绿肥和藁秆等在苏南地区土壤中的分解特征

植物物质是保持和提高土壤肥力的重要物质基础,它是土壤有机质最主要的来源,同时又是作物养分,特别是氮素的补充给源.在我国,农民历来把一切可能利用的植物残体,制作成各种有机肥料,以保持和提高土壤肥力.解放以来,绿肥的种类和面积都有显著增加,包括绿肥在内的有机肥料,现时在土壤氮素的补给中占有相当的比重.     

不同培肥措施对新垦耕地红壤肥力和作物产量的影响

在浙江省余杭区瓶窑镇选择2012～2013年开垦建成的红壤农田,设置对照、冬绿肥+秸秆还田、商品有机肥+冬绿肥+秸秆还田和食用菌废渣+冬绿肥+秸秆还田等4种培肥处理,在玉米-番薯旱粮种植模式下,连续进行3年定位试验,探讨了不同培肥措施对新垦耕地红壤肥力和作物产量的影响。田间试验结果表明,对新垦耕地红壤综合培肥效果最好的为冬绿肥+秸秆还田+商品有机肥处理,其土壤有机质、有效磷、全氮及速效钾含量分别比对照增加90.7%、71.1%、71.0%和28.6%,旱粮产量增加22.6%;其次为冬绿肥+秸秆还田+食用菌废渣处理,其土壤容重比对照处理下降了6.7%,土壤有机质、全氮、有效磷和速效钾含量分别比对照增加88.4%、40.3%、39.1%和18.3%,旱粮产量增加21.6%;单纯采用种植冬绿肥和秸秆还田措施对新垦耕地红壤培肥的效果不明显。试验结果也表明,在不施石灰的情况下,以施用有机物质为主的培肥措施可能会导致土壤酸化。据此认为,由于新垦红壤基础地力较差,应采用多种途径增加有机肥料的投入,如在种植冬绿肥和秸秆还田的基础上适当施用养分含量较高的有机肥料可获得更好的作物增产、地力提升效果。     

盐碱地稻田旱作后土壤肥力变化及其对作物生长的影响

研究了盐碱地稻田旱作后土壤肥力变化及其对作物生长的影响。结果表明,滨海滩涂盐碱地在水田改旱后土壤盐分呈现上升趋势,而土壤pH呈现下降趋势;不同培肥方法对水田改旱后土壤盐分、pH、土壤速效养分及有机质的影响作用不同,石膏处理能明显降低土壤pH值;绿肥处理能增加土壤速效养分和有机质含量;有机肥能抑制和延缓土壤盐分上升、降低土壤pH值、明显增加土壤速效养分和有机质含量,最终促进作物生长,增加作物产量。     

几种土壤结构改良剂的制备及其效用

近年来不少地区土壤中有机质减少,土壤结构状态变劣,成为生产上极需解决的问题。改良土壤结构,除多施有机肥料^[3,4],种植牧草等措施外,施用以天然的有机物及无机物制备的,或人工合成的高分子有机化合物,也是很有效的办法^[1]。本文介绍了几种土壤结构改良剂的研制及其效应,初步证明施用土壤结构改良剂能有效地增加土壤中团粒结构,改善作物生长条件,有利于提高产量。     

长期不同施肥对旱地红壤性质和作物生长的影响

通过对红壤旱地连续13年定位监测研究,发现在红壤旱地长期坚持有机肥料与无机肥料配合施用,土壤有机质含量逐步提高,土壤有机质从开始的11.5g/kg上升到24.3g/kg,增加的有机质以易氧化的有机质为主,稳定性高的有机质较少。红壤长期施用化学磷,明显提高土壤有效磷含量,土壤供磷性能大为改善,施用有机肥料能减少土壤对磷的固定,提高磷肥的有效性和利用率。红壤长期施用单一化学肥料,土壤明显酸化,土壤交换性氢铝显著增加,作物生长变差,产量降低。施用有机肥料,明显降低土壤交换性氢铝含量,增加土壤养分,保持作物的稳产和高产。     

