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以洞庭湖平原2个典型水稻土(红黄泥和紫潮泥)为对象,采用15N示踪技术,研究了淹水培养条件下稻草+硫铵配施(S+15NA)和单施硫铵(15NA)土壤微生物和粘土矿物对化肥氮的固定与释放及氮的残留形态.结果表明,淹水培养条件下BN(SMBN)总体变化趋势是在培养前期达到峰值,而后逐渐下降,最后趋于稳定.固定态铵在整个试验期间变化相对较小,但也随培养时间的延长而减少.淹水培养条件下,BN以原有BN为主.标记底物BN的比例红黄泥为0.30%~6.67%;紫潮泥为1.00%~3.47%.微生物同化的标记底物硫铵氮的比例红黄泥为0.15%~20.65%,紫潮泥为2.06%~15.93%;有机无机配施处理(S+15NA)均大于单施化肥(15NA),红黄泥S+15NA处理平均为6.78%,高于红黄泥15NA处理;紫潮泥S+15NA处理(10.78%)也高于紫潮泥15NA处理.粘土矿物对标记底物氮的固定率,红黄泥为2.48%~10.57%,紫潮泥为12.55%~30.04%.红黄泥S+15NA处理平均为7.14%,低于红黄泥15NA处理;紫潮泥S+15NA处理(21.53%)也低于紫潮泥15NA处理.淹水培养条件下底物硫铵氮的残留率均大于30%,有机无机配施处理提高了无机氮的残留率.红黄泥底物氮的残留形态主要为酸解有机氮(>72%),而紫潮泥以酸解有机氮(44.0%~53.2%)和固定态铵(35.2%~37.5%)为主,两种土壤底物氮矿质氮形态残留在10%~20%之间.研究表明土壤对外源无机氮的固定与释放是一个动态的过程,施肥方式和土壤粘土矿物组成对该过程有重要影响.化肥和秸秆配合施用能增强微生物对无机氮的同化,降低土壤粘土矿物对无机氮的固持.有机无机配施处理在降低化肥氮损失的同时提高了酸不溶性氮态的残留率,降低了无机氮形态(固定态铵和矿质氮)的残留.
Using 15N tracing technique, two typical paddy soils (red, yellow and purple tide mud) in the Dongting Lake Plain were used to study the effects of straw + ammonium sulfate (S + 15NA) and ammonium sulfate alone (15NA) The fixation and release of nitrogen and the residual forms of nitrogen by soil microbes and clay minerals were studied.The results showed that the general trend of BN (SMBN) peaked at the early stage of culture, then decreased gradually and finally decreased The change of fixed ammonium was relatively small during the whole experiment, but also decreased with the prolongation of culture time.Under flooding culture, BN was dominated by original BN.The ratio of labeled substrate BN was 0.30% ~ 6.67%, purple tide mud is 1.00% ~ 3.47%, the ratio of ammonium sulfate to labeled substrate for microbial assimilation is 0.15% ~ 20.65%, purple tide mud is 2.06% ~ 15.93% (S + 15NA) were all higher than that of chemical fertilizer (15NA). The average S + 15NA of reddish brown soil was 6.78%, which was higher than that of reddish purple soil 15NA. Purple Sidi S + 15NA treatment (10.78%) was also higher than purple tide The results showed that the fixation rates of clay minerals to labeled substrate nitrogen were 2.48% -10.57% for reddish clay and 12.55% -30.04% for purple tide mud.The average S + 15NA treatment of reddish brown mud was 7.14% Red purple yellow mud 15NA treatment; purple tide mud S + 15NA treatment (21.53%) is also lower than purple tide mud 15NA treatment under flooded culture conditions substrate ammonium sulfate nitrogen residues were greater than 30%, organic and inorganic combination treatment increased The residue of inorganic nitrogen was mainly residual organic acid (> 72%), while purple tide treated with organic nitrogen (44.0% ~ 53.2%) and fixed ammonium (35.2% % ~ 37.5%), and the contents of nitrogen and nitrogen in the two soil substrates remained between 10% and 20% .Research shows that the fixation and release of exogenous inorganic nitrogen in soils are a dynamic process. The fertilization mode and soil clay minerals The combination of chemical fertilizers and straw can enhance the assimilation of inorganic nitrogen by microorganisms and reduce the retention of inorganic nitrogen by soil clay minerals.The application of organic and inorganic fertilizers can reduce the nitrogen loss of fertilizers and increase the content of acid-insoluble nitrogen Of the residual rate, reducing inorganic nitrogen forms (fixed ammonium and mineral nitrogen) residues.