生物炭和秸秆对华北农田表层土壤矿质氮和pH值的影响

基于2014-2015年华北农田定位试验,设CK（单施氮磷钾肥）、C1（生物炭4.5t×hm^-2×a^-1+氮磷钾肥）、C2（生物炭9.0t×hm^-2×a^-1+氮磷钾肥）和SR（秸秆还田+氮磷钾肥）4个处理,对施用生物炭和秸秆还田对表层土壤矿质氮（NO₃^--N、NH₄⁺-N）含量以及土壤pH值的影响进行研究。结果表明,不同处理土壤矿质氮的动态变化趋势基本一致,施用生物炭和秸秆还田均可显著提高土壤NO₃^--N含量（P<0.05）,但对土壤NH₄⁺-N含量影响不大。与秸秆还田相比,高量施用生物炭有利于增加土壤NO₃^--N含量。各处理土壤中矿质氮主要以NO₃^--N为主,NH₄⁺-N含量均保持在一个较低水平。将冬小麦整个生育期内各处理土壤NO₃^--N、NH₄⁺-N含量与夏玉米的相比,前者显著高于后者。在整个冬小麦-玉米轮作周期内,高量施用生物炭显著提高了土壤pH值,且各处理土壤NO₃^--N与土壤pH值呈显著负相关（P<0.05）,土壤NH₄⁺-N含量与土壤pH值相关性不显著;而各处理土壤NO₃^--N、NH₄⁺-N含量与土壤含水量均呈显著正相关（P<0.05）。可见,添加生物炭对减少氮素的转化和流失具有较大潜力。     

喀斯特地区不同茎形态植物的水土保持和养分截留效果研究

在坡度为30°的坡地建立12个径流小区,试验设计4个处理,分析了3种不同茎形态植物的水土保持和养分截留效果,并在此基础上进一步探讨水土保持和养分截留之间的定量关系。结果表明:薜荔,马蔺和常青藤的覆盖度分别为53.1%,62.8%和60.0%。薜荔,马蔺和常青藤具有一定的水土保持效果,不同植物的保水固土效应存在显著性差异。薜荔,马蔺和常青藤对TP,DP,TN,NO₃^--N,NH₄⁺-N和K有一定的截留作用。薜荔对TP,DP,TN,NO₃^--N,NH₄⁺-N和K的截留效果分别为0.58,0.64,0.54,0.86,0.64,0.54;马蔺对TP,DP,TN,NO₃^--N,NH₄⁺-N和K的截留效果分别为0.76,0.64,0.68,0.78,0.53,0.56;常青藤对TP,DP,TN,NO₃^--N,NH₄⁺-N和K的截留效果分别为0.72,0.75,0.61,0.83,0.45,0.58。水土保持与养分截留效果之间呈现极显著性相关（Pearson相关性系数 > 0.698^**）,表明水土保持是养分截留的有效途径。     

