Notes and amendments to the recommendations on manuring of tea in south India

摘要

Nitrogen occurs in soil in several forms viz., N_2, NH_4~+, NH_3, NO_3, NO_2 and N_2O and their inter conversions are the net result of several dynamic processes. Among the various forms, nitrite (NO_2~-) was reported to be toxic to young tea bushes even at 0.1 ppm in the soil. We have come across several soil samples having more than 0.1 ppm nitrite and for such fields expensive pre-cultivation measures were advised. Subsequently, investigations were carried out to determine the toxic limits and toidentify the effects of the presence of nitrite. Soil samples were collected and filled in mud pots and planted with clone UPASI-9. Nitrite in the form of sodium nitrite was incorporated into the soil and the conversion of nitrite into other forms of nitrogen was studied on the first and the eighth days after imposing treatments.