利用根箱法解析甜椒根际土壤中氮的行为(英文)

为研究甜椒根际土壤中氮的行为,与既报同样的方法进行研究,即,利用15NH4+,15NO3-双标记的硝胺(NH,4>15NO3,15NH4NO3),在温室里对甜椒进行6周的根箱栽培.收割后,对土壤全氮,NO3-N,水溶性NH4-N,KCl抽出NH4-N和其各自的15N atom%进行测定.结果表明,土壤全氮从非根际到根际逐渐增加,与栽培前相比,土壤全氮在非根际中减少,却在根际中增大.土壤NO3-N浓度朝根际增加到离根际2 mm处,然后激减到根际.NO3-N的来自施给NO3-N的比例靠近根际逐渐升高,在根际达到了69%,反而,来自施给NH4-N的比例靠近根际逐渐降低,在根际将至7%左右.水溶性NH4-N和KCl抽出NH4-N浓度靠近根际逐渐降低,而且,从非根际到根际,二者匀保持3∶10的比例.KCl抽出NH4-N的来自施给NO3-N的比例靠近根际逐渐升高,但在根际仍低于3%,反而,其来自施给NH4-N的比例在非根际约为47%～55%,在根际降到41%.在整个根箱里,施用NO3-N的有機率达到62%,但其值在根际比非根圈要低.相反,施用NH4-N的有機率仅11%左右,但其值在根际比非根际要高.以上结果表明,在甜椒根际土壤中氮的无机化-有机化活性与水稻相比显著低.

Behavior of nitrogen in the rhizosphere of sweet pepper plant using the rhizobox system

The behavior of N in the rhizosphere of sweet pepper (Capsicum annuum L.) plant was investigated using a rhizobox sys-tem filled with a shirasu soil applied with NH415NO3 or 15NH4NO3. The rhizobox consisted of one 2 mm width center compart-ment(CC), five 1-mm width compartments (C1～C5), and one bulk compartment (BC) on both sides of CC. Sweet pepper was sowed and grown in CC. After six weeks of cultivation, the soil from each compartment were collected and analyzed for contents of the soil T-N, NO3-N, water-soluble NH4-N and KCl-extractable NH4-N and their 15N excess%. The obtained results were summa-rized as follows: 1. Although the T-N content of soil decreased in from BC to Cl compared to before cultivation, it gradually increased from BC toward the CC and it was higher before cultivation in the CC. 2. The NO3-N contents of soil increased from BC to C2, then rapidly decreased from C2 to CC. The ratio of NO3-N which de-rived from fertilizer NO3-N increased from BC toward the CC and it reached 69% in the CC. On the contrary, the ratio of NO3-N which derived from fertilizer NH4-N decreased from the BC toward the CC and it was 7% in the CC. 3. The water-soluble NH4-N and KCl-extractable NH4-N contents of soil decreased from the BC toward the CC and the ratio of water-soluble NH4-N to KCl-extractahle NH4-N are 3:10 in all compartments. The ratio of NH4-N which derived from fertilizer NO3-N increased from BC toward the CC, but it was only 3% in the CC. The ratio of NH4-N which derived from fertilizer NH4-N was 47～55% in the compartments from BC to Cl, but it was low at 41% in the CC. 4. The immobilization of fertilizer NO3-N reached 62% in the whole rhizobox, but the rate was lower in the CC than in the other compartments. On the other hand, the immobilization of fertilizer NH4-N was only about 11% in the whole rhizobox, while the rate was higher in the CC than in other compartments.