共查询到20条相似文献，搜索用时 406 毫秒
1.
Twenty fertilization experiments were set up in 1985 and 1986 in the Vosges mountains, using mostly calcareous or Mg fertilizers, in order to verify whether fertilization can attenuate defoliation and yellowing recently recorded in Silver fir and Norway spruce. In the Ardennes, a fertilization experiment set up in Norway spruce stands prior to the appearance of yellowing was assessed. In these areas, the total acid deposition is about 2 kg eq H+ ha–1 yr–1. Nitrogen deposition is much more important in the Ardennes (52 kg N ha–1 yr–1 in form of wet and dry deposition) than in the Vosges (16 kg N ha–1 yr–1). The results in the eight adult stands showed no uniform reaction to the treatments. Spontaneous improvement, further deterioration independently of the treatment, as well as a positive reaction to fertilization were observed. Additional N or P fertilization sometimes had a beneficial effect on Ca or Mg treatments. The selection of the stands with the best response turns out to be difficult, as the nutrient contents of needles alone seem not to be a satisfactory criterion for selection. Young plantations reacted positivley to the treatments. Soluble Mg fertilizer leads to an immediate response. Low solubility Ca-Mg fertilizers (Ca-Mg lime) did not produce reactions until three years after the application. In the Ardennes, in a 40 yr old spruce stand suffering from severe Mg deficiency, a Ca and Ca-phosphate fertilization applied 5 yr before yellowing appeared had positive effects on crown density, discoloration and wood production. Conversely, a single N fertilization in this experiment, as well as in a young plantation in the Vosges, had a marked negative effect on Mg nutrition, even at low levels. 相似文献
2.
A trial testing of the effect of several types of Mg fertilizer was established in a 9 yr old plantation of Norway spruce
at the Col du Donon in the Vosgian mountains (France). The plantation, which had exhibited symptoms of Mg deficiency (yellowing),
had been fertilized 5 yr prior to this study with 40 kg ha−1 of Mg applied as Epsom-salts. This alleviated the deficiency symptoms, but the yellowing reappeared 3 yr after the fertilization
and increased until the year in which the second fertilization trial (described in this paper) was established. Five Mg fertilizers
(2 forms of slag, 2 forms of limestone, and Epsom-salts) at two rates of Mg (40 and 80 kg ha−1) were compared to a control. Just after this second fertilization, the trees became green again and small positive effects
on circumference and basal area increments has been observed. However, 12 yr after the treatment, there were no differences
between the treatments regarding needle coloration, circumference, basal area or volume. 相似文献
3.
Lars Owe Nilsson 《Water, air, and soil pollution》1993,70(1-4):177-186
Carbon sequestration in 30 yr old Norway spruce in south Sweden following manipulation of nutrient and water availability is presented. The site has an annual precipitation of 1100 mm and a deposition of about 20 kg N and 25 kg S per ha?1 yr?1. The soil type is a poorly developed podzol. Treatment include irrigation; artificial drought; ammonium sulphate addition; nitrogen-free-fertilization and irrigation with liquid fertilizers including a complete set of nutrients. The experiment has a randomized block design with four replicates per treatment. A comprehensive investigation of the above ground C storage on an areal basis was made at the start of the experiment and after 3 yr of treatment. After 3 yr of treatment with simulated N-S deposition using ammonium sulphate (100 kg N, 114 kg S ha?1 yr?1), C accumulation rates in the above ground compartments had increased by 37%. Similarly, irrigation caused increased C accumulation rates by 25%, whereas simulated drought during the vegetation period during 2 yr followed by 1 yr of recovery caused a 15% reduction of the C accumulation rates. Irrigation combined with liquid fertilization (100 kg N ha?1 yr?1), including all important nutrient elements, led to 65% increase in C accumulation rates compared to the control. The C sequestration of the latter treatment gradually increased and, during yr 5 of treatment, 8.6 Mg C ha?1 accumulated in stems and branches, compared to 3.6 Mg ha?1 for the control. It is concluded that there is a strong interaction between N-deposition and C accumulation rates in Norway spruce in south Sweden. The C accumulation rates are also sensitive to water availability. The study indicates a great potential to cultivate Norway spruce in south Sweden as a renewable energy source. A shift in energy source from fossil fuels to renewable energy sources will directly reduce the net emissions of CO2 to the atmosphere. 相似文献
4.
