秸秆、有机肥及氮肥配合使用对水稻土微生物和有机质含量的影响

通过大田试验,研究了秸秆还田、施用有机肥和氮肥对水稻土微生物和土壤有机质含量的影响。试验结果表明:(1)在秸秆还田的情况下,增施氮肥(0-330kg/hm2范围内)可促进秸秆的的腐解;(2)秸秆还田、施用有机肥和氮肥中的单一措施均能不同程度地增加水稻土壤细菌、真菌、放线菌的数量;(3)综合运用秸秆还田、施用有机肥和氮肥措施能协同增加土壤微生物数量,提高土壤生物量态氮和有机质含量,以秸秆还田量为6000kg/hm2、施用有机肥量为4500kg/hm2、施用氮肥量为240kg/hm2效果较佳。     

秸秆焚烧对土壤有机质和氮磷钾含量的影响

秸秆露天焚烧作为对废弃秸秆常见的处理方式在中国普遍存在。目前的研究多集中在焚烧对区域大气环境的影响,对土壤环境的化学效应研究较少。因此,为揭示大田秸秆焚烧对土壤生物化学性质的影响,设置不焚烧(CK)、减量焚烧(A1)、全量焚烧(A2)、增量焚烧(A3)4个处理,通过连续4个月的田间小区定位试验,探究不同小麦秸秆焚烧量对耕层0—5 cm土壤有机质含量、微生物数量、土壤养分含量的即时效应和各指标在玉米各生育期内的变化情况。结果表明:小麦秸秆焚烧1 d后土壤有机质含量和微生物数量相对于CK显著降低(P0.05)。其中,有机质含量在焚烧后减少11.0%—22.1%,真菌数量降低30.8%—56.1%,细菌数量降低50.6%—72.6%,放线菌数量降低46.9%—68.3%。土壤全效和速效养分含量显著增加(P0.05):全磷含量增加6.5%—12.9%,全钾含量增加4.6%—18.1%,全氮含量增加2.6%—13.2%。速效磷含量增加9.8%—39.1%,速效钾含量增加13.2%—39.1%,铵态氮含量增加8.6%—38.7%,硝态氮含量增加1.4%—9.2%。各指标的变化幅度随焚烧量的增多而加大(A3A2A1)。玉米生育期内,焚烧处理的土壤有机质含量平均恢复5.6%(A1A2A3)。与有机质相比,焚烧处理土壤微生物数量恢复程度较高,其中细菌的恢复速率最快。在玉米苗期各焚烧处理的真菌、细菌和放线菌平均数量相对于CK依次降低12.7%、17.4%、11.9%,在大喇叭口期和成熟期,微生物数量与CK间差异不显著。速效养分含量在玉米生育期显著高于CK。在玉米苗期、大喇叭口期和成熟期,相对于CK速效磷含量平均增加24.9%、27.0%、29.2%,速效钾平均增加24.0%、14.1%、15.2%,铵态氮平均增加25.5%、23.1%、20.2%,硝态氮平均增加20.8%、19.2%、19.8%。     

Effect on digestibility and nitrogen content of barley straw of different ammonia treatments

The article discusses the effect on solubility in cellulolytic enzyme suspensions, digestibility in vitro and crude protein content (F × 6.25) of treating barley straw with various dosages of NH₃ (2.6–5.9%), at various temperatures (15–75°C) for various treatment times (1–14 days).An increase in any of the above factors resulted in an increased intensity of treatment, with an increase in temperature of 15°C being equal to an increased NH₃-dosage level of 1.5% or prolongation of the treatment time by a factor of 4.5Digestibility in vitro increased with increased intensity of treatment, until a maximum level was obtained. Beyond this point, an increase in NH₃-dosage, or especially in temperature, tended to decrease digestibility in vitro. Maximum digestibility could be obtained, for example, with 2.6% NH₃, 62°C and 4 days incubation, or 5.9% NH₃, 30°C and 3–7 days incubation.Likewise, both solubility in cellulolytic enzyme suspensions and crude protein content increased with increased intensity of treatment, up to a certain level. Thereafter, increased dosing with NH₃, higher temperatures or longer incubation times had little or no effect. However, maximum values were obtained with a greater intensity of treatment than the maximum digestibility in vitro, and no tendency towards decreased values was observed.Increased enzyme solubility, beyond that corresponding to maximum digestibility in vitro, was accompanied by an increased rate of fermentation and a decreased content of neutral detergent fibre.Treatment with heat (100°C) and pressure after incubation, to simulate pelleting before evaporation of surplus NH₃, was also investigated. Only after the lowest incubation temperatures, however, was there an obvious tendency towards increased digestibility. The enzyme solubility was, on the other hand, very obviously increased. Crude protein content was also slightly increased by the heat- and pressure-treatment.     

