Growth and Nitrogen Fixation in Soybean as Affected by Phosphorus Fertilizer and Sheep Manure using 15N Isotopic Dilution

A field experiment was conducted to study the effect of adding different phosphorus (P) fertilizer levels [0, 40, and 80 kg phosphorus pentoxide (P₂O₅) ha^?1 (abbreviated as P0, P1, and P2, respectively)] and rates of sheep manure (M) [0, 20, and 40 ton ha^?1 (abbreviated as M0, M1, and M2, respectively)] on growth and nitrogen (N₂) fixation of soybean (Glycine max L.). Sorghum bicolor L. was employed as a reference crop to evaluate N₂ fixation using the ¹⁵N-isotpic dilution technique. Results showed that addition of P fertilizer or sheep manure had positive effects on dry-matter production, N accumulation, and seed yield. Such effects were more pronounced when adding sheep manure and P together than adding separately. Solely P fertilizer had a small impact on N₂ fixation. A tangible increase in the amounts of N₂ fixed due to manure addition occurred. The efficient use of N fertilizer (%NUE) increased significantly as the result of adding a high level of P fertilizer. However, a drastic decrease in %NUE was observed when sheep manure was added solely or in combination with P fertilizer. From productivity and ecological standpoints, P2M1 and P2M2 surpassed the other treatments in showing greater grain yield and greater N₂ fixation. However, considering the high cost of sheep manure, P2M1 was the optimal treatment for improving growth and N₂ fixation in soybean plants with minimal manure consumption. In conclusion, the integrated use of manure and P fertilizer could be considered a useful agricultural practice for improving the performance of soybean plants grown in an Aridisol. Their beneficial effects were mainly attributed to the enhancement of N₂ fixation through root growth and soil property improvements besides being a source of P and other nutrients that are essential for N₂-fixation process.     

砂土和黏土的颗粒差异对土壤斥水性的影响

斥水性土壤广泛存在于自然界中,并且对土壤环境和作物生长等有重要影响。建立理想化的土壤颗粒模型对砂土和黏土的斥水特性进行计算分析。结果表明:当接触角很小时,砂土中不存在斥水现象。随着接触角的增大,砂土斥水性与含水率密切相关,砂土的密实度对其斥水性也有重要影响,当砂土比较密实时,土壤的"亲水"与"斥水"特性对含水率特别敏感,随着含水率的变化,砂土可能由亲水性较好的土壤转变为斥水性土壤;当砂土比较松散时,土壤颗粒的斥水性对含水率并不敏感。当黏土接触角略小于90°且湿润半径b也较小时,黏土也存在斥水现象。如果黏土颗粒的接触角较小或接触角小于90°且湿润半径b较大,黏土总是亲水的。黏土含水率较大时,斥水特性由土壤颗粒的接触角决定。     

Nodulation and Symbiotic Nitrogen Fixation of Cowpea Genotypes as Affected by Fertilizer Nitrogen

Abstract

Intercropping with legumes and non‐legumes is commonly practiced in many parts of the world to maximize productivity per unit area of land. In India, cowpea [Vigna unguiculate (L.) Walp] is a popular pulse legume component of intercropping farming systems. Often, however, potential production is compromised, particularly in high fertilizer input systems, because legume component competes with the non‐legume component of the system for nitrogen (N) in the soil. An experiment was conducted in order to identify lines of cowpea that could obtain the majority of their nitrogen requirements from symbiotic fixation of atmospheric nitrogen rather than from uptake of soil nitrogen. Twenty‐nine genotypes of cowpea were screened for tolerance to (applied) nitrogen in soil in field condition. The parameters used to appraise tolerance were extent of root nodulation, the amount of nitrogen fixed, nitrate reductase activity (NR) in roots and nodules, and nitrite content of roots and nodules. There were two nitrogen treatments applied as urea, 40 kg N per ha (N40), and 120 kg N per ha (N120). There were three genotypes whose nitrogen‐fixing effectiveness was apparently unimpaired by applications of nitrogen to the soil. Genotype EC‐170442‐3 nodulated and fixed atmospheric nitrogen satisfactorily at higher levels of applied nitrogen. At N40, genotypes EC‐244390 and EC‐240900 formed a great abundance of large nodules effective in nitrogen fixation; even at N120, EC‐240900 had better symbioses than the majority of the 29 cowpea lines originally screened. These three genotypes are deemed worthy of further examination for their suitability for intercropping systems. How this might be achieved is discussed.     

