Availability of fixed NH4+ to crops
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Significantly lower amounts of exchaneable NH4, soluble NO3 and clay-fixed NH4 forms of N were observed in the unfertilized fields with high rather than low-density cropped plots. Irrespective of planting densitites, the fixed NH4 content in soil increased with increase in the period of crop growth. N uptake by plant and total bacterial population of rhizosphere soil were significantly higher in the plots with the high than with the low-density planting. Availability of native fixed NH4+ to crops and biological utilization of a considerable amount of recently mineralized NH4+ in fixed form is indicated.
Key wordsAmmonium Fixed ammonium Maize Mineralization Nitrate Nitrite Rhizosphere
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