根际施肥调控对油菜硝酸盐含量的影响研究

利用盆栽试验,测定了肥料周围不同距离处土壤中NH4+与NO3-增量的变化,验证不同施肥方式对小油菜产量与NO3-含量的影响。结果发现,通过肥料在土壤中的扩散作用,肥料氮对土壤NH4+与NO3-增量的影响范围主要是在距肥料4cm内,但集中施肥与酸性根际肥(Ph1.0～2.0)的显著差异则是在2cm内;后者的NH4+扩散与硝化作用都较前者弱。其中,在距肥料1cm处,集中施肥的土壤NH4+增量于施肥一周后达最大值,而酸性根际肥则在两周后,且两者NH4+增量差异显著;在2cm处,二者土壤NH4+增量达最大值的时间都较1cm处晚一周,且前者显著低于后者,而后者土壤的NO3-增量都低于前者。在盆栽试验中,酸性根际肥使小油菜的土壤NH4+含量显著提高,而NO3-含量却很低。与集中施肥比较,土壤NH4+含量提高13%,NO3-含量降低72%～89%,小油菜的硝酸盐累积量降低了28%,小油菜产量增加39%。

Effects of rhizosphere fertilization on nitrate content of rape

A diffusion experiment was conducted to determine the changes of nitrate and ammonium concentration at different distance around the placement of fertilization in soil, and a pot trial was carried out to validate the effects of different means of fertilizer application on the nitrate content and yield of rape on a calcareous soil. Two kinds of fertilizers, the Acidic ball-like Rhizosphere Fertilizer (pH1.0-2.0) and normal concentrated fertilizer, were used. The results indicated that the sphere of influence on the concentration of nitrate and ammonium in soil were mainly within 4 cm apart from fertilization point; however, the difference of influence sphere of these two fertilizers was significant within 2 cm. The diffusion of ammonium and nitrification of the acidic fertilizer were slower than that of concentrate fertilizer. Therein, within 1 cm from fertilization point, the increment of the soil ammonium of the concentrated fertilizer measured up to the maximum after a week of application, but for the acidic fertilizer, the maximum was reached after two weeks, meanwhile, the difference of increment of these two fertilizers was significant. Within 2 cm from fertilization point, for both fertilizers, the maximum of ammonium was reached one week later than that at 1 cm, and the increment of ammonium of the concentrated fertilizer was lower than that of the acidic fertilizer. But the increment of nitrate of concentrated fertilizer was lower than that of acidic fertilizer. The results of pot experiment indicated that the application of acidic rhizosphere fertilizer increased ammonium concentration remarkably, but decreased nitrate concentration. Comparing with the concentrated fertilization, the application of acidic rhizoshpere increased ammonium concentration by 13% and decreased nitrate concentration by 71%-89%, respectively. As the result, the application of acidic rhizoshpere fertilizer decreased the amount of nitrate accumulated in the rape by 28% and increased the output of rape by 39%.