scholarly journals Physical Properties of Ground Fresh Rice Hulls and Sphagnum Peat Used for Greenhouse Root Substrates

2008 ◽  
Vol 18 (3) ◽  
pp. 384-388 ◽  
Author(s):  
Paolo Sambo ◽  
Franco Sannazzaro ◽  
Michael R. Evans
Keyword(s):  
Oryza Sativa ◽  
Physical Properties ◽  
Water Content ◽  
Pore Space ◽  
Rice Hull ◽  
Water Release ◽  
Rice Hulls ◽  
Available Water ◽  
Available Water Content ◽  
Water Holding

Ground fresh rice (Oryza sativa) hull materials were produced by grinding whole fresh rice hulls and passing the resulting product through a 1-, 2-, 4- or 6-mm-diameter screen to produce a total of four ground rice products (RH1, RH2, RH4, and RH6, respectively). The physical properties and water release characteristics of sphagnum peatmoss (peat) and the four ground rice hull products were evaluated. All of the ground rice hull products had a higher bulk density (Bd) than peat, and as the grind size of the rice hull particle decreased, Bd increased. Peat had a higher total pore space (TPS) than all of the ground rice hull products except for RH6. As grind size decreased, the TPS decreased. Peat had a lower air-filled pore space (AFP) than all of the ground rice hull products and as the grind size of the rice hull products decreased, AFP decreased. Peat had a higher water holding capacity (WHC) than all of the ground rice hull products. Grind sizes RH4 and RH6 had similar WHC, whereas RH1 and RH2 had a higher WHC than RH4 and RH6. Peat, RH4, and RH6 had similar available water content (AVW), whereas RH2 had higher AVW than these materials and RH1 had the highest AVW. However, peat had the lowest AVW and easily available water (EAW) as a percentage of the WHC. The ground rice hull products RH1 and RH2 had the highest AVW and EAW of the components tested. Peat had the highest water content at container capacity. As pressure was increased from 1 to 5 kPa, peat released water more slowly than any of the ground rice hull products. The RH1 and RH2 ground hull products released water at a significantly higher rate than peat, but RH4 and RH6 released the most water over these pressures. For all rice hull products, most water was released between 1 and 2 kPa pressure. The rice hull products RH1 and RH2 had physical properties that were within recommended ranges and were most similar to those of peat.

scholarly journals Physical Properties of Ground Parboiled Fresh Rice Hulls Used as a Horticultural Root Substrate

HortScience ◽  
2010 ◽  
Vol 45 (4) ◽  
pp. 643-649 ◽  
Author(s):  
Johann S. Buck ◽  
Michael R. Evans
Keyword(s):  
Physical Properties ◽  
Particle Density ◽  
Pore Space ◽  
Pine Bark ◽  
Rice Hull ◽  
Hammer Mill ◽  
Parboiled Rice ◽  
Greenhouse Crops ◽  
Rice Hulls ◽  
Water Holding

Fresh parboiled rice hulls ground in a hammer mill and screened through a 1.18-mm screen and collected on a 0.18-mm screen (RH3) and particles with a specific diameter of 0.5 to 1.0 mm had total pore space (TPS), air-filled pore space (AFP), and water-holding capacity (WHC) similar to that of Canadian sphagnum peat (peat). However, RH3 had more available water, a higher bulk density (BD), and a higher particle density (PD) than peat. When blended with 20% to 40% perlite or 1 cm aged pine bark, RH3-based substrates had lower TPS, similar AFP, and lower WHC than equivalent peat-based substrates. The RH3-containing substrates had higher BD and average PD than equivalent peat-based substrates. When blended with parboiled rice hulls (PBH), RH3-based substrates had lower TPS than equivalent peat-based substrates. When blended with 20% to 40% PBH, RH3-based substrates had lower AFP than equivalent peat-based substrates. RH3-based substrates containing up to 20% PBH had lower WHC than equivalent peat-based substrates. RH3-based substrates containing 40% PBH had a higher WHC than equivalent peat-based substrates. When blended with PBH, all RH3-based substrates had higher BD and average PD than equivalent peat-based substrates. The addition of 40% RH3 to a peat-based substrate containing 20% perlite decreased substrate TPS, whereas the addition of 10% to 40% decreased AFP. The addition of 10% to 30% RH3 increased WHC. The addition of 30% RH3 to a peat-based substrate containing 20% 1 cm aged pine bark decreased substrate TPS and the addition of 20% to 40% RH3 decreased AFP. The addition of 10% RH3 increased WHC, but the addition of 20% or more RH3 did not affect WHC. The addition of 30% RH3 increased the BD, but the addition of RH3 had no effect on average PD. The addition of 20% or more and 30% or more RH3 to a peat-based substrate containing 20% PBH decreased substrate TPS and AFP, respectively. The addition 20% RH3 decreased WHC. The addition of 10% to 40% RH3 increased BD. Overall, RH3 was the ground rice hull product that had physical properties most similar to peat. Peat-based substrates in which up to 40% of the peat was replaced with RH3 had physical properties that, although different from peat controls, were within commonly recommended ranges for substrates used to grow greenhouse crops.