侵蚀泥沙、有机质和全氮富集规律研究

在自然降雨下,研究降雨,坡度,耕作和施肥对侵蚀泥沙,有机质和全N富集率的影响,分析土壤和泥沙颗粒组成,富集与泥沙有机质和全N富集的关系,揭示土壤有机质和全N在泥沙中的富集规律,结果表明,泥沙粘粒的富集导致有机质和全N的富集,泥沙粘粒,有机质和全N富集率分别平均为1．77,2．09和1．61,土壤侵蚀模数与泥沙有机质和全N富集率呈显著的负相关关系,降雨,坡度,施肥和耕作措施对泥沙有机质富集作用的影响通过减少土壤侵蚀模数来实现的,减少土壤侵蚀的措施可增加泥沙有机质和全N的富集。     

氮高效利用基因型大麦的物质生产与氮素积累特性

通过土培盆栽试验,研究了22份大麦材料在低氮(125 mg·kg^-1)和正常氮(250 mg·kg^-1)处理下氮素吸收利用效率的基因型差异,探讨氮高效大麦干物质生产与氮素积累特性.结果表明： 大麦氮素吸收利用效率基因型差异显著.低氮处理下籽粒产量、氮素籽粒生产效率及氮素收获指数的最高值分别是最低值的2.87、2.92、2.47倍;氮高效基因型大麦籽粒产量、氮素籽粒生产效率和氮素收获指数均显著大于低效基因型,低氮处理下高效基因型3个参数较低效基因型分别高82.1%、61.5%和50.5%.氮高效基因型大麦各生育期干物质和氮素积累优势明显,干物质积累高峰出现在拔节-抽穗阶段,氮素积累高峰出现在拔节前;低氮处理下高效基因型典型材料DH61、DH121+的干物质量较低效基因型典型材料DH80分别高34.4%、38.3%,氮素积累量较DH80分别高54.8%、58.0%.供试大麦干物质和氮素的阶段性积累量对籽粒产量的影响为拔节前最大,且低氮处理下贡献率最高,分别为47.9%和54.7%;而干物质和氮素的阶段性积累量对氮素籽粒生产效率的影响在抽穗 成熟阶段最大,其次是播种-拔节阶段,低氮处理下这两个阶段的贡献率分别为29.5%、48.7%和29.0%、15.8%.氮高效基因型大麦在各生育期的物质生产和氮素积累能力强,低氮处理下优势较为明显,能够提高拔节前干物质生产和氮素积累能力,并协同提高大麦产量和氮素利用效率.     

水蚀条件下不同土壤氮素和有机质流失规律

人工模拟施水冲刷试验研究结果表明,随施水冲刷强度的增大,不同土壤硝态氮、铵态氮、有机质和全氮流失加剧,泥沙全氮和有机质富集程度减少;当给不同土壤施等量的硝酸铵时,发现随径流流失化肥的铵态氮和硝态氮分别占施入量的０．９％－３．５％和８．２％－１９．７％,硝酸铵主要随径流流失,以泥沙颗粒流失量甚微;土壤侵蚀、有机质和全氮流失量与〉２０μｍ团聚体相关系数分别为－０．８９３５、－０．７９２８和－０．８１５     

The feeding value of ammoniated flax straw,wheat straw and wheat chaff for beef cattle