A trial testing of the effect of several types of Mg fertilizer was established in a 9 yr old plantation of Norway spruce at the Col du Donon in the Vosgian mountains (France). The plantation, which had exhibited symptoms of Mg deficiency (yellowing), had been fertilized 5 yr prior to this study with 40 kg ha–1 of Mg applied as Epsom-salts. This alleviated the deficiency symptoms, but the yellowing reappeared 3 yr after the fertilization and increased until the year in which the second fertilization trial (described in this paper) was established. Five Mg fertilizers (2 forms of slag, 2 forms of limestone, and Epsom-salts) at two rates of Mg (40 and 80 kg ha–1) were compared to a control. Just after this second fertilization, the trees became green again and small positive effects on circumference and basal area increments has been observed. However, 12 yr after the treatment, there were no differences between the treatments regarding needle coloration, circumference, basal area or volume. 相似文献
5.
Karin Hansen Lars Vesterdal Annemarie Bastrup-Birk Jørgen Bille-Hansen 《Water, air, and soil pollution》2007,183(1-4):293-308
The aim of this study was to evaluate the suitability of the (Ca?+?Mg?+?K)/Al and the Ca/Al ratios in soil solution as chemical criteria for forest condition in critical load calculations for forest ecosystems. The tree species Norway spruce, Sitka spruce and beech were studied in an area with high deposition of sea salt and nitrogen in the south-western part of Jutland, Denmark. Throughfall and soil water were collected monthly and analysed for pH, NO3-N, NH4-N, K, Ca, Mg, DOC and Altot. Organic Al was estimated using DOC concentrations. Increment and defoliation were determined annually, and foliar element concentrations were determined every other year. The throughfall deposition was highest in the Sitka spruce stand (maximum of 40 kg N ha?1yr?1) and lowest in the beech stand (maximum of 11 kg N ha?1yr?1). The Sitka spruce stand leached on average 12 kg N ha?1yr?1 during the period 1988–1997 and leaching increased throughout the period. Only small amounts of N were leached from the Norway spruce stand whereas almost no N was leached from the beech stand. For all tree species, both (Ca?+?Mg?+?K)/Al and Ca/Al ratios decreased in soil solution at 90 cm depth between 1989 and 1999, which was mainly caused by a decrease in concentrations of base cations. The toxic inorganic Al species were by far the most abundant Al species at 90 cm depth. At the end of the measurement period, the (Ca?+?Mg?+?K)/Al ratio was approximately 1 for all species while the Ca/Al ratio was approximately 0.2. The lack of a trend in the increment rates, a decrease in defoliation as well as sufficient levels of Mg and Ca in foliage suggested an unchanged or even slightly improved health condition, despite the decreasing and very low (Ca?+?Mg?+?K)/Al and Ca/Al ratios. The suitability of these soil solution element ratios is questioned as the chemical criteria for soil acidification under field conditions in areas with elevated deposition rates of sea salts, in particular Mg. 相似文献
6.
