Congreso Nacional de la Ciencia del Suelo Punta Arenas – 2014 COMPOST EFFECTS ON MICROBIAL BIOMASS AND SOIL P POOLS AS AFFECTED BY PARTICLE SIZE AND SOIL PROPERTIES Lata, S. & Marschner, P. (School of Agriculture, Food and Wine, The University of Adelaide). e-mail: [email protected] RESUMEN (o) ABSTRACT
Previous studies have shown that finer composts release nutrients more quickly than coarse composts, but little is known about the nutrient release from different size fractions of a compost. To assess if compost size fractions differ in their effect on microbial biomass and soil P pools, a compost from garden waste was separated by sieving into different particle size fractions (> 5 mm, 3-5 mm and < 3 mm) and then mixed into three different soils (referred as soil A, B and C) at a rate of 50 mg total P kg-1. These soils were chosen because the size of soil P pools could be affected by soil properties which may also influence how the P pools respond to compost addition. Cumulative soil respiration, microbial biomass and soil P pools were determined after 25 and 50 days. Compost addition increased soil respiration and micobial biomass C and P, with the greatest increase in respiration with the > 5 mm fraction and in microbial biomass C and P with the < 3 mm fraction. The size of the P pools was mainly affected by soil type, the compost fractions had similar effects on soil P pools except for a greater increase in available P concentration by the finest fraction compared to the coarser size fractions. Soil A with the highest organic matter content had the highest concentrations of Fe/Al associated P (NaOH-P) and organic P whereas Ca-associated P (HCl-P) dominated in the alkaline soil C. The size of most P pools, even the so-called stable P pools changed over time in amended and non-amended soils. It can be concluded that the size of P pools is more strongly affected by soil properties such as organic matter content, texture and pH than by the compost fractions. Palabras clave: size fractions, soil properties, temporal changes COMPOST EFFECTS ON MICROBIAL BIOMASS AND SOIL P POOLS AS AFFECTED BY PARTICLE SIZE AND SOIL PROPERTIES Lata, S. & Marschner, P. (School of Agriculture, Food and Wine, The University of Adelaide). e-mail: [email protected] RESUMEN (o) ABSTRACT
Previous studies have shown that finer composts release nutrients more quickly than coarse composts, but little is known about the nutrient release from different size fractions of a compost. To assess if compost size fractions differ in their effect on microbial biomass and soil P pools, a compost from garden waste was separated by sieving into different particle size fractions (> 5 mm, 3-5 mm and < 3 mm) and then mixed into three different soils (referred as soil A, B and C) at a rate of 50 mg total P kg-1. These soils were chosen because the size of soil P pools could be affected by soil properties which may also influence how the P pools respond to compost addition. Cumulative soil respiration, microbial biomass and soil P pools were determined after 25 and 50 days. Compost addition increased soil respiration and micobial biomass C and P, with the greatest increase in respiration with the > 5 mm fraction and in microbial biomass C and P with the < 3 mm fraction. The size of the P pools was mainly affected by soil type, the compost fractions had similar effects on soil P pools except for a greater increase in available P concentration by the finest fraction compared to the coarser size fractions. Soil A with the highest organic matter content had the highest concentrations of Fe/Al associated P (NaOH-P) and organic P whereas Ca-associated P (HCl-P) dominated in the alkaline soil C. The size of most P pools, even the so-called stable P pools changed over time in amended and non-amended soils. It can be concluded that the size of P pools is more strongly affected by soil properties such as organic matter content, texture and pH than by the compost fractions. Palabras clave: size fractions, soil properties, temporal changes
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