This study was performed to determine the forms of P and to examine the influence of oven-drying on P forms in different organic amendments. Samples of biosolids, beef and dairy cattle manures, and hog manures from sow and nursery barns were used in this study. Both fresh and oven-dried amendments were analyzed for inorganic (Pi), organic (Po), and total phosphorus using a modified Hedley fractionation technique. Water extracted about 10% of total biosolids P and 30 to 40% of total hog and cattle manure P. The amount of P extracted by NaHCO3 ranged from 21 to 32% of total P in all organic amendments except in the dairy cattle manure with 45% of total P. The labile P fraction (sum of H2O- and NaHCO3-extractable P) was 24% of biosolids P, 60% of hog manure P, and 70% of dairy cattle manure P. The residual P was about 10% in biosolids and cattle manures and 5 to 8% in hog manures. Oven-drying caused a transformation in forms of P in the organic amendments. In hog manures, H2O-extractable Po was transformed to Pi, while in the dairy manure NaHCO3-extractable P was converted to H2O-extractable Pi with oven-drying. Therefore, caution should be exercised in using oven-drying for studies that evaluate forms of P in organic amendments. Overall, these results indicate that biosolids P may be less susceptible to loss by water when added to agricultural land.

. 2001. Ammonia volatilization from soils fertilized with urea and varying rates of urease inhibitor NBPT. Can. J. Soil Sci. 81: 239-246. Loss of N as ammonia (NH 3 ) from surface-applied urea fertilizer may be high if hydrolysis takes place at the soil surface. The urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) may reduce NH 3 loss from urea by delaying hydrolysis. Field studies using surface chambers were conducted in 1996 and 1997 to compare the amount of NH 3 volatilized from surface applications of granular urea (100 kg N ha -1 ) treated with varying concentrations of NBPT (0, 0.05, 0.10 and 0.15% NBPT wt/wt). The studies were conducted on two Orthic Black Chernozemic soils, a Stockton fine sandy loam and a Newdale clay loam, in May and again in July to determine the relative influence of soil texture and temperature on NBPT performance at the varying rates. Ammonia losses were measured at various times to 12 d after fertilization (DAF) in 1996 and to 21 DAF in 1997. Total NH 3 losses decreased in the order of 0% > 0.05% > 0.15% ≥ 0.10% where use of NBPT reduced total NH 3 loss by 28-88% over the entire study duration, and by 82 to 96% during periods of peak loss from unamended urea. Ammonia volatilization losses from NBPT-amended urea treatments were lower in May than in July. The total loss measured at all rates of NBPT was higher for the fine sandy loam soil except in May 1997 where cool conditions resulted in slightly lower loss than for the clay loam soil. Amending urea with NBPT at a rate as low as 0.05% wt/wt can reduce NH 3 loss from surface-placed urea fertilizer, so that a greater proportion of fertilizer N is retained in the soil for plant use. The inhibitor helps reduce the amount of NH 3 derived from urea entering the atmosphere to react or to be deposited elsewhere, and may lessen the need to overfertilize to compensate for potential NH 3 losses. Le N-(n-butyl)-triamide de l'acide thiophosphorique (NBPT) est un inhibiteur de l'uréase et pourrait réduire les pertes de NH 3 de l'urée en retardant l'hydrolyse. En 1996 et 1997, les auteurs ont effectué des études sur le terrain au moyen de chambres de surface en vue de comparer la quantité de NH 3 qui s'échappe dans l'air consécutivement à l'application d'urée granulaire (100 kg N ha -1 ) renfermant une quantité variable de NBPT (0, 0,05, 0,10 et 0,15 % en poids). Les essais se sont effectués sur deux tchernozems orthiques noirs, soit un fin loam sablonneux Stockton et un loam argileux Newdale, en mai puis en juillet, et devaient préciser l'influence relative de la texture et de la température du sol sur l'efficacité du NBPT aux concentrations à l'étude. Les auteurs ont mesuré la perte d'ammoniac à divers moments jusqu'à 12 jours après la fertilisation (JAF) en 1996 et 21 JAF en 1997. La perte totale de NH 3 diminue dans la séquence 0 % > 0,05 % > 0,15 % ≥ 0,10 %, et l'addition de NBPT a réduit la perte totale de NH 3 de 28 à 88 % pendant la durée de l'étude et de 82 à 96 % lors des périodes où les pertes de l'urée non traitées étaien...

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. 2004. Phosphorus fractions in soil amended with organic and inorganic phosphorus sources. Can. J. Soil Sci. 84: 83-90. Information on the P fractions in soils treated with different organic amendments is needed to better manage land application of organic amendments to agricultural soils. This study investigated the forms and distribution of P after 1, 4 and 16 wk in a Lakeland silty clay loam soil using a sequential fractionation procedure. Phosphorus was added at rates of 0, 123, 307 and 614 mg P kg -1 in the form of biosolids, hog manure, cattle manure and fertilizer P. The largest difference among the amendments was in the water-extractable P fraction, which was significantly lower in soil amended with biosolids. Regression analysis showed that the slope of P increment in the H 2 O fraction as a function of P application rate was four times lower for biosolids (0.06) than for hog manure (0.24) and seven times lower than for fertilizer (0.42) amended soils. In the biosolids-amended soil, there was a net increase of H 2 O-P, NaOH-Pi and HCl-P fractions at the expense of organic P (NaOH-Po) and residual P fractions after 16 wk of incubation, signifying net P mineralization. In hog manure amended soil, H 2 O-P decreased by 128 mg kg -1 with a corresponding increase in the NaHCO 3 -P, possibly due to P sorption during the 16 wk of incubation. The results for cattle manure indicated net immobilization of P as the H 2 O-P and NaHCO 3 -P declined while the inorganic P (NaOHPi), HCl-P and residual P increased with incubation time. The transformation of P in fertilizer-amended soil was similar to that of hog manure amended soil. The amount of labile P (defined as H 2 O-P plus NaHCO 3 -P) in amended soils followed the order of fertilizer P > hog manure > cattle manure > biosolids. La principale distinction entre ces amendements se rapporte à la fraction de P extractible dans l'eau, qui est nettement plus faible dans les sols bonifiés avec les solides biologiques. Selon l'analyse de régression, la hausse de la concentration de P dans la fraction aqueuse en fonction du taux d'application de P a une pente quatre fois plus faible dans les sols amendés avec des solides biologiques (0,06) que dans ceux fertilisés avec du purin (0,24) et sept fois plus faible que dans ceux bonifiés avec de l'engrais (0,42). Après 16 semaines d'incubation, on remarque une nette hausse des fractions P-H 2 O, Pi-NaOH et P-HCl au détriment du P organique (Po-NaOH) et du P résiduel dans les sols amendés avec les solides biologiques, signe qu'il y a une forte minéralisation du P. Dans le sol amendé avec du purin, la fraction aqueuse diminue de 128 mg de P par kilo tandis que la fraction P-NaHCO 3 connaît une hausse correspondante, sans doute à cause de l'adsorption du P pendant les 16 semaines d'incubation. Les résultats obtenus avec le fumier de bovin indiquent une nette immobilisation du P, car on assiste à une diminution des fractions P-H 2 O et P-NaHCO 3 alors que le P inorganique (Pi-NaOH), le P-HCl et le P résidu-el s'accroissent avec la du...

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