMICAL CHARACTERISTICS OF UNRIPE BANANA FLOUR

ABSTRACT Unripe banana flour is an important source of indigestible carbohydrates, mainly resistant starch (RS). However, during cooking of the fruit, the indigestible carbohydrates are transformed to digestible. The aim of this study was to test different treatments: cooking (5, 15 and 25 min), cooking plus high-moisture treatment (HMT) and cooking plus HMT plus storage (HMT + S), to increase the slowly digestible starch (SDS) and RS fractions. Polarization light microscopy, leached amylose, X-ray diffraction pattern, thermal and pasting characteristics, and starch digestibility analysis of the flours were evaluated. The longest cooking time decreased the RS content in the non-gelatinized samples; HMT and HMT + S increased the SDS level. These samples could be used in products without heat treatment during their preparation. The gelatinized samples presented a significant fraction of RS in comparison with the non-gelatinized, demonstrated that the samples can be used in products where cooking is necessary, conserving a high amount of indigestible carbohydrates. PRACTICAL APPLICATIONS Unripe bananas are an alternative source of indigestible carbohydrates, mainly resistant starch (RS) and dietary fiber (DF). Unripe banana is also considered the richest natural source of RS; however, this characteristic is lost when the fruit is cooked. The digestion rate of starch present in unripe banana flour can be modified to produce a functional or nutraceutical ingredient. The use of physical treatments on unripe banana flour such as cooking, high-moisture treatment, storage and combinations of these, have shown to increase the slowly digestible starch and RS fractions. The physical treatments on unripe banana flour produce a powder that, because of the high amount of indigestible carbohydrates, can be considered as nutraceutical ingredient and can be used in products such as pasta and bakery products in which cooking is necessary, while maintaining a high amount of indigestible carbohydrates.

Interactive effects of warming, soil humidity and plant diversity on litter decomposition and microbial activity

Human activity has induced a multitude of global changes that are likely to affect the functioning of ecosystems. Although these changes act in concert, studies on interactive effects are scarce. Here, we conducted a laboratory microcosm experiment to explore the impacts of temperature (9, 12 and 15 °C), changes in soil humidity (moist, dry) and plant diversity (1, 4, 16 species) on soil microbial activity and litter decomposition. We found that changes in litter decomposition did not mirror impacts on microbial measures indicating that the duration of the experiment (22 weeks) may not have been sufficient to determine the full magnitude of global change effects. However and notably, changes in temperature, humidity and plant litter diversity/composition affected in a non-additive way the microbial parameters investigated. For instance, microbial metabolic efficiency increased with plant diversity in the high moisture treatment but remained unaffected in low moisture treatment suggesting that climate changes may mask beneficial effects of biodiversity on ecosystem functioning. Moreover, litter decomposition was unaffected by plant litter diversity/composition but increased with increasing temperature in the high moisture treatment, and decreased with increasing temperature in the low moisture treatment. We conclude that it is inevitable to perform complex experiments considering multiple global change agents in order to realistically predict future changes in ecosystem functioning. Non-additive interactions highlight the context-dependency of impacts of single global change agents.

Quantifying the impacts of soil water stress on the winter wheat growth in an arid region, Xinjiang

Wheat growth in response to soil water deficit play an important role in yield stability. A field experiment was conducted for winter wheat (Triticum aestivum L.) during the period of 2002-2005 to evaluate the effects of limited irrigation on winter wheat growth. 80%, 70%, 60%, 50% and 40% of field capacity was applied at different stages of crop growth. Photosynthetic charac- teristics of winter wheat, such as photosynthesis rate, transpiration rate, stomatal conductance, photosynthetically active radiation, and soil water content, root and shoot dry mass accumulation were measured, and the root water uptake and water balance in different layer were calculated. Based on the theory of unsaturated dynamic, a one-dimensional numerical model was developed to simulate the effect of soil water movement on winter wheat growth using Hydrus-1 D. The soil water content of stratified soil in the experimental plot was calculated under deficit irrigation. The results showed that, in different growing periods, evapotranspiration, grain yield, biomass, root water up- take, water use efficiency, and photosynthetic characteristics depended on the controlled ranges of soil water content. Grain yield response to irrigation varied considerably due to differences in soil moisture contents and irrigation scheduling between seasons. Evapotranspiration was largest in the high soil moisture treatment, and so was the biomass, but this treatment did not produce the highest grain yield and root water uptake was relatively low. Maximum depth of root water uptake is from the upper 80 cm in soil profile in jointing stage and dropped rapidly upper 40 cm after heading stage, and the velocity of root water uptake in latter stage was less than that in middle stage. The effect of limited irrigation treatment on photosynthesis was complex owing to microclimate. But root water uptake increased linearly with harvest yield and improvement in the latter gave better root water uptake under limited irrigation conditions. Appropriately controlled soil water contents can improve the root water uptake and grain yield. Consistently high values of root water uptake and grain yield were produced under conditions of mild water deficit at the seedling and start of regrowth to stem-elongation stages, in addition to a further soil water depletion at the physiological maturity to harvest stage. We suggest that periods of mild soil water depletion in the early vegeta- tive growth period together with severe soil water depletion in the maturity stage of winter wheat is an optimum for limited irrigation regime in this oasis. Considerable potential for further improve- ment in agricultural water use efficiency in the arid zone depends on effective conservation of moisture and efficient use of the limited water.

