Aoyama, M., Angers, D. A. and N'Dayegamiye, A. 1999. Particulate and mineral-associated organic matter in water-stable aggregates as affected by mineral fertilizer and manure applications. Can. J. Soil Sci. 79: 295-302. Application of cattle manure generally improves soil structure and organic matter (OM) content. However, changes in forms and location of OM within the aggregate structure are less well known. The effects of long-term (18-yr) applications of cattle manure (20 Mg ha -1 yr -1 ) and NPK fertilizer on the distribution of particulate and mineral-associated organic matter in water-stable aggregates were investigated in a Le Bras loam (Humic Gleysol). Soil samples from the 0-to 10-cm depth were taken from the untreated control, NPK, manure and NPK + manure treatments. They were separated into four aggregate-size fractions (>1000 µm, 250-1000 µm, 53-250 µm, and <53 µm) by slaking air-dried soil, followed by wet sieving. Particulate (>53 µm) and mineral-associated OM (<53 µm) were separated from water-stable aggregates >53 µm by sieving after mechanical dispersion. After 18 yr, manure increased the OM level of the whole soil and favored formation of slaking-resistant macroaggregates (250-1000 µm). This effect was primarily a result of the OM added by the manure. In contrast, NPK fertilizer did not affect soil OM level or macroaggregation. The increase in OM induced by manure application was observed primarily in macroaggregates, and both as mineral-associated and particulate OM. However, manure did not change OM located in the fraction <53 µm confirming that recently deposited OM preferentially accumulates within the aggregate structure and not in the finely or non-aggregated material. Since previous studies have shown that most of the C in cattle manure is composed of coarse particles, we hypothesize that manure-derived OM first enters the soil primarily as particulate material, then, during decomposition, is transformed within the aggregate structure into mineralassociated material thereby contributing to aggregate stabilization.Key words: Cattle manure, mineral fertilization, particulate organic matter, soil structure Aoyama, M., Angers, D. A. et N'Dayegamiye, A. 1999. Influence de l'application de fertilisants mineraux et de fumier sur les formes de matière organique dans les agrégats stable à l'eau. Can. J. Soil Sci. 79: 295-302. L'incorporation de fumier de bovin au sol conduit généralement à l'amélioration de sa structure et de sa teneur en matière organique (MO). Cependant, les effets sur la nature et la localisation de la MO sont moins bien connus. Nous avons étudié les conséquences à long terme (18 années) de l'application de fumier de bovin (20 Mg ha -1 année -1 ) et de fertilisants minéraux sur la distribution de la MO fine et grossière dans les agrégats d'un loam Le Bras (Gleysol humique). Des échantillons de sol ont été prélevés de l'horizon 0-10 cm des parcelles témoin (sans amendement) et des parcelles traitées soit avec des fertilisants minéraux (NPK), du fumier de bovin, ou NPK + fumier....

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N. 1999. Protected organic matter in water-stable aggregates as affected by mineral fertilizer and manure applications. Can. J. Soil Sci. 79: 419-425. Effects of long-term (18-yr) applications of cattle manure (20 Mg ha -1 yr -1 ) and NPK fertilizer on the labile organic matter (OM) and its protection in water-stable aggregates were investigated in a Le Bras silt loam (Humic Gleysol). Soil from the 0-to 10-cm depth was sampled from the untreated control, NPK, manure and NPK + manure treatments and fractionated into four size classes of slaking-resistant aggregates (>1000 µm, 250-1000 µm, 53-250 µm, <53 µm). Intact and crushed macroaggregates (250-1000 and >1000 µm) and intact microaggregates (<250 µm) were incubated for 21 d at 25°C, and mineralized C and N were determined. The amount of mineralized C in intact aggregates increased with increasing aggregate size irrespective of the agronomic treatments, but there was no consistent trend for total N. Manure application led to an increase in mineralized C in most aggregate fractions. Crushing the macroaggregates enhanced mineralization of C by 14 to 35% and N by 17 to 103%. Additional C and N rendered mineralizable by crushing represents a fraction of the macroaggregate-protected OM. Manure application increased the protected pools of C (up to threefold) and N (up to fourfold) located in the small macroaggregates (250-1000 µm). In contrast, NPK fertilization increased the pool of macroaggregate-protected N by 2.5-fold but had no effect on the protected C. We conclude that manure application contributed to the accumulation of macroaggregate-protected C and N, whereas mineral fertilizers increased the protected-N pool only. Macroaggregates can provide a mechanism for the protection of labile soil OM in an annually tilled cropping system and this mechanism is enhanced with long-term manure application.Key words: Aggregate-protected organic matter, manure application, mineralization, mineral fertilizer, water-stable aggregates Aoyama, M., Angers, D. A., N'Dayegamiye, A. et Bissonnette, N. 1999. Effets de l'application de fumier et de la fertilisation minérale sur la matière organique protégée dans les agrégats stables. Can. J. Soil Sci. 79: 419-425. Cette étude a évalué les effets à long-terme (18 années) de l'application de fumier de bovin (20 Mg ha -1 année -1 ) et de l'engrais minéral sur la fraction labile de la matière organique (MO) et sur la protection physique de celle-ci dans les agrégats d'un loam Le Bras (Gleysol humique). A partir des échantillons de sol provenant de la couche 0-10 cm des traitements témoin, avec fumier, avec engrais minéraux (NPK) et avec fumier+NPK, nous avons obtenu, par tamisage sous eau, quatre fractions d'agrégats stables (>1000 µm, 250-1000 µm, 53-250 µm, <53 µm). Les quantités de C et N minéralisées ont été mesurées dans une incubation (21 jours à 25°C) de macroagrégats brisés et intacts (250-1000 and >1000 µm) et de microagrégats (<250 µm) intacts. Les résultats indiquent que les quantités de C minéralisé augmentent avec la taill...