Two experiments were conducted to assess the feeding value of ammoniated and untreated flax straw, wheat straw and wheat chaff in comparison to a mixed bromegrass/alfalfa hay. Anhydrous ammonia was applied to the crop residues at the rate of 35 kg t⁻¹ dry matter. In the first experiment, the effect of ammoniation on crude protein, acid detergent fibre (ADF), neutral detergent fibre (NDF) and acid detergent lignin (ADL), digestible organic matter in vitro and in vivo (DOM%), ADF and NDF digestibility of the crop residues was determined. In the second experiment, ammoniated flax straw, ammoniated wheat straw, ammoniated and untreated wheat chaff, each supplemented with barley, were compared to bromegrass/alfalfa hay as feed sources for wintering beef cows.Ammoniation increased the crude protein content of the crop residues ∼2-fold. Wheat straw DOM in vitro and in vivo was not increased by ammoniation. Ammoniation increased the DOM in vitro of wheat chaff from 36.3 to 46% and flax straw from 35.2 to 46.3%. The DOM in vivo increased from 53.3 to 63.4% (P < 0.05) for wheat chaff and from 33.9 to 58.4% (P < 0.05) for flax straw following ammoniation. Digestibility of ADF increased from 9.9 to 43.9% (P < 0.05) and of NDF from −0.6 to 37.9% (P < 0.05) in flax straw with ammoniation. Non-significant increases in ADF and NDF digestibility were observed for all other crop residues. Lignin content was not changed in the crop residues by ammoniation.In the winter feeding trial, young cows gained more weight than older cows (P < 0.05). Average daily gains of cows were greatest for hay followed by ammoniated flax straw, ammoniated chaff, untreated chaff and ammoniated wheat straw rations (P < 0.05). Increases in backfat in the younger cows was greatest with hay and ammoniated flax straw, followed by ammoniated chaff and ammoniated wheat straw (P < 0.05). Untreated chaff caused no increase in backfat thickness.Ammoniated flax straw (3.2 kg day⁻¹) given with barley (5.6 kg day⁻¹), is similar in feeding value to medium quality bromegrass/alfalfa hay. Furthermore, wheat chaff and ammoniated wheat chaff show good potential as alternatives to hay in winter feeding.     

A study on feeding ammoniated and processed barley to feedlot steers

A total of 120 commercial crossbred steer calves (284±1.9 kg) were allocated in a 2×2 arrangement to two barley processing methods; whole (W) or rolled (R) barley and two ammoniation treatments; ammoniated (A) or non-ammoniated (N) barley. Steers were randomly allocated to twelve pens with 10 steers per pen and 3 pens (replications) per diet. The study was divided into two stages, growing (0–84 day) and finishing (85–196 day). Average daily gain (ADG) for the overall 196 day period was affected by processing (p<0.01) averaging 1.10 and 1.20 kg day⁻¹ for steers on W and R barley, respectively. Steers on the R barley gained 19.6% more than those on W barley during the growing stage and 0.8% more during the finishing stage. There was a trend towards an improvement (p=0.06) in overall ADG by ammoniation. The ADG of steers was significantly higher (p<0.01) during the finishing (1.22 kg day⁻¹) than during the growing (1.06 kg day⁻¹) stage. Feed efficiency was better with R than with W barley (6.8 vs. 7.7; p=0.02). Processing and ammoniation had no effect (p>0.05) on carcass traits or grades.     

The effect of prolonged storage on the digestibility and nitrogen content of ammonia-treated barley straw

Barley straw in a 10-t stack was treated with anhydrous ammonia (40 kg t^?1 straw dry matter). Four bales, two buried in the stack and two with one face exposed, were sampled before treatment, at 54 days (1 day after the stack was first opened) and at regular intervals thereafter for a further 12 days. The total nitrogen content of the straw increased from the 6.7 g kg^?1 straw dry matter present before treatment to 20.7 g kg^?1 at day 54. Ammonia nitrogen contributed 7.4 g and non-ammonia nitrogen 6.6 g of this increase. There was a rapid loss of ammonia on opening the stack and this continued for the first week; thereafter ammonia was lost at a much slower rate. In all, 39% of the ammonia nitrogen present 1 day after opening was lost by the end of the sampling period. This loss accounted for the 18% reduction in total nitrogen recorded over the same period. Loss of nitrogen did not affect the digestibility of treated straw as determined by the nylon bag method using sheep. Digestibility, whether expressed as loss of dry matter or as digestibility of cellulose, remained constant throughout. Added water-insoluble nitrogen appeared to be more readily available than that initially present in untreated straw. The position of bales within the stack did not affect results significantly.     

Evolution of non-dissolved particulate organic matter during composting of sludge with straw

Long term composting induces loss of C and organic matter stabilisation. These two processes may have opposite effects on long term carbon storage in soils. To check whether raw materials should be composted or not before being spread on the soil, changes in particle size fractions were quantified during composting of 9 tons of sewage sludge and straw. Both the mass of the fine fraction (<2 microm) and the amount of carbon contained in it increased after seven months, respectively, +37% and +43%. The fine fraction contributes to carbon sequestration. A literature review supported the assumption that composting should increase long term C storage. Nevertheless, soil texture or agricultural practices modify the behaviour of this fraction. Thus, the fractionation method used for soils is relevant to predict the effect of composting as a mitigation option in greenhouse gas reduction strategies, but is not sufficient in itself.     

