. 1988. The mechanism of phosphorus-induced zinc deficiency in bean (Phaseolus vulgaris L.). Can' J. Soil Sci. 68: [345][346][347][348][349][350][351][352][353][354][355][356][357][358].The nature of the P-induced Zn deficiency in bean plants was studied in a growth chamber experiment using three pedogenically different soils. Application of P (0, 40' 80 and 160 mg P kg-r soil) resulted in significant dry matter (DM) yield increases. Maximum DM yields were attained at the 40 mg P kg-r application rate. Application of Zn (0, 5 or l0 mg Znkg-t soil) without P application had no effect on DM yields of bean plants. However, Zn application in combination with P application resulted in significant DM yield responses. There was no evidence that the P-induced Zn deficiency was a result of differences in soil characteristics or influence of P on the water soluble plus exchangeable, organically bound, Mn-and Fe-oxide bound or residual Zn fractions. The Zn concentration in bean plant tops was significantly reduced due to P application and ihe magnitude of the reduction was greatest with the first lncrement of applied P (40 mg P kg-t soil). Application

. 2004. Use of N-(n-butyl)thiophosphoric triamide (NBPT) to increase safety of seed-placed urea. Can. J. Plant Sci. 84: 105-116. Current guidelines for safe seedrow placement of urea N in the western Canadian prairies are based on texture, seedbed utilization and soil moisture conditions at the time of seeding. However, if N requirement is high, not all fertilizer N requirements can be met as excess urea N in the seedrow may result in plant stand reduction, delay in maturity and/or lead to yield loss. This study investigated the use of the urease inhibitor N-(n-butyl)thiophosphoric triamide (NBPT) as a means of increasing the safety of seedrow applied urea. Four experiments consisting of 39 trials were carried out over 3 yr to ascertain whether current guidelines could be modified through the use of NBPT. The experiments were carried out on loam to clay loam soils and barley, canola and wheat were sown with seedrow spacing and seed spread to produce seedbed utilization of approximately 10%. A safe N rate in this study was defined as the one that resulted in less than 15% reduction in the stand density of plants and no delay in maturity. There was no damage from seed-placement of N when the site received 5 to 10 mm of precipitation within 48 h of seeding. Treatment of urea with NBPT resulted in a significant improvement in stand density in two out of every three (20 of the 31) trials, where a significant reduction of stand density due to N application was observed. There were no cases where an increase in seedling damage was observed as a result of NBPT treatment of urea. Treatment of urea with NBPT resulted in an overall reduction in days to maturity with greater benefit at higher N rates of seed row placed N. However, there was a yield benefit as a result of NBPT application in only eight of the trials. Average guidelines for urea seedrow placement for barley, canola and wheat grown on medium textured soils with 10% seedbed utilization can be increased by 30, 20 and 15 kg N ha -1 , respectively, when urea is treated with NBPT. Les recommandations actuelles concernant l'application d'urée aux semences dans les prairies de l'Ouest canadien reposent sur la texture du sol, la préparation de la planche de semis et à la teneur en eau du sol au moment des semis. Quand le sol est très carencé cependant, il est impossible de lui fournir tout l'azote dont il a besoin, car un excédent d'urée dans la planche de semis peut réduire la densité du peuplement, retarder la maturation ou entraîner des pertes de rendement. Les auteurs ont tenté de voir si l'usage du N-triamide de l'acide thiophosphorique (NBPT), un inhibiteur de l'uréase, pourrait rendre l'urée plus sûre quand elle est appliquée à la planche de semis. Ils ont donc effectué 39 essais dans le cadre de quatre expériences étalées sur trois ans pour établir si les recommandations existantes pourraient être modifiées en fonction de l'usage de NBPT. Ils ont semé de l'orge, du canola et du blé sur un sol allant du loam au loam argileux en tenant compte de l'écartement des...

