Effectiveness of seedrow placement of granular copper products for wheat

• Published in: Canadian journal of soil science 2005-05, Vol.85 (2), p.295-306
• Main Authors: Karamanos, R.E, Walley, F.L, Flaten, P.L
• Format: Article
• Language: English
• Subjects: application rate; broadcasting and incorporation; chelates; copper; copper fertilizers; copper oxysulfate; copper sulfate; costs and returns; fertilizer application; foliar application; granular fertilizers; seedrow placement; tillage; Triticum aestivum; wheat
• ISSN: 0008-4271; 1918-1841
• DOI: 10.4141/S04-038

The practice of placing granular Cu fertilizers with the seed of cereals and oilseeds has been expanding in western Canada mainly due to the high cost of applying the minimum suggested broadcast and incorporation rate of 3.5 kg Cu ha -1 . The hypothesis made is that annual applications of small amounts of Cu in the order of 1 kg Cu ha -1 will satisfy the Cu requirement of a crop and, over a period of years, have the same effect as a single broadcast and incorporated application. We tested this hypothesis in a number of experiments aimed at assessing the effectiveness of seedrow placement of a variety of Cu products (sulphate, oxysulphate and chelated) at various rates (0 to 4 kg Cu ha -1 ) in the year of application, its residual effect after four annual applications and whether it can be combined with foliar Cu applications to provide an agronomic and economic solution both in the short and longer terms. Annual seedrow applications of up to 4 kg ha -1 were both agronomically and economically inferior to broadcasting and incorporation of 4 kg ha -1 as Cu sulphate; the former provided a statistically significant grain yield increase only in 3 of 10 site-years and only when the Cu fertilizer was in sulphate or chelated forms. However, yield increases thus obtained were neither economical nor as good as those obtained with broadcast and incorporated copper sulphate. The residual effects of seedrow-applied Cu at rates up to 4 kg ha -1 were very small compared to a single, 4-yr old broadcasting and incorporation of 4 kg Cu ha -1 , and were obtained primarily after 3 yr of annual applications and with sulphate or chelated products only. However, average yield increases as a result of residual effects in the fifth year were approximately 35% of those obtained with broadcasting and incorporation. Combining seedrow with foliar applications did not have any agronomic or economic advantage, since most benefit arose from the latter. Key words: Broadcast and incorporation, sulphate, oxysulphate, chelate, residual