The mineralization of nitrogen in a soil acidified with sulphur, aluminium sulphate or ferrous sulphate

Abstract

The mineralization of nitrogen in a soil which had been acidified to different degrees by applying sulphur, aluminium sulphate or ferrous sulphate a t three equivalent rates was studied. With low and medium applications of the acidifying materials pH was reduced to a similar extent at each rate by all materials, but with heavy applications sulphur had the least potent, and ferrous sulphate the most potent, effect in reducing pH. During incubation of the treated soils in the absence of added chalk, nitrate and total mineral nitrogen (ammonia plus nitrate) accumulation decreased, whereas ammonia accumulation increased with the amount of acidifying agent used. When the acidified soils were incubated with excess of added chalk, nitrate accumulation returned to normal, except where heavy application of sulphur and ferrous sulphate had been made ; total mineral-nitrogen accumulation returned to normal, except where heavy ferrous sulphate application had been made ; and ammonia accumulation occurred only where heavy ferrous sulphate application had been made.The reduction of soil pH by the application of acidifying materials such as sulphur has been practised in order (a) to increase the availability of trace elements such as manganese,l (b) to reduce disease incidence in plants (e.g. Hooker2 found that commercial control of potato scab was obtained by applying sulphur to the soil) and (c) to produce suitable soil conditions for the growth of acid-loving species such as rhododendrons and azaleas.Apart from a mention by Fraps & Sturges3 that the application of sulphur to a soil resulted in decreased nitrification, little attention has been paid to changes in ammonification and nitrification that may result in soils which have been acidified in this way. Since there is a

Effect of pH and organic acids on nitrogen transformations and metal dissolution in soils

“…Ammonium-N was detected only at pH 4. This is in agreement with the studies of Cornfield (1952Cornfield ( , 1953 and White (1959). The amount of NH^-N accumulated also depends on the soils used.…”

Effects of Soil Acidity and Liming on Mineralization of Soil Nitrogen

“…However (Thompson et al 1954) and that the increase in mineralization after liming is short-lived (Frercks and Kosegarten 1956;Mulder 1950;Schachtschabel 1953 For personal use only. Cornfield (1953) found that production of mineral N on incubation was Iessened when a soil was acidified frompH 6.5 to '4.9 or lower. On the other hand, when Thompson et al (1954) Brar and Giddens (1963) suggested that nitrification in a very acid Bladen soil was restricted bv hieh content…”

Liming and Fertilizer Efficiency1

“…The only difference is that an additional, preliminary step-conversion of the organic nitrogen to ammonia-is required. It is generally accepted ( 12) that the rate of conversion of organic nitrogen to the ammonium form increases as pH increases, although strictly speaking the final stages of the conversion are more strongly influenced by soil reaction than are the initial steps (8).…”