Karamanos, R. E., Flore, N. A. and Harapiak, J. T. 2010. Re-visiting Use of Penicillium bilaii with phosphorus fertilization of hard red spring wheat. Can. J. Plant Sci. 90: 265Á277. Penicillium bilaii is a fungus that lives in association with plant roots and has been shown to increase phosphorus (P) solubility and uptake by some crops. A series of 47 experiments with hard red spring wheat (Triticum aestivum L.) that were carried out in the three prairie provinces between 1989 and 1995 and included treatment with P. bilaii as a main plot (with or without) and four rates of fertilizer P (0, 4.4, 8.7 and 13.1 kg P ha(1 ) as subplots were statistically analyzed to ascertain whether use of P. bilaii resulted in increases in both yield and P uptake by wheat. Of the 47 experiments, response to fertilizer P was obtained in 33 experiments and to P. bilaii in 14, in five of which the response was positive and nine resulted in yield decreases. These responses could not be attributed either to extractable P soil concentration, soil organic matter (SOM) or texture, or weather conditions and are considered random events. Overall, P uptake was a function of fertilizer P rate only.Key words: Seed-treatment, seed yield, P uptake, P use efficiency Karamanos, R. E., Flore, N. A. et Harapiak, J. T. 2010. Usage de Penicillium bilaii avec des engrais phosphate´s dans les cultures de ble´roux vitreux de printemps : nouvelle e´tude. Can. J. Plant Sci. 90: 265Á277. Penicillium bilaii (P. bilaii) est un champignon qui vit en symbiose avec les racines des plantes. Cet organisme accroıˆt la solubilite´du phosphore (P) et son absorption par certaines cultures. De 1989 a`1995, les auteurs ont proce´de´a`une se´rie de 47 expe´riences sur le ble´roux vitreux de printemps (Triticum aestivum L.) dans les trois provinces des Prairies. Ces expe´riences incluaient une parcelle principale traite´e ou pas avec P. bilaii et des sous-parcelles amende´es par l'application d'un engrais P a`quatre taux (0, 4,4, 8,7 et 13,1 kg par hectare). L'analyse statistique des re´sultats devait e´tablir si P. bilaii accroıˆt ou pas le rendement du ble´et l'absorption du P par cette culture. Les auteurs ont releve´une re´action aux engrais P dans 33 cas sur 47 et une re´action aP. bilaii dans 14 cas, soit une hausse du rendement dans cinq cas et une baisse dans neuf. Ces re´sultats n'ont pas pu eˆtre attribue´s a`la concentration du P extractible dans le sol, a`la concentration de matie`re organique ou a`la texture du sol, ni aux conditions me´te´orologiques et sont conside´re´s comme dus au hasard. Dans l'ensemble, l'absorption du P de´pend uniquement du taux d'application de l'engrais.

Karamanos, R. E., Flore N. A. and Harapiak, J. T. 2005. Effect of post-emergence nitrogen application on the yield and protein content of wheat. Can. J. Plant Sci. 85: 327-342. Post-emergence application of N with wheat is contemplated as a practice for managing risk and reducing fertilizer N costs. An attempt was made to develop a comprehensive agronomic package relating to the practice of post-emergence applications by examining aspects relating to the rates of N, timing of post-emergence applications and products that might be used for that purpose. An extensive database of 49 trials conducted between 1995 and 1998 separated in five experimental plans was utilized to address the above issues. Nitrogen rates of up to 100 kg N ha -1 were employed as soil applied at seeding by side banding (0, 20, 40 and 60 kg N ha -1 ) plus topdressed (0, 20 and 40 kg ha -1 ) as post-emergence applications between Feekes growth stages 10.4 and 10.5. The effect of timing was explored in three different experimental designs that included rates up to 100 kg ha -1 applied at seeding or split, so that a post-emergence application of 20 kg N ha -1 was applied at Feekes growth stages 10 and 10.5, or up to 60 kg N ha -1 , applied either all at seeding time or 20 or 40 kg N ha -1 at seeding time accompanied by 20 or 40 kg N ha -1 in a post-emergence application at Feekes growth stages 3-4, 6, 10.5 or 11. A number of products (ammonium nitrate, ammonium sulphate, urea, urea ammonium nitrate, Pro N and N serve) were also evaluated for their effectiveness in post-emergence applications. Two distinct trends emerged from all experiments depending on whether application of N at seeding corrected an N deficiency. If N deficiency was corrected by the application rate at seeding then the post-emergence N application increased grain protein concentrations; however, this practice was shown to result in no economic advantage. If N deficiency was not corrected by the N application at seeding, post-emergence applications at late growth stages increased grain protein of wheat at the expense of grain yield. This increase was greater in soils containing soil organic matter (SOM) concentrations less than 5% than those over 5%. Increases in grain protein ranged from 0.7 to 1.5% depending on initial fertilization regime, but they were not sufficient in any of the circumstances to economically compensate for the loss in grain yield caused by insufficient application of N at seeding. The performance of a number of products used for post-emergence application on the protein of hard red spring wheat was mixed with none proving to be consistently superior. Post-emergence application of N to enhance either the grain yield or protein of hard red spring wheat could be effective under high moisture or irrigated conditions; however, this practice represents a relatively high-risk practice under dryland conditions in the western Canadian prairies.Key words: Economics, growth stage, N rates, N products, timing Karamanos, R. E., Flore, N. A. et Harapiak, J. T. 2005. I...

The spatial variability of natural 15N abundance of a cultivated Chernozemic soil and its native prairie counterpart were smaller than that of total N, organic C, and the C/N ratio. Further, the number of samples required to estimate the true mean of total N with a given precision at various probability levels were twofold those required to determine the mean 15N abundance in both soils. The variability of organic C was > 10 times that observed for total N. The results of this study indicate that the spatial variability of the natural 15N abundance of total soil N in the surface horizons may reflect the isotopic composition of the nitrogenous substances entering the soil system or changes in the isotopic composition of soil N due to humification processes, probably induced by variations in topographic and microrelief features of the soil.