Soil Nutrient and Fescue (Festuca spp.) Responses To Compost and Hydroseed on a Disturbed Roadside

Inadequate nutrients and poor soil quality pose challenges for turfgrass establishment on disturbed soils. Compost amendment has been shown to mitigate poor soil quality. This research was conducted to compare surface applications of compost to standard hydroseeding for improving soil chemical properties and turfgrass establishment. Plots established with either hydroseed or compost in spring 2007 were evaluated for soil pH, Mehlich-I extractable K, Mg, Zn, P, total N, organic C, and percent ground cover, fescue coverage and biomass production of tall (Festuca arundinacea Schreb.) and chewing's fescue [Festuca rubra L. ssp. fallax (Thuill.) Nyman]. Two years after plot establishment, the compost treatment had significantly increased Mehlich-I extractable soil P, K and Zn. Phosphorus increased 566% in the compost soil but only 17% in the hydroseeded soil. Higher percentages of ground coverage were reported in the compost than the hydroseed treatments with coverage in treatments declining from 2008 to 2009. Although the surface additions of compost initially enhanced the establishment and growth of fescue, vegetation may be limited in the long run by soil conditions in the root zone and competing broadleaf weeds.     

Mycorrhizal colonization is compatible with exponential fertilization to improve tree seedling quality

This study tested the ability of exponential fertilization to minimize the tradeoff of increased seedling size and nutrient concentration with good root colonization by mycorrhizae. Two native Hawaiian tree species were tested. Four rates of nitrogen (N) (0–3 g per seedling) were delivered by the method of exponential fertilization to seedlings with and without inoculation with a native strain of arbuscular mycorrhizal fungus. For both species, the highest growth and nutrient concentrations occurred with mycorrhizal colonization at 1–2 g N per seedling. Growth of inoculated seedlings was significantly lower at 3.0 g N per seedling, likely due to a large reduction in mycorrhizal colonization. Our results demonstrate that mycorrhizal colonization is not only compatible with exponential fertilization, combined they produce larger seedlings with higher nutrient content. This should improve outplanting success in degraded or challenging sites.     

EFFECTS OF NITROGEN APPLICATION TIMING ON GROWTH AND QUALITY OF A TURFGRASS MIXTURE

A 3-year field study was conducted to determine the influence of nitrogen (N) application timing on the growth and quality of a turfgrass mixture consisting of perennial ryegrass (Lolium perenne L.), Kentucky bluegrass (Poa pratensis L.), creeping red fescue (Festuca rubra var. rubra L.), and chewings fescue (Festuca rubra var. commutata Gaud.) under irrigated conditions. Nitrogen was applied annually at the rate of 30 g m^?2 year^?1, with six application regimes: control (no N), single spring (30 g m^?2), single fall (30 g m^?2), spring + fall (15 + 15 g m^?2), spring + summer + fall (10 + 10 + 10 g m^?2), and monthly from April through September (5 g m^?2).

Color, turf quality, clipping weights, and shoot density were correlated with fertilizer rates and application timing in this study. Fertilization monthly or every 2 months resulted in more uniform color and turf quality and less clipping weights than with comparable heavy spring and fall fertilizations. Heavy N applications in the fall did not cause winter injury and produced significantly darker color and more uniform appearance in early spring than other N applications. All N-fertilization regimes increased shoot density, but spring fertilization stimulated density the most. Nitrogen applied monthly or every 2 months was enough to enhance the color, turf quality, and shoot density of the turf during the growing season but did not greatly affect the growth rate.     

