Continuing Assessment of the 5-Day Sodium Carbonate-Ammonium Nitrate Extraction Assay as an Indicator Test for Silicon Fertilizers.
The 5-day sodium carbonate-ammonium nitrate extraction assay (5-day method) has been recognized by the American Association of Plant Food Control Officials as a validated test method to identify fertilizers or beneficial substances that provide plant-available silicon (Si). The test method used the molybdenum blue colorimetric assay to quantify percentage Si; however, laboratories may use inductively coupled plasma optical emission spectroscopy (ICP-OES) for elemental analysis. To examine the use of either colorimetric or ICP-OES methods for Si determination, the 5-day method was performed on the following Si-containing compounds; wollastonite, sand, biochar, and a basic oven furnace (BOF) slag. Grow-out studies using Zinnia elegans were also performed using varying rates of the wollastonite, biochar, and BOF slag. Our results show using the 5-day method, wollastonite had the highest extracted amounts of silicic acid (H4SiO4) at 4% followed by biochar (2%), BOF slag (1%), and sand (0%). Extraction values calculated using either the molybdenum blue colorimetric assay or ICP-OES for detection of the H4SiO4 had a significant correlation, supporting the application of either detection method for this type of analysis. However, when extracted values were compared to amounts of Si taken up by the plants, the 5-day method overestimated both wollastonite and biochar. While this method is a valid indicator test for determining a soluble Si source, other plant species and methods should be perused to potentially provide more quantitative analyses for plant-available Si content of all materials.
U.S. Department of Agriculture, Agricultural Research Service, Application Technology Research Unit, Greenhouse Production Research Group, 2801 W. Bancroft St, Mail Stop 604, Toledo, OH, USA.
Wendy
W
Zellner
Russell L
RL
Friedrich
Sujin
S
Kim
Douglas
D
Sturtz
Jonathan
J
Frantz
James
J
Altland
Charles
C
Krause
D002254:Carbonates / Q000737:chemistry*; D005308:Fertilizers / Q000032:analysis*; D009566:Nitrates / Q000737:chemistry*; D012825:Silicon / Q000032:analysis* / Q000302:isolation & purification; D013054:Spectrophotometry, Atomic
D002254:Carbonates; D005308:Fertilizers; D009566:Nitrates; C005686:sodium carbonate; C006568:ammonium nitrate; D012825:Silicon