Aluminum oxyhydroxide polymorphs and some micromorphological characteristics in sclerotium grains

The presence of aluminum oxyhydroxide and its micromorphological characteristics in sclerotium grains were examined by SEM, TEM, and EDX analyses. A spherical fraction with a diameter of 100 nm, which contained C and Al as the predominant elements, was recognized as the unit particle of the matrix of sclerotium grains. The Al polymorphs and the Si spherical structures found in the ignited grains were assumed to correspond to boehmite and opaline silica particles, respectively. SEMI analysis revealed the presence of a needle ball structure inside the hollow part of sclerotium grains. The relationship between the inner structure of sclerotium and biochemical processes of the host fungi was discussed.     

Effect of nitrogen supply on carbon and nitrogen partitioning after flowering in maize

Low nitrogen (N) supply may change assimilate partitioning between plant organs. We measured the effect of N supply on partitioning of recently assimilated ¹³C and recently absorbed ¹⁵N between generative and vegetative plant organs of two maize genotypes (Zea mays L.) 14 d after silking, i.e., during the lag phase of kernel growth. Furthermore, net partitioning of dry matter and N were assessed during grain filling. Plants were grown in a greenhouse in large containers. Our hypothesis was that N deficiency reduces grain set due to low partitioning of carbon (C) and N to the grains during the lag phase and reduces grain yield also because of excessive remobilization of N from the leaves during grain filling. During the lag phase, low N supply increased partitioning of recently assimilated photosynthates towards stem and roots at the expense of partitioning towards reproductive organs. However, despite of diminished sink strength of the reproductive organs for photosynthates, sugar concentrations in the grains of N‐deficient plants were increased, indicating that kernel set and potential kernel weight were not limited by low C supply at the end of the lag phase. In contrast to C, partitioning of recently absorbed N towards the reproductive organs was increased at low N supply at the expense of partitioning towards the roots. This indicates different mechanisms for the regulation of C and N distribution within the plant. During grain filling, biomass partitioning between plant organs was more affected by genotype than by rate of N supply. Nitrogen accumulation in the grains substantially exceeded total N uptake in the plant after flowering. Excess N accumulation in the grains was covered mainly by depletion of stem N at high N supply and by depletion of leaf N at low N supply. However, high concentrations of nonstructural carbohydrates in the stem at maturity indicated that grain yield of N‐deficient plants was not limited by low source strength of N‐depleted leaves.     

叶面喷施微肥对晋南小麦产量和微量元素含量的影响

在山西临汾盆地石灰性褐土进行冬小麦田间试验,在底施NPK肥的基础上,研究了在拔节中期和抽穗前期叶面喷施锌、铁和硒对"济麦22"产量及其构成因素、成熟期地上部分各器官微量元素含量和分配比例的影响。结果表明:叶面喷施3种微肥提高了小麦产量及其构成因素,增产效果为FeSeZn,喷施铁肥与喷施清水相比差异显著;叶面喷施微肥使籽粒、茎叶和颖壳中对应微量元素的含量提高,其中喷施硒肥效果最为明显,喷施锌肥次之;籽粒对3种元素的吸收相互影响,铁对锌单向拮抗,锌与硒、铁与硒相互促进;叶面喷施微肥使锌在籽粒中分配比例稍高于茎叶+颖壳,铁在籽粒中分配比例仅6.87%~8.25%,硒在籽粒中的分配比例稍低于茎叶+颖壳。建议临汾盆地在小麦拔节中期和抽穗前期对冬小麦叶面喷施0.4%ZnSO_4·7H_2O溶液750 kg/hm~(2)和0.017%Na_2SeO_3溶液750 kg/hm~(2),可显著提高籽粒中的锌、硒含量,从而改善籽粒品质;叶面喷施0.3%FeSO_4·7H_2O溶液750 kg/hm~(2)对产量有一定的提升作用。     

