Effects of N Application Rates and NO_3-N to NH_4-N Ratios on Yield and Quality of Flue-cured Tobacco Planted in Black Soil

A field experiment about effects of nitrogen application rates and different NO3-N to NH4-N ratios on agronomic, chemical and biological characteristics as well as yield and quality of flue-cured tobacco grown in a black soil was conducted from 2004 to 2005 in Heilongjiang Province. The results showed that the nitrogen application rates at 45 kg·hm^-2 with the ratio of 75% NO3-N to 25% NH4-N resulted in the highest potassium and reducing sugar contents in the flue-cured tobacco leaving with the highest quality grade and value. It is recommended that this ni- trogen application rate and NO3-N to NH4-N ratio should be widely applied on flue-cured tobacco grown in the black soil in Heilongjiang Province.

无土栽培中NH_4^+—N和NO_3^-—N的测定

2mol.l-1KCl溶液可作为无土栽培中基质的NH4+—N和NO3-—N的提取剂,其固∶液=1∶5,振荡时间为30min,NH4+—N测定采用靛酚蓝比色法,测定波长为645nm,标准曲线的回归方程为:A=0.7358C+0.0044,r=0.9994(n=7),回收率为:103.6%。NO3-—N测定采用紫外分光光度法,测定波长为205nm,标准曲线的回归方程为:A=0.5654C+0.0127,r=0.9994(n=9),回收率为:102.4%。

Nitrogen transformation in maize soil after application of different organic manures

The nitrogen transformation in maize soil after application of different organic manure was studied. The nitrogen mineralization in surface soil, NO - 3-N dynamics and distribution in soil profile, and N 2O emission were investigated. Eight treatments were laid out randomizing with three replications in 24 plots: maize plantation without fertilizer(CK1), bare soil without maize plantation and fertilization(CK2), swine manure(S1, S2), poultry manure(P1, P2), and cattle manure(C1, C2). Three manures were applied at two application levels(15 t/hm 2 and 30 t/hm 2). The results indicated that NH + 4-N in surface soil showed the same temporal pattern without much variation among different treatments. But NO - 3-N in the same layer exhibited large temporal pattern in all treatments, which was mainly due to its easy eluviations of NO - 3-N in soil, its transformation to N 2O and the influence of precipitation. The distribution of NO - 3-N in the soil profile during maize growing season showed the leaching tendency from surface soil to subsoil, which was different among the treatments. The poultry treatments showed the largest leaching tendency. The study also revealed that the emissions of N 2O were affected by the application of organic manures in the order of P2>S2>C2>P1>S1>C1>CK1>CK2. All these results showed that organic manure applications significantly affect nitrogen transformation and distribution in maize soil. Considering N 2O emission and NO - 3-N leaching, the management of organic manure in the agriculture needs further studies.

3种沉水植物碳氮代谢对水体氮源形态组成的响应

以沉水植物穗花狐尾藻(Myriophyllum spicatum L.)、伊乐藻(Elodea canadensis Michx)和金鱼藻(Ceratophyllum demersum L.)为试验对象,研究水体中不同硝态氮(NO_3^-N)和铵态氮(NH_4^+-N)浓度比对植物碳氮(C-N)代谢的影响。2015年春季栽培3种沉水植物;7月,截取长约10 cm的植物顶端于1 L的玻璃烧杯预培养,光暗比为14 L∶10 D,温度控制为光周期25℃,暗周期15℃,光照强度为110μmol/(m^2·s),预培养7 d后截取植物顶端1 g左右转入250 m L的锥形瓶,设计培养液总氮浓度为2 mg/L,按照NH_4^+-N与NO_3^-N的浓度比设置2∶1、1∶1、1∶2、2∶0、0∶2共计5个处理,以预培养液为对照,每个处理设置3个重复。结果表明:(1)与对照相比,氨氮添加显著提高了3种植物组织内游离氨基酸(FAA)的含量,且在氨氮浓度2 mg/L时FAA达最大;(2)植物体内可溶性糖含量(SC)存在显著的种间差异,二元方差分析显示处理间SC的差异,种间差异的贡献值为69%;(3)硝态氮完全替代氨态氮时,3种植物组织中的SC/FAA显著升高,二元方差分析显示处理间SC/FAA的差异主要源于氮源形态组成(56%);(4)伊乐藻体内FAA和SC含量均大于穗花狐尾藻和金鱼藻。这可能是它在富营养水体中更有优势的重要原因之一。

氮素形态和不同pH值对金脉单药花生长的影响

在pH 4.4、5.7、7.0的水培条件下,分别供应NO3--N、NH4+-N和NH4NO33种不同形态的氮源,研究不同形态氮素和pH值对金脉单药花(Aphelandra squarrosa)生长的影响。结果表明:金脉单药花供给NH4NO3时叶面积、生物量最大,仅供NH4+-N时叶面积、生物量最小,且叶面积与生物量呈极显著正相关;在供给NO3--N时开花率最小,供给NH4+-N时开花率最大;当营养液pH 4.4和5.7时,氮素形态对金脉单药花生长产生一定影响,表现出叶面积、生物量均为NH4NO3>NO3--N>NH4+-N;pH 7.0时,虽然施用不同的氮肥会对其生长产生一定的影响,但差异并不显著。

硫酸盐/氨的厌氧生物转化试验研究

采用厌氧上流式生物膜反应器,通过控制不同的水力停留时间、进水n(NH+4-N)/n(SO2-4-S)和HCO-3浓度研究了无机营养条件下硫酸盐/氨的厌氧生物转化特性.结果表明,反应器中NH+4和SO2-4发生了同步去除,最大NH+4-N和SO2-4-S去除速率分别为47.6 mg·(L·d)-1和16.9 mg·(L·d)-1,稳定去除率最高分别超过了80%和43%;反应过程中有NO-3-N的明显生成,出水NO-3-N浓度最大时为77.6 mg·L-1,整个过程中,未检测到S2-的生成,有单质硫附着在生物污泥表面;由于控制条件的不同,会产生不同的n(NH+4-N)/n(SO2-4-S)转化比,表明NH+4和SO2-4的厌氧生物反应并不是简单地接续反应,反应器中存在更为复杂的反应过程和转化途径.