周年施氮对冬小麦-夏大豆轮作产量及土壤氮素含量的影响

为探讨周年不同施氮组合对冬小麦-夏大豆轮作体系土壤氮素及产量影响规律,于2017—2018年,在伊宁县农业科技示范园内开展大田试验,以冬小麦-夏大豆轮作为研究对象,在前茬麦季设置4个施氮水平:0(N0)、104(N1)、173(N2)、242 kg·hm^-2(N3);后茬大豆设置3个施氮水平:0(S0)、69(S1)、138 kg·hm^-2(S2),研究周年不同施氮组合对两季作物收获后农田0~100 cm土层土壤硝态氮(NO₃^--N)、铵态氮(NH₄⁺-N)含量、无机氮残留量及产量的影响。结果表明,冬小麦不同施氮水平土壤NO₃^--N及NH₄⁺-N含量均在20~40 cm土层达到最大值,且N3的土壤NO₃^--N和NH₄⁺-N含量最高,分别达到14.65 mg·kg^-1和4.26 mg·kg^-1,土壤NO₃^--N含量平均分别较N0、N1、N2增加了92.86%、44.69%和17.03%,土壤NH₄⁺-N平均依次增加了69.95%、26.10%和8.46%;而冬小麦施氮量越高,其土壤无机氮残留量越大,以麦季N3平均最高,为200.62 kg·hm^-2。此外,前茬麦季施氮还能影响后茬大豆土壤中NO₃^--N、NH₄⁺-N含量及无机氮残留量;夏大豆的土壤NO₃^--N和NH₄⁺-N含量也在20~40 cm土层达到最大值,且N3S2的土壤NO₃^--N、NH₄⁺-N含量及无机氮残留量最大,平均分别为18.61 mg·kg^-1、 5.10 mg·kg^-1、258.36 kg·hm^-2。在麦季施氮173 kg·hm^-2时(N2),冬小麦产量最高,平均为7 828.64 kg·hm^-2,平均分别较N0、N1、N3增加35.45%、16.77%、6.26%;且在此基础上夏大豆当季再施氮69 kg·hm^-2时(S1),夏大豆获得产量最高,平均为2 988.93 kg·hm^-2,其周年总产量也达到最高平均,为10 817.5 kg·hm^-2。综上所述,麦季施氮173 kg·hm^-2,豆季施氮69 kg·hm^-2既有利于提高麦豆周年产量,又能减少土壤氮素的残留量,可为当地一年两熟制高效施氮制度提供一定的参考标准。     

黏土矿物混合生物炭包膜尿素的制备及其氮素污染减排潜力

为促进氮肥高效利用,实现氮素污染减排,选用膨润土和生物炭作为包膜材料,结合硝化抑制剂制备包膜尿素。设置包膜尿素淋溶模拟试验收集淋溶液,结合静态箱法收集N₂O,通过分析NH₄⁺-N,NO₃^--N淋失量和N₂O排放通量对包膜尿素氮素污染减排潜力进行了评估。结果表明:（1）膨润混合土生物炭包膜尿素（F₄）NH₄⁺-N淋溶损失率最低,较纯化肥尿素（F₁）NH₄⁺-N淋溶损失率降低19.76%。（2）硝化抑制剂型膨润土生物炭包膜尿素（F₅）NO₃^--N淋失率最低,较F₁降低16.74%。（3）F₅同时具有最优的N₂O减排效果,N₂O排放量较F₁降低77.8%。F₅氮素减排效果最优,其减排机制在于一方面硝化抑制剂可以从化学过程控制硝化和反硝化进程,延缓尿素酰胺态氮的水解和铵态氮的硝化,在降低NO₃^--N淋失的同时可以实现N₂O减排。另一方面F₅的包膜材料膨润土和生物炭可以通过吸附作用将更多的NH₄⁺-N富集在土壤表层,从而显著降低NH₄⁺-N淋失。综上所述,硝化抑制剂型膨润土生物炭包膜尿素氮素污染减排潜力最优,可使NH₄⁺-N,NO₃^--N和N₂O分别减排15.24%,16.74%和77.8%。     

镇江市古运河河岸沉积物氮及有机质分布特征

为揭示镇江市古运河河岸带表层沉积物中氮元素含量的分布特征,结合古运河周边环境状况,选择6个典型的采样点对其表层沉积物进行样品采集,对各样品沉积物总氮（TN）,氨氮（NH₄⁺-N）,硝氮（NO₃^--N）,亚硝氮（NO₂^--N）以及有机质（O.M）和pH值进行了分析,并根据经验公式对沉积物有机氮进行了计算。结果表明,TN,NH₄⁺-N,NO₃^--N,NO₂^--N以及Org-N含量介于0.39~2.40 g/kg,1.63~11.31 mg/kg,2.46~6.95 mg/kg,0.54~2.29 mg/kg,0.99~2.32 g/kg,总氮和有机氮的变异系数最大,为83.59%,氨态氮、硝态氮以及亚硝态氮的变异系数介于40.36%~49.15%,表现为中等离散程度,表明研究区域总氮和有机氮的离散程度较高,其在空间分布上呈现较为明显的异质性;古运河沉积物有机质含量介于0.99%~2.32%,变异系数为32.50%,表现为中等变异性,表明各采样点的沉积物有机质含量变化幅度中等;通过沉积物C/N值来判断,古运河有机质主要以陆源贡献为主;相关性分析结果表明,NO₂^--N与TN的关系最为密切,而氨氮与硝氮、亚硝氮以及有机氮之间的相关性不强,说明氨氮与其他形态氮在沉积物方式上存在一定的差异性。此外,pH值对古运河表层沉积物氮形态的具有较为显著的影响。     

