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1.
This study was conducted during 1992–1994 under semi-arid conditions in Burkina Faso. Our aim was to assess the influence of different mulch materials on soil variables affecting crop growth; i.e. water content, nutrient contents and temperature. The grain yield of Sorghum bicolor was used as a bioindicator, i.e. as an integrated measure of mulch effects.Six treatments were tested, two of which were leaf mulches of special interest for agroforestry. The treatments were chosen to represent mulch materials differing in nutrient content and decomposability (assumed to influence the duration of the impact on soil water content and temperature). The treatments were as follows: (1) control (no addition), (2) Azadirachta indica (neem) leaves, (3) neem leaves + aerobic compost of sorghum straw, (4) aerobic compost, (5) Acacia holocericea (acacia) phyllodes, and (6) wild grass. The mulching rate was 5 t dry matter ha-1, and base mineral fertilizers were applied to all plots.It was shown that the neem leaves, neem leaves + compost, wild grass and acacia phyllodes treatments all significantly influenced the soil by conserving water and reducing temperatures compared with the control or the treatment with compost alone. Plots treated with either neem leaves, neem leaves + compost or compost alone gave higher yields than the three other treatments, generally poorer in nutrients, between which there was little difference. Neem leaves gave the numerically highest response: 1.54 × control, corresponding to a grain yield increase of 554 kg dry mass ha-1 yr-1 when averaged over the three years of study.Thus, yields did not always increase in spite of increased soil moisture and decreased soil temperatures. It was concluded that nutrients were more limiting than water or high soil temperatures under the conditions studied. The highest yields were achieved with a mulch that combines high nutrient delivery with water conservation and temperature reduction, namely mulch from neem leaves. 相似文献
2.
Tesfay Teklay 《Plant and Soil》2004,267(1-2):297-307
Foliar inputs from indigenous agroforestry trees and shrubs could provide sufficient nutrients and organic matter to sustain
crop growth. However, concentrations of foliar nutrients and organic constituents show considerable seasonal, inter- and/or
intra-species variations. To determine this variability, green and senesced leaves were sampled during dry and wet seasons
from Cordia africana, Albizia gummifera and Milletia ferruginea trees at Wondo Genet, southern Ethiopia. Cordia is a deciduous, non-leguminous tree, while Albizia and Milletia are semi-deciduous and leguminous trees. Leaves were analyzed for concentrations of ash, N, P, K, cellulose, lignin, soluble
polyphenols, and condensed tannins. Results from statistical analyses showed significant seasonal variations (P < 0.001) in concentrations of all leaf constituents, except for P and cellulose. Foliar concentrations of ash, N, soluble
polyphenols, and condensed tannins were higher during the wet season while those of K and lignin were higher during the dry
season. Green leaves had significantly higher (p < 0.001) N and P concentrations than senesced leaves, while senesced leaves had higher concentrations of K, cellulose, soluble
polyphenols, and condensed tannins. The ‘ Relative Percentage Changes’ in concentration of N and P in senesced leaves, i.e.,
their enrichment or depletion with such nutrients relative to those in green leaves, were significantly higher (P < 0.001) for Cordia than Albizia and Milletia. On the other hand, there was no consistent pattern in the enrichment or depletion of senesced leaves with organic constituents,
but these leaves were in most cases more enriched with organic constituents than green leaves. Over all, the percentage depletion
or enrichment ranged from about 8% to 38% for N; 24% to 63% for P; −141% to 48% for K; −44% to 15% for cellulose; −44% to
51% for lignin; −203% to −61% for soluble polyphenols; and −290% to 11% for condensed tannins. It was concluded that variations
in species and life-form (legume versus non-legume), season, and developmental stage of leaves could affect the quality of
organic material from agroforestry species, which has important implications for management of organic residues in tropical
agricultural systems. 相似文献
3.