施肥推进了玉米生长及N缺乏的定量研究

Evidence that nitrogen （N） fertilization tends to accelerate maturation as well as increase rates of growth has received little attention when diagnosing N deficiencies in corn （Zea mays L.）. Such a tendency could be a potential source of errors when the diagnosis is solely based on comparing plants with different rates of growth. Whether N fertilization could accelerate rates of growth and maturation was tested in a field study with 12 paired plots representing relatively large variability in soil properties and landscape positions. The plots were located under conditions where preplant N fertilization reduced or avoided temporary N shortages for some plants but did not reduce for other plants early in the season. We measured corn heights to the youngest leaf collar, stages of growth and chlorophyll meter readings （CMRs）. The added N advanced growth stages as well as increased corn heights and CMRs at any given time. Fertilization effects on corn heights, growth stages and ear weights were statistically significant （P 〈 0.05） despite substantial variability associated with landscape. Reductions in growth due to a temporary shortage of N within a growth stage might be partially offset by longer periods of growth within that stage to physiological maturity. Temporary shortages of N, therefore, may produce symptoms of N deficiency in situations where subsequent additions of N should not be expected to increase yields. Recognition of these two somewhat different effects （i.e., increase growth rates and advance growth stages） on corn growth could help to define N deficiency more precisely and to improve the accuracy of diagnosing N status in production agriculture.     

短期NaHCO3胁迫对3种冷季型草坪草生理生态特征的影响

土壤盐渍化严重威胁草坪草的可持续发展,选育和种植耐盐草坪草可改良和利用大面积盐渍土壤。以3种冷季型草坪草黑麦草(Lolium perenne L.)、高羊茅(Festuca arundinacea L.)和早熟禾(Poa pratensis L.)为试验材料,采用盆栽法研究不同浓度NaHCO3胁迫(0,0.2%,0.4%,0.6%,0.8%,1.0%)对3种冷季型草坪草生理生态特征的影响。结果表明:不同浓度NaHCO3胁迫下3种冷季型草坪草草坪外观质量、叶片萎蔫系数、叶片相对含水量、叶片叶绿素含量和K+含量均随着NaHCO3浓度的增加而逐渐降低,且浓度越高,下降越明显;0.4%～1.0%NaHCO3胁迫降低了3种冷季型草坪草的地上部分和根系干重,且随着NaHCO3浓度的增加,生长受到胁迫的抑制程度显著增大,根系部分的受抑制程度比地上部分更明显;不同浓度NaHCO3胁迫下3种冷季型草坪草叶片相对电导率、脯氨酸含量、丙二醛含量和Na+含量随着NaHCO3胁迫浓度的升高呈上升趋势,且浓度越高上升越明显;NaHCO3浓度0.4%时,3种冷季型草坪草已受到伤害;黑麦草、高羊茅和早熟禾在不同浓度NaHCO3胁迫下的隶属函数平均值均表现为早熟禾黑麦草高羊茅,说明3种冷季型草坪草抗NaHCO3胁迫的能力均为早熟禾强于黑麦草和高羊茅。     

Growth and nitrogen uptake of jack pine seedlings in response to exponential fertilization and weed control in reclaimed soil

We evaluated the impact of exponential fertilization in nursery and weed removal in the field on growth and nitrogen (N) retranslocation and uptake from the soil of jack pine (Pinus banksiana Lamb.) seedlings planted on an oil sands reclaimed soil. Exponential fertilization is a method of supplying nutrients at an exponential rate to achieve constant internal nutrient concentrations in seedlings without changing their size during their growth in the nursery. The N retranslocation in seedlings was traced using ¹⁵N isotope labeling. Exponential fertilization increased nutrient reserve in the seedling in nursery production, and increased height (P = 0.003), root collar diameter (P < 0.001), total biomass (P < 0.001), and N content (P < 0.001) of seedlings at the end of first growing season in the field growth. Conventionally fertilized seedlings allocated a greater percent of biomass to roots than to current-year needles. The ¹⁵N isotope analysis showed that 59 to 82% of total N demand of new growth was met by retranslocation from old tissues. Exponential fertilization increased N retranslocation by 147% (P < 0.001) and N uptake from the soil by 175% (P = 0.012). Weed removal marginally increased (P = 0.077) N uptake from the soil but decreased (P = 0.046) N retranslocation with no net effect on total N content in new tissues. We conclude that exponential fertilization improves the early growth of jack pine and can help improve revegetation in reclaiming disturbed oil sands sites.     