EFFECT OF SOIL AMENDMENT WITH ALFALFA POWDERS AND DISTILLERS GRAINS ON NUTRITION AND GROWTH OF CANOLA

Two pot experiments were carried out under controlled environment conditions in the growth chamber to assess the potential use of alfalfa powders and distiller grains as organic fertilizers. Two types of dehydrated alfalfa powders (one with canola meal protein extraction by-product and one without) and two types of distiller grains (dried distillers grain with distillation solubles added and wet distillers grain without solubles) from wheat-based ethanol production were evaluated. Four different nitrogen (N)-based amendment application rates (0, 100, 200 and 400 kg N ha^?1) were used along with urea applications made at the same N rates to a Brown Chernozem (Aridic Haploboroll) loamy textured soil collected from south-central Saskatchewan, Canada. Canola biomass yield, N, phosphorus (P), potassium (K), zinc (Zn), and cadmium (Cd) uptake were measured along with soil properties including pH, salinity, organic carbon, total nitrogen, phosphorus and extractable nutrients and cadmium before and after canola growth in each of the treatments. Application of alfalfa powder and distiller grain amendments resulted in significant canola biomass yield increases along with increased N, P, and K uptake compared to the unfertilized control. However, only a portion of the N added (～30% to 50%) in the organic amendments was rendered available over the five week duration of the experiments. Amendments that had higher N content and lower carbon (C):N ratios such as dried distillers grain with solubles resulted in greater canola N uptake. Reduced germination and emergence of canola seedlings was observed at high rates of addition of distillers grain (400 kg N ha^?1), the reason for which is unclear but may be due to a localized salt or toxicity effect of the amendment. The amendment with alfalfa powders and distiller grains resulted in small increases in residual soil nutrients. Effects on pH, salinity, organic carbon and extractable metals tended to be small and often not significant. Alfalfa powders and distillers grains appear to be quite effective in supplying nutrients, especially N, for plant growth over the short-term.     

氮锌互作对水稻产量及籽粒氮、锌含量的影响

为探明氮锌互作对水稻产量及氮、锌含量的影响,以镇稻11号为供试材料,在大田条件下研究了2个氮肥用量（N 200、300 kg/hm2）下6个施锌水平（ZnSO47H2O 0、10、25、50、100、150 kg/hm2） 对水稻产量及成熟期植株氮、锌浓度及累积量的影响。试验结果表明: 在本试验条件下,锌肥的施用对水稻产量的增加不显著,但施锌能显著提高水稻各部位的锌浓度和籽粒锌累积量,并能提高水稻籽粒的氮浓度和粗蛋白含量,且表现出随施锌量的增加籽粒的氮浓度和粗蛋白含量增加的趋势; 高施氮量有利于水稻的增产及对锌的吸收与累积。因此,氮锌配施具有增加籽粒锌富集和提高蛋白质含量的双重效益。     

Biochar derived from agricultural wastes and wood residues for sustainable agricultural and environmental applications

Lignocellulosic biomass can be circulated to produce many materials and products, including biochar. This study analyzed five different types of biochar produced from agricultural wastes and wood residues. The raw materials included three agricultural by-products: corncob, cassava rhizome, rice husk, and two types of wood residues: rain tree (Samanea saman (Jacq.) Merr.) and krachid (Streblus ilicifolius (Vidal) Corner.). The biochar were made in patented retorts with locally-appropriated technology at a temperature range of 450–500°C. This research focuses on the primary physicochemical properties and biochar components, allowing biochar to become a vital material to support sustainable agriculture and the environment. Biochar properties used for agriculture consist of specific surface area, total pore volume, average pore diameter, pH, electrical conductivity (EC), and cation exchange capacity (CEC). The properties that benefit the environmental purposes are the element: carbon (C), hydrogen (H), nitrogen (N), oxygen (O), and the molar ratio of H/C, O/C, and C/N. The study found that all five types of biochar contained suitable properties for soil amendment and carbon sequestration. However, significant differences were shown in specific surface area, average pore diameter, pH, CEC, and EC of various biochar. Based on O/C and H/C ratios, all five types of biochar persisted in soil from 100 to over 1,000 years.     

Organic carbon and nitrogen dynamics in different soil fractions between broad-leaved Korean pine forests and aspen–birch forests in northeastern China

Purpose

Both overharvesting and climate changes have greatly altered forest composition in northeastern China; however, forest-specific effects on soil organic carbon (SOC), N, and compositional features in different soil fractions have not yet been defined.