We investigated the effect of leaf litter on below ground carbon export and soil carbon formation in order to understand how litter diversity affects carbon cycling in forest ecosystems. 13C labeled and unlabeled leaf litter of beech (Fagus sylvatica) and ash (Fraxinus excelsior), characterized by low and high decomposability, were used in a litter exchange experiment in the Hainich National Park (Thuringia, Germany). Litter was added in pure and mixed treatments with either beech or ash labeled with 13C. We collected soil water in 5 cm mineral soil depth below each treatment biweekly and determined dissolved organic carbon (DOC), δ13C values and anion contents. In addition, we measured carbon concentrations and δ13C values in the organic and mineral soil (collected in 1 cm increments) up to 5 cm soil depth at the end of the experiment. Litter-derived C contributes less than 1% to dissolved organic matter (DOM) collected in 5 cm mineral soil depth. Better decomposable ash litter released significantly more (0.50±0.17%) litter carbon than beech litter (0.17±0.07%). All soil layers held in total around 30% of litter-derived carbon, indicating the large retention potential of litter-derived C in the top soil. Interestingly, in mixed (ash and beech litter) treatments we did not find a higher contribution of better decomposable ash-derived carbon in DOM, O horizon or mineral soil. This suggest that the known selective decomposition of better decomposable litter by soil fauna has no or only minor effects on the release and formation of litter-derived DOM and soil organic matter. Overall our experiment showed that 1) litter-derived carbon is of low importance for dissolved organic carbon release and 2) litter of higher decomposability is faster decomposed, but litter diversity does not influence the carbon flow. 相似文献
4.
Soil water, nutrient availability and sapling survival
under organic and polyethylene mulch in a seasonally dry tropical forest 总被引:1,自引:0,他引:1
We examine the effect of mulches on the soil volumetric water content (SVWC), pH, carbon (C), total and mineral (NH4 and NO3) nitrogen (N), total and bicarbonate phosphorus (P), and on the survival and relative growth rate of three species, Ipomea wolcottiana Rose, Lonchocarpus eriocarinalis Micheli and Caesalpinia eriostachys Benth, in a degraded seasonally dry tropical forest (SDTF) area. Our study year was unusually dry, with only half of the mean annual rainfall. Sixteen plots (5 × 6 m) for each of our four treatments, mulches with alfalfa (Medicago sativa L.) straw, forest litter (SDTF litter), polyethylene and bare soil (control), were used. In each plot, 20 tree saplings were planted of each species. The SVWC was higher in plots mulched with polyethylene than in bare soil plots. The soil pH did not change with mulching, and there were no differences between treatments in the concentrations of soil organic C, total N, NO3 and total P. However, soil concentrations of NH4 were highest in plots with alfalfa straw and of bicarbonate P in plots with polyethylene. Sapling survival was higher in polyethylene mulch plots than in other mulching treatments, in the order I.␣wolcottiana > C. eriostachys > L. eriocarinalis. Sapling survival under organic mulches, alfalfa straw and forest litter were similar, and lowest in bare soil. The relative growth rate followed the order L. eriocarinalis < C. eriostachys < I. wolcotiana, and the growth rate of all species was greatest under polyethylene mulch. We conclude that a combination of polyethylene mulch with species of high growth rate is best for restoring seasonally dry tropical areas. 相似文献
5.
