不同密度马尾松人工林枯落物输入对土壤理化性质的影响

为研究不同密度马尾松人工林枯落物输入对土壤理化性质和林分生长影响,选择适宜的人工林经营措施提供参考.以2 500,3 300,4 500,6 000株/hm2(分别记为M1、M2、M3和M4)4种造林密度的马尾松人工林为研究对象,利用结构方程探究不同密度马尾松林枯落物输入对土壤性质的影响.结果表明:林分密度对枯落物和土...     

稻-麦轮作体系不同施肥模式对氮肥利用效率和土壤有效养分平衡的影响

土壤肥力和养分利用效率是保障可持续粮食生产的基础。通过田间试验研究了稻—麦轮作体系下不同施肥模式氮肥利用效率和土壤有效养分的变化,结果表明:在减少养分总投入量的条件下,有机肥部分替代化肥处理(RF-OM和RF-S处理)水稻地上部总生物量显著高于LRF处理(P<0.05),与FP处理差异不大;小麦秸秆生物量与FP和LRF处理差异均不显著,籽粒生物量及地上部总生物量与LRF处理相差不大。水稻收获期RF-OM处理地上部主要器官含氮量与LRF处理差异不显著,氮素积累总量显著高于LRF处理(P<0.05);小麦收获期RF-OM和RF-S处理秸秆、籽粒含氮量和氮素积累量与LRF处理均无显著差异。收获期RF-OM和RF-S处理水稻糙米和稻壳、小麦秸秆和籽粒含磷量及磷素积累量与FP和LRF处理差异都不大;水稻秸秆、稻壳及小麦秸秆含钾量和钾素积累量均显著高于FP和LRF处理(P<0.05)。有机肥部分替代化肥处理水稻、小麦氮肥农学利用率、氮肥表观回收率和氮肥偏生产力与FP和LRF处理相比均显著提高(P<0.05),氮素籽粒生产效率也高于FP和LRF处理,甚至达到显著水平(P<0.05)。试验表明,水稻、小麦收获期增钾处理(RF-OM和RF-S处理)土壤速效钾、缓效钾含量显著高于FP和LRF处理(P<0.05),水稻收获期土壤碱解氮和小麦收获期土壤有效磷含量与LRF处理差异不大,同时,经1个稻—麦轮作周期后,4个施肥处理土壤有效养分(碱解氮、有效磷、速效钾、缓效钾)含量均高于供试土壤。有机肥部分替代化肥能显著提高稻麦氮肥利用效率,有利于土壤有效养分平衡,并显著提高土壤速效钾和缓效钾养分含量,是适宜的稻麦化肥减量和稳产增效施用技术。     

肥液浓度和生物质掺混比例对微润灌溉湿润体内水肥分布的影响

微润灌溉作为一种新型地下连续灌溉节水技术,可为农业水肥一体化提供有效载体。为探明不同生物质掺混比例下竖插式微润灌溉施肥湿润体内水分和养分的分布规律,开展室内入渗试验,设置3个肥液浓度（清水F₀：0 g·L^-1;低浓度F_L：0.2 g·L^-1;高浓度F_H：0.4 g·L^-1）和4个土壤生物质（花生壳粉末）掺混比例（无掺混B₀：0;低掺混B_L：1.5%;中掺混B_M：3.0%;高掺混B_H：4.5%）,研究微润灌溉施肥湿润体内土壤含水率、硝态氮、速效磷和速效钾的分布特性。结果表明：掺混生物质后湿润体内水肥分布范围显著增大,而肥液浓度对水肥分布范围的影响不显著。土壤水肥含量随着与微润管水平距离的增加而逐渐减小,水肥含量最大值出现在微润管周围。在与微润管水平距离为0~10 cm范围内,土壤含水率和硝态氮分布较均匀,速效磷和速效钾则形成累积区。肥液浓度和生物质掺混比例对湿润体内水肥含量均值影响显著。与F₀相比,增加肥液浓度提高土壤含水率和养分（硝态氮、速效磷和速效钾）含量均值3.94%~14.09%和124.92%~458.05%;与B₀相比,增大生物质掺混比例提高土壤含水率和养分含量均值12.89%~33.32%和28.37%~115.44%。微润灌溉施肥湿润体内土壤含水率和硝态氮的分布均匀性较高,而速效磷和速效钾分布均匀性较低。增大肥液浓度和生物质掺混比例可提高湿润体内土壤含水率和硝态氮的分布均匀系数,而降低速效磷和速效钾的分布均匀系数。微润灌溉施肥湿润体内水肥含量均值与至微润管水平距离的关系符合四参数Log-logistic模型。总之,在土壤中掺混生物质有利于微润灌溉施肥下水分和养分的运移,增加肥液浓度和土壤生物质掺混比例可显著提高湿润体内的水肥含量,增大水分和硝态氮的分布均匀性,促使速效磷和速效钾在微润管周围的累积量增多。研究结果可为微润灌溉水肥一体化技术提供理论依据和实践参考。     