scholarly journals Physical Properties of Whole Fresh-ground Parboiled Rice Hulls for Use as a Horticultural Root Substrate

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 979B-979
Author(s):  
Johann S. Buck ◽  
Michael R. Evans ◽  
Paolo Sambo
Keyword(s):  
Plant Growth ◽  
Physical Properties ◽  
Bulk Density ◽  
Pore Space ◽  
Water Holding Capacity ◽  
Rice Hull ◽  
Particle Sizes ◽  
Parboiled Rice ◽  
Rice Hulls ◽  
Water Holding

Horticultural root substrates are designed to provide the optimal physical properties for plant growth. These properties include bulk density (g·cm-3), air-filled pore space (% v/v), total pore space (% v/v), water-filled pore space (% v/v), water-holding capacity (% v/v and w/w), and wettability. Whole, fresh parboiled rice hulls were ground to produce four grades with varying particle size distributions. Particle sizes for the four grades ranged from <0.25 to >2.80 mm. Additionally, discrete particle sizes of <0.25, 0.50, 1.00, 2.00, 2.80, and >2.80 mm were produced. For all grade distributions and particle point sizes, physical properties were determined and contrasted against Canadian sphagnum peat. As the proportion of smaller particle sizes in the distributions increased or as the particle point sizes decreased, total pore space (% v/v) and air-filled pore space (% v/v) decreased, while, bulk density (g·cm-3) and water-holding capacity (% v/v and w/w) increased. Additionally, as the proportion of particle sizes from <0.25–0.50 mm increased, the wettabilty of the whole fresh parboiled rice hull material decreased. Particle sizes ranging from 1.00–2.80 mm possessed the physical properties most suitable for plant growth in containerized greenhouse crop production and were most similar to peat.

scholarly journals Physical Properties of Sphagnum Peat-based Root Substrates Amended with Perlite or Parboiled Fresh Rice Hulls

2007 ◽  
Vol 17 (3) ◽  
pp. 312-315 ◽  
Author(s):  
Michael R. Evans ◽  
Mary M. Gachukia
Keyword(s):  
Physical Properties ◽  
Pore Space ◽  
Water Holding Capacity ◽  
Practical Significance ◽  
Equivalent Amount ◽  
Rice Hulls ◽  
Sphagnum Peat ◽  
Rate Of Increase ◽  
Water Holding

Ten substrates were formulated by blending perlite or parboiled fresh rice hulls (PBH) to produce root substrates (substrates) that contained either 20%, 30%, 40%, 50%, or 60% (by volume) perlite or PBH, with the remainder being sphagnum peatmoss. All substrates containing PBH had higher total pore space than substrates containing an equivalent amount of perlite. As the percentage perlite increased from 20% to 60%, the total pore space decreased. The total pore space increased as the amount of PBH increased to 50% and then decreased as the amount of PBH increased from 50% to 60%. The air-filled pore space was not different between substrates containing 20% perlite or PBH. However, the air-filled pore space was higher in PBH-containing substrates than in equivalent perlite-containing substrates when the amount of PBH or perlite was at least 40%. As the amount of perlite or PBH was increased, the air-filled pore space increased, but the rate of increase was higher for PBH-containing substrates. The 20% PBH-containing substrate had a higher water-holding capacity than the 20% perlite-containing substrate. However, at 30% or higher PBH, the PBH-containing root substrates had a lower water-holding capacity than equivalent perlite-containing substrates. As the percentage perlite or PBH was increased, the water-holding capacity decreased, but at a higher rate in PBH-containing substrates than in perlite-containing substrates. For all substrates except those containing 40% PBH or perlite, substrates containing PBH had lower bulk densities than equivalent perlite-containing substrates. The differences in bulk densities were not great enough to be of practical significance. Inclusion of PBH in the substrate provided for drainage and air-filled pore space as did perlite. However, less PBH would be required in a substrate to provide the same air-filled pore space as perlite when more than 20% perlite or PBH is used.