It is well known that surface mulched crop residues (CR) lead to large yield increases of pearl millet (Pennisetum glaucum
L.) on acid sandy soils of the West African Sahel. This effect is generally attributed to mulch-induced changes in chemical
properties of the surface soil and the protection of millet seedlings from erosive sand storms. However, previous research
has failed to separate the anti-erosive effects of CR on plant growth from chemical effects due to the release of nutrients
during CR decomposition. To this end a mulching trial with surface applied millet stalks at a rate of 2000 kg ha-1, an equivalent 10% surface coverage obtained by inert polyethylene (PE) tubes and a bare control treatment was conducted
from 1992 to 1994 on an acid sandy soil in southwest Niger. Across treatments, sand flux at 0.1 m height was more than twice
as high in the rainy seasons than in the dry months and mulching reduced sand flux by between 25 and 50% during rainy season
storms compared with 67% during the dry season. Over the 21 months measurement period, cumulative erosion by wind and water
was almost 270 t ha-1 of soil in unmulched control plots. In mulched plots, in contrast, between 160 and 200 t ha-1 of soil was deposited. Surface soil temperature at 0.01 m depth reached above 40 °C in bare plots but was up to 4 °C lower
with CR. Mulch reduced soil penetration resistance at 0–0.02 m and 0–0.05 depth by more than half and decreased runoff leading
to higher water contents at flowering and grain filling in the upper 0.3 m soil layers in 1993 and throughout the entire profile
in 1994, a year with particularly high rainfall. Both mulch types were similarly effective in increasing final stand density
of millet in the first two years between 5 and 23% compared with bare control plots. Relative to the bare control CR mulch
effects on total dry matter of millet at harvest increased from 35% in 1992 and 108% in 1993 to 283% in 1994, whereas PE mulch
led to respective relative increases in dry matter of only 6, 44 and 13%. In 1992 and 1993, CR mulch increased total nutrient
uptake of millet at harvest by between 34 and 86% for nitrogen (N), between 31 and 162% for P and between 56 and 126% for
potassium (K). These differences were mostly the result of differences in total dry matter and only to a smaller part due
to changed nutrient concentrations in plants.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
Effects of Initial Site Treatments on Early Growth and Three-Year Survival of Idaho Fescue 总被引:2,自引:0,他引:2
KernEwing 《Restoration Ecology》2002,10(2):282-288
Prairies in the Pacific Northwest have been actively restored for over a decade. Competition from non‐native woody and herbaceous species has been presumed to be a major cause for the failure of restoration projects. In this research, plugs of the native prairie bunchgrass, Festuca idahoensis Elmer var. roemeri (Pavlick), were grown from seed in a nursery and transplanted into a grassland site dominated by non‐native pasture grasses. The growth of the plants was followed for three years, and biomass of all volunteer plants was measured. Before planting, five treatments were applied to the plots: removal of vegetation by burning, removal of vegetation by an herbicide‐and‐till procedure, soil impoverishment by removal of organic matter, fertilizer application, and compost mulch application. Initial growth of Idaho fescue plugs was greatest with fertilizer and compost mulch. Plants grown in mulched plots were also able to photosynthesize later into the dry summer season. After the first year, plots initially fertilized or composted had the lowest survival rate of Idaho fescue. Impoverished and herbicide‐and‐till plots had the greatest 3‐year survival. Mulched plots supported the greatest weed growth after three years. Stressful environments give a competitive advantage to Idaho fescue in prairie restoration projects. As weedy species increase, growth and survival of Idaho fescue decreases. 相似文献
7.
Abstract Sustained‐release fertilizer and two kinds of mulch treatments were tested to determine their effects on survival and growth of planted Chamaecyparis thyoides (Atlantic white cedar) on a sandy extremely nutrient‐deficient site. Height, basal trunk diameter, dry weight, and concentrations of nitrogen (N), phosphorus (P), and potassium (K) were measured for each treatment. After two growing seasons, survival was very high in untreated controls (mean, 86%) and was not significantly increased by any treatment (significance was assessed at p = 0.05 throughout this work). Stem height and cross‐sectional area doubled in unamended plots during the course of the study. Fresh mulch alone caused no additional increase in growth, compared with unamended plots. Decomposed mulch caused a slight but significant increase. Sustained‐release fertilizer caused significant increases in height (threefold) and dry weight (approximately sixfold). Combined treatment with fertilizer and mulch gave significantly greater growth responses than did other treatments, increasing heights 4‐ to 5‐fold, trunk cross‐sectional areas 4‐fold, and dry weights 11‐ to 21‐fold over no‐treatment controls. Tissue concentrations of N and P correlated with growth trends, with combinations of mulch and timed‐release fertilizer providing the highest values. Though statistically different, the two mulch treatments were similar in their effects on tissue nutrient concentrations. When combined with fertilizer, undecomposed mulch stimulated increases in height and dry weight significantly more than did decomposed mulch. Thus, establishment of C. thyoides on low‐nutrient sandy soils is improved by combined soil amendment with sustained‐release nutrients and organic mulch. 相似文献
8.