Modelling Spring Growth of Timothy and Meadow Fescue by an Expolinear Growth Equation

The applicability of an expolinear growth equation for describing dry matter yield was investigated in seven field experiments for spring growth of timothy (Phleum pratense L.) and meadow fescue (Festuca pratensis Huds.) under two levels of N application. The equation was expanded by a growth index (GI) correcting for variations in radiation, temperature and plant-available soil moisture, and an ageing function describing the decrease in growth rate caused by advance in phenological development. The field sites covered a wide range of climatic conditions and the yield was recorded at five phenological stages from leaf stage to anthesis. The expansion of the equation appeared to be adequate for a combined analysis of the dry matter yield in meadow fescue and timothy. The estimated maximum growth rate during the linear phase (C _m) did not differ significantly between species. C _m increased with higher N application. It was concluded that C _m of the expanded model represented a potential rate, whereas the relative growth rate of the exponential phase (R _m) could not be considered as a potential rate. It varied more among locations and years, e.g. it was strongly affected by the length of the period from growth onset to the start of the linear phase.     

不同控水时段根区局部灌溉对玉米生理和水分利用效率的影响

【目的】根区局部灌溉(PRI)是一种节水灌溉方法,包括分根区交替灌溉(AI)和固定部分根区灌溉或称部分根区干燥灌溉(PRD),其中PRD技术是在作物生育时期一半根区总不灌水,另一半根区充分灌水,AI技术则是在作物生育期内根据生育时期和土壤水分情况交替对根系两侧进行灌水。本文研究在不同施肥条件下,拔节前期至抽雄期不同时段采用PRI对玉米生理指标、 干物质积累和水分利用效率(WUE)的影响,以期为玉米合理灌溉和施肥提供依据。【方法】采用盆栽方法,设3种灌溉方式为常规灌溉(每次对盆内全部土壤均匀灌水)、 分根区交替灌溉(每次交替对盆内1/2区域土壤灌水)和固定部分根区灌溉(每次固定对盆内1/2区域土壤灌水);2种灌水量为正常灌水(70%~80%f,f为田间持水量)和轻度亏水(60%~70%f); 2种施肥处理为100%化肥氮、 80%化肥氮+20%有机氮。在拔节期至抽雄期进行12 d、 24 d和36 d根区局部控水灌溉处理。分别测定玉米的光合速率、 气孔导度、 叶绿素、 类胡萝卜素、 可溶性糖和脯氨酸含量,总干物质量、 耗水量和水分利用效率。【结果】不同灌溉方式、 灌水水平和有机无机氮比例处理对拔节中期、 拔节末期和抽雄期玉米光合速率、 气孔导度、 类胡萝卜素含量、 叶绿素含量和可溶性糖含量的影响不显著,灌水量对抽雄期脯氨酸含量的影响也不显著,表明控水持续时间长短,根区局部灌溉、 轻度亏水和有机无机氮配施不会显著影响玉米生理指标。与常规灌溉相比,拔节前期至抽雄期3个控水时段根区局部灌溉对玉米总干物质量和水分利用效率的影响虽不显著,但是显著降低了玉米耗水量,在正常灌水量和单施化肥氮条件下,拔节末期控水24 d和抽雄期控水36 d,根区局部灌溉可分别提高水分利用率24.4%和16.3%。此外,轻度亏水、 有机无机氮肥配施(80%化肥氮+20%有机氮)对玉米生理指标、 总干物质量和水分利用率的影响也不显著。【结论】在正常灌水量和单施化肥氮条件下,在拔节期至抽雄期进行根区局部灌溉可显著降低玉米耗水量,而对玉米生理指标和总干物质量无明显影响,因而显著提高玉米水分利用效率。     

The effects of volcanic ash influenced soils and nitrogen fertilization on douglas‐fir seedlings

Abstract

An experiment was conducted to help understand the contributions of different soil layers to soil fertility, plant growth, and response to fertilization. Douglas‐fir (Pseudotsuga menziesii) seedlings were used in a pot bioassay to delimit the effects of volcanic ash soils, urea fertilization at 100 and 200 ppm, and the technique of using undisturbed soil as a growth medium. Volcanic ash horizons contained more available phosphorus and mineralized more nitrogen than underlying horizons. Best seedling growth occurred in ash horizons fertilized with 200 ppm of urea‐N. Fertilization decreased soil pH, mycorrhizae formation and foliar‐P levels but increased foliar‐N. The technique of using undisturbed soil had little effect on seedling growth in the weak structured ash horizons but did decrease root weights in the moderate structured sub‐ash layers.     

