Quantity and biodegradability of dissolved organic matter released from sequentially leached soils, as influenced by the extent of soil drying prior to rewetting

Soil rewetting can induce a flush of organic matter mineralisation, but the factors underpinning this mineralisation response are poorly understood. We investigated the effects of antecedent soil water content, before rewetting, on the quantity, quality and biodegradability of dissolved organic matter present in the leachate pore volumes from a soil under two different management histories: arable and grassland. Soils were collected at field capacity (FC) and dried to give four soil gravimetric water contents (θg): 22% (not dried, left at FC), 15%, 8% and <2% (air dry, AD). Soils were repacked to the same bulk density (1.1 g cm–3) and each core was sequentially leached, with four pore volumes collected. The total amount of dissolved organic carbon (DOC) leached increased (P < 0.001) only in the soils that had been air-dried before rewetting (3.8 and 5.3 mg g–1 soil C, for arable and grassland respectively), while among the other θg treatments differences were relatively small (1.6–2.4 mg g–1 soil C). The pre-rewetting θg treatment affected the DOC content of the pore volume leached (P < 0.001): in the grassland soil, the DOC of the AD treatment was consistently twice as high as the other θg treatments, but this trend was not as consistent in the arable soil. For all θg treatments and both soils, specific ultraviolet absorbance at 254 nm increased as leaching progressed. Biodegradability, expressed as cumulative CO2 produced per unit of DOC in leachates, was significantly lower in the first pore volume of all treatments in the grassland soil and increased with sequential leaching. In the arable soil, differences were small or insignificant across the pore volumes leached, but were large and inconsistent across the θg treatments. These findings improve our understanding of how antecedent soil water content affects the quantity and quality of dissolved organic matter released when soils are rewetted, and the potential for soil carbon losses.

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Response of Decagon 10HS soil water content sensor to different porous media

10.5194/egusphere-egu2020-5751 ◽

2020 ◽

Author(s):

Giuseppe Provenzano ◽

Giovanni Gugliuzza ◽

Ceres Duarte Guedes Cabral de Almeida

Keyword(s):

Water Content ◽

Bulk Density ◽

Soil Water ◽

Soil Water Content ◽

Irrigation Management ◽

Mineral Soil ◽

The Other ◽

Organic Substrates ◽

Soil C ◽

Other Hand

Optimizing irrigation management requires increasing the accuracy of moisture monitoring in soils or substrates, especially when it depends on electronic sensor readings. Substrates are widely used in horticulture, for growing urban ornamental plants, as well as on green roofs. Due to the lack of information about the accuracy of soil water content sensors on substrates, this research was carried out to evaluate the accuracy of the 10HS sensor (Decagon Devices Inc., Pullman, WA) to estimate soil water content (SWC) in organic substrates and mineral soil. The study was carried out at the Hydrology Laboratory of the University of Palermo. The sensors were inserted into substrates or soil in conical vessels (4 dm3 volume), drilled at the base to measure the drained volume and covered with a transparent film to limit surface evaporation. For both the substrates (A and B) and the mineral soil (C), a known amount was placed in the vessel and compacted to a value of bulk density equal to 0.177 g cm-3, 0.471 g cm-3, 1.480 g cm-3, respectively. The sensors were connected to a CR1000 datalogger (Campbell Scientific Inc., Logan, UT), which allowed the data acquisition and storage. The tests were conducted by wetting the samples with the progressive addition of known volumes of water (about 40 cm3) that were evenly distributed over the sample surface. After the end of the redistribution process of water applied to the container, the sensor readings were acquired. SWC monitoring was performed until reaching the value corresponding to the field capacity. The calibration equation recommended by the sensor manufacturer systematically underestimated the values of SWC of about 5% or more when the substrate A and B were used. On the other hand, when evaluating the sensor performance in the mineral soil (C), it was observed that the errors associated with the manufacturer's equation resulted in &#177;5%. Therefore, for both substrates specific calibration is necessary to improve the sensor&#8217;s accuracy, even accounting for the bulk density; on the other hand, for the mineral soil, the manufacturer's equation can be considered suitable.

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Changes in Soil Water Content with Ambient Relative Humidity in Relation to the Organic Matter and Clay

Tropical Agricultural Research and Extension ◽

10.4038/tare.v13i1.3130 ◽

2011 ◽

Vol 13 (1) ◽

pp. 6 ◽

Cited By ~ 9

Author(s):

DAL Leelamanie

Keyword(s):

Organic Matter ◽

Relative Humidity ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Ambient Relative Humidity

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Adsorption and Diffusion of Dinitroaniline Herbicides in Soils

Weed Science ◽

10.1017/s0043174500044362 ◽

1979 ◽

Vol 27 (4) ◽

pp. 450-455 ◽

Cited By ~ 18

Author(s):

G. L. Jacques ◽

R. G. Harvey

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Water Content ◽

Soil Water ◽

The Other ◽

Silt Loam ◽

Relative Mobility ◽

Water Saturated ◽

And Diffusion ◽

Dinitroaniline Herbicides

Adsorption of benefin (N-butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine), dinitramine (N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine), fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)aniline], oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide), profluralin [N-(cyclopropylmethyl)-α,α,α-tri-fluoro-2,6-dinitro-N-propyl-p-toluidine], and trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) was studied in 10 Wisconsin soils. Ratios of the quantity of each herbicide adsorbed and quantities remaining in the soil solution at equilibrium (Kd value) on a Piano silt loam (Typic Argiudoll fine-silty, mixed, mesic) remained relatively constant over a range of concentrations. Herbicide adsorption by the soils was related more closely to soil organic matter than to the other soil chemical and physical properties. Diffusion of the herbicides in Piano silt loam was affected by soil water. Diffusion of trifluralin, profluralin and benefin decreased as soil water increased. Diffusion of dinitramine and fluchloralin did not change significantly with change in water content. Diffusion of oryzalin increased at the highest soil water content. None of the herbicides moved more than 10 mm in the soil during a 17-day period. In unsaturated Piano silt loam, relative mobility of the herbicides was trifluralin ≥benefin>profluralin>fluchloralin>dinitramine≥oryzalin. Oryzalin reached highest mobility in water-saturated soil.

