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Fluid Journal : Fall 2017
11 The Fluid Journal Fall 2017 Table 11. Cluster comparisons of corn GS R1 ear leaf K, K:Mg and yield over five years, 112 sites. Year Low K Cluster 123 High K Cluster Delta Yield K (%) K:Mg K (%) K:Mg (bu/ac) 2011 1.77* 5.9* 2.64 11.1 40.9* 2012 1.52* 3.2 1.91 6.7 58.1* 2013 1.67 3.0* 1.95 8.3 34.5 2014 1.60* 4.7* 2.17 10.1 48.2* 2015 - - - - - 2016 1.50* 3.6* 2.93 14.3 45.6 1 Ear leaf K, Mg and yield measurements for 112 sites, 4-8 reps per site, across seven states. 2 Cluster analysis of five lowest and highest ear leaf K, 16 to 32 sites. Number of sites per year, yearly dependent. 3 Cluster means within a year followed by (*) are significant at the 0.05 level. The Fluid Journal • Official Journal of the Fluid Fertilizer Foundation • Fall 2017 • Vol. 25, No. 4, Issue #98 By Osler Ortez, Fernando Salvagiotti, Juan Enrico and Ignacio Ciampitti Genetic Gain Via Nitrogen Interaction in Soybeans ▼ DOWNLOAD Yield increases recorded in studies at U.S. and Argentina Sites. The United States (US) and Argentina (ARG) account for more than 50 percent of the global soybean production (USDA 2016). In the US, more than 85% of the soybean area is located in the Corn Belt region, where corn-soybean rotation (>60 percent) is the main cropping system. In Argentina, soybeans are primarily planted in the Rolling Pampas and Chaco regions, under rain-fed conditions, as monoculture or in rotation with corn. Soybean yield potential is genetically determined. Yield potential (Yp) can be attained under “ideal” conditions (genotype × environment × management practices, G × E × M), assuming no limitations of water and nutrient supply Summary:The overall goal of this ongoing research is to study the contribution of different nitrogen (N) sources in high yielding soybean systems using diverse germplasm and production practices. Closing yield gaps (actual on- farm yield vs. genetic yield potential) in a long-term perspective will require an improvement in the use of the available resources, which must be attained via implementation of better management decisions. Soybean yield improvement (1980s vs. 2010s) represented 30% for sites located in the US and Argentina. Seed N content followed similar trends as yields, highest seed N content observed for 2010s genotypes, represented a 25% gain. Yield response to N fertilizer was observed in both locations, up to 20% increase in the US and 5% in Argentina. For the US, N fertilization increased protein concentration by 1.3% relative to only inoculated soybeans. In synthesis, N limitation impacted not only on seed yield but also on protein concentration for soybean production systems. and absence of biotic and abiotic yield limiting factors (e.g., insects, diseases, etc.). Yield gaps between Yp and actual on-farm yield (YA) are primarily defined by crop management practices (e.g., row spacing, planting date, fungicide, and nutrient application, among others) and the interactions of those with the E (soil and weather factor). Maximum soybean yields are dependent on a balanced