乌梁素海沉积物中有机质和全氮含量分布特征

针对乌梁素海富营养化日趋严重和湿地面积逐渐萎缩,系统地研究了其生态环境地球化学效应.结果表明,乌梁素海表层沉积物中的全氮含量存在明显的经向和纬向分异特征;沉积物中全氮养分含量与有机质含量显著相关(r＞0.93);沉积物中C/N的平均值介于12.07～19.95之间,表明有机质主要来源于湖中水生植物,水体富营养化具有显著的内源性.TN和有机质在不同粒级表层沉积物中的粒度效应明显,且TN和有机质在IV粒级的含量分别为I粒级的3.1～7.6倍和2.5～8.0倍.     

Variations and controls of nitrogen stable isotopes in particulate organic matter of lakes

Nitrogen stable isotope (δ¹⁵N) data of particulate organic matter (POM) from the literature were analyzed to provide an understanding of the variations and controls of δ¹⁵N_POM in lakes at the global scale. The δ¹⁵N_POM variability characterized by seasonal mean, minimum, maximum, and amplitude (defined as δ¹⁵N_POM maximum − δ¹⁵N_POM minimum) from 36 lakes with seasonal data did not change systematically with latitude, but was significantly lower in small lakes than in large lakes. The seasonal mean δ¹⁵N_POM increased from oligotrophic lakes to eutrophic lakes despite large variations that are attributed to the occurrences of nitrogen fixation across the trophic gradient and the differences in δ¹⁵N of dissolved inorganic nitrogen (DIN) in individual lakes. Seasonal mean δ¹⁵N_POM was significantly correlated with DIN concentration and δ¹⁵N_DIN in two subsets of lakes. Seasonal minimum δ¹⁵N_POM in individual lakes is influenced by nitrogen fixation and δ¹⁵N_DIN while seasonal maximum δ¹⁵N_POM is influenced by lake trophic state and δ¹⁵N_DIN. As a result of the dominance of non-living POM in the unproductive surface waters, seasonal δ¹⁵N_POM amplitude was small (mean = 4.2‰) in oligotrophic lakes of all latitudes. On the other hand, seasonal δ¹⁵N_POM amplitude in eutrophic lakes was large (mean = 10.3‰), and increased from low to high latitudes, suggesting that the seasonal variability of δ¹⁵N in the phytoplankton-dominated POM pool was elevated by the greater spans of solar radiation and thermal regimes at high latitudes. The δ¹⁵N_POM from 42 lakes with no seasonal data revealed no consistent patterns along latitude, lake area, and trophic gradients, and a greater than 2‰ depletion compared to the lakes with seasonal data. Along with the large seasonal variability of δ¹⁵N_POM within lakes, these results provide insightful information on sampling design for the studies of food web baseline in lakes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A function for describing nitrogen uptake and dry matter production by winter barley crops

The quantityY, of dry matter produced,Y _d , and nitrogen taken up,Y _n , during the growth of winter barley, was shown to be a function of thermal time,x,

土壤有机氮组分的年际变化及其对秸秆还田的响应

阐明土壤有机氮组分的年际变化特征及其对秸秆还田的响应对合理调控土壤有机氮库和土壤可持续利用具有重要意义。在沈阳农田生态系统国家野外科学观测研究站进行田间微区试验(土壤类型为潮棕壤),设置单施氮肥(200 kg N·hm^-2,下同)、50%秸秆还田配施氮肥和100%秸秆还田配施氮肥3个处理,采用Bremner酸水解法对试验第1、3、6、9年的土壤有机氮组分进行分级。结果表明: 氨基酸态氮含量随着耕作年限的增加逐渐提升,提升幅度为39.8%;酸解未知态氮含量提升幅度为10.8%,且在第3年时最高;土壤总氮和其他有机氮组分含量随耕作年限变化不大。相对容易矿化的酸解总氮占土壤总氮的比例随耕作年限的增加逐渐增加,比较稳定的未酸解态氮占土壤总氮的比例随耕作年限的增加逐渐下降,说明随着耕作年限的增加土壤氮素有效性提高,土壤供氮能力增强。与单施氮肥相比,加入秸秆提高了土壤总氮和各酸解态氮含量,秸秆还田量越多,提升效果越明显。秸秆还田对酸解态氮组分的影响主要发生在试验第6、9年,增加的土壤总氮主要为氨基酸态氮和酸解未知态氮,从而提高了土壤中酸解态氮占土壤总氮的比例。秸秆还田能够提升土壤氮库容,提高土壤保氮供氮能力。     