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Effects of Ecological Projects on Grassland Soil Physicochemical Properties in Three-River Headwater

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.807-809.843 ◽

2013 ◽

Vol 807-809 ◽

pp. 843-847

Author(s):

Xu Dong Zhao ◽

De Gang Zhang ◽

Li Na Shi ◽

Yong Shun Yang

Keyword(s):

Organic Matter ◽

Physicochemical Properties ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Available Phosphorus ◽

Soil Physicochemical Properties ◽

Total N ◽

Effective Measure ◽

Artificial Grassland

The depth variations of soil physicochemical properties in the degraded native grasslands and the artificially restored grasslands were studied in the Three-river headwater areas of Qinghai-Tibetan plateau, China. The results showed: (1) With the increase of the gradient of restoration years, soil water content, total chemical properties, total potassium, phosphorus, available phosphorus and potassium were increased thereafter in the artificial grasslands. (2) With the increase of grassland degradation gradient, soil water content was gradually reduced, and the total N, K, the organic matter didnt gradually reduced also. (3) Both restoration years and degradation degree didnt influence the nutrient distribution in soil. (4) The organic matter, total N and K of degraded grassland were increased by artificial grassland construction. Therefore, artificial grassland construction canbe used as an effective measure of ecological projects in the Three-river headwater area.

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Distribution of carbon and nutrients and fluxes of mineral nitrogen after clear-felling a Pinusradiata plantation

Canadian Journal of Forest Research ◽

10.1139/x90-197 ◽

1990 ◽

Vol 20 (9) ◽

pp. 1490-1497 ◽

Cited By ~ 63

Author(s):

P. J. Smethurst ◽

E. K. S. Nambiar

Keyword(s):

Organic Matter ◽

Soil Temperature ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

N Mineralization ◽

Soil Depth ◽

Mineral N ◽

Southeastern Australia ◽

Nutrients Fluxes

The effects of clear-felling and slash removal on the distribution of organic matter and nutrients, fluxes of mineral N, and soil water and temperature were studied in a 37-year-old Pinusradiata D. Don plantation, on a sandy Podzol in southeastern Australia. Slash, litter, and the top 30 cm of soil combined contained 1957 kg N•ha−1, of which slash and litter contained 12 and 25%, respectively. Therefore, loss of slash and litter due to burning or other intensive site preparation practices would substantially reduce the N capital at the site. During the first 18 months after clear-felling, soil water content in the clear-felled area was up to 50% higher than in the uncut plantation, but there were only minor differences in soil temperature. Slash removal decreased the water content of litter, but had little effect on the water content or temperature of the soil. In the uncut plantation, N mineralized in litter and soil was completely taken up by the trees. Following clear-felling, rates of N mineralization increased in litter after 4 months, and in soil after 12 months, but changes were less pronounced with slash removal. After clear-felling, increased mineralization and the absence of trees (no uptake) led to increased concentrations of mineral N in both litter and soil, 64–76% of which was leached below the 30 cm soil depth prior to replanting. Despite leaching, concentrations of mineral N after clear-felling remained higher than those in the uncut plantation for at least 3 years.

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Evaluation of Improved Model to Accurately Monitor Soil Water Content

Water ◽

10.3390/w13233441 ◽

2021 ◽

Vol 13 (23) ◽

pp. 3441

Author(s):

Jingyu Ji ◽

Junzeng Xu ◽

Yixin Xiao ◽

Yajun Luan

Keyword(s):

Organic Matter ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Soil Texture ◽

Irrigation Management ◽

Clay Fraction ◽

Organic Matter Content ◽

Matter Content ◽

Improved Model

The accurate monitoring of soil water content during the growth of crops is of great importance to improve agricultural water use efficiency. The Campbell model is one of the most widely used models for monitoring soil moisture content from soil thermal conductivities in farmland, which always needs to be calibrated due to the lack of adequate original data and the limitation of measurement methods. To precisely predict the water content of complex soils using the Campbell model, this model was evaluated by investigating several factors, including soil texture, bulk density and organic matter. The comparison of the R2 and the reduced Chi-Sqr values, which were calculated by Origin, was conducted to calibrate the Campbell model calculated. In addition, combining factors of parameters, a new parameter named m related to soil texture and the organic matter was firstly introduced and the original fitting parameter, E, was improved to an expression related to clay fraction and the organic matter content in the improved model. The soil data collected from both the laboratory and the previous literature were used to assess the revised model. The results show that most of the R2 values of the improved model are >0.95, and the reduced Chi-Sqr values are <0.01, which presents a better matching performance compared to the original. It is concluded that the improved model provides more accurate monitoring of soil water content for water irrigation management.

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