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1.
《Southern Forests》2013,75(3):201-212
Forest plantation growers in Vietnam commonly burn residues after harvesting and often apply suboptimal amounts of nutrients during plantation establishment. We examined whether the retention of forest residue, and application of phosphorus fertiliser at higher rates, can increase rates of growth. A factorial combination of residue management (burning vs retention) and phosphorus fertiliser application at planting (15 vs 100 kg ha?1) treatments were applied at a steeply sloping site in northern Vietnam. Two adjacent experiments were established, one with Acacia mangium and the other with a Eucalyptus hybrid (Eucalyptus urophylla × Eucalyptus pellita). Standing volume and leaf area index in A. mangium were greater following burning; this was mostly attributable to the significantly higher survival rate of seedlings. Burning of residues was associated with increases in the number of large branches per tree, and a higher crown damage index (CDI). In the Eucalyptus hybrid, diameter and height responses to the higher rate of fertiliser were observed at age 6 and 12 months, but not beyond. High phosphorus application also led to higher CDI. Standard fertiliser treatment, applied in amounts equivalent to 17, 15 and 8 kg ha?1 of nitrogen, phosphorus and potassium, respectively, was adequate to meet the early growth requirement of eucalypt and acacia plantations at this site. The relatively low amounts of harvest residue and high fertility levels at the site may have masked more significant responses of trees to the silvicultural treatments applied in this study. On steep slopes, especially if soil is poorly fertile, harvest residue retention with adequate weed and termite control may be preferential to burning as it is closely correlated with reducing factors that negatively impact productivity, i.e. water run-off and soil erosion. 相似文献
2.
Incorporating cover crops into Christmas tree plantations may potentially improve soil fertility, tree growth and quality
and be an alternative to commercial nitrogen (N) fertilizers. However, cover crops may compete with the trees for water and
other nutrients than N. This study was carried out to assess whether soil fertility, tree survival and growth could be improved
by incorporating leguminous and non-leguminous cover crops into the Fraser fir (Abies fraseri) production system. Dutch white clover (Trifolium pratense), alfalfa (Medicago sativa) and perennial ryegrass (Lolium perenne) were grown in a newly established Fraser fir plantation using two cover crop management practices; no banding (NB) by growing
each cover crop throughout the entire plot and banding (B) by creating a 61 cm-wide bare zone centered on the tree rows. A
conventionally-managed system (CONV) was used as a control. The cover crop aboveground biomass and N content were assessed.
Soil available N (NO3
− and NH4
+) and N mineralization were measured at 0–15, 15–30 and 30–45 cm soil depths. Tree survival, growth, photochemical efficiency
of photosystem II (Fv/Fm), branch water potential (Ψw) and foliar nutrients were also evaluated. Biomass production was as high as 13.9, 10.2 and 5.9 Mg DM ha−1 year−1 for clover, alfalfa and ryegrass, respectively. Cover cropping increased soil available N by 1.5- and 2.2-fold relative the
CONV in the top soil layer in 2007 and 2008, respectively. Tree seedling survival and growth in the B and CONV systems were
similar. In contrast, NB treatments resulted in poor seedling survival and growth relative to the B and CONV plots. Plant
Ψw and Fv/Fm decreased significantly for A. fraseri seedlings on the NB treatments relative to their counterparts on the B and CONV plots. However, cover cropping had marginal
effects on foliar nutrients. Cover cropping with banding can be an efficient strategy for maintaining productivity in Fraser
fir Christmas plantations. 相似文献
3.
Effects of harvest residues on nutrient leaching and soil chemical properties were studied in a lysimeter experiment. Treatments
were: (A) forest floor litter and harvest residues, other than branches, incorporated into the soil, (B) as A, but with branches
cut in 20 cm long bits and placed on the soil surface, (C) as B, but with bits incorporated into the soil, (D) as B, but with
branches chopped into chips, (E) as C, but with branches chopped into chips, (F) forest floor litter and harvest residues
on the soil surface, with branches cut in 20 cm long bits, (G) as F, but with branches chopped into chips, and (H) absence
of harvest residues (control). Treatments were applied in zero-tension lysimeters containing 25 kg of soil. Leachates were
collected for a 6-year period. At the end of the experiment, lysimeters were dismantled and soil was divided in four layers.