Growth and nutrient uptake dynamics of Mytilaria laosensis seedlings under exponential and conventional fertilizations

The growth characteristics and nutrient uptake dynamics of Mytilaria laosensis Lec. seedlings treated weekly with conventional and exponential fertilizations were investigated at intervals of 3 weeks for 12 weeks in a greenhouse. Leaf area and pigment compositions were also examined at the final harvest. The fertility treatments (mg nitrogen seedling^–1) included two conventional (50C and 100C) and four exponential (50E, 100E, 200E and 400E) fertilizations, and no fertilization (0) as control. The biomass and nutrient contents of M. laosensis seedlings increased exponentially with time. Steady-state nutrition of nitrogen (N) and phosphorus (P) were achieved under exponential fertilization treatment of 50?mg?N?seedling^?1 (50E) and conventional fertilization treatment of 100?mg?N?seedling^–1 (100C), resulting from simultaneous increase of their biomass and nutrient contents. The nutrient uptake efficiency continuously increased over time in conventionally fertilized seedlings, but it increased initially and declined or remained stable from 11 weeks after transplanting in the exponentially fertilized seedlings. At the end of the experiment, the conventionally fertilized seedlings performed remarkably better than all exponentially fertilized seedlings except for seedlings in the exponential treatment of 200?mg?N?seedling^–1 (200E) in height, root collar diameter and biomass. The optimum N and P uptake occurred in 200E seedlings because their N and P contents were 71%/60% and 14%/9% higher than both conventionally fertilized seedlings (50C/100C) without significant differences in growth performance between them. The leaf areas and chlorophyll contents of seedlings increased significantly with the increase of fertilizer levels and nearly peaked at the range from 100 to 200?mg?N?seedling^–1, whereas the delivery schedule (conventional and exponential) had little effect on leaf areas and chlorophyll contents of seedlings at the same nutrient level (50 or 100?mg?N?seedling^–1). These findings will provide evidence to make guidelines on fertilization for nursery production of M. laosensis, and help understand the nutrient demands for this species and further benefit the development of its plantations.     

Seasonal variations in nutrient and carbohydrate levels of tall fescue cultivars in Japan

Quality (color and density) of tall fescue (Festuca arundinacea Schreb.) as a turfgrass is reduced during both the winter and summer in Japan. Seasonal variations in nutrient and carbohydrate levels of six cultivars of tall fescue were measured to determine if these changes are related to the reduction in the turf quality. There were significant differences among the cultivars in nutrient and carbohydrate levels. The nutrient and carbohydrate levels of tall fescue cultivars changed seasonally. Levels of calcium (Ca) and zinc (Zn) were below the sufficiency, but the concentrations of other nutrients were sufficient during the summer suggesting that the reduction in the quality of tall fescue cultivars during the summer in Japan may not be related to the lack of these nutrients in the plant tissues. The nitrogen (N), Ca, magnesium (Mg), phosphorus (P), Zn, iron (Fe), and copper (Cu) levels in the plant tissues were below the adequate range in the spring which could be attributed to high growth rate since no deficiency symptom was observed. With exception of Ca content, plants contained sufficient or more than sufficient nutrients in their tissues during the fall. Though concentrations of other nutrients were sufficient in the plant tissues in the winter, levels of N, Ca, Mg, P, molybdenum (Mo), Zn, and Cu were lower than plant's requirement which could be due to low temperature since availability of the nutrients reduces under low temperature. There were no deficiency symptoms of these nutrients, but lack of N in the plant tissue could be the cause of the reduction in the color of the tall fescue cultivare in winter. Levels of glucose, fructose, sucrose, fructan, and starch in the summer were higher or equal to those carbohydrate levels in the spring or fall suggesting that decline in tall fescue quality in Japan during the summer may not be related to carbohydrates shortages. Though starch levels were lower in the winter than other seasons, other carbohydrate levels were equal or higher than the levels in the spring and the total carbohydrate content was much higher in the winter than other seasons, suggesting that reduction in tall fescue quality in Japan during the winter may not be related to carbohydrates shortages.     