干湿循环下气—液界面张力对黏土收缩开裂的影响

气—液界面张力(表面张力)作为主要的外部环境因素之一,其变化势必会对土壤收缩开裂和土水特性有重要影响。开展了一系列不同温度条件下的干湿循环试验,脱湿温度设定为25℃和60℃两种,对3组不同表面张力的初始饱和试样进行干湿循环试验。在脱湿过程中,对试样的含水率变化及表面裂隙的演化过程进行定时测量拍照,利用数字图像处理技术对试样裂隙图像进行定量分析,最终得到表面收缩开裂裂隙度δ。结果表明:随着干湿循环次数的增加,试样的最终δ有所增加,但增长幅度不大;温度越高,试样初次出现裂隙的时间越快,当温度从25℃增加至60℃时,试样出现初始裂隙时对应的临界含水率从38%增至41%,试样的最终δ增长20%~40%;在同一温度环境下,土样的裂隙发育程度随着表面张力的降低而变慢,最终δ随着表面张力的降低而减小,无论何种温度环境,表面张力大小和裂隙度大小顺序一致,均为纯水试样酒精溶液试样肥皂水试样;含水率相同时,表面张力越大,对应试样的δ越大。     

N Mineralization as Affected by Long-Term N Fertilization and Its Relationship with Crop N Uptake.

A field experiment established in 1997 was conducted to study the effect of long-term N fertilizer application on N mineralization in a paddy soil determined using a laboratory anaerobic incubation followed with a field incubation and to measure the relationship between in situ N mineralization and crop N uptake. To estimate N mineralization in the laboratory, soil samples were collected from plots with N application at different rates for six years and were incubated. Soils treated with fertilizer N mineralized more N than unfertilized soils and mineralization increased with N application rates. Also, the fraction of total N mineralized increased with increasing N fertilizer application. These findings meant that a substantial portion of previously applied N could be recovered slowly over time in subsequent crops. The field incubation of the plot receiving no fertilizer N showed that the NH4^＋-N concentration varied greatly during the rice-growing season and seasonal changes of N mineralization were due more to accumulation of NH4^＋-N than NO3^-N. Hice N uptake increased up to a maximum of 82 kg N ha^-1 during the season. The close agreement found between in situ N mineralization and rice N uptake suggested that the measurement of in situ N mineralization could provide useful recommendations for adequate fertilizer N application.     

毛白杨对15N-硝态氮和铵态氮的吸收、利用及分配

以毛白杨新无性系50号插条苗为试材,应用15N示踪技术研究在相同施氮量下毛白杨(Populus tomentosa)苗木对不同形态氮素的吸收、分配及利用特性。结果表明：不同处理下毛白杨苗木在施肥1周后对肥料氮的吸收呈逐渐上升趋势,并在施肥后28d达到最大值,NO3-15N处理苗木全氮量为0.67g/株, NH4-15N处理苗木全氮量为0.60g/株;吸收NO3-15N为0.26g/株,吸收NH4-15N为0.12g/株,分别占苗木全氮的比例39.15%和19.95%。毛白杨苗木对两种氮素的利用程度差异显著,在利用率最高时期,NO3-15N利用率可达25.83%,约为NH4-15N（12.03%）的2倍。氮素在各器官中分配差异显著,总体趋势为叶﹥根﹥茎。叶中NO3-15N的分配率显著高于NH4-15N     

Gaseous Nitrogen Emission from Soil Aggregates as Affected by Clay Mineralogy and Repeated Urine Applications

Urine-treated soils make a significant contribution to gaseous N losses to the atmosphere. Our goal was to investigate the influence of clay type and content on ammonia (NH₃) and nitrous oxide (N₂O) emissions from urine under different wetting–drying soil conditions and to relate these results to urine-N transformation processes in soil. Three types of silt loam soils and synthetic sand–clay aggregates with three different clay-dominated materials (kaolinite, montmorillonite and vermiculite) were used in this laboratory study. Bulk soil, 4–4.75 mm and 9.5–11.2 mm aggregates were incubated with synthetic urine at 50% and 75% saturation under aerobic conditions. Repeated urine application affected the properties of the aggregates depending on the type of clay present. Greater clay content increased aggregate stability and reduced NH₃ volatilization. The variation in clay ammonium (NH₄ ⁺) fixation capacities was reflected in NH₃ volatilization as well as in the onset of N₂O emissions, occurring first from kaolinite-dominated and last from vermiculite-dominated soils. Nitrous oxide production was greater in aggregates than in bulk soil, a difference that consistently increased with repeated urine applications for kaolinitic and vermiculitic treatments. A dual-peak N₂O emission pattern was found, with the second maximum increasing with the number of urine applications. Emission of ¹⁵N-labeled N₂ was found at 75% saturation in kaolinite and vermiculite-dominated samples. Anaerobic conditions were less pronounced with montmorillonite-dominated samples because shrink–swell action caused aggregate breakage.     