Residues, other than branches, increased N leaching, as compared with the control. Branches on the soil surface reduced N
leaching when cut in chips. Branches incorporated into the soil reduced leaching independently of their size. Organic residues
on the soil surface showed similar effect to those incorporated into the soil. However, harvest residues on the soil surface
increased leachate volume, and reduced Ca and P losses. Such a placement of residues led to high contents of Ca and P in the
0–5 cm top soil layer. Contents of organic C, total N and base cations were not affected by the treatments. 相似文献
4.
The effect of harvest residue management options on biomass and nutrient accumulation in understory vegetation, as well as the contribution of understory to nutrient cycling, were assessed during the early rotation stage of a Eucalyptus globulus Labill. plantation in Central Portugal. The effects of residue management options on early tree growth were also evaluated. Treatments established at the time of plantation and replicated four times in a simple completely randomised design included removal of harvest residues (R), incorporation of residues into the soil by harrowing (I) and maintenance of residues on the soil surface (S). Understory biomass was sampled in the spring between 2002 and 2006, and every 2 months between March 2006 and March 2007. The latter samples were stratified into biomass, standing dead mass and litter for net above ground primary production (NAPP) assessment. Samples were oven dried, weighed and analysed for nutrient contents. Results showed that understory standing biomass strongly increased from the first to the third year and that quantities of nutrients accumulated in ground vegetation followed similar patterns between the three treatments. Nutrient accumulation in ground vegetation was greater than in tree biomass until at least the second spring after plantation. Bimonthly sampling revealed treatment R to have the largest amounts of standing biomass, standing dead mass, litter and nutrient immobilisation, while treatment S exhibited the lowest values. NAPP (4th–5th year) was 639, 511 and 362 g m−2 year−1, respectively in R, I and S, corresponding the standing biomass increase to 277, 183 and 143 g m−2 year−1. These values are comparable to those observed for litter fall in similar stands (age and tree density) in the same area. The contribution of ground vegetation to nutrient accumulation in the system was unaffected by harvest residue management methods, but further research is necessary in order to establish whether slash management options influence long term tree growth and vegetation dynamics. 相似文献
5.
A split plot trial involving Ailanthus triphysa (ailanthus) at four spacings (3 m×1 m, 2 m×2 m, 3 m×2 m and 3 m×3 m) and four fertiliser regimes (0:0:0, 50:25:25, 100:50:50 and 150:75:75 kg ha−1 per year N, P2O5, K2O) was initiated in June 1991. Objectives included evaluating the growth and yield potential of ailanthus grown under differing density and fertiliser regimes and to estimate the nutrient export through harvest. Ninety-six randomly selected average-sized trees were felled at 8.8 years of age for assessment. Results show that height, diameter, stand leaf area index, biomass production and volume yield were greater in the 2 m×2 m spacing. Repeated application of fertilisers at 1.2, 2.25 and 5.25 years after planting had little effect on biomass and volume yields, presumably because of weed competition (despite periodic weed control), higher pest incidence (in the heavily fertilised plots) and/or moderately adequate soil nutrient levels. Regarding partitioning of tree biomass, stem wood represented the principal component (>70%), while foliage contributed the least (<7%). Conversely, foliar N, P and K concentrations were the highest, followed by branch wood, coarse roots and stem wood. Denser stands showed greater accumulation of N, P and K with higher potential for nutrient export through harvest. However, as the bole fraction accounted for only about 56–64% of the total nutrients removed, leaving other biomass components (foliage and branches) at the site will reduce the associated nutrient export. Wider spacings (3 m×2 m and 3 m×3 m) were more efficient in N and K use, but P use efficiency was higher in 2 m×2 m. Likewise, trees in the no fertiliser plots exhibited greatest N, P and K use efficiencies. Available soil P, K and organic C levels declined with increasing tree density, while repeated fertilisation increased nutrient concentrations. Soil pH and available P levels declined in comparison to the pre-treatment values. 相似文献
6.