Elevated atmospheric inputs of NH4+ and NO3– have caused N saturation of many forest ecosystems in Central Europe, but the fate of deposited N that is not bounded by trees remains largely unknown. It is expected that an increase of NO3– leaching from forest soils may harm the quality of groundwater in many regions. The objective of this study was to analyze the input and output of NH4+ and NO3– at 57 sites with mature forest stands in Germany. These long‐term study sites are part of the European Level II program and comprise 17 beech, 14 spruce, 17 pine, and 9 oak stands. The chloride balance method was used to calculate seepage fluxes and inorganic N leaching below the rooting zone for the period from 1996 to 2001. Nitrogen input by throughfall was significantly different among most forest types, and was in the order: spruce > beech/oak > pine. These differences can be largely explained by the amount of precipitation and, thus, it mirrors the regional and climatic distribution of these forest types in Germany. Mean long‐term N output with seepage was log‐normal distributed, and ranged between 0 and 26.5 kg N ha–1 yr–1, whereby 29 % of the sites released more than 5 kg N ha–1 yr –1. Leaching of inorganic N was only significantly lower in the pine stands (P < 0.05) compared with leaching rates of the spruce stands. Median N output : input ratio ranged between 0.04 and 0.11 for the beech, oak, and pine stands, while the input : output ratio of the spruce stands was 0.24, suggesting a higher risk of NO3– leaching in spruce forests. Following log‐transformation of the data, N input explained 38 % of the variance in N output. The stratification of the data by the C : N ratio of the O horizon or the top mineral soil revealed that forests soils with a C : N ratio < 25 released significantly more NO3– (median of 4.6 kg N ha–1 yr–1) than forests with a C : N ratio > 25 (median of 0.8 kg N ha–1 yr–1). The stratification improved the correlation between N input and N output for sites with C : N ratios < 25 (r2 = 0.47) while the correlation for sites with C : N ratios > 25 was weaker (r = 0.21) compared with the complete data set. Our results suggest that NO3– leaching may increase in soils with wide C : N ratios when N deposition remains on a high level and that the potential to store inorganic N decreases with C : N ratios in the O horizons becoming more narrow. 相似文献
7.
Elevated emissions of nitrogen oxides (NOx) in the Athabasca Oil Sands Region, Alberta and higher foliar nitrogen (N) concentrations in jack pine (Pinus banksiana) needles close to major emission sources has led to concerns that the surrounding boreal forest may become N-saturated. Despite
these concerns, N deposition and impacts on upland forests in the region is poorly quantified. The objective of this study
was to characterize N cycling in five plots representing the two dominant upland forest types (jack pine and trembling aspen,
Populus tremuloides) close (<30 km) to the largest mining operations in the region, during a 2-year period. Despite the high level of NOx emissions, bulk throughfall and deposition measured at both study sites were surprisingly very low (<2 kg N ha−1 year−1). Internal N cycling was much greater in aspen stands; annual N input in litterfall was ten times greater, and net N mineralization
rates were two to five times greater than in jack pine stands. Nitrogen use efficiency (NUE) was much greater in jack pine
when calculated based on N litterfall indices, but not when N pools in biomass were considered. Despite differences in internal
cycling among forest types, nitrate leaching from mineral soil in both forest types was negligible (<0.1 kg N ha−1 year−1) and patterns of 15N in roots, foliage, and mineral soil were typical of N-limited ecosystems, and both sites show no evidence of N saturation. 相似文献
8.
FORECAST, an ecosystem simulation model, was calibrated for aspen (Populus tremuloides Michx) and white spruce (Picea glauca (Moench) Voss) stands using data collected in the Boreal White and Black Spruce biogeoclimatic zone in northeastern British Columbia and published data. Simulations were undertaken to examine the effects of initial density of aspen on yield of white spruce in an aspen and spruce mixedwood stand, and to compare the predicted stemwood biomass yields of aspen, white spruce and mixedwood stands. Results of the simulations suggest that mixedwood management regimes on the same medium quality site should have higher stemwood yield compared to pure white spruce stand. Simulated stemwood biomass yield of pure aspen stands over 240 years on medium site varied from 682.5 Mg ha?1 to 239.1 Mg ha?1 for different rotation lengths (30 to 120 years). Repeated rotations of monoculture white spruce produced much less stemwood biomass, simulated yields over 240 years ranging from 877.3 Mg ha?1to 248.4 Mg ha?1 for rotation lengths of 60 to 240 years. Simulated aspen and white spruce mixedwood stands produced higher stemwood biomass yields than the pure white spruce stands, but less than the pure aspen stands; from 217.4 Mg ha?1 to 292.8 Mg ha?1 over 240 years. Variations in initial densities of aspen did not affect spruce stemwood biomass yield over the simulation period. This model shows potential for comparing the relative effects of different management strategies on harvestable volume and variety of other ecosystem variables. A calibrated version of the model should be useful as both a management simulator and a research tool. However, shortcomings in the representation of the canopy architecture of mixed species stands suggested the need to develop an individual tree version of this ecosystem management model for application to mixed species stands. 相似文献
9.
