Pulp and paper mill sludges are produced from primary and secondary treatment of wastes derived from virgin wood fiber sources, recycled paper products, and non-wood fibers. Sludges and sludge composts may be utilized in agriculture to increase soil organic matter, improve soil physical properties, provide nutrients, and increase soil pH. Positive effects of primary, deinking, and low-nutrient combined sludges on soil quality are primarily due to increased soil organic matter, aggregation, water holding capacity, infiltration rate, and cation exchange capacity. Nitrogen and P immobilization are often induced by primary and deinking sludges, but can be overcome by delayed planting, adding N and P, planting of legumes, or composting. Improved crop production obtained with secondary treatment sludges is most often attributable to enhanced nutrient availability, particularly N, but improved soil physical properties are implicated in some studies. Pulp and paper mill sludges and sludge composts are useful soil amendments and plant nutrient sources. Key words: Paper mill sludge, soil physical properties, N and P immobilization, nutrient efficiency, land application

N. 2008. N 2 O fluxes in soils of contrasting textures fertilized with liquid and solid dairy cattle manures. Can. J. Soil Sci. 88: 175Á187. Manure is known to increase soil N 2 O emissions by stimulating nitrification and denitrification processes. Our objective was to compare soil-surface N 2 O emissions following the application of liquid and solid dairy cattle manures to a loamy and a clay soil cropped to silage maize. Manures were applied in 2 consecutive years at rates equivalent to 150 kg total N ha(1 and compared with a control treatment receiving an equivalent rate of synthetic N. Soil-surface N 2 O fluxes, soil temperature, and soil water, nitrate and ammonium contents were monitored weekly in manured and control plots. From 60 to 90% of seasonal N 2 O emissions occurred during the first 40 d following manure and synthetic fertilizer applications, indicating that outside that period one or several factors limited N 2 O emissions. The period of higher emissions following manure and fertilizer application corresponded with the period when soil mineral N contents were highest (up to 17 g NO 3 ( -N m

Gagnon, B. and Simard, R. R. 1999. Nitrogen and phosphorus release from on-farm and industrial composts. Can. J. Soil Sci. 79: 481-489. Source materials and manure management may affect compost nutrient availability to plants. A laboratory experiment was conducted to determine the impact of these factors on the N and P release from 23 on-farm and 6 industrial composts. Composts were mixed with the Ap horizon of an Arago sandy loam (Humo-Ferric Podzol), at 200 mg N kg -1 , and incubated for 13 wk in glass jars at 35°C. The soil mineral N content at the end of incubation was the highest from poultry litter, sheep manure, horse manure and vegetable residue sources whereas the fresh solid, beef and young dairy manure composts resulted in high N immobilization. The release of N from the compost organic N fraction was in most cases negative. The soil Mehlich-3 P content at the end of the incubation period was higher from the poultry litter than from any other sources, whereas P was strongly immobilized from week 1 to week 13 in the fresh solid, beef and young dairy manure compost amended soils. Septic tank sludge compost was the least efficient N and P source among industrial products whereas the others showed N and/or P release comparable to most on-farm composts. In dairy manure compost, use of wood in bedding, turning compost windrow, increasing composting duration and sheltering material against precipitation all reduced P immobilization during incubation. Organic N mineralization in soil was only significantly increased by composting duration. This study indicated that the short-term N and P potential nutrient value of composts are dependent upon compost source materials and manure management, and should be based on their inorganic N and P content.

Controlled-and slow-release nitrogen (N) fertilizers have been commonly used in high-value applications, such as horticultural production. Traditional controlledrelease products have not been economical for use in major grain crops because of high cost and low crop prices. New economical, controlled-release fertilizers are available for use in field crops such as corn (Zea mays L.), wheat (Triticum aestivum L.), and other commodity grains. Technology improvements have reduced manufacturing costs, while high N prices and interest in improved N-use efficiency have increased demand for new products. Polymer-coated fertilizers seem to offer the most promise. Nitrogen release from polymer-coated fertilizers is by temperature-controlled diffusion. Coupling N release with soil temperature, a primary factor in crop growth rate and N demand, allows N release to be programmed to better match crop needs. Research shows that controlled N release improves crop output per unit of applied N and reduces N losses.

Synthetic N fertilizers are a major source of NjO emissions from soil. A field experiment was conducted during three growing seasons (2004)(2005)(2006) on a clay soil (fine, mixed, frigid Typic Humaqucpt) under corn {Zea mays L.) to evaluate the impact of N fertilizer source and application race on NjO emissions. Treatments consisted of three sources of N fertilizer (urea-NH4NO3 32% [UAN], Ca-NH^NOj [CAN], and aqua NHj [AA]) at four different rates (0,100,150. and 200 kg N ha"'). Fertilizers were banded 5 cm below the soil surface between corn rows at the six-leaf stage and NjO emissions were measured weekly. For all 3 yr of this study, cumulative NjO emission decreased in the order UAN > CAN > AA. Averaged across years, fertilizer-induced post-sidedress emissions were greater than the Intergovernmental Pand on Climate Change default factor (0.01 kg NjO-N kg" ' N), with values of 0.038,0.033, and 0.027 kg NjO-N kg"' N for UAN, CAN, and AA, respectively The NjO emissionsincreased linearly with N rate, even at rates exceeding the optimum level for grain yield. Peaks of NjO flux occurred on the days following fertilizer application and in early fall when the soil was re-wetted. Emissions of NjO were higher at water-filled pore space >0.57 m' m"' and were also related to soil inorganic N and water-extractable organic C contents. Our results confirm that N fertilizer source and application rate can impact NjO emissions but these effects are modulated by soil environmental conditions. Abbreviations: AA, aqua ammonia; CAN, calcium-ammonium nitrate; FIEF, fertilizer-induced emission factor; UAN, urea-ammonium nitrate; WEOC, water-extractable organic carbon; WFPS, water-filled pore space.