7.
A factorial experiment was established in a plantation of Eucalyptus nitens in southern Tasmania on a site which had formerly carried native eucalypt forest. Before planting, the site had been cleared of weeds with foliar translocated and pre-emergence herbicides. The first factor of the experiment examined the effects on tree growth of no post-planting weed control, control by hand or with three levels of application of granulated atrazine, 0.9, 1.8 and 8 kg ha–1. The second factor examined the effects of no fertiliser application or the application of nitrogen as urea at 200 kg ha–1 N plus triple superphosphate at 120 kg ha–1 P. Tree growth responses to treatments were examined at 11, 16, 23 and 29 months of age.Fertiliser application increased tree height and diameter growth. Application of atrazine generally reduced height and diameter growth, but this was statistically significant only at the highest rate of application. Growth reduction occurred even though atrazine reduced post-planting weed cover on the site and hence potential competition with the tree crop for site resources. Hand weeding reduced the weed crop on the site even more than atrazine, but this did not increase growth of the tree crop.Given satisfactory establishment practices which include the use of herbicides pre-planting, it was concluded that post-planting weed regeneration was not sufficiently vigorous to warrant post-planting weed control on these sites. The use of atrazine for post-planting weed control could even be deleterious to eucalypts. 相似文献
8.
在淮北平原宿县,通过大穴整地、施肥改良砂姜黑土、营造Ⅰ-69杨的五年试验证明,大穴整地当年效应明显(径、高增长19.8%、91.8%);头二年肥效不显;第三年起N肥、有机肥、N×有机肥交互作用效应极显著(材积增加77%),施P+K肥效应较差,N+K肥和N+P肥经济效益较高,投入/产出为1/6.22和1/3.78;材积增加60%和58%。整地加施肥综合效益明显,有效施肥占综合效益85.1%～88.8%。 相似文献
9.
Rabel Diego de Oliveira Maeda Shizuo Araujo Eloá Moura Gomes João Bosco Bognolla Itamar Antônio Prior Stephen A. Magri Ederlan Frigo Cleiton Brasileiro Bruno Portela dos Santos Mariana Custodio Pedreira Guilherme Quaresma Motta Antônio Carlos Vargas 《New Forests》2021,52(2):249-270
Alkaline residues of recycled paper production (ARRP) can be an alternative for correcting soil acidity and adding bases to Pinus taeda L. systems. Our aim was to investigate the effect of increasing doses of ARRP on tree, forest floor (litter and root), and soil composition in a 3-year-old Brazilian pine forest plantation. In 2007, ARRP treatments of 0, 10, 20, 30 and 40 T ha?1 were imposed. Tree growth and needle elemental composition were evaluated in 2008 and 2018; elemental composition of the trunk was evaluated in 2018. In 2017, accumulation and composition of litter layers were assessed: new litter, old litter, first and second sublayers of fragmented litter (Fr and Fm), and the humified layer (H); roots present in F and H layers were quantified (amount and elemental composition). In addition, soil chemical properties at different depths were evaluated in 2008, 2012, and 2017. The application of ARRP improved growth by ~?16% up to 20 T ha?1 after 10 years. Also, ARRP increased Ca concentration in needles, trunks, roots, and all litter fractions since Ca was a major component of ARRP. There was no change in total litter accumulation with ARRP application, but an increase in the humidified fraction was observed. Root growth was enhanced by ARRP, leading to great changes in root composition in Fr and H fractions. Changes in soil pH, Ca2+, and Al3+ were observed in the 0–10 cm soil layer. Findings suggest that application of ARRP to established pine forests has the potential for improving productivity.
相似文献10.