Materials and methods

By sampling from broad-leaved Korean pine forest (the climax vegetation) and aspen–birch forest (the secondary forest), five soil fractions were separated by a physicochemical soil fractionation method, and Fourier transform infrared spectroscopy, X-ray diffraction analysis, and X-ray photoelectron spectrometry were used for functional groups, mineral diffraction, and elemental composition determination together with SOC and N measurements.

Results and discussion

Aspen–birch forests tended to sequestrate more SOC in the slow fractions (sand and aggregate [SA] and easily oxidized fractions) and more N in the sensitive fractions (particulate and soluble fractions), indicating that in aspen–birch forests, high SOC sequestration (1.26-fold) coincided with the active and rapid N supply. Much higher percentages (13.1–40.5 %) of O–H and N–H stretching, O–H bending, and C=O, COO–, and C–H stretching, and also the much lower quartz grain size and mineral diffraction peaks in SA and acid-insoluble fraction (over 85 % of total soil mass), in aspen–birch forests were possibly associated with the 1.17- to 1.53-fold higher SOC compared to broad-leaved Korean pine forest. However, elemental composition on soil particles might marginally contribute to the SOC and N forest-dependent differences.

Conclusions

Considering the increase of aspen–birch forests and the decrease of broad-leaved Korean pine forests in historical and future scenarios in northeastern China, more SOC has been and also will sequestrate in intact soils and stable soil fractions, with more N in sensitive fractions, and these should be highlighted in evaluating forest C and N dynamics during forest successions in this region.

     

不同时期追氮对冬小麦植株氮素积累及转运特性的影响

采用盆栽和大田相结合,并应用15N示踪技术,研究了不同时期追氮对两个不同穗型冬小麦品种植株氮素积累及转运特性的影响。结果表明,成熟期小麦植株各部位氮素积累量和分配比例均表现为子粒茎鞘+叶根系或颖壳+穗轴;子粒中氮素积累量以拔节期追氮处理最高,氮素在子粒中的分配比例以抽穗期追氮最高,在根系中的分配比例则以全部底施处理最高。小麦植株吸收追施15N的比例为16.45%～26.6%,兰考矮早八和豫麦49-198分别以返青期追氮和拔节期追氮吸收的比例最高;子粒中氮素来自15N的比例均以返青期追氮最高,分别为27.16%和22.20%,但和拔节期追氮处理差异不显著。随着追氮时期推迟,氮的花后同化量、花后贡献率增加,而花前贡献率呈下降趋势;全氮对子粒贡献率表现为花前转运的贡献大于花后同化的贡献,但抽穗期追氮处理中,15N对子粒的贡献率表现为花后同化率大于花前转运贡献率。综合考虑子粒产量、蛋白质含量以拔节期追氮较为合适。     

Comparison of protein quality and mineral element concentrations in grain of spelt (Triticum spelta L.) and common wheat (Triticum aestivum L.)

The cultivation of Triticum spelta (spelt) has no tradition in Hungary. In recent years the interest towards this old species renewed in many countries. This high‐nutritional cereal, which has a high ash and fibre content, can be used in many health‐oriented grain‐based food products. Therefore, field experiments have been conducted for some years to test the performance of this species under home growing conditions. Here we report the results of analyses for some important quality parameters of grain samples from the 1996/97 season in comparison with those of older and new home‐grown bread wheat cultivars. Three common wheat cultivars and one advanced spelt line were grown on small plots fertilised with an NPK dose necessary to reach the highest yield and quality. Spikes were sampled weekly from the time of 70–77% grain moisture to full ripening. The grains were analysed for ash, N, P and K content and amino acid composition. Concentrations of 16 other macro + micro elements and in the ripe grains, baking quality parameters were also assessed. The grain development of spelt showed a remarkable time‐lag compared to that of the common wheat cultivars. However, the highest thousand‐grain‐masses, ash, N, and P concentrations were measured in this cultivar after milk ripening. The grains of spelt contained the macro‐nutrient Mg and four micro‐nutrients (Zn, Mn, Fe, Cu) in higher concentrations compared to those of the common wheat varieties. The total and essential amino acid concentrations measured in the ripe grains of spelt were also remarkably higher.

