Effect of Varying Rates of Silicon and Nitrogen Fertilizer on Grain Yield, Yield Components, and Nutrient Uptake of Wheat.

Silicon (Si) fertilization provides numerous benefits to plants which can in turn lead to improved crop yields. In order to elucidate which of these benefits influences grain yield in wheat (Triticum aestivum L.) production, a field study was established at multiple sites in 2012 and 2013 on alluvial flood plain soils of Louisiana. Treatments were arranged in a randomized complete block design with four replications consisting of twelve treatments: a factorial combination of two N (101 and 145 kg ha^-1) and five Si rates (0, 1, 2, 4.5, and 9 Mt ha^-1 as calcium silicate slag - CaSiO₃, 17% Si), and two control plots (with and without lime). Biomass samples were collected at three different growth stages, including harvest, and analyzed for Si and essential nutrient content. Soil samples taken at midseason and harvest were analyzed for Mehlich-3 extractable nutrients and Si content by 0.5 M acetic acid extraction procedure. Yield components were analyzed from a biomass sample collected prior to whole-plot harvesting. In 2013, higher grain yields were observed at 101 kg N ha^-1 compared to 145 kg N ha^-1 with the highest yields seen in conjunction with 2 Mt ha^-1 CaSiO₃. In 2014, higher yields were achieved at the higher N rate of 101 kg ha^-1. Higher yields at certain combinations of N and Si were correlated with increased number of tillers and panicle weight (P≤0.1). Data show an increase in some essential nutrients (e.g. Ca, Mg, S) but these increases did not correspond with higher yields.  The results of this research will help establish the links among Si fertilization rates, level of soil Si and plant essential nutrients, grain yield and its components.