Long term effects of manure, charcoal and mineral fertilization on crop production and fertility on a highly weathered Central Amazonian upland soil 总被引:58,自引:0,他引:58
Christoph Steiner Wenceslau G. Teixeira Johannes Lehmann Thomas Nehls Jeferson Luis Vasconcelos de Macêdo Winfried E. H. Blum Wolfgang Zech 《Plant and Soil》2007,291(1-2):275-290
Application of organic fertilizers and charcoal increase nutrient stocks in the rooting zone of crops, reduce nutrient leaching
and thus improve crop production on acid and highly weathered tropical soils. In a field trial near Manaus (Brazil) 15 different
amendment combinations based on equal amounts of carbon (C) applied through chicken manure (CM), compost, charcoal, and forest
litter were tested during four cropping cycles with rice (Oryza sativa L.) and sorghum (Sorghum bicolor L.) in five replicates. CM amendments resulted in the highest (P < 0.05) cumulative crop yield (12.4 Mg ha−1) over four seasons. Most importantly, surface soil pH, phosphorus (P), calcium (Ca), and magnesium (Mg) were significantly
enhanced by CM. A single compost application produced fourfold more grain yield (P < 0.05) than plots mineral fertilized in split applications. Charcoal significantly improved plant growth and doubled grain
production if fertilized with NPK in comparison to the NPK-fertilizer without charcoal (P < 0.05). The higher yields caused a significantly greater nutrient export in charcoal-amended fields, but available nutrients
did not decrease to the same extent as on just mineral fertilized plots. Exchangeable soil aluminum (Al) was further reduced
if mineral fertilizer was applied with charcoal (from 4.7 to 0 mg kg−1). The resilience of soil organic matter (SOM) in charcoal amended plots (8 and 4% soil C loss, mineral fertilized or not
fertilized, respectively) indicates the refractory nature of charcoal in comparison to SOM losses over 20 months in CM (27%),
compost amended (27%), and control plots (25% loss). 相似文献
9.
Two challenges frequently encountered in the production of ornamental plants in organic horticulture are: (1) the rate of
mineralization of phosphorus (P) and nitrogen (N) from organic fertilizers can be too slow to meet the high nutrient demand
of young plants, and (2) the exclusive use of peat as a substrate for pot-based plant culture is discouraged in organic production
systems. In this situation, the use of beneficial soil microorganisms in combination with high quality compost substrates
can contribute to adequate plant growth and flower development. In this study, we examined possible alternatives to highly
soluble fertilizers and pure peat substrates using pelargonium (Pelargonium peltatum L’Her.) as a test plant. Plants were grown on a peat-based substrate with two rates of compost addition and with and without
arbuscular mycorrhizal (AM) fungi. Inoculation with three different commercial AM inocula resulted in colonization rates of
up to 36% of the total root length, whereas non-inoculated plants remained free of root colonization. Increasing the rate
of compost addition increased shoot dry weight and shoot nutrient concentrations, but the supply of compost did not always
completely meet plant nutrient demand. Mycorrhizal colonization increased the number of buds and flowers, as well as shoot
P and potassium (K) concentrations, but did not significantly affect shoot dry matter or shoot N concentration. We conclude
that addition of compost in combination with mycorrhizal inoculation can improve nutrient status and flower development of
plants grown on peat-based substrates. 相似文献
10.
