IMPACT ON AMMONIA VOLATILIZATION LOSSES OF MIXING KCI OF HIGH PH WITHUREA

Ammonia volatilization associated with urea hydrolysis has been shown to be primarily associated with the pH of the soil solution and its bu ffering ability in the immediate zone of the fertilizer granule. Numer ous studies have also shown that these losses can be reduced significa ntly by the addition of large amounts of KCl with the urea. Because th e pH of commercial sources of potash ranges from 6.5 to 9.5, investiga tions were conducted to determine if the high pH of these K sources ha d an effect on the ammonia lost from three contrasting soils. Despite large ammonia losses (approximately 50% of N applied) and a significan t reduction in loss due to the use of KCI (30%-50% reduction), the exp eriments showed no effect of potash pH on ammonia loss. It may be conc luded that no risk of enhanced ammonia loss can be associated with the use of high-pH potash sources.