Copper and zinc nutrition of cereal and oilseed crops in Manitoba

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McAndrew, David Wayne.
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Copper nutrition of barley, oats, wheat, flax and rapeseed seed on a severely Cu deficient organic soil was studied in the environmental growth chamber. Copper deficiency symptoms were exhibited by all crops when no Cu was applied... Concentrations below those ranges were considered deficient and above those ranges sufficient. The order of tolereance to low Cu was rapeseed > barley > oats > wheat > flax. Field studies were conducted in 1977 and 1978 to determine mine severity and extent of Cu and Zn deficiencies in Manitoba and the relative effectiveness of various carriers, placement methods and rates of C and Zn. It was also hoped that information concerning DTPA extractable soil Cu and Zn critical levels could be obtained. Cereal and oilseed crops grown on Lakeland clay loam containing as little as 0.8 ug DTPA extractable Zn/g soil did not respond in grain yield to Zn fertilization although shoot Zn concentrations often increased. In addition, plant Zn concentrations in control treatments were usually above critical levels suggested in the literature... Armyworm damage in 1977 and hail damage in 1978 limited yields in Cu experiments on Pine Ridge and Menisino sands so that it was impossible to determine the extent and severity of Cu deficiency or to estimate DTPA extractable soil Cu critical levels on mineral soils in Manitoba... Chelated forms of Cu and Zn were 3 to 5 times as effective as sulfates of Cu and Zn in increasing shoot micronutrient concentrations in barley. Mixing water solutions of chelates of sulfates of Cu and Zn with the surface 10 cm of soil was usually more effective than banding dry materials with the seed. This was particularily true for Cu on organic soils. The differences between the two methods were smaller for Cu on mineral soils. The effectiveness of ZnEDTA was greater when mixed than when drilled. However, placement method did not influence the effectiveness of ZnSO4 for barley in the field. Since mixing ZnSO4 was superior to banding in other research with barley in the growth chamber and blackbeans in both the field and growth chamber, it was concluded that all Cu and Zn carriers whould be dissolved in water, sprayed onto the soil surface and mixed thoroughly with the surface 10 cm to maximize efficiency. The commercial products ZnMNS from Cominco and ZincGro from Eagle-Picher were totally ineffective at increasing barley grain yields or shoot Zn concentrations in the year of application, with the methods used. There may be residual effects in subsequent years.