施肥深度对大豆氮磷钾吸收及产量的影响

采用分层施肥和15N示踪方法,研究施肥深度对大豆氮磷钾吸收及产量的影响,为大豆合理施肥深度的确定提供理论依据。研究表明,施肥深度对大豆前、中期植株干物质、氮磷钾的积累影响较大,而对植株成熟期影响较小;大豆苗期(V3)与种子同层施肥处理植株干物质和氮磷钾的积累量最大;盛花期(R2)以种下6cm处理效果最明显。施肥深度对大豆产量的影响也表现为种下6cm处理最高,但与种子同层施肥、种下12、18和24cm施肥处理差异不显著;施于种子同层至种下6cm最有利于大豆苗期氮肥吸收,表层施肥、种下24cm施肥处理氮肥吸收效果不好。     

Seasonal variations of soil microbial biomass and activity in warm- and cool-season turfgrass systems

Plant growth can be an important factor regulating seasonal variations of soil microbial biomass and activity. We investigated soil microbial biomass, microbial respiration, net N mineralization, and soil enzyme activity in turfgrass systems of three cool-season species (tall fescue, Festuca arundinacea Schreb., Kentucky bluegrass, Poa pratensis L., and creeping bentgrass, Agrostis palustris L.) and three warm-season species (centipedegrass, Eremochloa ophiuroides (Munro.) Hack, zoysiagrass, Zoysia japonica Steud, and bermudagrass, Cynodon dactylon (L.) Pers.). Microbial biomass and respiration were higher in warm- than the cool-season turfgrass systems, but net N mineralization was generally lower in warm-season turfgrass systems. Soil microbial biomass C and N varied seasonally, being lower in September and higher in May and December, independent of turfgrass physiological types. Seasonal variations in microbial respiration, net N mineralization, and cellulase activity were also similar between warm- and cool-season turfgrass systems. The lower microbial biomass and activity in September were associated with lower soil available N, possibly caused by turfgrass competition for this resource. Microbial biomass and activity (i.e., microbial respiration and net N mineralization determined in a laboratory incubation experiment) increased in soil samples collected during late fall and winter when turfgrasses grew slowly and their competition for soil N was weak. These results suggest that N availability rather than climate is the primary determinant of seasonal dynamics of soil microbial biomass and activity in turfgrass systems, located in the humid and warm region.     

The role of tree leaf mulch and nitrogen fertilizer on turfgrass soil quality

 The influence of tree leaf amendment and N fertilization on soil quality in turfgrass environments was evaluated. Our objective was to assess changes in soil quality after additions of leaf materials and N fertilization by monitoring soil chemical and physical parameters, microbial biomass and soil enzymes. Established perennial ryegrass (Lolium perenne) plots were amended annually with maple (Acer spp.) leaves at three different rates (0, 2240, and 4480 kg ha^–1 year^–1) and treated with three nitrogen rates (0, 63, and 126 kg N ha^–1 year^–1). Tree leaf mulching did not significantly affect water infiltration or bulk density. However, trends in the data suggest increased infiltration with increasing leaf application rate. Tree leaf mulching increased total soil C and N at 0–1.3 cm depth but not at 1.3–9.0 cm. Extracted microbial phospholipid, an indicator of microbial biomass size, ranged from 28 to 68 nmol phospholipid g^–1 soil at the 1.3–9.0 cm depth. The activity of β-glucosidase estimated on samples from 0–1.3 cm and 1.3–9.0 cm depths, and dehydrogenase activity estimated on samples from 1.3–9.0 cm were significantly increased by leaf mulching and N fertilizer application. Changes in microbial community composition, as indicated by phospholipid fatty acid methyl ester analysis, appear to be due to seasonal variations and did not reflect changes due to N or leaf amendment treatments. There were no negative effects of tree leaf mulching into turfgrass and early data suggest this practice will improve soil chemical, physical, and biological structure. Received: 10 December 1997     