Charlotte Marchand William Hogland Fabio Kaczala Yahya Jani Lilian Marchand Anna Augustsson 《International journal of phytoremediation》2016,18(11):1136-1147
Several Gentle Remediation Options (GRO), e.g., plant-based options (phytoremediation), singly and combined with soil amendments, can be simultaneously efficient for degrading organic pollutants and either stabilizing or extracting trace elements (TEs). Here, a 5-month greenhouse trial was performed to test the efficiency of Medicago sativa L., singly and combined with a compost addition (30% w/w), to treat soils contaminated by petroleum hydrocarbons (PHC), Co and Pb collected at an auto scrap yard. After 5 months, total soil Pb significantly decreased in the compost-amended soil planted with M. sativa, but not total soil Co. Compost incorporation into the soil promoted PHC degradation, M. sativa growth and survival, and shoot Pb concentrations [3.8 mg kg?1 dry weight (DW)]. Residual risk assessment after the phytoremediation trial showed a positive effect of compost amendment on plant growth and earthworm development. The O2 uptake by soil microorganisms was lower in the compost-amended soil, suggesting a decrease in microbial activity. This study underlined the benefits of the phytoremediation option based on M. sativa cultivation and compost amendment for remediating PHC- and Pb-contaminated soils. 相似文献
11.
Ma Teresa Hernandez Fernandez Jorge Mataix-Solera L’ubomír Lichner Vlasta Štekaurová Anton Zaujec Carlos Garcia Izquierdo 《Biologia》2007,62(5):542-546
The way of improving degraded soils fertility and particularly of improving its microbial activity is to add “young” exogenous
organic matter that contribute to provide labile organic matter to stimulate the life of the microorganisms existing in the
soil. This organic matter will also improve both the retention and hydraulic characteristics of the degraded soils, all this
contributing to soil restoration. In this study, the microbiological, biochemical, soil-physical and hydrological effects
of the addition of a municipal solid waste compost to a degraded soil in El Campello, SE Spain were evaluated in a field experiment.
Soil samples from experimental plots were analyzed 6 and 18 months after soil amendment. In both sampling time treated plots
showed significantly higher microbial biomass carbon and dehydrogenase activity values than control, indicating that soil
microbial population’s development and activity were stimulated by compost addition, this effect being not ephemeral but lasting
in the time. Soil urease activity was not affected by compost addition while protease hydrolysing N-α-benzoil-L-argininamide (BAA) activity was strongly stimulated by the incorporation of compost into the soils. Phosphatase
and β-glucosidase activities were also stimulated by the organic amendment, this stimulation being particularly noticeable 18 months
after the compost addition. Nevertheless, this increase in soil microbial populations and activity did not result in an increase
in soil aggregation and hydrological parameters. This can be due to the high content of carbonates and Ca2+ ions in these calcareous soils, that lead to an initially high content of water-stable macroaggregates.
Presented at the International Conference on Bioclimatology and Natural Hazards, Poľana nad Detvou, Slovakia, 17–20 September
2007. 相似文献
12.
Formation of non-bioavailable organic residues in soil: Perspectives for site remediation 总被引:1,自引:0,他引:1
Whenever possible, total clean-up of soils and sediments should have priority over methods to contain the pollutants in the soil environment in a way which reduces their potential eco-toxicological effects. Nevertheless, often a very important fraction of the pollutant remains non-available to the cleaning process, either physico-chemical or biological. This constitutes a major obstacle for both environmental technologists and legislators. Yet, the concept of non-extractable organic residues is well accepted in the EU-legislation for pesticides. In this context, an assessment is made to bind organic pollutants to soil. Physical sorption (comprising surface adsorption, absorption and migration in micro- and nanopores) and chemical binding are examined in terms of quantities and kinetics. Chemical binding offers at present no direct possibilities for practice. Making toxic pollutants less bioavailable by increasing physical sorption represents a pragmatic approach to contractors and regulators. For organic pollutants with acceptable concentration in the soil solution of the order of 1 mg/l, a sorptive loading of the order of 10 000 mg pollutant per kg activated carbon respectively organic matter appears a workable assumption. In case of toxic substances such as pesticides which have a 1000 times lower acceptable level, a sorptive loading of up to 10 mg organic pollutant per kg sorbent can be used. Non-bioavailable pollutants can be considered as representing no direct harm to the environment. In practice, the application of up to 100–200 kg dry weight quality compost per ton dry weight soil or alternatively the supplementation of other sorbents such as powdered activated carbon (up to 100 kg per ton soil) offer possibilities to cost-effective remediation of organic pollutants. Yet, aspects of worst-case ecotoxicology as e.g. excessive leaching with dissolved humic substances or ingestion of soil containing substantial amounts of poorly extractable contaminants by human and soil organisms, need to be examined. 相似文献
13.
