Journal article

Publication year: 1995

Pages: 197-203

Journal: Plant and Soil

Volume number: 176

Issue number: 2

ISSN: 0032-079X

DOI Link: https://doi.org/10.1007/BF00011783

Publisher: Springer

Abstract: 

A soil incubation experiment was carried out over 70 days (aerobic, 15 degrees C) using a clay and a sandy soil produced by amendment with bentonite and quartz sand respectively. Fresh endive leaves were added as green manure (109 mg N kg(-1) soil). Controls without green manure were also included. Samples were taken periodically in order to determine CaCl2 extractable N fractions and N in microbial biomass by a fumigation-extraction method.

With the green manured soils CaCl2 extractable organic N was maximal at day 2 of incubation followed by an exponential decrease until constant levels were reached. At day 2 of incubation the apparent recovery rate of applied green manure as CaCl2 extractable organic N was 44% (clay) and 46% (sandy soil). Without green manure the organic N extracted was only 0.3% (clay) and 0.5% (sandy soil) related to the total soil organic N. NH4+ showed an intermediate increase (maximum at day 14) with green manured soils and was always negligible with controls. From day 14 onwards the NO3- accumulation was more pronounced with green manured soils compared with controls. The apparent extent of green manure mineralization at the end of incubation was 47.2 and 43.3% of the applied N in the clay and the sandy soil respectively.

To summarize, bentonite amendment had no substantial effect on the rate and extent of N mineralization nor on the amount of CaCl2 extractable organic N.

The extractability of N released on fumigation appears to be restricted by bentonite. Green manure increased the amount of extractable N released on fumigation with both soils.

It is concluded that CaCl2 extractable organic N largely consists of organic substances which, in contrast to some constituents released on fumigation are only weakly adsorbed to clay surfaces and therefore are highly accessible to mineralization.

Harvard Citation style: APPEL, T., SISAK, I. and HERMANNSSELLEN, M. (1995) CACL2 EXTRACTABLE N FRACTIONS AND K2SO4 EXTRACTABLE N RELEASED ON FUMIGATION AS AFFECTED BY GREEN MANURE MINERALIZATION AND SOIL TEXTURE, Plant and Soil, 176(2), pp. 197-203. https://doi.org/10.1007/BF00011783

APA Citation style: APPEL, T., SISAK, I., & HERMANNSSELLEN, M. (1995). CACL2 EXTRACTABLE N FRACTIONS AND K2SO4 EXTRACTABLE N RELEASED ON FUMIGATION AS AFFECTED BY GREEN MANURE MINERALIZATION AND SOIL TEXTURE. Plant and Soil. 176(2), 197-203. https://doi.org/10.1007/BF00011783