David M.B. Cupples A.M. Lawrence G.B. Shi G. Vogt K. Wargo P.M. 《Water, air, and soil pollution》1998,105(1-2):183-192
The responses of temperate and boreal forest ecosystems to increased nitrogen (N) inputs have been varied, and the responses of soil N pools have been difficult to measure. In this study, fractions and pool sizes of N were determined in the forest floor of red spruce stands at four sites in the northeastern U.S. to evaluate the effect of increased N inputs on forest floor N. Two of the stands received 100 kg N ha-1 yr-1 for three years, one stand received 34 kg N ha-1 yr-1 for six years, and the remaining stand received only ambient N inputs. No differences in total N content or N fractions were measured in samples of the Oie and Oa horizons between treated and control plots in the three sites that received N amendments. The predominant N fraction in these samples was amino acid N (31-45% of total N), followed by hydrolyzable unidentified N (16-31% of total N), acid-soluble N (18-22% of total N), and NH4 + (9-13% of total N). Rates of atmospheric deposition varied greatly among the four stands. Ammonium N and amino acid N concentrations in the Oie horizon were positively related to wet N deposition, with respective r2 values of 0.92 and 0.94 (n = 4, p < 0.05). These relationships were somewhat stronger than that observed between atmospheric wet N deposition and total N content of the forest floor, suggesting that these pools retain atmospherically deposited N. The NH4 + pool may represent atmospherically deposited N that is incorporated into organic matter, whereas the amino acid N pool could result from microbial immobilization of atmospheric N inputs. The response of forest floor N pools to applications of N may be masked, possibly by the large soil N pool, which has been increased by the long-term input of N from atmospheric deposition, thereby overwhelming the short-term treatments. 相似文献
10.
Nitrogen deposition and leaching in European forests — Preliminary results from a data compilation 总被引：1，自引：0，他引：1
P. Gundersen 《Water, air, and soil pollution》1995,85(3):1179-1184
Input-output fluxes of nitrogen (N) and other ecosystem data from 64 European forest ecosystem studies have been compiled in a database (ECOFEE). Sites with high N deposition (up to 64 kg N ha–1yr–1) were characterized by high input of ammonia/ammonium. The deposition of oxidized N was usually only 10 to 15 kg N ha–1yr–1 Of all the sites included, 60 % leached more than 5 kg N ha–1yr–1. Elevated nitrate leaching appeared at inputs above 10 kg N ha–1yr–1. At several sites with inputs of 15–25 kg N ha–1yr–1 nitrate leaching approached the N input, whereas ammonium dominated sites with high input still retained c. 50 % of the input. 相似文献
11.
S. Kundu Ranjan Bhattacharyya Ved Prakash H. S. Gupta H. Pathak J. K. Ladha 《Biology and Fertility of Soils》2007,43(3):271-280
A long-term (30 years) soybean–wheat experiment was conducted at Hawalbagh, Almora, India to study the effects of organic
and inorganic sources of nutrients on grain yield trends of rainfed soybean (Glycine
max)–wheat (Triticum
aestivum) system and nutrient status (soil C, N, P and K) in a sandy loam soil (Typic Haplaquept). The unfertilized plot supported
0.56 Mg ha−1 of soybean yield and 0.71 Mg ha−1 of wheat yield (average yield of 30 years). Soybean responded to inorganic NPK application and the yield increased significantly
to 0.87 Mg ha−1 with NPK. Maximum yields of soybean (2.84 Mg ha−1) and residual wheat (1.88 Mg ha−1) were obtained in the plots under NPK + farmyard manure (FYM) treatment, which were significantly higher than yields observed
under other treatments. Soybean yields in the plots under the unfertilized and the inorganic fertilizer treatments decreased
with time, whereas yields increased significantly in the plots under N + FYM and NPK + FYM treatments. At the end of 30 years,
total soil organic C (SOC) and total N concentrations increased in all the treatments. Soils under NPK + FYM-treated plots
contained higher SOC and total N by 89 and 58% in the 0–45 cm soil layer, respectively, over that of the initial status. Hence,
the decline in yields might be due to decline in available P and K status of soil. Combined use of NPK and FYM increased SOC,
oxidizable SOC, total N, total P, Olsen P, and ammonium acetate exchangeable K by 37.8, 42.0, 20.8, 30.2, 25.0, and 52.7%,
respectively, at 0–45 cm soil layer compared to application of NPK through inorganic fertilizers. However, the soil profiles
under all the treatments had a net loss of nonexchangeable K, ranging from 172 kg ha−1 under treatment NK to a maximum of 960 kg ha−1 under NPK + FYM after 30 years of cropping. Depletion of available P and K might have contributed to the soybean yield decline
in treatments where manure was not applied. The study also showed that although the combined NPK and FYM application sustained
long-term productivity of the soybean–wheat system, increased K input is required to maintain soil nonexchangeable K level. 相似文献
12.
