Effect of glyphosate on soil nitrogen mineralization

Abstract

In this study, glyphosate was used to determine the effect of increasing rate of application on soil Nitrogen mineralization. The experiment comprised three glyphosate treatments (i.e. 0.3546, 3.456,and 35.46 jug/g soil) with a control (without glyphosate). A Completely Randomized Design (CRD)was used with four replicates. Determination of NHf -N and N 0 3'-N were carried out at 1, 3, 5, 7, 10, 14, 21,35 and 56 days after herbicide application. Result showed that NHf -N content was not significantly (P < 0.05) reduced at the recommended fie ld rate after one-day incubation. After 7 days and thereafter, no significant (P <0.05) changes were observed among treatments. Results also revealed that NO3-N content of the treatment 35.46 pg/g soil was significantly (P d ” 0.05) increased from the control after one and three days of Incubation period. Thereafter, significant (Pd n 0.05) changes were not observed fo r any treatment throughout the incubation period. Glyphosate had a positive effect on ammonification at all Application rates, in spite of slight inhibition at the beginning of the experiment. In contrast, glyphosate showed no significant (P <0.05) stimulatory or inhibitory effects on nitrification. It could be concluded that nitrification was less affected by glyphosate even at higher rates (35.46 pg/g soil) and thus, application of glyphosate in red yellow podzolic soils would not be harmful to of N mineralization.