J. 2014. Organic carbon and nitrogen stocks in a clay loam soil 10 years after a single compost application. Can. J. Soil. Sci. 94: 357Á363. Household food waste compost (FWC), yard waste compost (YWC) and pig manure plus wheat straw compost (PMC) were applied once in the fall of 1998 to a Brookston clay loam soil in southwestern Ontario to determine immediate and long-term effects of organic amendments on soil quality and productivity. In this report, we describe the residual effects of these single compost applications on soil organic carbon (SOC) and total soil nitrogen (TN) stocks 10 yr after compost addition (2009). FWC was applied at 75 Mg ha (1 , 150 Mg ha (1 and 300 Mg ha (1 , while YWC and PMC were applied at the single rate of 75 Mg ha (1 . The 75 Mg ha (1 additions of YWC, PMC and FWC increased SOC in the top 30 cm relative to a control (no compost additions) by 12.3% (9.0 Mg ha (1 ), 16.6% (12.2 Mg ha (1 ) and 0%, respectively; and they increased TN relative to the control by 8.0% (0.53 Mg ha (1 ), 11.7% (0.77 Mg ha (1 ), and 0%, respectively. The 150 and 300 Mg ha (1 additions of FWC increased SOC in the top 30 cm by 13.0 and 24.7 Mg ha (1 , respectively, and they increased TN by 0.93 and 1.70 Mg ha (1 , respectively. These results indicate that increases in SOC and TN stocks accruing from a single compost addition can persist for at least a decade, but the degree of increase depends strongly on compost type and addition rate. It was concluded that high compost addition rates of FWC and/or addition of composts derived from recalcitrant organic materials may be a good strategy for achieving long-term carbon and nitrogen sequestration in the cool, humid fine-textured soils of southwestern Ontario. , J. 2014. Re´serves de carbone organique et d'azote dans un loam argileux dix ans apre`s une seule application de compost. Can. J. Soil. Sci. 94: 357Á363. À l'automne 1998, du compost de de´chets alimentaires domestiques (CDA), de re´sidus de jardinage (CRJ) et de fumier de porc meˆle´a`de la paille de ble´(CFP) ont e´te´applique´une seule fois a`un loam argileux Brookston dans le sud-ouest de l'Ontario. L'expe´rience devait e´tablir les effets imme´diats et prolonge´s de ces amendements organiques sur la qualite´et la productivite´du sol. Le pre´sent article de´crit les effets re´siduels de ces applications uniques sur les stocks de carbone organique du sol (COS) et d'azote total (AT), dix ans apre`s l'amendement (2009). Le CDA a e´te´applique´a`raison de 75 Mg, 150 Mg et 300 Mg par hectare, tandis que le CRJ et le CFP l'ont e´te´au meˆme taux de 75 Mg par hectare. Comparativement a`la parcelle te´moin (aucun amendement), l'addition de 75 Mg de CRJ, de CFP et de CDA a respectivement augmente´la concentration de COS dans la couche supe´rieure de 30 cm du sol de 12,3 % (9,0 Mg par hectare), de 16,6 % (12,2 Mg par hectare) et de 0 %; paralle`lement, elle a accru respectivement la quantite´d'AT de 8,0 % (0,53 Mg par hectare), de 11,7 % (0,77 Mg par hectare) et de 0 %, par rapport a`celle releve´e dans la parcel...

Effects of 49 years of fertilization on the distribution and accumulation of soil carbon under corn cultivation. Can. J. Soil Sci. 92: 835Á839. The effects of 49 yr of monoculture corn (Zea mays L.) production with/without chemical fertilizer addition on the origin and distribution of soil organic carbon (C) among the sand (53Á2000 mm), silt (2Á53 mm), and clay (B2 mm) particle size fractions in the top 20 cm of a clay loam soil were evaluated using the carbon-13 isotope abundance technique. The C derived from corn (newly formed C4-plant C) was greater under chemical fertilization relative to no fertilization in all three size fractions. However, the resident (old) C derived from C3-plants grown prior to corn was similar between the fertilized and unfertilized treatments for each size fraction. Fertilization of monoculture corn had little impact on the amount of native-formed C3-plant C, particularly in the silt and clay fractions, but did increase the amount of newly formed C4-plant C.