西南山地林下经济模式对土壤养分和土壤微生物数量的影响

为进一步加强农林牧业资源共享,推动生态农业的发展,在重庆市荣昌县6种不同的林下经济模式下,分别对土壤养分和微生物数量的变化及其相互关系进行了研究。结果表明,不同的林下经济模式对土壤养分的影响各有差异,有机质和全钾在麻竹林下养禽模式中增加最多,全磷在桉树林下养禽模式中增加最多,全氮、碱解氮、速效钾含量则在马尾松林下养畜模式中增加最多。从微生物总量来看,土壤中表现为桉树林下禽模式最多,其次为桉树林下种菌模式,最少的是麻竹林下种菌模式;腐殖层中最多的是麻竹林下养禽模式,最少的是桉树林下种菌模式。微生物数量与有机质、有效磷和碱解氮呈正相关关系。由于土壤养分和微生物数量的变化趋势不一致,因此在研究林下经济过程中应将二者结合起来。     

氮素有机替代对东北黑土区土壤微生物碳磷资源限制的影响

  【目的】  土壤微生物数量和结构普遍受到碳 (C),氮 (N)、磷 (P)等养分有效性的影响,研究不同施肥措施对东北黑土区土壤理化性质、微生物量和酶活性的影响,深入了解土壤微生物养分资源限制状况及其变化规律,为提高土壤生物肥力提供理论依据。  【方法】  试验设在黑龙江省哈尔滨市,土壤类型为黑土,种植制度为玉米单作。试验开始于2019年,共设9个处理:不施肥 (CK)、习惯施肥 (FP)、推荐施肥 (OPT)、推荐施肥不施氮 (–N);有机氮替代推荐施氮量的10% (M1)、20% (M2)、30% (M3)、40% (M4) 和50% (M5)。玉米收获后,采集0—20 cm土壤样品,测定土壤含水量、pH、有机质、全氮、速效磷、速效钾、可溶性有机碳、可溶性有机氮、微生物量碳、微生物量氮和4种土壤酶 (酸性磷酸酶、β-D-葡萄糖苷酶、L-亮氨酸氨基肽酶、β-N-乙酰氨基葡萄糖苷酶) 活性。  【结果】  与OPT处理相比,有机氮替代化肥氮处理提高了土壤速效养分含量 (可溶性有机碳、有效磷、速效钾) 和微生物量 (微生物量碳、微生物量氮),其中可溶性有机碳、有效磷和速效钾的含量随替代比例的增加分别增加了15.5%～46.6%、1.4%～18.5%和2.4%～18.8%;MBC和MBN的含量随有机替代比例的增加分别增加了1.4%～19.9%和0.04%～22.7%。PCA分析显示出CK、化肥处理 (FP、OPT、–N) 和有机氮替代化肥氮处理 (M1、M2、M3、M4、M5) 下的土壤酶活性具有显著差异;RDA分析进一步表明有效磷 (F = 14.1,P = 0.002) 是影响酶活性变化的主要理化因子,解释了不同处理间酶活性差异的36.1%。酶化学计量散点图显示出试验点的土壤微生物均受到磷的限制,FP处理下的土壤微生物还受到碳的限制。此外,与CK相比,有机氮替代化肥氮显著提高了β-D-葡萄糖苷酶与酸性磷酸酶的比值,但是矢量角度在不同有机替代处理间并无显著差异。  【结论】  在本试验区中,未施肥处理下土壤微生物受到碳和磷的共同限制,习惯施肥和优化施肥均会加剧微生物的碳限制。有机氮替代化肥氮可以显著提高土壤的养分含量与生物肥力,解除土壤微生物的碳限制,并显著减轻土壤微生物的磷限制。但是磷限制的减轻效果并未随有机氮替代化肥氮比例的增加而显著增加,考虑到有机肥养分释放较为缓慢,具体的有机替代比例还需开展长期试验。     