scholarly journals Physical Properties of and Plant Growth in Peat-based Root Substrates Containing Glass-based Aggregate, Perlite, and Parboiled Fresh Rice Hulls

2011 ◽  
Vol 21 (1) ◽  
pp. 30-34 ◽  
Author(s):  
Michael R. Evans
Keyword(s):  
Plant Growth ◽  
Physical Properties ◽  
Bulk Density ◽  
Catharanthus Roseus ◽  
Pore Space ◽  
Santa Fe ◽  
Rice Hulls ◽  
Sphagnum Peat ◽  
Impatiens Walleriana ◽  
Water Holding

Aggregates produced from finely ground waste glass [Growstones (GS); Earthstone Corp., Santa Fe, NM] have been proposed to adjust the physical properties of peat-based substrates. The GS had a total pore space (TPS) of 87.4% (by volume), which was higher than that of sphagnum peat and perlite but was similar to that of parboiled fresh rice hulls (PBH). The GS had an air-filled pore space (AFP) of 53.1%, which was higher than that of sphagnum peat and perlite but lower than that of PBH. At 34.3%, GS had a lower water-holding capacity (WHC) than sphagnum peat but a higher WHC than either perlite or PBH. The bulk density of GS was 0.19 g·cm−3 and was not different from that of the perlite but was higher than that of sphagnum peat and PBH. The addition of at least 15% GS to sphagnum peat increased the AFP of the resulting peat-based substrate. Substrates containing 25% or 30% GS had a higher AFP than substrates containing equivalent amounts of perlite but a lower AFP than substrates containing equivalent PBH. Substrates containing 20% or more GS had a higher WHC than equivalent perlite- or PBH-containing substrates. Growth of ‘Cooler Grape’ vinca (Catharanthus roseus), ‘Dazzler Lilac Splash’ impatiens (Impatiens walleriana), and ‘Score Red’ geranium (Pelargonium ×hortorum) was similar for plants grown in GS-containing substrates and those grown in equivalent perlite- and PBH-containing substrates.

scholarly journals Factors determining the soil available water during the last two decades (1997–2019) in southern Spain

2021 ◽  
Vol 14 (19) ◽  
Author(s):  
José A. Sillero-Medina ◽  
Jesús Rodrigo-Comino ◽  
José D. Ruiz-Sinoga
Keyword(s):  
Climate Change ◽  
Water Content ◽  
Southern Spain ◽  
Retention Capacity ◽  
Essential Information ◽  
Hydrological Conditions ◽  
Available Water ◽  
Available Water Content ◽  
The Mediterranean ◽  
The Impact

AbstractAssessing soil hydrological conditions can provide essential information for understanding the environmental processes that affect ecosystem services and, particularly in the context of ongoing climate change. This is key in areas affected by water scarcity such as the Mediterranean belt. Therefore, the main goals of this research are (i) to assess the main rainfall dynamics and trends of some representative hotspots along with southern Spain and (ii) to determine the impact on the soil available water content (AWC) over the last two decades. An analysis of daily precipitation and soil hydrological conditions was combined with soil sampling (543) and laboratory analyses to evaluate the properties related to the soil infiltration and retention capacity. The results show that the organic factors control soil properties and their hydrodynamics in southern Spain. Furthermore, a general declining trend in soil water availability is observed over the last two decades. This is more extreme in arid and semi-arid areas, where there have been several years in the last decade with more than 200 days without the available water content. Moreover, in these areas, heavy rainfall during specific moments of the year is the key factor that manifests a greater incidence in areas with steeper slopes, which in turn, also conditions the biological factors and the hydrodynamics of the soil. In short, in the context of climate change, the analysis of soil hydrological dynamics could be used to identify biodiversity thresholds in the Mediterranean area and even to detect phenological changes in specific plant species.

