Wheat Yield and Disease Response to Amending Soil with Silicon.

In determining critical soil silicon levels for rice (Oryza sativa L.) using Cate and Nelson procedures, Korndörfer et al., 2001 arrived at a critical soil Si response level of 19 mg kg^-1 for Florida soils.  Previous work in New Jersey (2003) reported that silicon fertilization of a Quakertown silt loam was beneficial to pumpkin (Cucurbita pepo L.) fruit yield and powdery mildew disease (causal agent Podosphaera (sect. Sphaerotheca) xanthii (Castagne) U. Braun & N. Shishkoff) suppression when the soil test Si level was 127 mg kg^-1.  During three consecutive years of field trials on a Typic Hapludult soil in northwestern New Jersey, CaSiO₃ was added as a liming material at a calcium carbonate equivalent (CCE) rate of 4480 kg ha^-1 to winter wheat (Triticum aestivum L.) and evaluated for its effects on powdery mildew disease incidence (causal agent Blumeria graminis (DC) Speer f. sp. tritici emend. Marchal (syn. Erysiphe graminis DC.) and grain yield response.  Control plots received CaCO₃ at the same CCE liming rate and the site received natural fungal inoculate.  The mean soil silicon levels of the controls were 18 mg kg^-1 in 2006, 27 mg kg^-1 in 2007, and 33 mg kg^-1 in 2008, compared with 45 mg kg^-1, 62 mg kg^-1, and 94 mg kg^-1 respectively in the silicate-treated plots, well above expected response levels, in most years, based on predictions for Florida soils. In all three study years, fungal lesions were significantly lower in the silicon treated plots: 29% in 2006 (powdery mildew), 25% in 2007 (Alternaria spp. leaf blotch), and 43% in 2008 (powdery mildew), with a yield response of 10% measured in year three of the trial.  Our findings suggest that crops grown on some Ultisols in the Mid-Atlantic region may benefit from silicon addition, providing disease suppressive effects and increased yield.