Although its wet gluten content (47.5%) was considerably higher than that of the bread wheat cultivars, its breadmaking quality was poor.     

Poorly crystalline mineral phases protect organic matter in acid subsoil horizons

Soil minerals are known to influence the biological stability of soil organic matter (SOM). Our study aimed to relate properties of the mineral matrix to its ability to protect organic C against decomposition in acid soils. We used the amount of hydroxyl ions released after exposure to NaF solution to establish a reactivity gradient spanning 12 subsoil horizons collected from 10 different locations. The subsoil horizons represent six soil orders and diverse geological parent materials. Phyllosilicates were characterized by X-ray diffraction and pedogenic oxides by selective dissolution procedures. The organic carbon (C) remaining after chemical removal of an oxidizable fraction of SOM with NaOCl solution was taken to represent a stable organic carbon pool. Stable organic carbon was confirmed as older than bulk organic carbon by a smaller radiocarbon (¹⁴C) content after oxidation in all 12 soils. The amount of stable organic C did not depend on clay content or the content of dithionite–citrate-extractable Fe. The combination of oxalate-extractable Fe and Al explained the greatest amount of variation in stable organic C (R² = 0.78). Our results suggest that in acid soils, organic matter is preferentially protected by interaction with poorly crystalline minerals represented by the oxalate-soluble Fe and Al fraction. This evidence suggests that ligand exchange between mineral surface hydroxyl groups and negatively charged organic functional groups is a quantitatively important mechanism in the stabilization of SOM in acid soils. The results imply a finite stabilization capacity of soil minerals for organic matter, limited by the area density of reactive surface sites.     

Late nitrogen fertilization affects carbohydrate mobilization in wheat

An experiment was carried out to determine how the late application of nitrogen (N) fertilizer affects the use of pre‐anthesis carbon reserves during the grain‐filling period of pot‐grown wheat with no water shortage. Increasing doses (equivalent to 0, 140, and 180 kg N ha^–1) of N fertilizer were applied, either in two amendments (stages GS20 and GS30) or in three amendments (stages GS20, GS30, and GS37, according to Zadoks scale). The management of fertilizer by combining an increased N rate with late N application was able to stimulate canopy development, to raise photosynthetic capacity and carbohydrate accumulation during the vegetative stages, and to increase grain yield. Based on the dynamics of carbohydrate accumulation in the ear, three phases were differentiated during the grain‐filling period, whose temporary pattern remained stable regardless of the fertilizer management. The net remobilization of carbohydrates started 12 d after anthesis from the leaves and 28 d after anthesis from roots and stems. The increase of the N dose with late N application allowed on one hand a lower use of the pre‐anthesis carbon reserves in favor of greater de novo photosynthesis during the grain‐filling period, and on the other hand greater relative contribution of the leaf and ear C reserves to remobilization towards the grain. Further splitting the dose increased only the relative contribution of ear C reserves. The stem contribution seemed to be independent of N applied whereas the root contribution tended to diminish with late N application.     

Soil organic matter stabilization in acidic forest soils is preferential and soil type-specific