Effects of White Clover Inclusion on Turf Characteristics,Nitrogen Fixation,and Nitrogen Transfer from White Clover to Grass Species in Turf Mixtures

Abstract

An irrigated field trial was conducted to test the effects of white clover in three turfgrass species (perennial ryegrass, Kentucky bluegrass, and creeping bentgrass) on color, clipping yield, and botanical composition and to estimate nitrogen (N)₂ fixation and N transfer from white clover to associated turfgrass species under different N‐fertilization conditions in 1999–2002.

Nitrogen fertilizers significantly increased color ratings in all observations. Grass–white clover mixtures had better color ratings than pure grass at all sampling dates and seasonal averages in unfertilized conditions. Fertilized pure grass plots yielded significantly more than control plots in all turfgrass species. Nitrogen fertilization did not affect clipping yield greatly in turfgrass–white clover mixtures. Nitrogen application significantly decreased white clover percentage in the harvested clippings in second and third year.

Nitrogen fertilization increased tissue N concentration positively in all turfgrass species grown alone. In contrast, N fertilization did not greatly affect tissue N concentration of either turfgrass species or white clover in the mixtures. Nitrogen fixation of white clover was estimated as 24.6, 30.7, and 33.8 g m^?2 year^?1 in perennial ryegrass, Kentucky bluegrass, and creeping bentgrass, respectively. The total estimated N₂ fixation gradually decreased with increasing N fertilization. Nitrogen transfer from white clover to the associated turfgrass varied from 4.2 to 13.7% of the total N that the white clover fixed annually.     

育秧期钵盘施用全量控释肥显著降低稻田氮素损失风险

[目的]研究将全量控释氮肥由常规育秧大田施肥改为育秧钵盘中施用后,水稻产量及田面水氮素含量动态变化,为提高氮肥利用率、控制稻田的氮素流失提供理论依据.[方法]田间试验在湖北省安陆市车站村进行,供试水稻品种为'华夏香丝'.试验设常规育秧+大田不施肥(CK)、常规育秧+大田常规施肥(FF)、钵盘育秧全量施肥(PF)?3个处...     

Crop yield—nitrate‐n and total n and k concentration relationships: Corn and fescuegrass

Abstract

Six greenhouse pot experiments were conducted in which yield and nutrient uptake responses of corn (Zea mays L.) or tall fescue (Festuca arundinacea Shreb) to N, P, K, lime, or temperature variables were measured. This paper describes yield—NO₃‐N and total N concentration trends in these experiments. Crop concentrations of total N and NO₃‐N during early growth increased consistently with amount of applied N. These concentrations usually decreased (by dilution and assimilation) with time of growth and yield response to other growth‐limiting nutrients and other factors. Concentrations of K also increased in corn with amount of applied K, and high K was associated with higher concentrations of NO₃‐N during early growth in some experiments. This was usually true only for early crop growth periods during which rates of nutrient uptake exceeded growth rate. High K concentrations may have retarded growth and NO₃‐N reduction and assimilation.     