添加葡萄糖对红壤农田肥料氮转化及其酸化的影响

采用室内培养实验,初步研究了外加葡萄糖对红壤肥料氮素转化及其酸化作用的影响,其中葡萄糖添加量充足,为8 g·kg^–1干土,氮肥以(NH4)₂SO₄和KNO₃为例。结果表明,在对照、单施(NH4)₂SO₄或KNO3处理中,土壤中氮转化过程主要以有机氮净矿化和铵态氮净硝化为主,这主要是由于红壤可利用碳源较少。而外加足够葡萄糖碳源可快速(2 d内)促进土壤及其100 mg·kg^–1氮肥中的NH₄⁺-N和NO₃^--N几乎全部被微生物同化,30 d培养期间微生物同化促进28%~50%的肥料氮迅速转化为固相有机态氮。单施(NH4)₂SO₄或KNO₃主要通过硝化作用和盐效应降低土壤pH,但微生物对NH₄⁺-N的生物固定可抑制其硝化导致的酸化作用,而微生物对NO₃^--N的生物固定可提高土壤pH高达0.78个单位。因此,添加葡萄糖等碳源可促进农田土壤中NH₄⁺-N和NO₃^--N的微生物同化,缓解氮肥引起的土壤酸化作用。研究结果对提高农田土壤的保氮能力和氮肥利用率、抑制土壤酸化等具有重要意义。     

不同硝化抑制剂对黑土N2O的减排效果

【目的】施用硝化抑制剂是削减农田N₂O排放的有效措施，本文研究不同种类硝化抑制剂对土壤N₂O排放的影响，为选择高效硝化抑制剂以实现黑土N₂O减排提供科学依据。【方法】在黑龙江省东部典型旱作黑土区进行田间试验。设置6个处理：不施氮肥(N0)，常规施氮(N200)，减氮20%(N160)，减氮20%分别配施硝化抑制剂双氰胺(N160+DCD)、3,4-二甲基吡唑磷酸盐(N160+DMPP)和2-氯-6 (三氯甲基)-吡啶(N160+CP)。测定全年土壤N₂O排放通量，同步测定土壤温度和含水量以及玉米生长季土壤铵态氮(NH₄⁺-N)、硝态氮(NO₃^--N)和可溶性有机碳(DOC)含量。【结果】施氮显著提高了土壤NH₄⁺-N含量，且各施氮处理间差异不显著。施用硝化抑制剂处理降低了土壤NO₃^--N含量，DCD和DMPP处理的NO3--N...     

基于三维Copula函数的滴灌硝态氮淋失风险评估方法

硝态氮淋失是滴灌系统设计和运行管理需要考虑的重要因素。该研究构建了滴灌条件下的水氮运移模型,利用HYDRUS-2D软件进行了求解,模拟分析了田间尺度砂壤土饱和导水率和初始含水率空间变异对NO₃^--N淋失率的影响,并利用三维Gumbel-Hougaard Copula函数构建了土壤饱和导水率、初始含水率和NO₃^--N淋失率的联合分布函数,分析了给定土壤饱和导水率和初始含水率条件下NO₃^--N淋失率超过某一阈值的条件概率。结果表明,NO₃^--N淋失率概率密度函数可用指数函数表示;土壤饱和导水率和初始含水率的空间变异会明显增加NO₃^--N淋失风险;NO₃^--N淋失率超过给定阈值（6.4%,均质土壤条件下的NO₃^--N淋失率）的条件概率基本随土壤饱和导水率和初始含水率的增大而增大。构建田间尺度土壤特性参数（如饱和导水率、初始含水率等）与NO₃^--N淋失率的联合分布函数为研究多变量空间变异条件下NO₃^--N淋失风险评估提供了参考。     