Pine plantations on selected sites in the extensive zone of degraded oak coppice of northern Greece are deemed necessary for increasing wood production in the area and suitable site preparation may accelerate early tree growth. Seven site preparation treatments including raking (R), with sub-soiling (RS), disc harrowing (RD), tine ploughing (RT) and their combinations (RSD), (RDT) and (RSDT) were compared for the establishment of black pine (Pinus nigra Arn) in an oak coppice site, of conglomerate parent material at Anthrakia, northern Greece. The randomised blocks trial of three replications and 110 trees per treatment, half of which were fertilised with 150 g NPK per plant, was assessed at the age of 15 years for diameter, dominant tree height and survival. There was no significant difference between the treatments in any of the traits examined, nor did the fertilisation had any effect. Only the fertiliser × treatment interaction was found significant at p<0.001 for dominant height, accounting for 37% of the observed variation in this trait. The lack of response to site preparation treatments may be attributed to the hard Bt3 clay horizon, extending beyond cultivation depth (50 cm), that prevents the roots penetration into deeper moist soil layers. The F × T interaction, where the combination of (RSDT) treatment and fertiliser was found to accelerate tree height growth in relation to the same treatment without fertiliser, indicates that thorough soil cultivation is needed for fertilisation to be effective in such sites. 相似文献
11.
Schulz H Schäfer T Storbeck V Härtling S Rudloff R Köck M Buscot F 《Tree physiology》2012,32(1):36-48
Ectomycorrhiza (EM) formation improves tree growth and nutrient acquisition, particularly that of nitrogen (N). Few studies have coupled the effects of naturally occurring EM morphotypes to the nutrition of host trees. To investigate this, pine seedlings were grown on raw humus substrates collected at two forest sites, R2 and R3. Ectomycorrhiza morphotypes were identified, and their respective N uptake rates from organic (2-(13)C, (15)N-glycine) and inorganic ((15)NH(4)Cl, Na(15)NO(3), (15)NH(4)NO(3), NH(4)(15)NO(3)) sources as well as their phosphate uptake rates were determined. Subsequently, the growth and nutritional status of the seedlings were analyzed. Two dominant EM morphotypes displayed significantly different mycorrhization rates in the two substrates. Rhizopogon luteolus Fr. (RL) was dominant in R2 and Suillus bovinus (Pers.) Kuntze (SB) was dominant in R3. (15)N uptake of RL EM was at all times higher than that of SB EM. Phosphate uptake rates by the EM morphotypes did not differ significantly. The number of RL EM correlated negatively and the number of SB EM correlated positively with pine growth rate. Increased arginine concentrations and critical P/N ratios in needles indicated nutrient imbalances of pine seedlings from humus R2, predominantly mycorrhizal with RL. We conclude that different N supply in raw humus under Scots pine stands can induce shifts in the EM frequency of pine seedlings, and this may lead to EM formation by fungal strains with different ability to support tree growth. 相似文献
12.
Growth and nitrogen status of young walnuts as affected by intercropped legumes in a Mediterranean climate 总被引：1，自引：0，他引：1
C. Dupraz V. Simorte M. Dauzat G. Bertoni A. Bernadac P. Masson 《Agroforestry Systems》1998,43(1-3):71-80
Walnut trees (Juglans nigra L. and Juglans nigra × regia NG23) were intercropped with alfalfa (Medicago sativa L.) or sainfoin
(Onobrychis sativa L.) forage legumes compared to a grass (Festuca arundinacea Schr., fescue), or to spontaneous weeds as
a control in two Mediterranean sites (Castries and Notre-Dame de Londres) near Montpellier (France). Tree growth, soil water
depletion and nitrogen content of the tree leaves were monitored to assess the impact of both water competition and possible
facilitation resulting from fixed nitrogen transfer from the leguminous crops to the trees. At Castries, where alfalfa and
fescue were compared, they were found to have the same impact on tree growth. At Notre-Dame de Londres where sainfoin was
compared with a spontaneous grassing treatment, the sainfoin crop was more competitive to the walnuts. The nitrogen content
of walnut leaves was enhanced when intercropped with nitrogen fixing species at both sites. Perennial leguminous intercrops
were more competitive for soil water resources than fescue or weeds, but in the long term this may be compensated by the improved
nitrogen status of the trees. This compensating effect was observed during a rather rainy year. The overall impact of leguminous
intercrops on tree growth may depend on the frequency of dry (competitive) and wet (non-competitive) years.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
13.