Correlation between Solvita Labile Amino-Nitrogen and CO2-Burst Soil Health Tests and Response to Organic Fertilizer in a Turfgrass Soil

ABSTRACT

The Solvita Soil Labile Amino-Nitrogen (SLAN) and Soil CO₂-Burst (SSCB) tests are used in soil health assessments. Field experiments were conducted from 2014–2016 in Connecticut, USA to: (1) determine if SLAN and SSCB concentrations are correlated for a sandy loam soil under predominately Kentucky bluegrass (Poa pratensis L.) and tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] turfgrass lawns, and (2) compare the response of SSCB–C and SLAN–N concentrations in relation to varying rates of an organic fertilizer. Concentrations of SLAN–N were positively and significantly (P < .001) correlated with concentrations of SSCB–C for all years, both species, and combinations of years and species (r = 0.477 to 0.754). The response of SSCB–C and SLAN–N concentrations to organic fertilizer rates were positively linear and significant (P < .01) in all cases but one (2014 tall fescue SSCB–C concentrations). Rates of change across fertilizer rates were generally greater for SLAN–N concentrations. There was greater variation within the SSCB test than within the SLAN test. The results suggest that the SLAN and SSCB tests are well-correlated and both may be able to provide an estimate of a turfgrass soil’s N mineralization potential.     

重金属Cu、Zn在施入畜禽粪的菜园土中的淋溶研究

The leaching characteristics of a garden soil may be greatly affected by application of poultry and livestock manures from intensive farming. Packed soil columns of a garden soil （CK） and the soils after respectively receiving 2% pig manure （PM）, chicken manure （CM）, and commercial organic manure （OM） were leached with 0.05 mol L^-1 Ca（NO3）2 and 0.01 mol L 1 EDTA solutions. The leachate EC （electric conductivity） values gradually increased at the beginning and then reached a stable value when the soil columns were leached with 0.05 mol L^-1 Ca（NO3）2 solution. The leachate EC values showed a peak-shape when leached with 0.01 mol L^-1 EDTA solution. In all the soil columns, the pH values of the leachates decreased with increase of displacement volumes when the Ca（NO3）2 solution was used. The total amounts of Cu and Zn eluted from the four soil columns were significantly correlated with the extracted soil Cu and Zn concentrations by 1.0 mol L^-1 NH4NO3, but were not correlated with the leachate dissolved organic carbon （DOC） contents. The Zn concentration in the leachate of the PM-treated soil column with 0.05 mol L^-1 Ca（NO3）2 solution was above the Quality Standard III for Ground Water of China （GB/T 14848-93, Zn 〈 1.0 mg L^-1）. When compared with 0.05 mol L^-1 Ca（NO3）2, the EDTA solution significantly accelerated Cu and Zn elutions in the manure-treated columns. This suggested that applying poultry and livestock manures from intensive farming to farmland might pose a threat to the groundwater quality.     

施肥模式对连作菊花生长状况及产量的影响

长期连作以及大量化肥尤其是化学氮肥的投入导致农作物连作障碍严重,中药材也面临同样的困境。为寻找一种绿色无污染、环境友好、可持续的防控连障方法,我们在连作药用菊花十余年的田块进行小区试验,设置当地施肥育苗（D）和优化施肥育苗（T）2种育苗;当地施肥（CK）、优化施肥+减氮20%（T1）,优化施肥+减氮40%（T2）3种施肥,共6个处理,研究减氮配合优化施肥种类对连作药用菊花生长状况及产量的影响。试验结果显示：①T育苗植株地上部生物量、株高、分枝数、叶面积优于D育苗,TCK处理地上部生物量、分枝数分别是DCK的2.26倍和3.5倍,差异显著;DCK与DT1处理植株地上部生物量、株高、分枝数和现花蕾期叶面积差异均不显著。②T育苗各个施肥处理的菊花单株花蕾数高于D育苗相应施肥处理,在CK施肥处理差异极显著,T1 施肥处理中差异显著,DCK与TT2 处理的花蕾数无显著性差异;单株产量和花蕾比均以T育苗较高但不显著。③小区产量以T育苗和优化施肥的处理较高,TT1处理小区产量是DCK的1.88倍,差异极显著。优化施肥模式提高了药用菊花株高、分枝数以及现蕾花期叶面积,改善了连作菊花的生长状况,从而提高了地上部生物量;优化施肥模式有增加花数、提高开花整齐度的趋势,从而提高产量,优化施肥模式可弥补减氮的影响;优化施肥在育苗阶段的效果优于生长阶段。