Responses of a Widespread Weed and an Endangered Congeneric Plant to Potassium

Acid rain is leading to soil potassium (K) loss. A hydroponic experiment was conducted to determine the growth and physiological and stoichiometrical traits of Mosla hangchowensis (an endangered plant) and M. scabra (a weed) in response to three K concentrations. For M. hangchowensis, compared with standard Knop's solution (K₃), low K (K₀) induced reductions in net photosynthetic rate, soluble protein content, superoxide dismutase activity, total biomass, tissue K concentration, and leaf nitrogen (N) concentration and induced increases in malondialdehyde content and tissue sodium (Na) concentration (P < 0.05). In contrast, none of these factors were affected by K₀ for M. scabra. Critical values of N/K and K/P (phosphorus) ratios in shoots indicated that limitation in K uptake occurred for M. hangchowensis but not M. scabra under K₀. The continuing decline of K content due to acid rain may worsen the situation of M. hangchowensis, whereas M. scabra can maintain vigorous growth and develop well in the future.     

Growth Parameters,Leaf Characteristics and Nutrient Status of Banana as Influenced by Organics,Biofertilizers and Bioagents

Nutrients play an important role in improving productivity and quality of banana. It has been observed that the nutrient applied alone was less effective in improving banana production as compared to nutrients applied in combination with organic manures and biofertilizers. Keeping in view the conservation of soil health and quality production on a long-term basis, a field experiment was conducted during 2009–2011 to find out the influence of Integrated Nutrient Management of banana on leaf characteristics, growth and nutrient status of tissue cultured banana cv. ‘Grand Naine’. The study indicates that combination of inorganic fertilizers with organic manures, biofertilizers and bioagents significantly increased growth parameters, leaf characteristics, and leaf nutrient status of banana. The leaf characteristics in terms of functional leaves, total number of leaves, phyllochron, leaf area, and leaf area index were significantly influenced by the combination of inorganic fertilizers with different biofertilizers and organic manures. Similarly, leaf nutrient status like nitrogen, phosphorus pentoxide_, (P₂O₅), potassium dioxide (K₂O), and leaf relative water content were also influenced greatly by different nutrients. Treatment involving combination of 100% recommended dose of fertilizer (RDF) + arbuscular mycorrhizal fungi (AMF) + Azospirillum+ Trichoderma harzianum showed overall superiority in most of the parameters.     

The Effect of Phosphorus,Mucuna, and Nitrogen on the Biomass,Leaf Area Index,and Foliar Nutrient Content of Maize on a Depleted Sandy Loam Soil in Zimbabwe

Sufficient nutrient levels in leaves of crops have substantial effects on plant growth, development, and grain yield, as it is a fundamental constituent of many leaf cell components. The effect of phosphorus (P), mucuna management options, and nitrogen (N) on the biomass, leaf area index (LAI) and leaf nutrient content of maize on a depleted sandy loam soil in Zimbabwe were investigated. The experimental design was a split-split-plot with two P rates, four mucuna management options, and four N treatments (applied to a subsequent maize crop). Biomass, LAI, and foliar N, P, potassium (K), calcium (Ca), and magnesium (Mg) in the subsequent maize crop were determined. A significant three-way interaction (P < 0.05) between mucuna management options, N rates, and time was observed in terms of biomass production and all nutrients in the leaves of the subsequent maize crop.     

Seasonal Biomass Accumulation and Nutrient Uptake of Pea and Lentil on a Black Chernozem Soil in Saskatchewan