Evaluation of four grasses for use in phytoremediation of Cs-contaminated arid land soil

We used greenhouse experiments to evaluate cesium (Cs) uptake by four grasses, Agropyron spicatum (Pursh) Scribn & Smith, Leymus cinereus Scribn & Merr., Agropyron cristatum (L.) Gaertn. and Bromus tectorum L., to determine their potential as phytoremediation agents for Cs-contaminated soils. These four species grow well in the Intermountain region of western North America primarily on moderately coarse to coarsely textured soils where annual precipitation ranges from 20 to 50 cm. Whereas A. cristatum and B. tectorum are introduced species from Asia and the Mediterranean region of Europe, respectively, A. spicatum and L. cinereus are native to the Great Plains and Intermountain regions of North America. Plants were grown under two treatments each of: (1) soil Cs (ambient and 50 mg kg−1 + ambient), (2) soil fertility (ambient and ambient + 40 mg N kg−1 and 60 mg P kg−1), and 3) soil moisture (35% and 70% water holding capacity of the potted soils). Shoot Cs concentration in high soil Cs treatments was approximately ten times greater than in low soil Cs treatments. Even though shoot Cs concentrations tended to be lower in high soil Cs-high fertility-high soil moisture treatments than in high soil Cs-ambient fertility-low soil moisture treatments, total Cs uptake was greater because shoot biomass was approximately ten-fold greater. Shoots did not show signs of Cs toxicity in the high soil Cs treatments. We concluded, however, based on the low transfer factors (∼1.0) for all these grasses, that none were strong candidates as phytoremediation agents for Cs-contaminated soils.

Selected Additives Did Not Improve Flowability of DDGS in Commercial Systems

An experiment was conducted at a commercial, dry-grind ethanol plant to determine if selected additives would improve flowability of dried distillers grains with solubles (DDGS). Main treatment effects were moisture content of DDGS (9 vs. 12% w.b.) and anti-caking agent (ACA). The ACA treatments were: No additive (Control); a moisture migration control agent at 2.5 kg/metric ton (DMX-7); calcium carbonate at 2% w.b. (Calcium carbonate); or a clinoptilolite zeolite at 1.25% w.b. (Zeolite). The ACA were added at the desired level to about 2,275 kg of DDGS using a vertical-screw feed mixer. Batches of DDGS were weighed and loaded into one of eight compartments in an auger-equipped feed truck. After loading, the truck traveled 250 km, sat motionless for at least 60 h, and traveled 250 km back to the ethanol plant. Time required to unload each compartment was recorded. There were no significant interactions between moisture level and ACA for any response criteria. Mean moisture levels were 9% and 11.6% for low and high moisture treatments. Flow rate of DDGS at unloading was higher (P < 0.01) for the 9% compared with 12% moisture level (620 vs. 390 kg/min). Flow rates of DDGS at unloading were: 509 (Control), 441 (DMX-7), 512 (Calcium carbonate), and 558 (Zeolite) kg/min. None of the ACA created flow rates that differed significantly from Control. In conclusion, increasing moisture content from 9% to 11.6% clearly decreased flowability of DDGS. The ACA used in this experiment at the selected concentrations did not improve flowability of DDGS.

Moisture modulates rhizosphere effects on C decomposition in two different soil types

While it is well known that soil moisture directly affects microbial activity and soil organic matter (SOM) decomposition, it is unclear if the presence of plants alters these effects through rhizosphere processes. We studied soil moisture effects on SOM decomposition with and without sunflower and soybean. Plants were grown in two different soil types with soil moisture contents of 45% and 85% of field capacity in a greenhouse experiment. We continuously labeled plants with depleted 13C, which allowed us to separate plant-derived CO 2-C from original soil-derived CO 2-C in soil respiration measurements. We observed an overall increase in soil-derived CO 2-C efflux in the presence of plants (priming effect) in both soils. On average a greater priming effect was found in the high soil moisture treatment (up to 76% increase in soil-derived CO 2-C compared to control) than in the low soil moisture treatment (up to 52% increase). Greater plant-derived CO 2-C and plant biomass in the high soil moisture treatment contributed to greater priming effects, but priming effects remained significantly higher in the high moisture treatment than in the low moisture treatment after correcting for the effects of plant-derived CO 2-C and plant biomass. The response to soil moisture particularly occurred in the sandy loam soil by the end of the experiment. Possibly, production of root exudates increased with increased soil moisture content. Root exudation of labile C may also have become more effective in stimulating microbial decomposition in the higher soil moisture treatment and sandy loam soil. Our results indicate that moisture conditions significantly modulate rhizosphere effects on SOM decomposition.