Red clover root material confined in mesh bags was buried in three different limed and unlimed soils and incubated for 196
days at room temperature. Remaining amounts of organic matter, as well as concentrations of C and N of the decomposing material
were determined three times during the incubation and finally the concentration of soil mineral N and pH of remaining roots
was also assessed.
Liming only temporarily affected the decomposition rate of organic matter and N release, and at the end of the incubation
no effects could be observed due to liming. A possible explanation is that the decomposing root residues provide a well buffered
micro-environment for the decomposing microflora. Liming did not change the pH of the root residues even when 97–98% of dry
mass had disappeared from the mesh bags.
Concentrations of mineral N were higher in limed than in unlimed soils. 相似文献
14.
Tsehaye Tesfamariam H. Yoshinaga S. P. Deshpande P. Srinivasa Rao K. L. Sahrawat Y. Ando K. Nakahara C. T. Hash G. V. Subbarao 《Plant and Soil》2014,378(1-2):325-335
Aims
Organically-certified orchard floor management was assessed for its ability to improve soil fertility and biological activity and apple orchard performance.Methods
‘Ambrosia’/B9 apple was maintained for the first six growing seasons with four orchard floor treatments, including 1) annual compost application; 2) in-row application of mown alfalfa grown between the rows; 3) bark mulch plus in-row application of mown hay; and 4) black plastic mulch.Results
Soil collected from 0 to 10 cm indicated high soil organic matter and exchangeable K were measurable for all treatments by the second year. After 6 years, highest organic matter, total-, particulate- and mineral–C were associated with soil beneath the bark mulch treatment which also had most vigorous trees, decreased leaf N and elevated leaf P and K. Addition of alfalfa and bark mulch were equally effective at maintaining high exchangeable K and soil phosphatase enzymes, high total and particulate-N by the fourth year.Conclusions
Despite measurable improvements in soil properties among treatments, fruit yield and quality were minimally affected by management implying no limitations to adoption of any of the assessed strategies. 相似文献15.
The contamination of soils with heavy metals is a global disaster that is related to human activities. Phytostabilization basically refers to the use of metal-tolerant plants and inexpensive mineral or organic soil amendments to reduce the concentrations or toxic effects of contaminants in the environment. Here, we tested the effects of four cost-effective amendments (CaCO3, phosphate rock, activated carbon, and exhausted olive cake ash) on Cd, Zn, and Cu leaching and uptake by ryegrass (Lolium perenne L.). The results showed that all amendments reduced Cd, Zn, and Cu leaching, mainly due to the alkalinity increase. Among all amendments tested, CaCO3 was the most effective treatment in decreasing both the heavy-metal leaching and concentrations in ryegrass shoots. Results obtained suggest the efficacy of several amendments, but further work is needed to gain insight into their possible synergetic effects. 相似文献
16.