In permanent observation plots across Switzerland, nitrogen (N) concentration in the foliage of mature beech has increased by 15% and phosphorus (P) concentrations in beech and mature Norway spruce decreased by 12 and 13% respectively between 1984 and 1995, leading to increased N:P ratios. Modelled N deposition was correlated with stem increment in both beech and spruce, with indications of P limitation in some beech plots. Experimental application of 0-160 kg N ha-1> yr-1> over four to five years caused nutrient imbalances in various afforestation plots comparable to those observed in the permanent observation plots. The changes in the trees caused by N treatment led to increased attacks by parasites such as Apiognomonia errabunda, Phomopsis sp., Phyllaphis fagi in beech and Botrytis cinerea, Sacchiphantes abietis and Cinara pilicornis in Norway spruce. The results suggest current N deposition in Switzerland induces significant changes in the forest ecosystem. 相似文献
13.
Yadvinder-Singh R. K. Gupta H. S. Thind Bijay-Singh Varinderpal-Singh Gurpreet-Singh Jagmohan-Singh J. K. Ladha 《Biology and Fertility of Soils》2009,45(7):701-710
Poultry litter (PL) is an important nutrient source; however, no information is available regarding its value in supplying
N and P in rice–wheat (RW) production. A three-year field study was conducted at Ludhiana, Punjab, India on a loamy sand soil
to identify optimum combination of PL and N and P fertilizers for a sustainable RW production. The litter was applied to rice
at 5 Mg ha−1 as a single application and supplemented with different rates of N. The residual effect of PL and the direct effects of the
different combinations of N and P were studied in the following wheat. Nitrogen and P mineralization from PL was studied under
controlled conditions in the laboratory, and macronutrient input–output balances were estimated from field results. About
46% of the N from PL was released after 60 days of incubation. The release of P from the PL occurred mainly during the initial
20 days after incubation, accounting for 15–17% of the total P. Combining PL with fertilizer N (40 kg ha−1) increased rice yield and nutrient uptake similar to what was obtained with the application of recommended fertilizer N (120 kg
ha−1). In the following wheat, the residual effect of PL was equal to 30 kg N ha−1 and 13 kg P ha−1. After three annual cropping cycles and PL application, mean soil organic C increased by 17%, Olsen-P by 73%, and NH4OAc-extractable-K by 24%. Most treatments had positive P but negative K balances. About 11% of the net P balance was recovered
from the soil as Olsen-P. The study showed that optimum N and P fertilizer doses for an RW system receiving 5 Mg ha−1 of PL are 40 kg N ha−1 for rice and 90 kg N + 13 kg P ha−1 for the following wheat. Safe and effective management of PL should be based on P balance, particularly when regular applications
of PL are to be made in the RW system. 相似文献
14.