Quantification of Available Water Capacity Comparing Standard Methods and a Pedostructure Method on a Weakly Structured Soil

2019 ◽  
Vol 62 (2) ◽  
pp. 289-301
Author(s):  
Amjad T. Assi ◽  
Rabi H. Mohtar ◽  
Erik F. Braudeau ◽  
Cristine L. S. Morgan
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Field Capacity ◽  
Soil Aggregate ◽  
Pedotransfer Functions ◽  
Water Retention Curve ◽  
Aggregate Structure ◽  
Standard Methods ◽  
Available Water ◽  
Water Holding

Abstract. The purpose of this study was to evaluate the use of the pedostructure concept to determine the soil available water capacity, specifically the field capacity (FC). Pedostructure describes the soil aggregate structure and its thermodynamic interaction with water. Specifically, this work compared the calculation of soil water-holding properties based on the pedostructure concept with other standard methods for determining FC and permanent wilting point (PWP). The standard methods evaluated were the FAO texture estimate (FAO method), the Saxton-Rawls pedotransfer functions (PTFs method), and the water content at predefined soil suction (330 and 15,000 hPa) as measured with a pressure plate apparatus (PP method). Additionally, two pedostructure methods were assessed: the thermodynamic water retention curve (TWRC method) and the thermodynamic pedostructure (TPC method). Undisturbed loamy fine sand soil from a field in Millican, Texas, was analyzed at both the Ap and E horizons. The results showed that the estimated water content at FC and PWP for the three standard methods and for the TWRC method were in relative agreement. However, the TPC method used characteristic transition points in the modeled contents of different water pools in the soil aggregate and was higher for the Ap horizon, but in agreement with the other methods for the E horizon. For example, for the Ap horizon of the soil analyzed in this study, the FC estimated with the standard and TWRC methods ranged from 0.073 to 0.150 m3H2O m-3soil, while the TPC method estimate was 0.221 m3H2O m-3soil. Overall, the different methods showed good agreement in estimating the available water; however, the results also showed some variations in these estimates. It is clear that the TPC method has advantages over the other methods in considering the soil aggregate structure and modeling the soil water content within the aggregate structure. The thermodynamic nature of the TPC method enabled the use of both the soil shrinkage curve and the water retention curve in a weakly structured soil. It is expected that the TPC method would provide more comprehensive advances in understanding the soil water-holding properties of structured soils with higher clay contents. Keywords: Available water, Field capacity, Pedostructure, Pedotransfer functions, Permanent wilting point.

scholarly journals Soil typologies in the wine-growing areas of Mallorca, with special emphasis on available water content.

2018 ◽  
Vol 50 ◽  
pp. 01011
Author(s):  
Joan Rossello ◽  
José M. Escalona ◽  
Josep Cifre ◽  
Jaume Vadell ◽  
Hipólito Medrano
Keyword(s):  
Water Content ◽  
Water Availability ◽  
Soil Depth ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Available Water ◽  
Available Water Content ◽  
Water Classification ◽  
Grape Varieties ◽  
Very High

Under the conditions of the semi-arid Mediterranean climate, soil depth and water retention capacity are the most important characteristics of the soil related to the quality of the wines. The availability of water will mark the development of the vines and the development and maturity of the grape. The characterization and agronomic evaluation of the soil has been carried out from the excavation of 38 soil pits in the main wine growing areas of Mallorca. Cambisols are the most predominant soil typology followed by Cambisols, Regosols and Luvisols. The water classification of the soils has been made according to the maximum water availability (useful water) in 2 m of soil (mm water / 2 m soil). The proposed levels are: very low (<120 mm), low (120-180 mm), Medium (180-240 mm), High (240-300 mm) and Very high> 300 (mm). The most abundant soil type we find that 47% have high soil water availability, 27% very high, 14% normal and 14% low. Establishing an area based on available water content is a tool that allows us to adjust the selection of the most suitable grape varieties in each soil, thus taking advantage more efficiently of the potential of each type of grape.

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