ABSTRACT

Close relationships usually exist among biomass accumulation, nutrient uptake, and seed yield during the growing season. Field experiments with pea (Pisum sativum L.) and lentil (Lens cultinaris L.) were conducted in 1998 and 1999 at Melfort, Saskatchewan, Canada, to determine relationships of biomass accumulation and nutrient uptake with days after emergence (DAE) or growing degree days (GDD). For both biomass accumulation and nutrient uptake, maximum rates and amounts increased with time at early growth stages and reached a maximum value at late growth stages. The R² values for cubic polynomial regressions were highly significant, indicating their suitability to estimate the progression of biomass accumulation and nutrient uptake as a function of days after emergence (DAE). Both pulse crops followed a similar pattern in biomass accumulation and nutrient uptake, which increased in the early growth stages and reached a maximum late in the growth cycle. Pulse crops usually reached their maximum biomass accumulation rate and amount at early to late bud formation (42–56 DAE or 390–577 GDD) and at medium pod formation to early seed filling (75–82 DAE or 848–858 GDD) growth stages, respectively. Maximum biomass accumulation rate was 175–215 kg ha^{? 1}d^?1 for pea and 109–140 kg ha^{? 1}d^{? 1} for lentil. Maximum nutrient uptake rate and amount usually occurred at branching to early bud formation (28–49 DAE or 206–498 GDD) and at the flowering to seed filling (66–85 DAE or 672–986 GDD) growth stages, respectively. Maximum uptake rate of nitrogen (N), phosphorus (P), potassium (K), and sulfur (S), respectively, was 4.6–4.9, 0.4–0.5, 5.0–5.3 and 0.3 kg ha^{? 1}d^{? 1} for pea, and 2.4–3.8, 0.2–0.3, 2.0–3.4 and 0.2 kg ha^{? 1}d^{? 1} for lentil. In general, maximum nutrient uptake rate and amount occurred earlier than maximum biomass accumulation rate and amount, respectively; and the maximum accumulation rates of both biomass and nutrients occurred earlier than maximum amounts. The findings suggest that adequate supply of nutrients from soil and fertilizers at early growth stages, and translocation of biomass and nutrients to seed at later growth stages are of great importance for high seed yield of pulse crops.     

Genotypic variation in foliar nutrient concentrations, δ13C,and chlorophyll fluorescence in relation to tree growth of radiata pine clones in a serpentine soil

This study investigated the genotypic variation in foliar nutrient concentrations, isotopic signature (δ¹³C), and chlorophyll fluorescence (F_v/F_m) and tree growth of 40 radiata pine clones grown on a New Zealand serpentine soil, and the relationships between growth and physiological traits of these clones from improved and unimproved groups. Genotypic variation in growth and physiological traits existed within (i.e., clonal) and between groups, with larger variation among clones. The clonal repeatabilities were greater for foliar nitrogen (N), calcium (Ca), magnesium (Mg), boron (B) concentrations, δ¹³C, and Ca : Mg ratio (0.35–0.64) than for growth traits (0.14–0.27) and other physiological traits (0.08–0.24). Significant phenotypic correlations were found between growth traits and foliar phosphorus (P), potassium (K), sulfur (S), iron (Fe), and K : Mg and Ca : Mg ratios and F_v/F_m (positive), and foliar Mg (negative). This study indicates that the trees on this serpentine soil generally suffered from multiple nutrient deficiencies and imbalances and the clonal variation in growth performance was more related to their capabilities of acclimation to nutrient than water stresses. Overall, the clones that absorbed more P, K, S, and Fe and less Mg from the soil grew better on this serpentine soil. For unimproved clones, the most limiting nutrients for tree growth were foliar K and Fe, while for improved clones it was foliar K.     

Sustaining Productivity of Baby Corn–Rice Cropping System and Soil Health through Integrated Nutrient Management

Organic matter is essential to enhance the soil quality and sustainability of an agroecosystem and ecological services. Thus a 2-year (2007–2009) study was carried out at Agriculture Experiment Farm, Giridih, India. Baby corn (Zea mays L.) yielded maximum cobs (0.84 Mg/ha) and green fodder (17.65 Mg/ha) yield when grown with inorganic fertilizers alone (F₁, nitrogen, phosphorus pentoxide, potassium oxide (N:P₂O₅:K₂O):: 150:60:60 kg/ha). Rice (Oryza sativa L.) produced most grain (3.10 Mg/ha) and straw (4.16 Mg/ha) yield when the preceding crop received nutrients in equal proportion of organic and inorganic (50:50) sources (F₄ and F₅). System productivity in terms of baby corn equivalent yield (1.08 Mg/ha) was greatest when nutrients were applied in 30:70 ratio (F₂ and F₃). Baby corn grown with F₁ took up the maximum nitrogen (N), phosphorus (P), and potassium (K). Remarkable improvement was noticed in microbial activity (microbial population, soil respiration, microbial biomass carbon), soil enzymes (urease and acid phosphatase), and soil fertility parameters [NPK, organic carbon, and cation exchange capacity] with F₄ and F₅ treatments as compared to others. Integrated nutrient-management practices improved soil health. Almost all the parameters were nonsignificantly greater in vermicompost than that of farmyard manure.     