Effects of mycorrhizal fungus isolates on mineral acquisition by Panicum virgatum in acidic soil 总被引:1,自引:0,他引:1
Plant ability to withstand acidic soil mineral deficiencies and toxicities can be enhanced by root-arbuscular mycorrhizal
fungus (AMF) symbioses. The AMF benefits to plants may be attributed to enhanced plant acquisition of mineral nutrients essential
to plant growth and restricted acquisition of toxic elements. Switchgrass (Panicum virgatum L.) was grown in pHCa (soil:10 mM CaCl2, 1 : 1) 4 and 5 soil (Typic Hapludult) inoculated with Glomus clarum, G. diaphanum, G. etunicatum, G. intraradices, Gigaspora
albida, Gi. margarita, Gi. rosea, and Acaulospora
morrowiae to determine differences among AMF isolates for mineral acquisition. Shoots of mycorrhizal (AM) plants had 6.2-fold P concentration
differences when grown in pHCa 4 soil and 2.9-fold in pHCa 5 soil. Acquisition trends for the other mineral nutrients essential for plant growth were similar for AM plants grown in
pHCa 4 and 5 soil, and differences among AMF isolates were generally higher for plants grown in pHCa 4 than in pHCa 5 soil. Both declines and increases in shoot concentrations of N, S, K, Ca, Mg, Zn, Cu, and Mn relative to nonmycorrhizal
(nonAM) plants were noted for many AM plants. Differences among AM plants for N and Mg concentrations were relatively small
(<2-fold) and were large (2- to 9-fold) for the other minerals. Shoot concentrations of mineral nutrients did not relate well
to dry matter produced or to percentage root colonization. Except for Mn and one AMF isolate, shoot concentrations of Mn,
Fe, B, and Al in AM plants were lower than in nonAM plants, and differences among AM plants for these minerals ranged from
a low of 1.8-fold for Fe to as high as 6.9-fold for Mn. Some AMF isolates were effective in overcoming acidic soil mineral
deficiency and toxicity problems that commonly occur with plants grown in acidic soil.
Accepted: 14 June 1999 相似文献
17.
This study was aimed at making a quantitative evaluation of the biomass, carbohydrates and mineral nutrients partitioning
in the canopy of aspen (Populus tremula L.) growing in a forest stand. Tree canopy biomass was divided into ten equal horizontal layers and the material for the
study was sampled from all canopy layers. The results indicated that the specific leaf mass and the dry matter content increased
but the area of leaves decreased toward the top of the canopy. The content of the non-structural carbohydrates depended largely
on the position of the leaves in the canopy and the N, P and K contents in the leaves, reaching a maximum in the upper canopy
layers better exposed to light. Regression analysis showed a linear relationship between the leaf mass per area and the percentage
of dry matter on the one hand and the content of carbohydrates, N, P and K in the canopy on the other.
Received: 11 March 1997 / Accepted: 16 June 1997 相似文献
18.
Coffee beans and tea leaves contain large amounts of potentially metal-chelating substances which could remain in the wastes
after extraction by hot water. The following two experiments have been carried out: a) an incubation experiment with the objective
of verify whether coffee grounds and green tea wastes could be used as an Fe chelating agent to increase Fe availability to
plants in the soil; b) a pot experiment to verify the effect of those composts on the Fe content of the edible part of vegetables.
Japanese leaf radish (Raphanus raphanus sp), whose the leaves are the edible part, was chosen as test plant. Calcareous subsoil (shell fossil soil) with original
pH 9.3 and a B horizon of Andisol (Typic melanudand) with pH adjusted to 7.7 were used. For the incubation experiment, the
treatments included of the direct addition of Fe at rates of 0 (control), 10, 20 and 40 μg g−1 dry soil as ferrous sulfate (FS); coffee waste compost (CWC) and tea waste compost (TWC). Both composts contained approximately
40 g Fe kg−1 dry mass. Thus, the total amounts of CWC and TWC added were of 0, 0.25, 0.5 and 1.0 mg g−1 soil. Considering a soil density of 1 g cm−3 and 10 cm of plow layer, the total amounts of compost applied were of 0, 0.25, 0.5 and 1.0 ton ha−1. Soil samples were collected after 30 and 60 days of incubation and then analyzed for plant available Fe. For the pot experiment,
the doses of 0 (control) and 1 mg g−1 soil of CWC or TWC were used to grow radish. Plants were harvested after 60 days. For samples incubated for 30 days, the
CWC and TWC treatments led to the largest increase in the ammonium bicarbonate diethylene triamine pentaacetic acid (AB-DTPA)
extractable Fe levels of both soils (P < 0.05). After 60 days of incubation the amounts of AB-DTPA-extractable Fe in soil samples treated with both composts were
always higher than in those treated with FS alone. For both soils, the application of 40 μg Fe g−1 dry soil as CWC or TWC enhanced significantly (P < 0.05) the total Fe content of radish shoots compared to the control. We concluded that it has been possible to increase
the plant-available Fe in neutral to alkaline soils using coffee grounds and tea leaf wastes composted with FS. However, more
research on the effectiveness in field conditions are necessary. 相似文献
19.