作物品种和化学固定剂对玉米谷物中镉和锌积累的影响

A field experiment was conducted to investigate the effects of soil amendments(lime,nano-Si foliar solution and used diatomite) on the growth and metal uptake of three maize(Zea mays L.) cultivars grown in a Cd and Zn-contaminated acidic soil.The addition of lime significantly increased the maize grain yields and decreased the concentrations of Zn and Cd in the grains and shoots of maize when compared with the control.Among the three maize cultivars,Yunshi-5 accumulated the lowest amounts of Cd and Zn in the grain.The concentrations of Zn and Cd in the grain of Yunshi-5 conformed to the Chinese feed standards.These data revealed that a combination of low metal-accumulating maize and chemical fixation could effectively provide a barrier to prevent metals from entering the human food chain.     

Ammonium (15N) metabolism in cotton under salt stress

Plant growth and metabolism is impaired under stress conditions, resulting in decreased crop yields. The purpose of this investigation was to evaluate the NaCl stress effects on NH⁺ ₄ metabolism in cotton plants at vegetative and reproductive stages of growth.

Cotton (Gossypium hirsutum L.) plants grown in normal (control) and NaCl treated Hoagland solutions were analyzed for distribution of N¹⁵ in NH⁺ ₄ plus amide‐N, free α‐amino‐N, total soluble‐N and protein‐N after the plants were provided ¹⁵NH₄NO₃ in nutrient solutions for 6, 12 and 24 h. The concentration of protein‐¹⁵N was enhanced under a low level of NaCl (‐0.4 MPa osmotic potential) at the vegetative growth stage. The difference between the protein‐¹⁵N concentration of the moderately salinized (‐0.8 MPa) plants and the controls was not significant. A high level of NaCl (‐1.2 MPa) significantly decreased protein‐N content of plants compared with the controls and any other level of salinity. The NaCl increased accumulation of NH₄ ⁺ plus amide‐N, free (α‐amino‐N, and total soluble‐N in cotton shoots, at both stages of growth. Low osmotic potential (high osmotic pressure) of the nutrient solution induced by excessive amounts of NaCl in nutrient solution inhibited NH⁺ ₄ metabolism and decreased protein synthesis, thus resulting in accumulation of soluble N‐compounds. The ionic effect probably contributed also to inhibition of protein synthesis.     

Recovery and Purity of Isolated Barley Starch and Protein as Affected by Fractionation Water Temperature

Wet fractionation of barley flours was conducted to identify appropriate fractionation water temperature considering the recovery and purity of starch and protein. In abraded hulless regular barley, yield of starch fraction, starch recovery, and purity of the protein fraction increased from 43.3 to 45.7%, from 61.7 to 64.8%, and from 37.6 to 65.2% when water temperature in fractionation was increased from 23 to 60°C. In abraded hulless waxy barley, recovery of starch with 40°C water was much greater (67.7%) than that at other temperatures (<61.7%). Starch recovery and protein purity of regular barley cultivars were higher than those of waxy barley cultivars with fractionation water of 60°C. In whole hulless barley flours fractionated with 60°C water, waxy barley flours showed similar to or higher protein purity (44.8–48.9%) than regular barley flours (42.8– 44.6%), while regular barley flours exhibited higher starch recovery (>60.6%) than waxy barley flours (<57.3%). The purity of isolated starch was >97.7%, regardless of water temperature and barley type. Considering yield and recovery of the isolated starch, and purity of the isolated protein, 60°C water for hulless regular barley and 40°C for hulless waxy barley seem to be appropriate for fractionation of barley flour for isolation of starch and protein.     

施肥和耕作方式对棕壤微生物生物量碳氮的影响

以辽宁省昌图县主要粮食产区为研究对象,分析施肥(化肥、玉米秸秆和有机肥)和耕作方式(旋耕、深松和隔行深松)对棕壤微生物生物量碳、氮(SMB-C、-N)的影响。结果显示,与对照处理相比,施用化肥处理SMB-C、-N分别下降14.3%和13.3%,秸秆回田处理下降12.3%和12.2%,而施用有机肥则显著提高SMB-C、-N,幅度分别为31.7%和38.6%。说明施用化肥明显降低土壤微生物生物量,配施秸秆在短时期内无法缓解化肥施用对微生物生物量的抑制作用,而有机肥却能迅速缓解抑制作用,提高土壤微生物生物量。深松(行行)和隔行深松作为保护性土壤耕作方式,与常规耕作(NPK处理)相比,显著提高了SMB-C、-N,其中深松提高幅度为56.8%和77.0%,隔行深松则为27.7%和36.1%。试验伊始,有机肥处理SMB-C/SOC(土壤有机碳)最高,达到1.57,至实验结束,深松处理最高,为2.15,其次为隔行深松处理。有机肥处理SMB-N/TN(土壤全氮)受年际影响上下波动,深松和隔行深松处理呈现先下降后上升的态势。深松和隔行深松能有效保存土壤养分含量,特别是活性碳、氮库,是土壤肥力贫瘠地区推荐的土壤耕作方式,从人力和机械消耗角度而言,隔行深松更有利于我国农业可持续发展。     