南方稻区绿肥生态服务功能及生态价值评估研究

为探究我国南方稻区绿肥种植的生态服务价值,本文以我国南方稻区农田引入绿肥紫云英为例,界定了稻田种植紫云英的生态服务功能,并运用实际市场法、替代市场法和虚拟市场法等研究方法,构建了绿肥生态价值评估的理论模型,核算了绿肥的生态服务价值,得到了以下研究结论：1）南方稻区绿肥生态服务功能主要涉及调节和支持两类,调节服务包括气体调节、水分涵养和土壤保持3种功能,支持服务则包括土壤有机质累积和土壤营养物质循环两种功能;对应地,南方稻区农田轮作冬绿肥紫云英的生态价值也被界定为以上5种。2）南方稻区冬闲田种植紫云英在一个轮作周期中能够产生1.125万元·hm^-2的生态价值,其中,气体调节价值最大,为0.380万元·hm^-2,其次是土壤有机质累积价值,为0.279万元·hm^-2,营养物质循环价值和土壤保持价值分别为0.204万元·hm^-2和0.214万元·hm^-2,土壤水分涵养价值最小,为0.048万元·hm^-2。3）南方稻区绿肥种植投入成本为0.173万元·hm^-2,绿肥种植所产生的生态价值是种植投入成本的6.5倍。研究表明农田冬种绿肥紫云英的生态服务价值是客观存在的。该研究为南方稻区绿肥引入冬闲田后生态价值的评估提供了较为科学的研究方法和基础参数,同时,也为未来政府制定绿肥种植的生态补偿机制提供了理论依据。     

华北冬绿肥作物养分累积特征及对翻压前土壤养分的影响

采用大田试验方式研究华北地区冬绿肥生态适应性。试验设置冬闲、二月兰、毛叶苕子、黑麦、黑麦草、毛叶苕子二月兰混播、毛叶苕子黑麦混播7个处理,分析其养分累积及其对翻压前土壤养分的影响。结果表明,供试冬绿肥翻压前生物产量为4991～7262 kg/hm²,氮、磷、钾累积吸收量分别为121.5 ～191.4、26.8～41.9、140.7～261.5 kg/hm²,显著高于冬闲处理。其中,毛叶苕子氮吸收量最高,黑麦磷、钾吸收量最高;冬绿肥翻压前土壤硝态氮、有效磷含量显著降低,土壤速效钾含量显著增加。研究结果为冬绿肥种植减少土壤氮、磷养分淋失和钾素固持提供了理论支持。     

泥炭利用的新途径——胡敏酸肥料及其应用

泥炭(亦称草炭、草煤)在全国土壤普查中发现有大量分布,是农业上一种重要的有机肥料肥源,其中富含有机质、腐殖质及氮素和其他养分元素,但这些养分均呈有机化合物结合,直接施用,一般不易为作物利用,肥效当年不大。     

三种绿肥对烤烟产质量及土壤养分和酶活性的影响

绿肥是一种优质的有机肥源,但不同种属的绿肥植物生态适应性迥异,且其对后茬作物的增产和土壤培肥效果受气候、土壤等环境条件影响,亟需因地制宜地筛选适宜绿肥种类。该试验在贵州省植烟黄壤上设置种植翻压光叶紫花苕(CV)、黑麦草(CL)、油菜(CB)和常规施肥(CK)处理,研究3种绿肥对烤烟产质量及土壤肥力的影响。结果表明,与CK相比,CV、CL和CB处理分别减施复合基肥150、75和75 kg/hm²,并替代了1800 kg/hm²商品有机肥,3种绿肥翻压后增加了烤烟产量、产值和产出投入比,表现为CV>CB>CL,烤烟产量分别增加了28.79%(CV)、16.10%(CB)和0.95%(CL)。绿肥翻压处理的烤烟总氮、磷、钾、氯和烟碱含量及上等烟比例高于常规施肥,其增幅分别为10.0%～17.78%(总氮)、8.33%～25.0%(总磷)、16.56%～24.84%(总钾)和34.20%～61.47%(烟碱),其中以CV处理的烟叶品质提升效果最好。此外,绿肥种植翻压增加了土壤有机质、有效态氮磷钾的含量,提升了蔗糖酶、脲酶和蛋白酶的活性。相较油菜和黑麦草,光叶紫花苕在贵州遵义烟区的生长最好,且翻压后对后茬烤烟产量、品质和经济效益的提升及对土壤速效养分及酶活性改善效果更优。因此,光叶紫花苕是一种较适宜黔北烟区种植的绿肥品种。     