Effects of alkali salts on carbon and nitrogen mineralization of organic matter in soil

Summary In an incubation experiment the mineralization of gulmohur leaves (Delonix regia L.) added to soil was studied at increased levels of exchangeable sodium percentage (ESP). CO₂ evolution, total mineralization of carbon and humic/fulvic acid carbon ratio increased with increased ESP and the process of nitrification was inhibited completely between 70–92 ESP. The mineralization and losses of nitrogen were equal to control up to 70 ESP but were very high at 92 ESP. The extractable carbon varied from 26% in case of control to 31% at 48.6 ESP.     

Effect of moisture and temperature on the degradability of fiber and on nitrogen fractions in barley straw treated with urea

The effect of the treatment of barley straw with urea (6% of the D.M.) on its chemical composition, digestibility, degradability and nitrogen fractions was studied varying the initial straw-treatment moisture level (20%, 30% and 40%) and storage temperature (25°C and 35°C). The urea treatment fundamentally affected the NDF content of the straw, which decreased as a result of hemicellulose solubilization. The decrease in NDF was greatest when the initial temperature and moisture content of the straw were both high, under which conditions the maximum solubilization of hemicellulose (25%) occurred. In vitro digestibility and degradability also improved with the urea treatment. In this regard, the greatest improvement (up to 20 points in the case of the digestibility results) was seen when hemicellulose solubilization was maximum. The amount of nitrogen retained by the straw (after deducting the residual urea) rose under conditions of increased moisture and temperature, reaching its highest values at moisture levels of 35% and 40%, when the best urea hydrolysis also took place.     

水溶性有机质对土壤中镉吸附行为的影响

水溶性有机质 (DOM)是陆地生态系统和水生生态系统中的一种很活跃的组分 .本文以赤红壤、水稻土和褐土作为供试土壤 ,研究了来源于稻秆和底泥的DOM对土壤中Cd吸附行为的影响 .DOM对土壤中Cd的吸附行为具有明显的抑制作用 .这种抑制作用与土壤类型和DOM种类有关 .在 3种供试土壤中 ,无论添加稻秆DOM还是底泥DOM ,都会使Cd的最大吸附容量和吸附率明显降低 ,其下降幅度为17 3%～ 93 9%.在添加同一种DOM的前提下 ,DOM对Cd吸附的抑制作用均为 :赤红壤 >水稻土 >褐土 .如果不添加DOM ,则土壤对Cd的最大吸附容量主要取决于土壤固相的吸附特性 ,添加DOM后土壤对Cd的最大吸附容量则主要取决于液相中的DOM .由此推断 ,传统的看法 ,通过施用有机肥来固定土壤中的Cd并达到治理重金属污染土壤的观点值得商榷 .     

Long-term effects of elevated nitrogen on forest soil organic matter stability

Nitrogen addition may alter the decomposition rate for different organic-matter pools in contrasting ways. Using a paired-plot design, we sought to determine the effects of long-term elevated N on the stability of five organic-matter pools: organic horizons (Oe+a), whole mineral soil (WS), mineral soil fractions including the light fraction (LF), heavy fraction (HF), and a physically recombined fraction (RF). These substrates were incubated for 300 days, and respiration, mineralized N, and active microbial biomass were measured. Samples with elevated N gave 15% lower cumulative respiration for all five substrates. Over the 300-day incubation, the Oe+a gave twice the cumulative respiration (gCkg^–1 initial C) as the LF, which gave slightly higher respiration than the HF. Respiration was 35% higher for the WS than for the RF. Mineralized N was similar between N treatments and between the LF and HF. Net N mineralized by the LF over the course of the 300-day incubation decreased with higher C:N ratio, due presumably to N immobilization to meet metabolic demands. The pattern was opposite for HF, however, which could be explained by a release of N in excess of metabolic demands due to recalcitrance of the HF organic matter. Mineralized N increased with respiration for the HF but showed no pattern, or perhaps even decreased, for the LF. WS and RF showed decreasing active microbial biomass near the end of the incubation, which corresponded with decreasing respiration and increasing nitrate. Our results show that long-term elevated N stabilized organic matter in whole soil and soil fractions.