The objectives of the present work were (a) to quantify the effects of wood ash on forest ecosystems through a meta-analysis
approach associated with a detailed review of the literature (mainly composed of work carried out in Nordic countries) and
(b) to extrapolate the effects on forest growth to other contexts (i.e. warm temperate countries) by identifying the cases
for which wood ash applications can be beneficial to forest production. Three databases were built regarding the effects of
wood ash on soil (151 observations; 33 experimental field trials), on nutrient concentrations of tree foliage (68 observations;
28 trials) and on annual stem biomass growth rate (70 observations; 27 trials). We obtained information on the wide variability
of ash properties due to differences in burnt compounds, combustion processes and ash conditioning. Two important properties
of wood ash are its high pH value and neutralizing capacity. These properties result in biochemical modifications of forest
soils limed with ash. In the short term, soil solution composition was dramatically modified. Intense peaks of the K, Na or
SO4 concentrations were observed, resulting from the dissolution of salts contained in ash. At the same time, Ca and Mg concentrations
increased as the carbonate pool of wood ash started to dissolve. The consequence of this dissolution process was an increase
in the pH in all the soil phases. These modifications increased the activity of the soil microflora and some isolated peaks
in the mineralization of soil organic matter may be observed in mineral soils. In the longer term, that is to say after the
first year following ash application, only the effect on the acidity status of the soil remained significant. The effects
of ash addition on forest ecosystems usually increased with the dose and were more pronounced with loose ash compared to aggregated
ash. The addition of wood ash into forest ecosystems increased the foliar Ca status of trees. Some modifications of other
nutrients, like P or K, were also observed but only for a few years after treatment. For most stands growing on mineral soils
of Nordic countries, this treatment did not result in an increase in tree growth, probably because of the absence of N in
the ash. For stands growing on organic soils of the same area, this input, associated with a long-lasting increase of soil
organic matter mineralization, was sufficient to improve tree growth significantly (median = +59% compared to the control).
For soils located in warm temperate regions, similar responses are expected for organic soils. For mineral soils, the wood
ash application is expected to be suitable for stands showing deficiencies in K, Ca or Mg. Ash may contain high amounts of
toxic heavy metals such as Cd. The bioavailability of most of these elements appeared to be very low in a forest context.
No contamination of food chains has been observed, except possibly via some species of fungi, and heavy metals remain in the
forest litter or in the topsoil. Based on all the reviewed results, several guidelines for wood ash application into forest
ecosystems are proposed. Wood ash application should be restricted to acidic soils. Applications should consist of low doses
of a stabilized ash form. Wood ash should be applied to adult stands rather than onto seedlings. 相似文献
20.
Direct effects and after-effects of soil drought for 7 and 14 d were examined on seedling dry matter, leaf water potential
(ψ), leaf injury index (LI), and chlorophyll (Chl) content of drought (D) resistant and sensitive triticale and maize genotypes.
D caused higher decrease in number of developed leaves and dry matter of shoots and roots in the sensitive genotypes than
in the resistant ones. Soil D caused lower decrease of ψ in the triticale than maize leaves. Influence of D on the Chl b content was considerably lower than on the Chl a content. In triticale the most harmful D impact was observed for physiologically younger leaves, in maize for the older ones.
A period of 7-d-long recovery was too short for a complete removal of an adverse influence of D. 相似文献