Minerals with large specific surface areas promote the stabilization of soil organic matter (SOM). We analysed three acidic soils (dystric, skeletic Leptic Cambisol; dystric, laxic Leptic Cambisol; skeletic Leptic Entic Podzol) under Norway spruce (Picea abies) forest with different mineral compositions to determine the effects of soil type on carbon (C) stabilization in soil. The relationship between the amount and chemical composition of soil organic matter (SOM), clay content, oxalate‐extractable Fe and Al (Fe_o; Al_o), and dithionite‐extractable Fe (Fe_d) before and after treatment with 10% hydrofluoric acid (HF) in topsoil and subsoil horizons was analysed. Radiocarbon age, ¹³C CPMAS NMR spectra, lignin phenol content and neutral sugar content in the soils before and after HF‐treatment were determined and compared for bulk soil samples and particle size separates. Changes in the chemical composition of SOM after HF‐treatment were small for the A‐horizons. In contrast, for B‐horizons, HF‐soluble (mineral‐associated) and HF‐resistant (non‐mineral‐associated) SOM showed systematic differences in functional C groups. The non‐mineral associated SOM in the B‐horizons was significantly depleted in microbially‐derived sugars, and the contribution of O/N‐alkyl C to total organic C was less after HF‐treatment. The radiocarbon age of the mineral‐associated SOM was younger than that of the HF‐resistant SOM in subsoil horizons with small amounts of oxalate‐extractable Al and Fe. However, in horizons with large amounts of oxalate‐extractable Al and Fe the HF‐soluble SOM was considerably older than the HF‐resistant SOM. In acid subsoils a specific fraction of the organic C pool (O/N‐alkyl C; microbially‐derived sugars) is preferentially stabilized by association with Fe and Al minerals. Stabilization of SOM with the mineral matrix in soils with large amounts of oxalate‐extractable Al_o and Fe_o results in a particularly stable and relatively old C pool, which is potentially stable for thousands of years.     

小麦秸秆热解过程中碳和微量元素迁移转化规律

为研究小麦秸秆热解过程中碳元素和微量元素的迁移转化规律,依托连续式作物秸秆分段均匀炭化联产系统,基于热解炭化生产工艺,测算及分析碳元素在秸秆热解过程中的存在形式及迁移转化量,利用HSC Chemistry软件模拟微量元素在秸秆热解炭化过程中的组分变化,分析了8种微量元素的迁移转化规律,为生物质热解机理的进一步研究提供支撑,为提高秸秆热解炭品质提供强有力保证。结果表明:经测试及测算得到的碳元素迁移足迹图符合碳元素质量守恒定律,碳元素迁移到热解炭中41.12%,以固定碳存在;22.83%迁移到焦油中,以大分子长链烃和环链烃存在;26.62%的碳元素以六碳内的短链烃存在于热解气;4.71%迁移到木醋液中为醛、酮、酸等。小麦秸秆中含量在100μg/L以上的8种高富集微量元素里,K、Na、Ca、Mg主要以硫酸盐、磷酸盐及氯化物形式存在于热解炭中,Al、Fe多以氧化物、硫化物以及硅、氧共融物形态被大量保留在热解炭中,而P、S元素在热解炭化过程中的析出主要是有机结合物的分解。     

Pedogenic processes of placic and spodic horizons in subtropical subalpine forest soils with contrasting textures

Placic (Bsm) and spodic (Bhs) horizons are common in subalpine or alpine forest soils in Taiwan. Bsm horizons are found more usually in finer textured soils than those with Bhs horizons. To understand the different formation processes in Bsm and Bhs horizons in a humid subtropical ecosystem, we identified micro‐morphological features by using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and electron probe micro‐analysis (EPMA), and determined the physiochemical properties by chemical extractions and clay mineralogy. The study included four pedons with well‐developed Bsm horizons from our previous study and four with well‐developed Bhs horizons at other sites. Both sites were in subtropical mountain forests with similar climate, topography and general geology but over regoliths with distinctly different textures. Micro‐morphology revealed a vughy (small cavities lined with in‐washed materials) microstructure in Bsm horizons but a granular structure with bridge microstructures between coarse grains in Bhs horizons. Chemical analysis revealed more free pedogenic iron (Fe_d) and aluminium (Al_d) in Bsm than in Bhs horizons, but more organically complexed Al (Al_p) in Bhs horizons. Energy dispersive spectrometry revealed predominant Fe, oxygen (O) and carbon (C) in the matrix of the Bsm horizons, whereas Al, silicon (Si) and C were the major elements of interstitial materials in Bhs horizons. Polarizing microscopy and EPMA spectra confirmed the illuvial nature of organic Al complexes in Bhs horizons. The transformation of clay minerals showed more intense podzolization in Bhs horizons than in Bsm horizons. The different formation mechanisms in Bsm and Bhs horizons result from contrasting texture; redox processes are predominant in Bsm horizons because of the clayey texture whereas podzolization is predominant in sandy Bhs horizons.     