天津农田三种典型冬绿肥的施磷效应

绿肥是促进土壤培肥、增加作物产量和保障粮食安全的重要途径,对绿肥生长季施磷效应的研究有助于 为华北旱地绿肥应用模式中磷肥的管理与调控提供理论依据。采用盆栽试验,对天津农田 3 种典型冬绿肥生育期 施用不同用量磷肥(100%P、80%P、60%P、0P),研究其对绿肥作物生长、土壤性状、土壤健康和施磷效应的影 响。结果表明,毛叶苕子和黑麦草在生育季施用 60%P(P2O5 54 kg/hm²)、二月兰施用 80%P(P2O5 72 kg/hm²)有 利于绿肥生物量的形成和养分积累。二月兰在 80%P 处理的磷肥偏生产力较 60%P 和 100%P 处理分别显著提高 了 25.2% 和 43.1%,表观损失率显著降低了 19.3% 和 17.4%。相较于 80%P 和 100%P 处理,毛叶苕子和黑麦草在 60%P 的磷肥偏生产力均有大幅提高,同时表观损失率显著降低。在 60% 施磷量下,毛叶苕子和黑麦草的土壤有 机碳含量显著提高了 12.9% 和 22.2%,全氮含量提高了 20.2% 和 27.4%。毛叶苕子和黑麦草在 60%P 处理下的绿 肥生长功能指数和土壤功能综合指数均高于其他处理,提高了土壤健康水平。综上,在天津农田常见的冬绿肥种 植模式下,毛叶苕子和黑麦草在生长季施用 60% 磷肥,二月兰施用 80% 磷肥有利于提高绿肥产量和养分积累量, 提高磷肥利用率和土壤健康水平。     

Q/I relations and electroultrafiltration of soils as measures of potassium availability to plants

The equilibrium activity ratio (AR_o) of soil potassium and the K extracted by electroultrafiltration (EUF) within a desorption time of 10 min (EUF₁₀) were compared as measures of K availability indicated by K uptake and dry matter yield of barley plants grown in four soils receiving different rates of K fertilization in a glasshouse experiment. As could be expected, both methods indicated that K intensity in soils increased with higher amounts of K dressings and decreased with progressive crop growth. With EUF₁₀, 56–77% of the variation in plant response in dry matter yield and K uptake could be explained, where as with AR_o, it was only 36–65%. There was good linear correlation between AR_o, and EUF₁₀ for a particular soil; but there was differential variation in the two parameters for the different soils. When compared on the basis of plant response, EUF₁₀ was found to better describe K availability to plants and differentiate better between soils of different K selectivity.     

Evolution of soil properties and plant communities along an extreme edaphic gradient

Plant-litter-soil interactions were investigated along a soil chronosequence occurring on five coastal terraces in northern California that range in age from about 100 000 to 500 000 YBP. Soil and plant communities vary dramatically and consist of slightly acidic, fertile soils supporting highly productive mixed-conifer forests on the youngest terrace to highly acidic, infertile soils supporting pygmy forests of dwarf (< 3 m) conifers and Ericaceae species on the older terraces. Soil genesis, soil nutrient status, soil acidity and plant community structure reach a steady-state after approximately 250 000 years. All major species of the pygmy forest are polyphenol-rich, and those species that also grow elsewhere on the gradient have their highest concentrations of extractable polyphenols when growing on the most highly acidic, infertile sites. Polyphenols provide several beneficial effects on highly acidic and infertile soils, such as nutrient conservation, detoxification of soluble aluminum and enhanced phosphorus availability. Polyphenols may also provide some plant species with a competitive advantage by altering nitrogen cycling, allowing these plants to alter forest succession. The convergent evolution of polyphenol-rich plant communities on highly infertile soils throughout the world may be due to the ability of polyphenols to ameliorate acid soil infertility factors and regulate the nitrogen cycle.     