亚热带地区土壤硝酸盐异化还原成铵速率的空间差异和驱动因素

土壤硝酸盐异化还原成铵(DNRA)是生态系统土壤氮转化的重要途径，理清环境因素对土壤DNRA速率的影响意义重大。本研究通过收集246项试验观测值采用整合分析方法(Meta-analysis)研究了亚热带地区不同生态系统中DNRA速率的变化范围及其影响因素。结果表明：纬度对亚热带土壤DNRA速率无显著影响；土壤p H、全氮(TN)、SOC/NO₃^–-N、Fe(Ⅱ)、阳离子交换量(CEC)、易氧化有机碳(EOC)、有效磷(AP)、黏粒含量和年平均气温(MAT)的增加均会促进DNRA速率；年平均降水量(MAP)和土壤NH₄⁺-N含量的增加会抑制土壤DNRA速率。此外，环境因子对DNRA速率的影响随生态系统的不同表现出较大差异。结构方程模型分析结果显示，SOC/NO₃^–-N是DNRA主要驱动因素，p H、NH₄⁺-N、MAP和MAT对土壤DNRA也有较大影响。     

离子型稀土闭矿区土壤铵态氮富集特征

离子型稀土开采使用的浸矿剂(硫酸铵)造成土壤铵态氮(NH₄⁺-N)残留,带来严重的氮污染,危及生态环境和人体健康,导致稀土矿开采受限。为明确已开采矿区土壤中NH₄⁺-N的富集特征及其影响因素,选择江西省赣州市龙南县一个已闭矿4年的原地浸矿离子型稀土矿山,在山体不同坡位布点,自土表至矿体底板(土体与基岩交界处,深度为5.5～9.7 m)分层采样,并测定了土体中的NH₄⁺-N及其相关的土壤性质。结果表明,矿区土壤NH₄⁺-N含量范围为2.32～1 056.44 mg·kg^-1(263.12±301.59mg·kg^-1),是自然和农田土壤的数倍甚至上百倍。从土体分布来看,矿体部分土壤NH₄⁺-N含量高于其上部土壤,不同土层间差异显著。从不同地形部位来看,NH₄⁺-N的平均含量坡顶>坡...     

三类土壤不同酰硝比供应下的辣椒产量、品质和氮素损失

【目的】酰胺态氮、铵态氮和硝态氮是蔬菜施肥的主要氮源,不同氮素形态配比既影响蔬菜的产量品质,又影响氮素损失,而氮素在不同土壤中转化进程不同。为确定辣椒主产区主要土壤类型上合适的氮素形态配比,本试验选用广东赤红壤 (pH 5.97)、安徽菜园土 (pH 7.09) 和山东潮土 (pH 8.33) 为供试土壤,研究辣椒产量和品质在三种不同类型土壤上对不同氮素形态配比的响应,确定适宜各土壤类型上辣椒生长的酰硝比,以期为辣椒主产区氮肥调控提供理论依据。 【方法】采用土壤培养试验和盆栽试验,土壤培养试验每种土壤类型设两个处理:单施尿素 (对照)、尿素添加硝化抑制剂处理。盆栽试验设:不施氮肥 (CK)、NO₃-N 100% (T1);CO(NH₂)₂-N 25% + NO₃-N 75% (T2)、CO(NH₂)₂-N 50% + NO₃-N 50% (T3)、CO(NH₂)₂-N 75% + NO₃-N 25% (T4)、CO(NH₂)₂-N 100% (T5) 6 个处理。培养试验测定不同培养时期土壤铵态氮和硝态氮含量;盆栽试验在辣椒收获期测定辣椒的产量与品质、植株氮浓度,在施肥后不同时期测定土壤无机氮的含量。 【结果】土壤培养试验结果表明三类土壤的硝化能力强弱顺序是潮土 > 菜园土 > 赤红壤,添加硝化抑制剂 2-氯-6-(三氯甲基) 吡啶 (N-Serve) 后能调控三类土壤的氮素转化速率,在培养第 4 天表观硝化率分别降低了 30.3%、38.0% 和 8.3%。盆栽试验结果表明与不施氮肥处理相比,施氮处理能显著提高辣椒产量和品质,产量的提高源于单果重和果实数的增加,品质提升主要包括维生素 C 和可溶性固形物含量的提高;在添加 N-Serve (酰胺态氮纯氮量的 1%) 的基础上,三类土壤上辣椒产量和品质对酰硝比的响应不同,赤红壤、菜园土和潮土最高产量对应的硝态氮占氮肥供应总量的 75%,25% 和 50%,品质较优对应的硝态氮占比分别是 75%,50% 和 25%;辣椒氮素吸收量也表现为菜园土 > 潮土 > 赤红壤,且与单施硝态氮相比,硝态氮与酰胺态氮配施在赤红壤、菜园土和潮土上氮肥利用率分别提高 25.3%、9.0% 和 22.4%,淋洗液氮素损失量分别降低 58.4%,53.6% 和 51.7%。 【结论】统筹考虑辣椒优质高产以及环境代价等因素,在赤红壤、菜园土和潮土上适宜的硝态氮占比分别是 50%～75%,25%～50% 和 25%～50%。     