Aluminum concentrations in sclerotia from a buried humic horizon of volcanic ash soils in Mt. Myoko,Central Japan

The morphology and chemical composition of fungal sclerotium-like grains collected from the buried humic horizon of volcanic ash soil in Mt. Myoko were examined using a scanning electron microscope (SEM), energy dispersion xray micro-analyzer (EDX), and electron probe micro-analyzer (EPMA). A high C content, low level of Si and high concentration of Al characterized the grains considered to correspond to the sclerotia of Cenoccocum graniforme. The ²⁷Al MAS NMR spectrum of the sclerotia showed the existence of 6- and 4-coordinated Al. X-ray diffraction analyses supported the presence of amorphous Al (ex. Al-humus complex) in the sclerotia.     

Effects of nitrogen fertilization on pot‐grown wheat photosynthate partitioning within intensively farmed soil determined by 13C pulse‐labeling

Understanding rhizodeposited carbon (C) dynamics of winter wheat (Triticum aestivum L.) is important for improving soil fertility and increasing soil C stocks. However, the effects of nitrogen (N) fertilization on photosynthate C allocation to rhizodeposition of wheat grown in an intensively farmed alkaline soil remain elusive. In this study, pot‐grown winter wheat under N fertilization of 250 kg N ha^?1 was pulse‐labeled with ¹³CO₂ at tillering, elongation, anthesis, and grain‐filling stages. The ¹³C in shoots, roots, soil organic carbon (SOC), and rhizosphere‐respired CO₂ was measured 28 d after each ¹³C labeling. The proportion of net‐photosynthesized ¹³C recovered (shoots + roots + soil + soil respired CO₂) in the shoots increased from 58–64% at the tillering to 86–91% at the grain‐filling stage. Likewise, the proportion in the roots decreased from 21–28% to 2–3%, and that in the SOC pool increased from 1–2% to 6–7%. However, the ¹³C respired CO₂ allocated to soil peaked (17–18%) at the elongation stage and decreased to 6–8% at the grain‐filling stage. Over the entire growth season of wheat, N fertilization decreased the proportion of net photosynthate C translocated to the below‐ground pool by about 20%, but increased the total amount of fixed photosynthate C, and therefore increased the below‐ground photosynthate C input. We found that the chase period of about 4 weeks is sufficient to accurately monitor the recovery of ¹³C after pulse labeling in a wheat–soil system. We conclude that N fertilization increased the deposition of photoassimilate C into SOC pools over the entire growth season of wheat compared to the control treatment.     

Nitrogen Redistribution Characteristics of Oilseed Rape (Brassica napus L.). Varieties with Different Nitrogen-Use Efficiencies during Later Growth Period

To determine the relationship between nitrogen (N) redistribution of oilseed rape (Brassica napus L.) varieties and N-use efficiency during later growth stages, the differences in N-use efficiency between two varieties (X-36 and X-50) were studied using the ¹⁵N labeling method with sand culture under complete nutrient solution conditions. Results showed that X-36 had greater grain yield not because of greater N uptake but because of greater grain yield per unit N in the plant and N-harvesting index. The average proportion of N in the two varieties that was redistributed from the vegetative organs to the grain was 65.1%. The redistribution amount and the proportion of N absorbed at the stem elongation stage and redistributed into the grain of two varieties were the greatest; the least were amounts absorbed at the siliquing stage. The high-N-use-efficiency variety (X-36), when compared with the low-N-use-efficiency variety (X-50), had slower redistribution speed of N before the siliquing stage, which then became faster after the siliquing stage. The amount of N redistributed to the grains and its proportion were larger, whereas those toward the silique husk were smaller. The amount of N loss from the plant and its proportion were smaller, and the velocity of N loss was also slower. This explains why varieties with high N efficiency have high N-harvesting index. At the later growth stages, N redistribution in the vegetative organs will significantly affect N-use efficiency.     

