Chemical tests for potentially available nitrogen in soil

摘要: Previous work on the distribution of radioactivity in organic matter soils incubated with 14C labelled ryegrass suggested that amount extracted by barium hydroxide might serve as an index potentially available N soil. This suggestion was tested a set for which amounts mineralised during incubation, and taken up grown soils, were known. The C non-nitrate correlated fairly closely released soils; polysaccharide (measured glucose equivalent) more release N. ‘glucose’ significantly yield unfertilised barley 36 field experiments (r = 0.83**); correlation response to smaller −0.54**). The from soil increased air-drying, but once air-dry no further change occurred, even prolonged storage. Barium hydroxide-extractable is proposed coefficients between uptake pots (14 soils) measurements 0.70**, 0.65**, 0.67**, 0.28, respectively, ‘glucose’, extractable boiling water, or sodium bicarbonate, ammonia hot aqueous calcium hydroxide, alkaline permanganate. None chemical tests grass, when re-wetted air-dried incubated.