Nitrogen leaching from soils in the Kopais area of Greece

Abstract. The contribution of agriculture to the nitrogen pollution of surface and ground waters of calcareous lake soils in the Kopais area (190 km²) of Greece was studied over three cropping seasons. Sample fields were chosen from seven representative soil units under different crop rotations. The distribution of mineral N (NO₃-N + NH₄-N) throughout the soil profile and the concentration of NO₃-N in the ground water and drainage water were measured and allocated to 6-month winter or spring periods. For all fields N was leached to the deeper soil layers and to the saturated zones by both excess winter rainfall and spring irrigation of different crops The amount of nitrogen leached depended on the amount of nitrogen fertilizer applied; the depth of leaching varied with the physical properties of the soils. Losses in individual fields accounted for the equivalent of 17.6–80.8% of the nitrogen applied to maize and 70.5–94.1% of that applied to wheat. For the whole region estimated minimum N losses ranged from 175, 912 to 783, 564 kg for the 6-month period. Nitrate concentrations in the ground and surface waters were often more than the EC target level of 25 mg/1.     

Increase in the Nitrogen Content of Soil by the Introduction of Earthworms into Soil

The contribution of an earthworm species ( Amynthas vittatus ) to the increase of the nitrogen content of soil was examined. Three specimens of adult earthworms were introduced into 300 g of soil (Gray Lowland soil, silty clay) supplemented with 1% carboxymethyl cellulose in a container and incubated for 32 d at 22°C in the dark. The contents of total-N, NH₄-N and NO₃-N, and the population of aerobic nitrogen-fixing bacteria in soil significantly increased after incubation with the earthworms, while the natural abundance of ¹⁵N (δ¹⁵N) in soil decreased. The amount of nitrogen in the earthworms did not decrease during the incubation in the microcosm. Both acetylene reduction activity of the microcosm and incorporation of ¹⁵N to soil from atmospheric ¹⁵N₂ were significantly enhanced by the introduction of the earthworms into soil, though the observed increment of nitrogen in soil was much higher than the estimated one based on the nitrogen-fixing activity. The results obtained in the present study indicated that the earthworms increased the nitrogen content of soil, presumably due to the enhancement of the nitrogen-fixing activity of the soil from the microcosm by the earthworms.     