有机无机肥配施和根瘤菌接种对拉巴豆生长、品质及养分吸收的影响

选取优良高产豆科牧草拉巴豆为供试材料,研究了接种根瘤菌和有机无机肥配施对拉巴豆结瘤、 生长、 饲料品质、 养分吸收及土壤酶活性的影响。结果表明,F0.5M0.5（50%有机肥+50%无机肥）和F0.75M0.25（25%有机肥+75%无机肥）处理的拉巴豆生长最好,F（纯施化肥）和F0.25M0.75（75%有机肥+25%无机肥）处理次之,M（纯施有机肥）处理较差,CK（不施肥）最差,F0.5M0.5和F0.75M0.25处理比F分别增产19.46%和16.49%。F和CK结瘤数最少,瘤重也最低,但根瘤数量和重量随有机肥施用的比例增加而提高。在施用有机肥的4个处理中,拉巴豆净光合速率相似,介于14.39~15.32 CO2 mol/(m2s)之间,显著高于F和CK处理。此外,施用有机肥显著改善拉巴豆饲用品质,尤以F0.5M0.5和F0.75M0.25处理最显著,并提高过氧化氢酶、 蔗糖酶、 脲酶活性。相关分析表明,拉巴豆根瘤重与地上部生物量、 氮、 磷、 钾吸收量呈显著正相关,相关系数依次为0.6758、 0.7269、 0.9759、 0.9488（n=36）,说明根瘤形成改善了拉巴豆的氮、 磷、 钾营养,促进了生长,提高了品质。在重庆市的拉巴豆栽培实践中,提倡接种根瘤菌和有机无机肥适量配施很有必要。     

Effects of co-inoculation of Bradyrhizobium japonicum SAY3-7 and Streptomyces griseoflavus P4 on plant growth,nodulation, nitrogen fixation,nutrient uptake,and yield of soybean in a field condition

ABSTRACT

Co-inoculation of nitrogen-fixing bacteria with plant growth-promoting bacteria has become more popular than single inoculation of rhizobia or plant-growth-promoting bacteria because of the synergy of these bacteria in increasing soybean yield and nitrogen fixation. This study was conducted to investigate the effects of Bradyrhizobium japonicum SAY3-7 and Streptomyces griseoflavus P4 co-inoculation on plant growth, nodulation, nitrogen fixation, nutrient uptake, and seed yield of the ‘Yezin-6’ soybean cultivar. Nitrogen fixation was measured using the acetylene reduction assay and ureide methods. Uptake of major nutrients [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] was also measured. This study showed that single inoculation of SAY3-7 significantly increased shoot biomass; nodulation; Relative Ureide Index (RUI %), percent nitrogen derived from N fixation (% Ndfa); N, P, K, Ca, and Mg uptakes; during the later growth stages (R3.5 and R5.5), compared with control. These observations indicate that SAY3-7 is an effective N-fixing bacterium for the plant growth, nodulation, and nitrogen fixation with an ability to compete with native bradyrhizobia. Co-inoculation of SAY3-7 and P4 significantly improved nodule number; nodule dry weight; shoot and root biomass; N fixation; N, P, K, Ca, and Mg uptake; at various growth stages and seed yield in ‘Yezin-6’ soybean cultivar compared with the control, but not the single inoculation treatments. Significant differences in plant growth, nodulation, N fixation, nutrient uptake, and yield between co-inoculation and control, not between single inoculation and control, suggest that there is a synergetic effect due to co-inoculation of SAY3-7 and P4. Therefore, we conclude that Myanmar Bradyrhizobium strain SAY3-7 and P4 will be useful as effective inoculants in biofertilizer production in the future.     