A study was established to evaluate several management practices for improving American sycamore (Platanus occidentalis L.) establishment on land subjected to daily paper-mill sludge spray irrigation, and where a dense herbaceous cover dominated by pokeweed (Phytolacca americana L.) was nearly 2 m tall. Treatments studied included: two sludge application treatments (spray vs no spray), five weed control treatments (control, hand-release, oxyfluorfen, glyphosate and atrazine, and sulfometuron methyl), and two tree shelter treatments (control vs tree shelter). Survival and growth of sycamore seedlings were evaluated after one growing season. Sludge application treatment had the greatest effect on tree survival; survival was greatest on plots that were not sprayed during the year of tree growth. Among the weed control treatments, the hand-release treatment resulted in best survival; survival was 100% when hand release was used on unsprayed plots. Tree shelters provided no benefit to tree establishment. 相似文献
14.
Understanding the changes in soil properties in silvopastoral systems is important in regulating the interactions between
tree and understorey pastures. In this study, the effects of understorey management on soil mineral N and moisture availability,
soil temperature, soil C, and tree growth were investigated in a seven-year-old silvopastoral agroforestry experiment in Canterbury,
New Zealand. The systems included understorey treatments of bare ground and ryegrass (Lolium perenne) pasture. Soil mineral N, moisture content, and temperature were monitored from July 1997 to July 1998 in two positions (0.9
and 3.5 m north of tree rows) and two soil depths (0–10 and 10–20 cm). Soil C and N in the 0–10 cm depth were higher in the
ryegrass than in the bare ground plots, reflecting the organic C and N input in the ryegrass plots, as well as greater N loss
from the bare ground plots in the form of nitrate leaching and/or denitrification. Soil C was higher in the position 0.9 m
than 3.5 m away from the tree rows, possibly caused by the greater C input from decomposing fine tree roots and needle litterfall
at the 0.9 m position. Soil moisture availability was greater in the bare ground than in the ryegrass plots in the summer.
No effect of understorey management on soil temperature was found. Soil nitrate levels were lower in the ryegrass plots and
may be limiting when soil moisture supply was adequate. Tree volume growth from winter 1997 to 1998 was significantly greater
in the bare ground treatment, reflecting better soil moisture and N supply conditions.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
15.
The adequate use of sewage sludge in silvopastoral systems could enhance positive relationships between pasture and trees
to increase farm incomes at medium, short and long term. The main aspects related to adequate sewage sludge use as a fertiliser
are dose and timing of application, once heavy metal concentrations have been taken into account. This paper aims to evaluate
the date and dose of sewage sludge applications on soil (KCl pH, soil organic matter), pasture production and tree growth
after the establishment of a silvopastoral system with Pinus radiata D. Don developed on sandy soils with an initial pH of 5. It is concluded that the contribution of sewage sludge does not
modify the soil conditions in a consistent manner, but cause detectable edaphic improvements depending on the climatic conditions,
the results of which are manifested in enhancement of pasture and trees. The application of high doses of sewage sludge is
the best option within those studied, as tree growth and pasture production tend to be increased. There are no clear effects
with regard to the date of application, but if the desire is to increase pasture production during the spring season, the
sewage sludge will be applied in the first of the application dates, whereas the greatest growth in the diameter of trees
is produced in the plots fertilised in February, although the date of application does not appear to have a clear effect on
their growth in height. 相似文献
16.
