Effect of different soil cultivation systems, including no-tillage, on electro-ultrafiltration extractable organic nitrogen
The effect of different long-term soil-cultivation systems (ploughing, two types of cultivator, notillage) on organic N, extracted with the electroultrafiltration (EUF) technique, was studied in two arable soils, a Luvic Phaeozem derived from loess and a Eutric Cambisol. A modified EUF extraction procedure (the 80°C fraction extended from 5 to 90 min) was used to investigate the release of organic N from the ploughing and no-tillage treatment, and the content of hydrolysable N was measured in the combined filtrates. No-tillage and the two non-turning cultivation systems led to an accumulation of EUF organic N in the 0- to 10-cm depth compared to the ploughing treatment. In the lower horizon (15–25 cm) the reverse pattern was found in the loamy soil, with higher concentrations after ploughing than after reduced tillage. However, in the sandy soil all four cultivation treatments showed similar values in the 15- to 25-cm depth. During the time of investigation (May 1987 to February 1989) an EUF organic N accumulation occurred, which was about twice as high in the loamy as in the sandy soil. Therefore we conclude that in the sandy soil the mineralization of organic N was faster, and that reduced tillage retarded its degradation. In the total 0- to 25-cm depth, this delay was not observed in the loamy soil. The N release rates were much lower in the sandy than in the loamy soil and they were higher for the notillage than for the ploughing treatment. Only 30–40% of the total organic N desorbed was hydrolysable and the amino acid composition indicates that part of it originated from microbial Cells. The overall evaluation showed clearly that EUF-extractable organic N is a sitespecific factor.
Electro-ultrafiltration of aqueous soil suspension with simultaneously varying temperature and voltage
SummaryThe procedure of electro-ultrafiltration (EUF) with simultaneously varying voltage and temperature for the determination of nutrient fractions in soil as well as for the characterization of important soil properties such as kind of clay, content of K-selective clay minerals, of CaCO3etc. is described. The interpretation of the EUF-N, EUF-P and EUF-K fractions is discussed in detail with regard to their availabilities. Moreover the influence of soil properties and soil management on the EUF nutrient fractions is discussed.For characterization of the EUF values needed for optimum plant nutrition, it is suggested to combine the EUF values at 20°C and 200 V on the one hand (easily available fraction) and the EUF values at 80°C and 400 V on the other (nutrient reserves). The higher, in fact, the nutrient contents at 80°C and 400 V are the lower can be the EUF values at 20°C and 200 V. In contrast to conventional methods of soil analysis, the nutrient contents determined by EUF are expressed in mg/100 g soil/time unit of desorption (min) at given temperature and voltage.The EUF procedure proved highly advantageous for an assessment of the fertilizer requirements of soils as this method allows for the determination of soil properties such as kind of clay, content of K-selective clay minerals, of CaCO3 and of easily desorbable heavy metals in one single operation. These soil properties play a decisive role in the sorption of K and P.
Luminescence Phenomena Involving Metal Enolates
1 
Introduction 
 
2 
Metal Enolates 
 
3 
Luminescence of Rare-Earth Enolates 
 
4 
Luminescence Involving s, p and d Metal Block Enolates 
 
5 
Applications 
 
6 
Acknowledgments 
 
 
 
Keywords: 
 
luminescence phenomena involving metal enolates; 
chemistry of metal β-diketonate complexes; 
luminescence of rare-earth enolates; 
photoluminescence of rare-earth β-diketonates; 
diketonate ligand–rare-earth ion energy transfer rates; 
luminescence involving s, p and d metal block enolates; 
photoluminescence of d-transition metal enolates; 
applications - time-resolved detection of luminescence for bioassays