Silicon In Soil Fertility and Crop Production; Ten Years of Research.

Silicon added to a Quakertown silt loam as calcium silicate slag (Agrowsil™, Sarver, PA) was evaluated on crops grown in NJ.  Field experiments were initiated with pumpkin (Cucurbita pepo L.) in year 2000.  The initial soil pH was 5.7.  Liming materials calcium silicate slag or limestone each applied at the rate of 7840 kg/ha of calcium carbonate equivalent was compared.  Each liming agent raised soil pH to 6.8.  Calcium silicate slag suppressed powdery mildew disease and delayed senescence of pumpkin foliage.  In year 2000 only, pumpkin yield was increased by 60%.  In year 2001, yield was not different.   Adding silicon to soil increased in pumpkin foliage Si concentration 5 fold.  In years 2002 and 2003, the research plots were used to study Si in corn (Zea Mays L.) plant tissue and European corn borer (ECB) (Ostrinia nubilalis Hubner) feeding activity.   Corn stem tissue Si increased from 1.6 to 2.5 g/kg as a result of Si amendment.  Silicon tended to decrease the amount of damage to the stem both years but this protection from ECB did not significantly increase grain yield.  The plots were next cropped to winter wheat (Triticum aestivum L.) to evaluate silicon for effects on powdery mildew disease and yield.  Additional calcium silicate slag or limestone was applied each year as needed.  In 2006, powdery mildew lesions were reduced 29% on wheat foliage in the silicon amended plots.  In 2007, powdery mildew was not diagnosed, but non–pathogenic Alternaria spp. leaf blotch lesions were reduced 16% on the foliage in the silicon plots.  During 2008, powdery mildew lesions on wheat foliage were 44% less and yields were 10% greater in silicon amended plots.  Current investigations are examining forage responses to silicon.  A decade of research suggests that silicon amendment may suppress plant disease and increase crop yield.