有机无机肥配施对滨海脱盐土栽培菊芋及其养分吸收的影响

以蚯蚓粪和无机复合肥为材料,设置CK(不施肥)、T1(无机复合肥300kg/hm²)、T2(无机复合肥600kg/hm²)、T3(蚯蚓粪7.5 t/hm²)、T4(蚯蚓粪7.5 t/hm²、无机复合肥300 kg/hm²)、T5(蚯蚓粪7.5 t/hm²、无机复合肥600 kg/hm²)、T6(蚯蚓粪15 t/hm²)、T7(蚯蚓粪15 t/hm²、无机复合肥300 kg/hm²)、T8(蚯蚓粪15 t/hm²、无机复合肥600 kg/hm²)共计9个处理,研究了蚯蚓粪和无机复合肥配施下滨海脱盐土土壤性质的变化,栽培菊芋生长特性及养分吸收规律,以确立滨海脱盐土菊芋高效栽培最适有机无机肥配施方案。结果表明：随菊芋生育进程推进,土壤可溶性盐含量下降,T6处理幼苗期和开花期的可溶性盐含量均最低,分别为0.28和0.29 g/kg,较...     

不同种类生物质炭对植烟土壤保育及烤烟生长和品质的影响

通过盆栽试验,研究施加等量(3%)椰壳炭、竹炭、猪炭和烟秆炭对植烟土壤基本理化性质、土壤养分、烤烟生长状况以及烤烟常规化学成分的影响。结果表明:施用生物质炭对土壤电导率、有效养分含量、有机碳含量和酶活性有显著影响,其中施用竹炭后土壤有机碳含量较CK增幅最大,达146.37%;而施加猪炭能显著提高植烟土壤中电导率、有效磷、速效钾含量以及过氧化氢酶和脲酶的活性(p0.05)。生物质炭对烤烟农艺性状的影响较小,仅在猪炭处理下,烤烟茎围较对照增加0.78cm。施用生物质炭能显著提高烤烟的生物量(p0.05),其中猪炭和烟秆炭处理下烤烟叶片干质量较CK分别提高了58.07%和47.01%。另外,在施用竹炭、猪炭和烟秆炭后,烤烟叶片中烟碱、总氮、还原糖和钾均处于优质烟叶适宜范围内。猪炭处理还可以显著提高烟叶氯含量(p0.05),并使烤后烟叶糖碱比和氮碱比达到优质烟叶标准。综上所述,在各类生物质炭中,施用猪炭和烟秆炭对于改善植烟土壤理化性质和养分状况、提高烤烟产量和品质的效果较好。     

YIELD,FRUIT QUALITY AND NITROGEN UPTAKE OF ORGANICALLY AND CONVENTIONALLY GROWN MUSKMELON WITH DIFFERENT INPUTS OF NITROGEN,PHOSPHORUS, AND POTASSIUM

The effects of varied amounts of fertilization on yield, fruit quality, and nitrogen (N) uptake of muskmelons (Cucumis melo L. var reticulatus Naud) grown under both organic and conventional farming conditions were evaluated. Organic fertilizer (0.0, 0.55, 1.1, and 2.2 kg m^?2) and mineral fertilizers containing the same amounts of estimated plant available nutrients [N, phosphorus (P), and potassium (K)] were applied to organic and conventional farming plots, respectively, in both the spring and autumn seasons of 2005. In comparison to conventional farming conditions, muskmelons grown under organic farming conditions had the same yield, total soluble solids (TSS) and soluble sugar contents in both growing seasons, and fruit pulp nitrate content was significantly reduced by 12% on average in spring and 16% on average in autumn. At harvest maturity the aboveground plant N concentration was significantly higher in the conventional treatments than in the organic treatments. At the vine growth stage, the plant N concentrations were similar in all treatments in both seasons. The ratios of nitrate N to total N amount in aboveground biomass were higher in conventional and high fertilized organic treatments than in low or not fertilized organic treatments under limited N supply from the soil. Muskmelon plants absorbed mainly inorganic N, and the protein N fraction in the xylem sap was larger than the amino acid N fraction. Plants grown in the organic system had a higher proportion of organic N in their xylem sap, especially when manure input was low.     

