Transitional grassland/forest light soils in Saskatchewan are often deficient in Cu. The high cost of micronutrient fertilizers necessitates extreme care in identifying micronutrient deficiencies and selecting effective products and methods of application. Comparison of tissue and grain or seed analysis for spring wheat (Triticum ustivum L.), canola (Brassica napus L.), and flax (Linum usitatissimum L.) vs. DTPA-extractable soil Cu levels revealed that diagnosis of Cu deficiencies can more accurately be achieved via the latter. The critical DTPA-extractable Cu levels were 0.40 mg Cu kg-• of soil for spring wheat and 0.35 mg Cu kg-• of soil for canola and flax. A series of field experiments comparing different forms of soil and foliar Cu fertilizers were conducted on several transitional grassland/forest soils. Copper oxide applied in the spring was generally ineffective in the year of application but alleviated Cu deficiencies in the following year. Copper-sulfate (blue stone) and chelated products (polylignosulphonic acid) were effective in the year of application. However, the latter had no residual value at the rates of application used. This, combined with their extremely high current prices, makes them an undesirable Cu fertilizer source for the soils in the study area. Foliar Cu applications of either Co-sulfate or Co-chelate may be effective, but their performance has been erratic; hence, they should only be considered as an emergency measure for correcting of Cu deficiency.

Seedrow-placed urea minimizes soil disturbance in reduced tillage systems, but it generally decreases emergence at nitrogen (N) rates adequate for optimum crop yield. The objective of this study was to determine the influence of coating urea fertilizer granules with a urease inhibitor or a polymer on the emergence and seed yield of durum wheat (Triticum turgidum L.) and canola (Brassica napus L.) with seedrow-placed urea, and to determine the appropriate rate of Agrotaine coating for seedrow-placement. Protein content and N uptake in wheat seed were also determined. Field experiments were conducted at three locations using durum wheat (Aneroid) and canola (Scott and Swift Current) in Saskatchewan, Canada. The combinations of N rates (28, 56, 84, 112, and 140 kg N ha 21 for durum wheat and 34, 68, 102, and 136 kg N ha 21 for canola) and urea coatings [non-coated urea (NCU)], urea coated with Agrotaine at full rate (Agr1, 5.2 L t 21 ), 2/3 rate (Agr2/3) and 1/3 rate (Agr1/3), and with polymer (Plmr, at 3% by weight) treatments were the main plots. A zero-N check was also included. There were two seed opener types (knife with 1.9 cm wide band and spreader with 7.6 cm wide band) used for the seedrow-placed urea subplots. Agrotaine contained N-(n-butyl)-thiophosphoric triamide (NBPT) urease inhibitor at 25% by weight as active ingredient. With increase in N rate from 28 to 140 kg N ha 21 for wheat, the decline in emergence was greater for NCU (by 59.5 plants m 22 ) than for coated urea treatments (by 23.0 to 29.1 plants m 22 ); the seed yield declined in NCU and Agr1/3 treatments but increased up to 84 or 112 kg N ha 21 in Agr1, Agr2/3 and Plmr treatments. With increasing N rates, the N uptake in wheat seed was not influenced for NCU, slightly increased (by 10.3 kg N ha 21 ) for Agr1/3 and substantially increased (by 31.6 to 34.9 kg N ha 21 ) for Plmr, Agr1 and Agr2/3 treatments. The protein content in wheat seed was increased for all the coated urea treatments up to 140 kg N ha 21 . Compared to the zero-N check, canola emergence with 34 kg N ha 21 declined slightly at Scott (relatively moist area) and substantially at Swift Current (relatively dry area). With an increase in the N rate from 34 to 136 kg N ha 21 , the decline in canola emergence at Scott was much greater with NCU than the coated urea treatments but at Swift Current it was similar for all the urea treatments. With increasing N rate, canola seed yield declined for the NCU treatment at both sites while it increased up to 68 kg N ha 21 for Agr1, Agr2/3 and Agr1/3 at Scott, up to 102 kg N ha 21 for Agr2/3 and Agr1/3 at Swift Current, and up to 136 kg N ha 21 for Plmr at Scott and for Agr1 and Plmr at Swift Current. Both crops responded to higher rates of seedrow-placed N with coated urea compared to NCU. Polymer coating was somewhat more effective than Agrotaine coating at the N rates used in this study. The effectiveness of Agrotaine tended to decline with reduction in coating rate (a trend of Agr1 . Agr2/3 . Agr1/3). The wider spreader opener resulted i...

A survey of the DTPA-extractable Cu levels of approximately 1000 fields representing a large number of soil types in Saskatchewan suggested that, under current cropping systems, Cu deficiencies appear to be concentrated in the Grey Soil Zone. They are especially probable in seven soil associations, which include light Transition of Grey and Brownish-Grey Podzolic soils. Soil criteria for detecting Cu deficiencies in cereal crops cannot be fully documented using conventional calibration tests and techniques. However, data from 21 field trials and a growth chamber study indicated that the critical level of DTPA-extractable Cu in these soils is approximately 0.4 mg∙kg−1 for cereals. Large spatial variability of DTPA-extractable Cu levels has been found to occur in a level field, thus suggesting that the Cu status of a field may not be adequately described by assessing the Cu levels of composite field samples. Key words: DTPA-extractable Cu, soil survey, critical level, spatial variability

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KeneueNos, R. E., Knucen