黄淮海平原小麦-玉米轮作制度下的地下水NO3-N污染研究

The North China Plain, where summer corn (Zea mays L.) and winter wheat (Triticum aestivum L.) are the major crops grown, is a major agricultural area in China. Permeable soils make the region susceptible to groundwater pollution by NO₃-N, which is applied to fields in large amounts of more than 400 kg NO₃-N ha^-1as fertilizer. A field experiment was established in 2002 to examine the relationship among N fertilization rate, soil NO₃-N, and NO₃-N groundwater contamination. Two adjacent fields were fertilized with local farmers' N fertilization rate (LN) and double the normal application rate (HN), respectively, and managed under otherwise identical conditions. The fields were under a traditional summer corn/winter wheat rotation. Over a 22-month period, we monitored NO₃-N concentrations in both bulk soil and soil pore water in 20-40 cm increments up to 180 cm depth. We also monitored NO₃-N concentrations in groundwater and the depth of the groundwater table. No significant differences in soil NO₃-N were observed between the LN and HN treatment. We identified NO₃-N plumes moving downward through the soil profile. The HN treatment resulted in significantly higher groundwater NO₃-N, relative to the LN treatment, with groundwater NO₃-N consistently exceeding the maximum safe level of 10 mg L^-1, but groundwater NO₃-N above the maximum safe level was also observed in the LN treatment after heavy rain. Heavy rain in June, July, and August 2003 caused increased NO₃-N leaching through the soil and elevated NO₃-N concentrations in the groundwater. Concurrent rise of the groundwater table into NO₃-Nrich soil layers also contributed to the increased NO₃-N concentrations in the groundwater. Our results indicate that under conditions of average rainfall, soil NO₃-N was accumulated in the soil profile. The subsequent significantly higherthan-average rainfalls continuously flushed the soil NO₃-N into deeper layers and raised the groundwater table, which caused continuous groundwater contamination with NO₃-N. The results suggest that under common farming practices in the North China Plain, groundwater contamination with NO₃-N was likely, especially during heavy rainfalls, and the degree of groundwater contamination appeared to be proportional to the N application rates. Decreasing fertilization rates, splitting fertilizer inputs, and optimizing irrigation scheduling had potential to reduce groundwater NO₃-N contamination.     

聚丙烯酰胺对盐渍化土壤氮素的影响

为了研究河套地区盐渍化土壤施用聚丙烯酰胺（PAM）后葵花全生育期内土壤氮素的时空变化规律及其利用率,采用正交试验对葵花生育期内0—100 cm土层土壤碱解氮的动态变化规律及氮肥利用率进行分析。结果表明:施用PAM处理的盐渍化土壤在PAM施用层能够保持一定的碱解氮且不易使碱解氮下移,未施PAM的4个灌水处理在不同程度上均下移至40 cm左右,表明施用PAM明显抑制了氮素深层移动效应。通过正交试验处理及SPSS主效应分析选取三因素最优的适用量为:水量1 800 m³/hm²,氮素168 kg/hm²,PAM量为18.75 kg/hm²,并且PAM施用对中度盐渍化土壤氮肥利用率的影响显著。研究结果可为河套灌区盐渍化土壤合理施氮量及施用PAM对氮肥利用率的影响提供理论依据。     

Effects of Shifting Cultivation on Soil Ecosystems in Sarawak, Malaysia. III. Results of Burning Practice and Changes in Soil Organic Matter at Niah and Bakam Experimental Sites

The effects of burning on the levels of soil organic matter, soil nitrogen, and soil microbial biomass were studied by carrying out experimental shifting cultivation at two sites, Niah and Bakam in Sarawak, Malaysia. Vegetation biomass was burned in plots (10 × 10 m²) at the rates of 0 (control), 100, 200, and 300 Mg ha⁻¹ at the Niah site and 0, 20, and 100 Mg ha⁻¹ at the Bakam site. At the Niah site, the levels of total C and N of the soils did not change throughout the experiment in spite of enhanced soil respiration until 2 months after burning. Although burning induced an increase in the amount of NH₄-N of the soils, the readily available pool of N (the sum of the NH₄-N, NO₃-N, microbial biomass N, and extractable organic N pools) in the burned plots was depleted appreciably at the end of rice cultivation. The effects of burning on these properties tended to be substantial with increasing amounts of the vegetation biomass burned. On the other hand, the levels of total C and N and the readily available N pool at the Bakam site were low before burning compared with those at the Niah site, and the burning treatments did not affect them appreciably. While the rice yield at the Niah site reached the average value obtained in traditional shifting cultivation in Sarawak, that at the Bakam site was much lower. It was suggested that the flush of NH₄-N induced by burning was one of the major factors for rice growth.     