Haydon S. Jones Peter N. BeetsMark O. Kimberley Loretta G. Garrett 《Forest Ecology and Management》2011,262(3):339-347
Growing interest in the use of planted forests for bioenergy production could lead to an increase in the quantities of harvest residues extracted. We analysed the change in C and N stocks in the forest floor (LFH horizon) and C and N concentrations in the mineral soil (to a depth of 0.3 m) between pre-harvest and mid-rotation (stand age 15 years) measurements at a trial site situated in a Pinus radiata plantation forest in the central North Island, New Zealand. The impacts of three harvest residue management treatments: residue plus forest floor removal (FF), residue removal (whole-tree harvesting; WT), and residue retention (stem-only harvesting; SO) were investigated with and without the mean annual application of 190 kg N ha−1 year−1 of urea-N fertiliser (plus minor additions of P, B and Mg). Stocks of C and N in the forest floor were significantly decreased under FF and WT treatments whereas C stocks and mass of the forest floor were significantly increased under the SO treatment over the 15-year period. Averaged across all harvesting treatments, fertilisation prevented the significant declines in mass and C and N stocks of the forest floor which occurred in unfertilised plots. The C:N ratio of the top 0.1 m of mineral soil was significantly increased under the FF treatment corresponding to a significant reduction in N concentration over the period. However, averaged across all harvesting treatments, fertilisation prevented the significant increase in C:N ratio of the top 0.1 m of mineral soil and significantly decreased the C:N ratio of the 0-0.3 m depth range. Results indicate that residue extraction for bioenergy production is likely to reduce C and N stocks in the forest floor through to mid-rotation and possibly beyond unless fertiliser is applied. Forest floors should be retained to avoid adverse impacts on topsoil fertility (i.e., increased C:N ratio). Based on the rate of recovery of the forest floor under the FF treatment, stocks of C and N in the forest floor were projected to reach pre-harvest levels at stand age 18-20. While adverse effects of residue extraction may be mitigated by the application of urea-N fertiliser, it should be noted that, in this experiment, fertiliser was applied at a high rate. Assessment of the sustainability of harvest residue extraction over multiple rotations will require long-term monitoring. 相似文献
17.
Ginkgo (Ginkgo biloba L.) is a traditional economic tree species in China, and often cultivated in agroforestry systems. The objective of the study
was to examine the effects of different Ginkgo and crop species combinations on soil fertility. We established two Ginkgo
and crop species systems: Ginkgo + wheat + soybean (G+W+S), Ginkgo + rape + soybean (G+R+S), and one Ginkgo + mulberry (G+M)
system, one pure mulberry plantation (M), and one crop systems of rape + soybean (R+S) in the field. Soil chemical properties
and enzymes activities were measured 4 years after planting. These soil chemical properties and enzyme activities were used
as soil fertility indicators (FI). Soil fertility of the five planting systems was finally evaluated by using improved Analytic
Hierarchy Process (AHP). The result showed that soil chemical properties (including pH, organic matter, total N, hydrolysable
N, available P and K, total K) and soil enzyme activities (including catalase, sucrase, urease, dehydrogenase, phosphatase,
polyphenol oxidase and protease) in the five planting systems were significantly different from each other (P = 0.0237). The above parameters were also different at different soil depths. The concentration of total N, P, organic matter,
available P and K of soil decreased significantly with soil depth (P = 0.0146), however, pH increased. The concentrations of organic matter, total N, hydrolysable N, available P and K of soil
under rape + soybean (R+S) was lowest among the five planting systems. The activities of sucrase, urease, dehydrogenase, phosphatase
and protease decreased with soil depth, however, the activity of catalase and polyphenol oxidase increased. Except for catalase,
the activities of these enzymes in the R+S system were the lowest among the five planting systems. The integrated evaluation
of soil fertility showed that soil fertility indicators (FI) were significantly different, and the FI values for the five
systems followed order: G+M (0.847) > G+W+S (0.446) > M (0.399) > G+R+S (0.343) > R+S (0.211). These results indicated that
adoption of a Ginkgo-crop combination could lead to increased long-term sustainability of soil fertility by improving levels
of soil organic matter, pH, available nutrient and soil enzyme activity. 相似文献
18.