Variable inhibition of iron uptake by oat phytosiderophore in five soybean cultivars

Abstract

Greenhouse experiment was conducted to evaluate the effect of arbuscular mycorrhizal fungi (AMF) on plant growth, and nutrient uptake in saline soils with different salt and phosphorus (P) levels. The following treatments were included in this experiment: (i) Soil A, with salt level of 16.6 dS m^?1 and P level of 8.4 mg kg^?1; (ii) Soil B, with salt level of 6.2 dS m^?1 and P level of 17.5 mg kg^?1; and (iii) Soil C, with salt level of 2.4 dS m^?1 and P level of 6.5 mg kg^?1. Soils received no (control) or 25 mg P kg^?1 soil as triple super phosphate and were either not inoculated (control) or inoculated with a mixture of AM (AM1) and/or with Glomus intraradices (AM2). All pots were amended with 125 mg N kg^?1 soil as ammonium sulfate. Barley (Hordeum vulgar L., cv. “ACSAD 6”) was grown for five weeks. Plants grown on highly saline soils were severely affected where the dry weight was significantly lower than plants growing on moderately and low saline soils. The tiller number and the plant height were also lower under highly saline condition. The reduced plant growth under highly saline soils is mainly attributed to the negative effect of the high osmotic potential of the soil solution of the highly saline soils which tend to reduce the nutrient and water uptake as well as reduce the plant root growth. Both the application of P fertilizers and the soil inoculation with either inoculum mixture or G. intraradices increased the dry weight and the height of the plants but not the tiller number. The positive effect of P application on plant growth was similar to the effect of AM inoculation. Phosphorus concentration in the plants was higher in the mycorrhizal plant compared to the non mycorrhizal ones when P was not added. On the other hand, the addition of P increased the P concentration in the plants of the non mycorrhizal plants to as high as that of the mycorrhizal plants. Iron (Fe) and zinc (Zn) uptake increased with AM inoculation. The addition of P had a positive effect on micronutrient uptake in soil with low level of soil P, but had a negative effect in soil with high level of soil P. Micronutrient uptake decreases with increasing soil salinity level. Inoculation with AMF decreases sodium (Na) concentration in plants grown in soil of the highest salinity level but had no effect when plants were grown in soil with moderate or low salinity level. The potassium (K) concentration was not affected by any treatment while the K/Na ratio was increased by AM inoculation only when plant were grown in soil of the highest salinity level.     

Long‐term effects of leguminous cover crops on microbial indices and their relationships in soils of a coconut plantation of a humid tropical region

In this study, leguminous crops like Atylosia scarabaeoides, Centrosema pubescens, Calopogonium mucunoides, and Pueraria phaseoloides. grown as soil cover individually in the interspaces of a 19‐yr‐old coconut plantation in S. Andaman (India) were assessed for their influence on various microbial indices (microbial biomass C, biomass N, basal respiration, ergosterol, levels of ATP, AMP, ADP) in soils (0–50 cm) collected from these plots after 10 years. The effects of these cover crops on . CO₂ (metabolic quotient), adenylate energy charge (AEC), and the ratios of various soil microbial properties viz., biomass C : soil organic C, biomass C : N, biomass N : total N, ergosterol : biomass C, and ATP : biomass C were also examined. Cover cropping markedly enhanced the levels of organic matter and microbial activity in soils after the 10‐yr‐period. Microbial biomass C and N, basal respiration, . CO₂, ergosterol and levels of ATP, AMP, ADP in the cover‐cropped plots significantly exceeded the corresponding values in the control plot. While the biomass C : N ratio tended to decrease, the ratios of biomass N : total N, ergosterol : biomass C, and ATP : biomass C increased significantly due to cover cropping. Greater ergosterol : biomass C ratio in the cover‐cropped plots indicated a decomposition pathway dominated by fungi, and high . CO₂ levels in these plots indicated a decrease in substrate use efficiency probably due to the dominance of fungi. The AEC levels ranged from 0.80 to 0.83 in the cover‐cropped plots, thereby reflecting greater microbial proliferation and activity. The ratios of various microbial and chemical properties could be assigned to three different factors by principal components analysis. The first factor (PC1) with strong loadings of ATP : biomass C ratio, AEC, and . CO₂ reflected the specific metabolic activity of soil microbes. The ratios of ergosterol : biomass C, soil organic C : total N, and biomass N : total N formed the second factor (PC2) indicating a decomposition pathway dominated by fungi. The biomass C : N and biomass C : soil organic C ratios formed the third principal component (PC3), reflecting soil organic matter availability in relation to nutrient availability. Overall, the study suggested that Pueraria phaseoloides. or Atylosia scarabaeoides were better suited as cover crops for the humid tropics due to their positive contribution to soil organic C, N, and microbial activity.     

