Impact of Silicate Slag Fertilization on Grain Yield, Silicon Accumulation, and Plant Essential Nutrient Content of Rice.

A vast amount of documentations have shown silicon (Si) fertilization promoting rice productivity, but limited studies have linked yield increases to enhanced uptake of plant essential nutrient specifically in rice. This study intends to: 1) determine the effect of increasing silicate slag application rate on rice grain yield, and 2) evaluate the changes in essential nutrient content of rice with increasing Si uptake. This field study was established at five locations in Louisiana in 2013 and 2014. Plots were treated with varying rates of silicate slag (1, 2, 4, 6 and 8 MT ha^-1) and lime (2 and 4 MT ha^-1) prior to sowing rice seeds (CL 151 variety). All treatments, including a control, were replicated four times and arranged in randomized complete block design. Grain and straw yield along with soil Si, pH, and Mehlich-3 extractable nutrients were determined at harvest. Silicon and plant essential nutrient content of grain and straw were also quantified. While there was an evident increase in soil Si level with increasing silicate slag rate, significant increase in grain yield was observed in only two sites in 2013 (P<0.05). Soil Si showed positive relationships with grain Si (r²=0.54) and straw Si (r²=0.35) uptake. The Si content in the grain had a negative relationship with copper and nickel, while it showed a positive relationship with phosphorus and zinc content. Our study showed that the enhanced level of Si in rice brought about by Si fertilization can influence the rate of uptake of several plant essential nutrients which can potentially contribute to overall rice productivity.