Abstract
Nuclear Institute for Agriculture and Biology, Faisalabad. Pakistan. Ammonia volatilization losses of nitrogen from urea, sulphur coated urea. ammonium sulphate and ammonium nitrate in alluvial alkaline calcareous soil were trkcaiured under laboratory conditions. The results showed that ammonia volatilization loss from urea was 50 per cent higher than that from ammonium sulphate. Over a period of 49 days the loss of nitrogen as ammonia was about 30 and 20 per cent from urea and ammonium sulphate, respectively. Whereas NH3, volatilization loss of nitrogen from. sulphur coated urea was not detected undr these conditions, Ammonia volatilization loss from urea was reduced to 7 per cent (about 77 per cent suppression) by amending the soil with straw of Leprochicafirsca (Kallar grass) or straw of Oryza sans (rice) at t per cent of soil (W/ 1, The ammoniacal loss of nitro-gen from urea could be reduced significantly by thiourea, phenol and hpdroquinorie. Phenol was the most effective to reduce the volatilization of ammonia. Thiourea., hydroquinone • and phenol suppressed NH3 volatilization by about 50, 87 and 95 per cent for 112 days, respectively.
INTRODUCTION
Nitrogen is the leading ntitrient in terms of tonnage for crop produc-ILIOLI. Most of the soils do not contain enough native nitrogen to sustain high production of crops. Modern agriculture, therefore, now relies heavily on the commercial nitrogen fertilizers for obtaining higher yields of crops. However, the efficiency of fertilizer nitrogen use by crops is low, with cnly per cent of applied fertilizer nitrogen taken up by non-legume crops such as maize and wheat and only 30 to 40 per cent by paddy rice (I-lardy at al., 1975). Recent research (MikkeIsen and DeDatta, 1979; Vick and Craswell, 1979; 1981) showed that this low efficiency is largely due to NI-I3 volgtiIization which is encouraged by the high pH of soil. As the nitrogen fertilizers used in Pakistan