To investigate some basic aspects of soil remediation using biomimetic catalysts, the effects of humic substances (HSs) on the removal of xenobiotics, such as pentachlorophenol (PCP), were investigated. The use of a biomimetic catalytic system using tetra(p-sulfophenyl)porphine-iron(III) (Fe(III)-TPPS) and potassium monopersulfate (KHSO5) resulted in the disappearance of PCP, accompanied by dechlorination. In addition, this process was enhanced by the presence of several types of HSs. The degrees of enhancement (% delta(PCP)60) achieved by the presence of HSs from peat and compost soils were larger than those in the presence of other types of HSs (tropical peat, brown forest, and ando soils). In control experiments, no PCP disappearance and dechlorination were observed in the presence of only KHSO5, only Fe(III)-TPPS, or combinations of HSs and either KHSO5 or Fe(III)-TPPS. To better understand the role of added HS in enhancing or inhibiting PCP disappearance, correlations between the chemical parameters of the HSs and % delta(PCP)60 were investigated. The most effective HSs had lower carboxylic acid contents and lower degrees of unsaturation. The carboxylic acid content and degree of unsaturation increase with the extent of humification. Therefore, HSs of a lower degree of humification would be predicted to be more useful in enhancing the disappearance of PCP in an Fe(III)-TPPS/KHSO5 system.

Simple 5-5 type l i g n i n model compounds have been s y n t h e s i z e d from d e h y d r o -d i v a n i l l i n and i t s e t h e r d e r i v a t i v e s by decarbonylation, hydrogenation, and r e d u c t i o n w i t h metal hydride. The chemical s h i f t s f o r t h e aromatic carbons of t h e s e compounds were ?5signed, and t h e s u b s t i t u e n t e f f e c t s have been eluci.dated from C NMR s p e c t r a of guaiacyl-type monomeric and 5-5 type l i g n i n model compounds. I n a d d i t i o n , e v a l u a t i o n of t h e observed v a l u e s of s u b s t i t u e n t chemical shift (SCS) f o r t h e aromatic carbons l e a d s t o formulation of a g e n e r a l i z e d SCS a d d i t i v i t y r u l e f o r t h e aromatic carbons i n 5-5 t y p e s u b s t r u c t i i r e s . The r u l e is complementary t o t h e similar r u l e formulated e a r l i e r f o r t h e 6-0-4 and P -5 type l i g n i n s u b s t r u c t u r e s . The r u l e can be used f o r t h e e s t i m a t i o n of t h e chemical s h i f t s of aromatic carbons i n ligrijn model compounds and l i g n i n p r , y a r a t i o n s w i t h reasonable accuracy. On t h e b a s i s of t h e observed C NMR s p e c t r a l d a t a f o r aromatic ~k Universidade Federal de Minas Gerais-Departamento d e QuimicaICEx CP 702-Cidade Universitaria-Pampulha-30'l61 Belo Horizonte, M . G . , B r a s i l .