توزيع شكل هاي نيتروژن در خاك هاي آهكي تحت كشت استان فارس و رابطه آنها با ويژگي هاي خاك

Twenty-five surface samples of calcareous soils of Fars Province were used to study the distribution of different nitrogen (N) forms to determine the relationship between the N forms and soil charcteristics, and to obtain regression equations for prediction of N forms from soil characteristics. The forms determined were: soil total nitrogen; N03-N by phenol disulfunic acid; N03-N extractable by 2 M KCI; NH4-N extractable by 2 M KCI, 1 N sulfuric acid, and 0.25 N sodium hydroxide; oxidative released N by acid permanganate and alkaline permanganate; and NH.4-N extractable by 2 M KC1 at 100 °C. The highest amount of N was that released by alkaline permanganate which constituted 4.47% of soil total N and the lowest form was exchangeable NH4+ which amounted to only 0.6% of total N. Water soluble and exchangeable forms accounted for less than 2% of total N. Highly significant correlations were found between total N and acid permanganate-N (r-0.931) and total N and alkaline permanganate-N (r=0.850). Highly significant regression equations were obtained for prediction of soil total N, acid permanganate-N, and alkaline permanganate-N from soil organic matter (OM), which is an indication of a close relationship of these N forms with OM.