Compaction Of Media Research Articles

Soil compaction and its effects on soil microbial communities inCapsicumgrowing soil

Soil compaction is a serious problem confronting horticultural production systems globally and occurs more readily in tropical systems as a consequence of wet-dry climatic oscillations in these regions. Soil compaction alters soil microbial structure and function as a result of the limitation of air permeability and oxygen availability, which has implications for soil nutrition and soil-borne disease. This study investigates the influence of compaction on soil microbial functional diversity and activity in the presence and absence of capsicum plant roots, and with the addition of compost or changes to irrigation regimes, both of which are management strategies traditionally designed to reduce compaction in the paddock. Experimental treatments of four levels of soil compaction were established, with or without capsicum seedlings planted into the compacted media. A further experimental set-up, with two water treatments (optimal or low) and compost additions in factorial combination with compaction was also established. The findings revealed that microbial functional diversity and activity was higher in uncompacted bare (unplanted) soil compared to soil with the presence of capsicum plant roots. Further, there were lower levels of activity at higher soil compaction levels, and lower functional diversity. The results suggest that compaction is a significant driver of soil microbial health in sub-tropical horticultural systems, particularly when soil moisture and soil carbon is low, and that careful ongoing management of compaction will be required.

Compaction of chemically defined cell culture media increases its dissolution rate through an increase of solvent accessible surface area

Cultivation of mammalian cells for the generation of therapeutics requires the use of cell culture media which is a defined mixture of nutrients including carbohydrates, amino acids, lipids, vitamins, and inorganic salts. Its composition influences the cell density, yield, and quality of the molecule expressed. These chemically defined cell culture media are manufactured as powders since they offer advantages of storage, handling and stability. To prevent de-mixing of the powders and maintain homogeneity, these powders are milled down to small particle size ranges. However, this small particle size allows for inter-particle forces to impact powder flow properties, and decreases the surface area available to dissolution. Hence a method is required that improves these powder parameters, without altering their composition. A deeper understanding of the dissolution mechanism of multi-component mixtures like cell culture media is also needed. Here, cell culture media granules, generated from homogeneous powders by roller compaction are evaluated. The granulation process did not alter the composition of the media and properties of solutions generated thereof. The analysis and comparison of the dissolution profile of powder and compacted media enabled the calculation of the actual surface area available to dissolution. The improvement in granule dissolution can be attributed to dispersion and disintegration of the granules on wetting increasing available surface area. Decrease in inter-particle forces in granules also improves flow-ability properties. Surface character and pores on the granules further augments the improvement in dissolution.

Compaction of an Oxisol and chemical composition of palisadegrass

Compaction is an important problem in soils under pastoral land use, and can make livestock systems unsustainable. The objective of this research was to study the impact of soil compaction on yield and quality of palisade (UROCHLOA BRIZANTHA cv. Marandu). The experiment was conducted on an Oxisol in the State of Mato Grosso, Brazil. Treatments consisted of four levels of soil compaction: no compaction (NC), slight compaction (SC), medium compaction (MC) and high compaction (HC). The following soil properties were evaluated (layers 0-0.05 and 0.05-0.10 m): aggregate size distribution, bulk density (BD), macroporosity, microporosity, total porosity (TP), relative compaction (RC), and the characteristics of crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and dry matter yield (DMY) of the forage. Highly compacted soil had high BD and RC, and low TP (0-0.05 m). Both DMY and CP were affected by HC, and both were strongly related to BD. Higher DMY (6.96 Mg ha-1) and CP (7.8 %) were observed in the MC treatment (BD 1.57 Mg m-3 and RC 0.91 Mg m-3, in 0-0.05 m). A high BD of 1.57 Mg m-3 (0-0.05 m) did not inhibit plant growth. The N concentration in the palisade biomass differed significantly among compaction treatments, and was 8.72, 11.20, 12.48 and 10.98 g kg-1 in NC, SC, MC and HC treatments, respectively. Increase in DMY and CP at the MC level may be attributed to more absorption of N in this coarse-textured soil.

Establishment of Prairie Forbs and Grasses after Production in Compacted Media

Native prairie plants are believed to grow better in compacted soils than traditional bedding plants. We used 10 species of forbs and grasses to test the hypothesis that establishment in the field would be improved by greenhouse production of seedlings in compacted media and in topsoil as opposed to a peat-based medium. Media were compacted by applying 50 g·cm–2 while filling cells in a tray. Uncompacted controls were simply loose-filled. The seedlings were transplanted into plots that were untilled or tilled. Plants were photographed with a digital camera at different stages and the images were analyzed by computer to estimate growth non-destructively. At the time of transplanting estimated area per seedling was 15 to 140% higher for plants grown in compacted media than in uncompacted for 10 out of 13 species. Preliminary observations indicated that differences between plants from compacted and uncompacted media persisted in the field and that plants grew better in the tilled plots than in untilled. Seedling area was similar after production in topsoil or peat medium and there was no overall difference in the field. Plants from seedlings produced in topsoil were larger than those from peat-based medium in untilled plots but the converse was true for plants in tilled plots.

Effect of Soil Compaction on Physical Properties of Potting Media and Growth of Pilea pubescens Liebm. ‘Silver Tree’1

Abstract Physical characteristics were determined for 5 potting media composed of varying ratios of Florida sedge peat and pine bark subjected to compaction pressures of 0.0, 0.1, 0.2, or 0.3 kg/cm2. Percent noncapillary pore space decreased as compaction pressure and amount of peat in the mixture increased, while water holding capacity by volume increased with peat addition and compaction pressure. Top growth of Pilea pubescens ‘Silver Tree’ in compacted media was generally as good as in noncompacted media, but root growth was restricted.