Sorption and Binding Mechanism of Polysaccharide Cleaving Soil Enzymes by Clay Minerals

Analyses of the sorption of five polysaccharide cleaving soil enzymes by Na-homoionic clay minerals revealed a dependency on the cation exchange capacity of the clays: montmorillonite displayed the highest sorbing capacity, followed by palygorskite and kaolinite. Variation of the experimental conditions using cellulase and montmorillonite showed a maximum sorption at pH 4.8 and temperatures between 25°C and 45°C. Urea had no effect on the sorption, whereas humic acids and acetylation of enzymes lead to a decrease. No sorption was observed in the presence of bivalent cations. A discussion of possible binding mechanisms lead to the conclusion that interactions can be ascribed to van der Waals forces rather than to ionic reactions. It is assumed that the enzymes penetrate into the interlayers of montmorillonite, but not of palygorskite and kaolinite.     

粘土矿物固定化微生物对土壤中阿特拉津的降解研究

以粘土矿物为载体,采用吸附挂膜法对已筛选的阿特拉津降解菌株进行固定化,并应用固定化微生物降解土壤中的阿特拉津。结果表明,该菌株在粘土矿物上生长良好,根据菌种生理生化特性、环境扫描电镜图片以及16S rDNA基因的相似性分析初步鉴定该菌株为Ochrobactrum sp.。接种降解菌能明显加快阿特拉津在土壤中的降解速率,粘土矿物固定化微生物的降解效果要明显优于游离菌,粘土矿物粒径越小,固定化微生物的降解效果越好,纳米粘土矿物固定化微生物的降解效果要好于原粘土矿物。用一级动力学方程描述阿特拉津在土壤中的降解过程,不同土壤中阿特拉津的降解速率不同。阿特拉津在红壤、砂姜黑土、黄褐土中的降解半衰期（t1/2）分别为36.9、49.1、55.0 d,投加纳米蒙脱石固定化降解菌后的半衰期则分别为16.3、25.3、21.7 d。     

Cadmium and Nutrient Heavy Metals Uptake by Rice,Barley, and Spinach as Affected by Four Ammonium Salts

This experiment was conducted to investigate the influence of ammonium salts on the uptake of cadmium (Cd) and nutritional heavy metals (copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe)) by rice, barley, and spinach. These plants were grown in Cd, Cu, and Zn contaminated entisol (ES) or andisol (AS). The following ammonium salts were used: ammonium nitrate (NH₄NO₃), ammonium sulfate ((NH₄)₂SO₄), ammonium chloride (NH₄Cl), and ammonium dihydrogen phosphate (NH₄H₂PO₄). In ES, the Cd concentrations in three plant shoots were higher with NH₄Cl than with the other salts. The concentrations of Cd in soil solutions collected from ES were higher with NH₄Cl. Thus, the increase of Cd uptake by three plants with NH₄Cl treatment would be caused by the increased concentration of Cd in the soil solution. In contrast, in AS, the concentrations of the heavy metals in the shoots of all plants were not different among NH₄ applications, with one exception, the Mn concentration in rice increased with NH₄Cl in both ES and AS.     

纳米粘土矿物对阿特拉津的吸附-解吸特性研究

采用批量平衡实验,研究了纳米粘土矿物与原粘土矿物对除草剂阿特拉津的吸附解吸特陛。结果表明,粘土矿物对阿特拉津的吸附-解吸均能用Freundlich方程很好地拟合。随着溶液中阿特拉津浓度的增加,粘土矿物对阿特拉津的吸附量增加;粘土矿物粒径越小,吸附量越大,纳米粘土矿物的吸附量显著大于原粘土矿物。粘土矿物对阿特拉津吸附量大小顺序为：纳米SiO2）纳米蒙脱石〉凹凸棒石〉蒙脱石〉SiO2。粘土矿物对阿特拉津的解吸表现出一定的滞后效应,即粘土矿物吸附的阿特拉津越多,解吸的越少。粘土矿物对阿特拉津的解吸率大小顺序为：SiO2〉凹凸棒石〉纳米蒙脱石〉纳米SiO2〉蒙脱石。     