Microbial Immobilization and Plant Uptake of Different N Forms in Three Forest Types in Shikoku District, Southern Japan

Soil microbial immobilization and plant uptake of N were evaluated for three forest types in Kochi, Shikoku district. During 196-d laboratory incubation, soil NO₃-N production in the Hinoki cypress forest was negligible for the initial 40 d and then rapidly increased, whereas NO₃-N production was rapid from the beginning in Japanese cedar and deciduous hardwood forests. Microbial immobilization of the labeled ¹⁵N decreased in the order of NH₄-N>glycine-N>NO₃-N. The ¹⁵N immobilization was higher for soil in the Hinoki cypress forest than other two soils. The delayed NO₃-N production in the Hinoki cypress forest was likely related with low availability of NH₄-N due to NH₄-N immobilization and substantial NO₃-N immobilization. In the field experiment, ¹⁵N uptake by roots decreased in the order of NH₄-N>NO₃-N>glycine-N. The absorption of the labeled ¹³C suggested direct uptake of organic N. The preference of N forms by root uptake was not different among forest types. Trees in three forest types can absorb inorganic and organic forms of N, suggesting trees absorb the N form that is the most abundant in the soil.     

一个稻田土壤-作物体系的氮素循环模型

模型为一维模型,其主要框架由土壤水分运动、N素迁移转化以及水稻生长3个模块组成。在土壤水分运动模拟中,考虑了可能存在的饱和流和非饱和流;在N素运移中将土壤中的NH4 、NO3-和尿素视为土壤溶质,用对流弥散方程模拟其在垂直方向上的运移;在N素转化过程中考虑了尿素水解、有机N矿化、氨挥发、硝化、反硝化以及NH4 的吸附这6个过程;对于作物生长的模拟,选用了ORYZA水稻生长模型,并结合田间实验修改了其中一些参数。使用该模型对3年的田间试验进行了模拟验证,对于土壤中矿质态N素以及水稻生长的模拟,都得到了较好的模拟结果,通过与实测值的分析比较,耕作层的NH4 -N浓度,水稻各部分的生物量模拟值与实测值的吻合都达到了显著水平。     

不同形态氮肥及其用量对强筋小麦氮素转运、产量和品质的影响

【目的】研究强筋小麦产量品质形成的适宜氮肥形态和施氮量,对增加小麦产量、提高籽粒品质及减少农田氮污染有重要意义,同时为合理精确运筹施氮提供理论依据。【方法】田间试验采用二因素裂区设计,氮肥形态为主区(硝态氮肥、铵态氮肥、酰铵态氮肥),氮肥用量为副区(低氮75kg/hm^2、中氮150kg/hm^2、高氮225kg/hm^2)。分析小麦的氮转运量和产量、品质。【结果】1)在同一形态氮肥下,小麦成熟期氮累积量、籽粒产量和收获指数均在中氮(150kg/hm^2)处理达到最大值,中氮(150kg/hm^2)处理能通过显著增加花前氮转运量和花后氮积累量进而提高籽粒含氮量。生物产量、籽粒蛋白质组分含量(除醇溶蛋白)、蛋白质含量、湿面筋含量、面筋指数、总淀粉、直链淀粉、支链淀粉、可溶性糖和蔗糖含量均随施氮量增加而提高。2)在同一施氮量下,硝态氮肥和酰胺态氮肥处理的小麦各时期植株含氮量、生物产量和籽粒产量均显著高于铵态氮肥(P<0.05),硝态氮肥和酰胺态氮肥的籽粒产量处理无显著差异(除低氮处理)。铵态氮肥处理的品质最差,酰胺态氮肥处理更有利于增加蛋白质和淀粉含量,改善籽粒品质,酰胺态氮肥处理的氮素吸收效率和氮素生产效率最高。3)不同形态氮肥显著影响穗数,施氮量显著影响千粒重。产量和品质达到最优所需的氮肥用量不同,中氮(150kg/hm^2)时产量最高,高氮(225kg/hm^2)时品质最优。4)方差分析表明,不同形态氮肥和施氮量对冬小麦各生育阶段氮素积累量及所占比例有极显著的影响(P<0.01),且二者存在极显著的互作效应。通径分析表明,叶片花前氮转运量对产量的直接影响最大,直接通径系数为0.614。【结论】酰胺态氮肥是适合该地区的氮肥种类,酰胺态氮肥在中氮(150kg/hm^2)条件下能显著提高强筋小麦产量和籽粒含氮量,在高氮(225kg/hm^2)条件下能显著改善强筋小麦品质,因此在实际小麦生产中要根据产量品质要求合理运筹氮肥。