The Influence of Aging of P Fertilizer and Rainfall on the Yield and P Uptake by Setaria

An experiment to look into the influence of aging of phosphorus (P) fertilizer, P forms, P levels and rainfall on the yield and P uptake by pasture grass Setaria splendida on a Bungor Series soil (Typic Paleudult) was carried out. It was concluded that P treatment levels have more influence than the aging and forms of P fertilizer used on the dry matter yield and P uptake by Setaria. Variations in rainfall during the growing period of Setaria could account for up to a difference of39% in dry matter yield and 20% of the P taken up

Automised potentiometric end point titration for carbon and organic matter determinations.

Pengukuran bahan organik tanah dengan metode "Dichromate Wet Combustion" meliputi proses titrasi senyawa dikhromat yang tersisa dengan menggunakan ion ferro. Titrasi redoks potensiometrik diduga mampu berperan sebagai pengganti metode indikator warna diphenllamina. Modifikasi ini memungkinkan pengukuran akhir yang cepat dan teliti, dan dapat diandalkan bagi laboratoria yang analisis rutinnya mencakup pengukuran bahan organik. Metode usulan ini diperbandingkan dengan metode konvensional Walkley dan Black, untuk tanah-tanah mineral yang berbeda dari Jawa Barat dan Jawa Tengah, untuk gambut untuk kompos dan limbah organik. Metode usulan terbukti sangat teliti dan dapat diulang serta dapat direkomendasikan bagi pengukuran bahan organik tanah di laboratoria penguji tanah. Abstract The dichromate wet combustion determination of soil organic matter involves a titration of the excess of dichromate with ferrous ions. An automised potentiometric redox titration is proposed as a substitute for the diphenylamine colour indicator method. This modification enables a fast and accurate end point determination, and is very reliable for laboratories where organic matter determinations are part of the routine analysis. The proposed method is compared with the traditional Walkley and Black method for different mineral soils from West and Central Java, for peat, for compost and organic waste. The proposed method is highly accurate and reproducible and can be strongly recommended for soil organic matter determinations in soil testing laboratories

IUPAC-NIST Solubility Data Series. 95. Alkaline earth carbonates in aqueous systems. Part 1. Introduction, Be and Mg

The alkaline earth carbonates are an important class of minerals. This volume compiles and critically evaluates solubility data of the alkaline earth carbonates in water and in simple aqueous electrolyte solutions. Part 1, the present paper, outlines the procedure adopted in this volume in detail, and presents the beryllium and magnesium carbonates. For the minerals magnesite (MgCO 3), nesquehonite (MgCO 3.3H 2O), and lansfordite (MgCO 3.5H 2O), a critical evaluation is presented based on curve fits to empirical and=or thermodynamic models. Useful side products of the compilation and evaluation of the data outlined in the introduction are new relationships for the Henry constant of CO 2 with Sechenov parameters, and for various equilibria in the aqueous phase including the dissociation constants of CO 2(aq) and the stability constant of the ion pair MCO 3 0(M=alkaline earth metal). Thermodynamic data of the alkaline earth carbonates consistent with two thermodynamic model variants are proposed. The model variant that describes the Mg 2+-HCO 3 - ion interaction with Pitzer parameters was more consistent with the solubility data an d with other thermodynamic data than the model variant that described the interaction with a stability constant