Forage Seed Response to Copper Fertilization 2013-2015 Report

by STEWART BRANDT, NORTHEAST AGRICULTURAL RESEARCH FOUNDATION

Copper is an essential micronutrient needed for proper fertilization and seed formation. Copper deficiencies are not widespread in Northeastern Saskatchewan, but where they occur they can result in very substantial yield losses to susceptible grain crops. Deficiencies are most common on organic (peat) and coarse textured (sandy) soils. Deficiency symptoms can include yellowing and curling of young leaves, pigtailing (curling) of leaf tips, delayed heading, aborted heads or spikelets, stem or head bending or browning of stems and heads.

In June 2013, we selected 4 sites in the Choiceland, Nipawin, White Fox, SK regions where there was evidence of copper deficiency. Sites were those on soils where copper deficiencies could typically occur, and where previous yields were below expectations. None of the sites showed typical symptoms of severe copper deficiency like pig-tailing of leaves, late tillering or very poor growth. All sites were on sandy soils with moderate organic matter. Three sites were established Timothy, and one was established Hybrid bromegrass. At each site we located 5 pairs of 0.18 m2 mini-plots. At the late flag leaf stage, we applied foliar EDTA chelated copper solution at a rate of 0.22 lb/ac in 40 gallons per acre (gpa) of water to one of each pair of mini-plots. The remaining plots were left untreated.

In 2014 and 2015, we used three of the same sites as in 2013, but dropped site 1 from 2013 and added a site at Carrot River. The 2014 and 2015 protocol was the same as for 2013, but we added 2 more foliar copper treatments; one with a Nexus Liquid Copper 5% product applied to supply 0.22 lb/ac Cu in 40 gpa of water and the second with a YARA product called Coptrac 500 also applied at a rate that supplied 0.22 lb/ac of Cu.

At maturity, all mini-plots were harvested by cutting forage near the soil surface and bagging each. After drying, the seed was stripped from the straw and cleaned to remove non-seed material. The clean seed and straw were weighed separately.

Results from 2013 to 2015 suggest that copper can be a factor in low yields of established Timothy and Hybrid bromegrass grown for seed. Results also confirm that application of foliar copper at relatively low rates (0.22 lb/ac) can be effective at correcting deficiencies. Results also confirm that applying foliar copper to mini-plots and comparing yield to adjacent untreated areas is an effective way of identifying where copper applications may be economical. What is troubling is that responses on the same fields vary from year to year, making it difficult to predict when Cu responses can be anticipated. Considering the low cost of foliar Cu fertilization and the relatively large responses to foliar Cu, it may be a useful practice to apply foliar Cu to all forage grass seed fields where the crop is grown on light textured soils with limited capacity to supply Cu. The question that remains is whether we can develop a reliable predictor or threshold for soil or tissue Cu to be used to assess the need for foliar Cu.

The Northeast Agriculture Research Foundation would like to express their gratitude to the Saskatchewan Forage Seed Development Commission, along with Nexus Ag Business Inc. and YARA Canada Inc. for financial support for this project and for providing Cu product. In addition, the support of Darwin Leach, Karen Strukoff and Kerry O’Brien for technical assistance and of Clayton Myhre (DLF-Pickseed) in finding suitable sites and assisting with timing of operations is acknowledged.

The full project report is located on this website under Research - Past Research.