Residue retention is an important issue in evaluating the sustainability of production forestry. However, its long-term impacts have not been studied extensively, especially in sub-tropical environments. This study investigated the long-term impact of harvest residue retention on tree nutrition, growth and productivity of a F1 hybrid (Pinus elliottii var. elliottii × Pinus caribaea var. hondurensis) exotic pine plantation in sub-tropical Australia, under three harvest residue management regimes: (1) residue removal, RR0; (2) single residue retention, RR1; and (3) double residue retention, RR2. The experiment, established in 1996, is a randomised complete block design with 4 replicates. Tree growth measurements in this study were carried out at ages 2, 4, 6, 8 and 10 years, while foliar nutrient analyses were carried out at ages 2, 4, 6 and 10 years. Litter production and litter nitrogen (N) and phosphorus (P) measurements were carried out quarterly over a 15-month period between ages 9 and 10 years. Results showed that total tree growth was still greater in residue-retained treatments compared to the RR0 treatment. However, mean annual increments of diameter at breast height (MAID) and basal area (MAIB) declined significantly after age 4 years to about 68–78% at age 10 years. Declining foliar N and P concentrations accounted for 62% (p < 0.05) of the variation of growth rates after age 4 years, and foliar N and P concentrations were either marginal or below critical concentrations. In addition, litter production, and litter N and P contents were not significantly different among the treatments. This study suggests that the impact of residue retention on tree nutrition and growth rates might be limited over a longer period, and that the integration of alternative forest management practices is necessary to sustain the benefits of harvest residues until the end of the rotation. 相似文献
19.
Trees in farming systems can improve fertility of soils through mineralization of N in their litter. This study was to determine
the quality parameters (i.e., chemical composition) of organic residues that are associated with N mineralization in soils
under submerged and aerobic conditions, and to demonstrate that aeration conditions should be taken into account in categorization
of organic residues as N sources in farming systems. Incubation experiments were conducted in Aeric Paleaquult soil under
submerged and Oxic Paleustult soil under aerobic conditions. Treatments included litter and some fresh materials from trees
as well as rice straw available in farming systems of Northeast Thailand. S. grandiflora and L. leucocephala (32 g kg−1 N) had the highest net N mineralization in both conditions. Some lower-quality (< 20 g kg−1 N) residues did exhibit low net N mineralization during the 16-week period under submerged conditions, but displayed almost
no net N mineralization in aerobic conditions. Under submerged conditions, their net N mineralization was higher and more
rapid. The nitrogen content of the residues was the most important factor controlling N mineralization under both conditions.
Polyphenols exerted the highest negative influence on N mineralization in aerobic conditions, but exhibited no negative effect
in submerged conditions. In categorizing organic residues for their effective use in soil fertility management, soil aeration
conditions, as well as other environmental factors, should be taken into consideration in addition to residue quality. 相似文献
20.
Matti Uimonen 《Southern Forests》2013,75(1):4-7
The final results are presented of a comprehensive N, P,K and dolomitic lime factorial experiment with Eucalyptus grandis planted on a fully cultivated Mispah soil series. On this marginal site, fertilising had a marked effect on the growth of E. grandis as measured at clearfelling at eight years and three months. The response to single fertiliser elements was greatest for potassium, followed by phosphorus and nitrogen, dolomitic lime having a depressive effect. The best N:P elemental fertiliser ratio was 3:1, while that for P:K was 1:3. Overall, an elemental N:P:K mixture of 3:1:3 was superior, increasing growth with rate of application. Fertilising with 100 g LAN (26% N), 100 g single superphosphate (8,3% P) and 50 g potassium chloride (50% K) increased yields at clearfelling from 56,7 t/ha for no fertiliser to 85.0 t/ha, an improvement of 49,8%. This fertiliser application is recommended for planting E. grandis on shallow soils derived from Ecca shale. Fertiliser treatments also affected form factor significantly, ranging from 0,370 to 0,411 and resulting in volume differences of 11.1% for trees with the same D.B.H. and height. Not only was the response to fertilising highly profitable in itself, but it also rendered the establishment of E. grandis to be viable on an otherwise uneconomically suitable site. 相似文献