
TY  - JOUR
A1  - Strong, D. T. 
A1  - Sale, P. W. G. 
A1  - Helyar, K. R. 
T1  - The influence of the soil matrix on nitrogen mineralisation and nitrification III. Predictive utility of traditional variables and process location within the pore system
JF  - Soil Research
JO  - Soil Res.
Y1  - 1998
VL  - 37
IS  - 1
SP  - 137
EP  - 150
KW  - pore size distribution, pore system, soil organisation, microsites, nitrification inhibition.
UR  - https://doi.org/10.1071/S98042 
N2  - Regression analysis was used to examine the importance of organic nitrogen (%N), soil water content (&thgr;v), soil pH, and C: N ratio for predicting N mineralisation in a small field plot. Undisturbed soil cubes (c. 1&#183;7 cm3) were collected from the soil surface and received treatments of drying and rewetting, urea, substrate derived from clover leachate, or no amendment, and were incubated at either &#8211;10 or &#8211;30 kPa for 20 days. The data confirm the hypothesis that within a small field plot, &thgr;v and %N explain most of the variation in net N mineralisation and nitrification. The pore size classes of 0&#183;6&#8211;10 and 10&#8211;30 &#181;m made disproportionately small and large contributions to N mineralisation, respectively, apparently due to non-uniform distribution of organic N through the pore system. When soluble N substrate was added to the soils, both these pore classes appeared to support mineralisation. We concluded that prior to sampling, the microbial biomass had been more active in the pores 0&#183;6&#8211;10 &#181;m, and had nearly exhausted the organic substrates in this pore class, whereas this was not so for the 10&#8211;30 &#181;m pore class. Drying and rewetting increased the importance of %N as a predictor of N mineralisation, probably because this treatment disrupted physical protective mechanisms of organic N. Soil pH was generally not a useful predictor of N mineralisation and often seemed to be a dependent rather than an independent variable in relation to nitrification. Neither was C: N ratio a useful predictor of N transformation processes, and this was probably related to physical regulatory mechanisms in the soil. 
ER  -