腾格里沙漠边缘区植被恢复与土壤养分变化研究

为了研究腾格里沙漠东缘植被恢复过程中不同阶段土壤养分和pH值的变化,在研究区从东向西分别采集6种植被恢复阶段的土壤,分别测定了其pH值、有机质和全效速效养分含量。结果表明,沙丘固定过程中,土壤有机质和全氮含量都呈逐渐增加趋势,分别从1.32和0.025g/kg增加到1.89和0.061g/kg,均达到了显著水平。半固定沙丘速效氮、速效钾含量均明显增加,发展为固定沙丘后由于大量植物的生长土壤速效氮、速效钾含量反而比半固定沙丘低。荒漠草原土壤中有机质、全氮及速效氮含量最高,退化草原速效磷含量比荒漠草原略高,差异不显著随退化荒漠草原恢复进程,人工梭梭林速效磷含量降低,速效钾总体呈显著增加趋势pH值以人工梭梭林较低。植被恢复过程中,沙生植被的存在对有机质和氮素的富集起着决定性作用,随着流沙固定和退化荒漠草原恢复,土壤有机质、氮和磷的含量增加,土壤有机质含量与土壤全氮、全磷和有效氮的含量呈较强的正相关关系。     

Effect of biofertilizers on the nutrient availability in soil in relation to growth,yield and yield attributes of Stevia rebaudiana

A field experiment was conducted at Rani Chandramma Agricultural University (Arabhavi, Belgaum), Karnataka, India, in basic soil to study the nutrient availability in soil, yield and yield attributes of the medicinal plant stevia (Stevia rebaudiana). The results showed that the availability of nutrients such as nitrogen (N), phosphorus (P) and potassium (K) in the soil increased up to the fifth month; and thereafter, decreased by the same amount with the progress of the plant growth up to the sixth month, irrespective of treatments. Results also showed that the fresh and dry biomass yields significantly increased up to the sixth month with different treatments, but the yield attributes like plant height and the number of branches were observed to be varied with various treatments, being highest in the combined application of biofertilizers over that of their corresponding sole applications.     

不同水肥处理对苕子和后茬玉米生长及土壤肥力的影响

在田间试验条件下,研究不同水肥处理对光叶紫花苕子(简称苕子)生长,及其翻压后对后茬玉米产量和土壤肥力的影响。结果表明,灌溉和施肥均显著促进苕子生长。在绿肥季,不论施肥与否,灌溉处理均可显著提高苕子的生物量、根系活力和N、P养分累积,NPW(绿肥季施氮磷肥和灌溉)和CKW处理(绿肥季不施肥,只进行灌溉处理)的苕子生物量、根系活力和N、P养分累积分别比相应的未灌溉处理提高34.58%和56.10%,26.49%和37.92%,43.47%和146.89%,103.84%和113.94%。苕子翻压的养分还田量为125.32～274.49kg/hm2,约占玉米季化肥总养分的26.95%～59.03%。与冬闲处理(CF)相比,不同施肥和灌溉处理的绿肥翻压均促进玉米产量和养分累积,以及土壤养分含量的提高,其中以NPW处理的提升效果最明显。周年等养分条件下,玉米季15.56%氮或50.00%磷肥料前移至绿肥季,可明显促进绿肥养分还田量的增加,后茬玉米产量(增幅为8.39%～31.19%)和养分累积量(增幅为7.31%～29.20%)也有不同程度的增加。综上,在适量灌溉和施肥条件下,苕子生物量明显增加,进而促进后茬玉米产量和养分累积量增加。研究结果可为我国绿肥农田应用及化肥减施提供数据支撑和实践依据。     

NUTRIENT AND GROWTH RESPONSES OF LEERSIA ORYZOIDES,RICE CUTGRASS,TO VARYING DEGREES OF SOIL SATURATION AND WATER NITROGEN CONCENTRATION

Leersia oryzoides (rice cutgrass) is an obligate wetland plant common to agricultural drainage ditches. The objective of this greenhouse study was to expose plants to various flooding and aqueous nitrogen (N) concentrations and then to quantify the allocation of nutrients and biomass to plant components. Plants in the continuously flooded treatment (CF) had the highest tissue concentrations of copper (Cu), sulfur (S), zinc (Zn), potassium (K), sodium (Na), and manganese (Mn) in one or more plant components. Plants in the partially flooded treatment (PF) had the highest concentrations of magnesium (Mg) in leaves. The N input affected phosphorus (P) and S concentrations in roots. Leaf, stem, and root biomass were highest in PF plants. Rhizome biomass was the lowest in CF plants. These results indicate that L. oryzoides may significantly affect elemental concentrations in surface waters by its ability to uptake various elements and subsequent sequestration in various biomass components.