Heavy‐Metal Inhibition of Nitrification in Selected Iowa Soils Treated with Stay‐N 2000

Abstract

Heavy-metal inhibition of nitrification in soils treated with reformulated nitrapyrin was investigated. Clarion and Okoboji soils were treated with ammonium sulfate [(NH 4 ) 2 SO 4 ] and a nitrification inhibitor. Copper(II) (Cu), Zinc(II) (Zn), Cadmium(II) (Cd), or Lead(II) (Pb) were added to each soil. A first-order equation was used to calculate the maximum nitrification rate (K max ), duration of lag period (t 0 ), period of maximum nitrification (Dt), and the termination period of nitrification (t s ). In the Clarion soil, the K max decreased from 12 mg kg 21 d 21 without the nitrification inhibitor to 4, 0.25, 0.86, and 0.27 mg kg 21 d 21 , respectively, when the inhibitor and Cu, Zn, Pb, or Cd were applied. In the Okoboji soil, K max decreased from 22 mg kg 21 d 21 with no inhibitor to 6, 3, 4, and 2 mg kg 21 d 21 , respectively, when an inhibitor and Cu, Zn, Pb, or Cd were added. The t 0 varied from 8 to 25 d in the Clarion soil and from 5 to 25 d in the Okoboji soil, due to addition of Cu, Zn, Pb, or Cd and the inhibitor.

Field Evaluation of Newly-Developed Controlled Release Fertilizer on Rice Production and Nitrogen Uptake

“…The use of DMPP in CRF was widely studied on various crops, resulting in significant yield increment. Heavy metal elements also have been studied as nitrification inhibitors previously with positive effects on reducing nitrification (Rovita & Killorn 2008). Yield increment in PS+Cu could be attributed to lower nitrification in soil, which enhances N use efficiency by rice.…”