田间管理对华北平原冬小麦产量土壤碳及温室气体排放的影响

选取华北平原冬小麦为研究对象,针对（1）秸秆移除;（2）秸秆表覆;（3）免耕;（4）秸秆深施;（5）施农家肥这5种典型的田间管理,使用农田自动温室气体测定系统对冬小麦农田全生育期进行了原位长期观测,并采用^13C自然丰度法对土壤碳的转化进行了监测,同时对冬小麦产量及生物量、土壤有机碳的变化进行了监测。结果表明,冬小麦产量及生物量高低顺序为施农家肥、秸秆深施、秸秆表覆、秸秆移除和免耕,而且土壤有机碳的更新也有同样的趋势;施农家肥能显著增加土壤有机碳而秸秆移除和免耕则会导致土壤有机碳的轻微下降;冬小麦甲烷的排放或吸收只占总增温潜势的不到1％,在进行统计总排放当量时基本可以忽略,N2O在总排放当量中的比例在2．55％-11．62％范围内;N2O的大量排放主要来自于拔节期及开花期,秸秆移除、施农家肥和秸秆深施会导致N2O排放在总当量中的份额增加至10％左右,而秸秆覆盖和免耕N2O排放在总排放当量中的份额只有3％左右,冬小麦农田总的温室气体排放88％以上来自于CO2的排放,特别是秸秆表覆和免耕95％以上来自土壤碳的损失而释放的CO2。总体来看,秸秆深施能保证较高的产量,减少碳的损失,增加土壤碳并产生相对较少的总温室气体排放量,是较好的固碳减排方式。     

不同分子量黄腐酸对冬小麦生长和养分吸收利用的影响

【目的】黄腐酸在作物生产中有较为显著的促生、抗逆作用,但黄腐酸的结构复杂、分子量分布宽,影响其效果的稳定性。因此,我们研究了不同分子量黄腐酸对冬小麦生长和养分吸收利用的影响。【方法】采用生物半透膜将黄腐酸按分子量分为<3000 D (W1)、3000～10000 D (W2)和>10000 D (W3) 3个等级,对其进行结构分析,并进行冬小麦盆栽试验。在小麦拔节期将黄腐酸溶液施入土壤中,每个分子量的黄腐酸均设置0(CK)、10 (C1)、25 (C2)、50 (C3) mg/kg共4个施用量。在冬小麦开花期和成熟期采集植株样品和土壤样品,测量生物量、产量和养分含量等指标。【结果】结构分析表明,W1和W2的芳香烃饱和度更低,含氧官能团更多,侧链更发达,并且具有更高的亲水性。与对照相比,施用不同分子量黄腐酸均显著提高了冬小麦籽粒产量(21.62%～49.06%)、籽粒铁浓度(62.81%～100.67%)、籽粒氮累积量(19.47%～38.49%),提高了氮吸收效率(10.67%～19.66%)和氮肥偏生产力(21.63%～49.07%)。施用W1,以上各指标随黄腐酸施用量的...     

氮素和水分处理对稻米植酸含量和蛋白组分的影响

以直立密穗型粳稻品种秀水110和弯曲散穗型粳稻品种春江15为材料,对不同氮素水平处理和水分管理方式下稻米植酸含量和蛋白组分的影响及其互作效应进行了研究。结果表明,旱作栽培处理会导致水稻籽粒中植酸含量上升,而施氮处理对籽粒植酸含量的影响效应与水稻的水分管理方式有关,在常规水作条件下,高氮处理（N3）的籽粒植酸含量有所提高,但在旱作栽培方式下,中氮（N2）和低氮处理（N1,不施N）的籽粒植酸含量却略高于高氮处理（N3）,氮素水平与水分管理方式间的互作效应明显; 水稻籽粒植酸含量与粗蛋白总量、4种蛋白组分（清蛋白、球蛋白、醇溶蛋白和谷蛋白）及有关产量性状指标（有效穗数、每穗粒数、千粒重和结实率）在不同水肥处理间的相关性不显著,但氮肥用量过高不仅会导致水稻的产量水平下降,而且也不利于稻米营养品质的改良; 水肥处理对水稻籽粒植酸含量、蛋白总量和4种蛋白组分穗内粒位分布也存在一定影响,着生在稻穗下部的弱势粒,其稻米植酸含量高于稻穗上部或中部的强势粒,因此改善弱势粒灌浆的水肥管理措施将有利于稻米植酸含量的降低。