Dissipation of AM Nitrification Inhibitor in Soil Supplemented with Organic Amendments

Abstract

ABSTRACT To examine the effect of organic amendments on the dissipation and nitrification inhibition activity of 2-amino 4-chloro 6-methyl pyrimidine (AM), a laboratory study was conducted on a sandy loam soil (Typic Hapludoll) receiving no organic amendments (Control) or application of farmyard manure (FYM) or pine needles biochar (PNB) @ 5 t ha−1. Dissipation of AM was initially faster during the first 7 d, and then it slowed down. Dissipation kinetics of AM conformed to the first-order model (R2 values = 0.973 to 0.981, significant at p ≤ .01). The conventionally estimated time for the dissipation of half the amount of initially detected AM (half-life) was 15.9, 23.6, and 12.1 d for the control, FYM, and PNB treatments, respectively. All treatments receiving AM had numerically lower NO3 −–N concentrations compared to no AM but significantly lower NO3 −–N concentrations were recorded under, especially the PNB + AM treatment at 15, 30, 45, 60 and 90 d. The higher effectiveness of AM under PNB could be attributed to the sorption of AM in the micro-pores of PNB with slower release. Percent distribution of sorbed AM onto FYM and PNB revealed that desorption of sorbed AM from PNB was comparatively very limited. FTIR spectra revealed that both FYM and PNB strongly retained AM. Application of AM @1 mg kg−1 soil (equivalent to 2.24 kg ha−1) seems to effectively retard the nitrification of urea in soil amended with PNB and help reduce the leaching losses of NO3 −–N in agriculture.