Influence of natural essential oils and their by-products as nitrification retarders in regulating nitrogen utilization for Japanese mint in sandy loam soils of subtropical central India

摘要

Nitrogen inhibitory properties in plant materials offer potential benefits for agriculture and environment. In order to evaluate the relative performance of Mentha spicata and Artemisia annua oils and dementholized oil (DMO) as natural nitrification inhibitors in regulation of soil mineral nitrogen (N) and yield and N accumulation in Japanese mint (Mentha arvensis cv. Hy-77), field experiments were conducted for 2 years at the Central Institute of Medicinal and Aromatic Plants, Lucknow, India. For comparison, dicyandiamide (DCD), a chemical nitrification inhibitor was also used in the study. Urea was coated with the essential oils and DMO at the rate of 0.50% (w/w) of prilled urea, using appropriate coating technique. Results revealed that urea coated with these natural nitrification inhibitors significantly increased the herb and essential oil yields of the crop, compared to DCD coated and uncoated urea. During the field experimentation in 1997, among the three nitrification inhibitors at 100 kg N ha(-1) rate of fertilizer application, the highest increase in oil yield (36.5%) was with M. spicata oil followed by the A. annua oil (21.6%) and DCD (16.5%) compared to uncoated urea. Corresponding increases during 1998 with the M. spicata oil and DCD were 12.0 and 11.2%, respectively, while it was the highest (16.2%) with DMO. With 200 kg N ha(-1) application, increase in oil yield during 1997 with Artemisia oil was 46.7%, followed by M. spicata oil (43.2%) and DCD (23.7%), while during 1998 corresponding increase with the M. spicata oil. and-DCD were 14.5 and 10.3%, respectively; It was 11.4% with DMO. Higher yield of herb and essential oil may be attributed to better utilization of N by the crop due to retarded losses of N by these nitrification inhibitors. It can be concluded that these essential oil bearing plants can be used as potential nitrificafion inhibitors to reduce mineral N loss through different mechanisms thereby reducing the load of nitrogenous gases in the atmosphere and nitrate in the ground water.