Selecting for nutrient use efficiency within forage grass species: I. Development of a screening system

One means of achieving increased forage grass production on infertile soils is to select plant genotypes which grow efficiently at low levels of available nutrients. This requires methods to identify variability in individual plant nutrient response from among large populations of plants grown under controlled environmental conditions.

A compact, containerized system, partially developed for growing large numbers of forage grass seedlings for use in automatic machine transplanter research, was adapted as the basis for such a screening technique. Three trials were made with 100‐plant samples of a kleingrass‐75 (Panicum coloratum L.) population to test the utility of the system. Results of these trials showed that differences in nutrient use efficiency (= reciprocal of nutrient concentration in the plant tissue, or milligrams dry matter produced per milligram nutrient absorbed) among the grass plants could be effectively identified by using the system in conjunction with laboratory analysis of the material grown. Plants could be maintained in vigorous condition during several harvest periods, and those selections that were retained could be easily transplanted for further propagation and evaluation.     

Improvement of the physical fertility of a degraded Alfisol with planted and natural fallows under humid tropical conditions

Abstract. Topsoil (0–15 cm) bulk density, aggregate stability, soil dispersibility, water retention and infiltration were measured between 1989 and 1996 on an Alfisol under rehabilitation in southwestern Nigeria. The planted leguminous species were Pueraria phaseoloides, Senna siamea, Leucaena leucocephala, Acacia leptocarpa and A. auriculiformis. Also, plots with natural fallow and maize/cassava intercropping were included. Level (minimum) and mound tillage with hoes was adopted for the cultivated areas under study after 4 and 6 year fallow periods. Under fallow, the soil bulk density decreased from1.56 to 1.11 t m73.The continuously cropped treatment (level tillage) had significantly higher bulk density than the fallowed subplots after 6 years. Mean soil penetrometer resistance ranged from 75 to 157 kPa for fallowed plots and from 192 to 295 kPa for the continuously cropped (level tillage) subplot. Surface soilwater contentswere similar for all the treatments during the soil strength measurements. Although soil aggregates were generally of low stability and not well formed, they were improved by fallowing.
Soil structural improvement by planted fallows was similar to that by natural fallow, but the trees were more promising for long-term fallow (>6 years) than the herbaceous P. phaseoloides. However, the improvement in soil structure after 4 or 6 year fallow could not be maintained in subsequent cropping. Furthermore, the significant improvement in soil bulk density caused by A. auriculiformis and natural fallow was more rapidly lost on the cultivated subplots compared with other fallow treatments. Thus, soil structure recovery under a fallow does not imply a sustained improvement when stress is applied to this soil. Post-fallow soil management options such as residue incorporation and tillage to ameliorate compaction or soil strength will be necessary to enhance the improvements by fallow species.     