Characteristics of Clay Minerals in Podzols and Podzolic Soils

The clay minerals in Podzols and podzolic soils developed under coniferous forests in the Subarctic and Cool-temperate zones are characterized by the predominance of smectite and/or mica-smectite interstratified minerals in the eluvial horizons and chlorite-vermiculite intergrade in the illuvial horizons. A large amount of vermiculite is present in the eluvial horizons of some podzolic soils in the Cool-temperate zone. The illuvial horizons of these soils also contain free iron oxides such as goethite. Imogolite and allophane are present in the illuvial horizons of several soils derived from volcanic ashes. It is suggested that the critical bioclimate for the release of interlayered aluminum from the 2:1-type minerals lies between the Cool- and Warm-temperate zone. In the eluvial horizons of Podzols and podzolic soils, mica minerals and chlorite, as primary minerals, have been transformed to smectite through the pedogenic process. Based on previous studies on the structure and degradation of the dioctahedral mica minerals, it is considered that smectite is transformed from 1M-type mica minerals directly, and from 2M-type mica minerals via mica-smectite interstratifled minerals. The formation of a smectite lattice in the eluvial horizon should be a clay-mineralogical indicator of podzolization.     

几种土壤及黏土矿物对多氯联苯吸附特性的研究

采用批量平衡试验,研究了不同土壤及长黏土矿物对多氯联苯吸附特性。结果表明:多氯联苯浓度范围为0.25~5.0mg L-1时,不同土壤及黏土矿物对多氯联苯的吸附均能用Freundlich方程很好地拟合,随着溶液中多氯联苯浓度的增加,土壤及黏土矿物对多氯联苯的吸附量增加;几种土壤对多氯联苯吸附量大小顺序为:红壤>黄褐土>砂姜黑土,土壤有机质、粘粒等对多氯联苯吸附起主要作用,土壤更易吸附高氯代PCB77;黏土矿物对多氯联苯吸附量大小顺序为:纳米蒙脱石>纳米SiO2>凹凸棒石,黏土矿物吸附多氯联苯能力的大小与黏土矿物的比表面积、粒径、层状结构等有关;多氯联苯本身分子的大小影响其在黏土矿物上的吸附;土壤中添加黏土矿物可以提高对多氯联苯的吸附。     

Fate of 15N Derived from Composts and Urea In Soils under Different Long-term N Management In Pot Experiments

Understanding of dynamics of N derived from organic N sources in soil is required for the development of sustainable agricultural systems. The aim of this paper is to compare, using pot experiments, the fate of N from urea (UF) and organic N sources such as rice straw compost (RC) and cattle compost (CC) using ¹⁵N labeled materials in paddy soil planted with rice. Two soils with a history of long-term applications of chemical fertilizers (LTCN) and organic N sources, i.e. straw compost +soybean cake, (LTON), were also compared. Nitrous oxide emissions were monitored during the growing period. Yield and N uptake of rice were higher in LTON soil than LTCN soil with no significant interaction with N applications. Chemical fertilizer increased yield and N uptake with a recovery rate by rice of 36 to 45%. Nitrogen recovery from RC and CC by rice was less than 10%. When recovery of N in soil was included with that recovered in the plant, 70% and 61% of applied N in the UF treatment was recovered from the LTCN and LTON soils, respectively. In comparison, more than 95% of applied N was recovered in the plant and soil for the RC and CC treatments. There was a sharp increase in N₂O emission during the aerated period in nonplanted pots regardless of whether supplemental N was added, and this was associated with the increase in NO₃- in soil solution at 0.5 cm depth. There was a much lower N₂O emission in planted pots than nonplanted pots with no significant difference among the LTCN and LTON soils or the N treatments. The results indicated that the application of organic N source provided lower N supply to the plant than urea, but also could reduce N loss because of higher retention in the soil. Long-term continuous application of organic N sources enlarged the labile N pool without increasing N₂O emission. Nitrous oxide emission was important during the mid-season aerated period from pot experiments and was partly related to the concentration of NO₃- and the rate of nitrification.     

硅酸盐黏土矿物的表面酸性研究进展

表面酸性是硅酸盐黏土矿物的重要表面化学性质之一。本文综述了硅酸盐黏土矿物表面酸性的主要测定方法,讨论了黏土矿物表面酸性的发生源及其影响因素,并论述了黏土矿物表面酸性与有机碱化合物吸附固定行为之间的关系。