不同热水处理方式对橡胶园覆盖绿肥种子萌发的影响

通过对10种橡胶园覆盖绿肥种子进行不同时长的热水处理,分析其发芽时间、发芽势、发芽率及发芽指数,研究不同热水处理方式对绿肥种子萌发的影响。结果表明,毛蔓豆、爪哇葛藤、刺毛黧豆的发芽率、发芽势随着热水处理时间的缩短而下降,而印尼乌绿豆则随着热水处理时间的缩短而上升,铺地木蓝、决明先升高后下降,圆叶决明、十一叶木蓝、长果猪屎豆、钝叶决明先下降后升高。绿肥种子2~4 d开始萌发,不同热水处理方式对绿肥种子开始萌发时间影响不大。毛蔓豆、圆叶决明、决明、钝叶决明的发芽持续时间随热水处理时间的缩短而延长,爪哇葛藤、印尼乌绿豆、长果猪屎豆随热水处理时间的缩短而缩短;不同时长热水处理对铺地木蓝、十一叶木蓝、刺毛黧豆的发芽持续时间影响不大,且这3种种子发芽不整齐、持续时间长,可考虑采用育苗后再移栽。毛蔓豆、爪哇葛藤、刺毛黧豆、圆叶决明、钝叶决明5种绿肥种子加热水直至自然冷却处理效果最好,印尼乌绿豆、十一叶木蓝、长果猪屎豆加热水倒掉冷水骤冷处理效果最好,铺地木蓝、决明加热水马上倒掉处理效果最好。     

Growth and nitrogen fixation by Medicago littoralis in pot experiments: Effect of plant density and competition from Lolium multiflorum

The legume Medicago littoralis cv. Harbinger, was grown either alone (1–4 plants per pot) or with Lolium multiflorum (ryegrass) at a total of 4 plants per pot, using two soils of contrasting N status. An ¹⁵N dilution technique was used to distinguish the amounts of plant N due to N₂ fixation and to N uptake from soil. Medic outyielded (dry weight and total plant N) ryegrass in a soil which released low amounts of inorganic N (Roseworthy) but ryegrass outyielded medic in a soil of higher N availability (Avon).For both soils, all combinations of medic and ryegrass plants utilized 70–73% of the inorganic N released on incubation. Competition from ryegrass invariably reduced yields of dry matter, total N, and fixed N of the medic plants, especially in the Avon soil. For both soils, the percentage reduction in the amounts of fixed N resulting from competition from ryegrass was directly proportional to the percentage increase of plant dry matter due to ryegrass. Medic plants grown in Roseworthy soil contained much higher proportions of N due to N₂-fixation than did medic plants grown in Avon soil. The amounts of plant N, fixed N and plant dry weight increased with increasing numbers of medic plants, when grown alone in Roseworthy soil, but not in the Avon soil containing more than two plants per pot. Nevertheless, irrespective of the soil used, medic numbers per pot, or competition from ryegrass, the amounts of fixed N correlated well with total N and with dry matter yields of medic plants. The proportions of fixed N to total N varied consistently in each of the medic plant parts (roots < = leaves < stems < pods).     

水磷互作对潮土玉米苗期生长及磷素积累的影响

利用温室盆栽试验研究了水磷互作对潮土玉米苗期生长及磷素积累的影响。结果表明,水、磷能显著影响玉米株高与叶面积状况。水分胁迫条件下,适度施磷处理比对照玉米株高和叶面积分别增加69.7%和33.6%;而适水条件下分别增加38.3%和48.0%。适度施磷条件下,水分胁迫促进了玉米根系发育,根干重与根冠比均高于适水处理。水磷配合能提高了玉米干物质积累量,表现出显著正交互效应。适度施磷范围内,适水处理能显著提高植株体磷素吸收积累总量,但对植株磷含量影响不大;适水处理下,过量施磷会导致植株对磷素奢侈吸收,而在水分胁迫下反而降低对磷素的吸收积累。水磷适度配合表现出较好的耦合效果,达到“以水促磷”与“以磷促水”的目的。     

西吡对抑制硝化过程和其它微生物活性的影响

作物对氮肥的利用率很低^[3,4],水稻对氮肥的利用率又低于旱作.稻田中氮素平衡的资料指出,水稻对氮肥的利用率在20-60%之间,平均35%,土壤中残留3-21%,平均12%,损失31-61%,平均50%.