Studies on Alnus rubra Bong. (red alder) were carried out to assess its potential for use as a component of a silvopastoral system. Comparison was
between two treatments: red alder at 400 stems ha−1 (silvopasture) and red alder at 2,500 stems ha−1 (forestry control). δ15N values close to zero were recorded in all red alder plant parts except for root nodules, indicating that a large proportion
of N in red alder was fixed from the atmosphere. Overall, it was estimated that there was 63.45 kg N ha−1 fixed N accumulated in red alder trees, and the rate of N fixation was estimated at 30.95 kg ha−1 year−1 in the silvopasture treatment. The total amount of N that could potentially be added to the soil in the silvopasture treatment
as a result of decomposition of senescent leaves, roots, and dead nodules was estimated at 40.56 kg ha−1 year−1. Of the total N added to the soil, 27.1 kg ha−1 year−1 was due to N fixation from the atmosphere. These results show that red alder has a potential to improve and maintain soil
fertility in a silvopastoral system. 相似文献
15.
Kannan Iyyemperumal James GreenJr. Daniel W. Israel Noah N. Ranells Wei Shi 《Biology and Fertility of Soils》2008,44(3):425-434
This study characterized soil chemical and microbiological properties in hay production systems that received from 0 to 600 kg
plant-available N (PAN) ha−1 year−1 from either swine lagoon effluent (SLE) or ammonium nitrate (AN) from 1999 to 2001. The forage systems contained plots planted
with bermudagrass (Cynodon dactylon L.) or endophyte-free tall fescue (Festuca arundinaceae Schreb.). In March 2004, the plots were sampled for measurements of a suite of soil chemical and microbiological properties.
Nitrogen fertilization rates were significantly correlated with soil pH and K2SO4-extractable soil C but not with total soil C, soil C/N ratio, electrical conductivity, or Mehlich-3-extractable nutrients.
Soil supplied with SLE had significantly lower Mehlich-3-extractable nutrients than the soil supplied with AN. Two indicators
of soil N-supplying capacity (potentially mineralizable N and amino sugar N) varied with plant species and the type of N fertilizer.
However, they generally peaked at an application rate of 200 or 400 kg PAN ha−1 year−1. Soil microbial biomass C also peaked at an application rate of 200 or 400 kg PAN ha−1 year−1. Nitrification potential was significantly higher in soil supplied with AN than in the unfertilized control but was similar
between SLE-fertilized and unfertilized soils. Our results indicated that an application rate as high as 600 kg PAN ha−1 year−1 did not benefit soil microbial biomass, microbial activity, and N transformation processes in these forage systems. 相似文献
16.
D. F. Karnosky Z. E. Gagnon D. D. Reed J. A. Witter 《Water, air, and soil pollution》1992,62(3-4):189-199
Elevated O3 concentrations and N deposition levels co -occur in much of eastern United States. However, very little is known about their combined effects on tree growth. The effects of three O3 treatments: charcoal-filtered air, non-filtered air and O3, added at the rate of 80 ppb for 6 hr d?1 3 d per week), four N deposition levels (0, 10, 20 and 40 kg ha?1 yr?1), and their interactions on growth of two Populus tremuloides clones in open-top chambers at two sites 600 km apart in Michigan were examined. Our results revealed a highly significant fertilization effect of the N treatments, even at the 10 kg ha?1 yr?1 rate. Ozone alone induced foliar injury, but not significant growth reductions. There was an indication that O3 decreased growth at the O N level, but this decrease was reversed in all N treatments by the N fertilization effect. Further study is needed to more fully understand the combined effects of N deposition and O3. 相似文献
17.
A field plot experiment on fertilization with N, Mg and P in Scots pine forest was established. The experiment had a factorial design with three levels of N (0, 30 and 90 kg ha?1), two levels of Mg (0 and 1.5 kg ha?1) and two levels of P (0 and 5.3 kg ha?1). The application was done annually. There was a significant growth increase for the two N treatments. During a period of 5-years the mean increase in volume increment was 2.3 and 4.5 m3 ha?1 for the 30 N and 90 N kg ha?1 yr?1 treatments, respectively. This represents a percentage increase in volume increment of 53 and 102% compared to the untreated control plots. No significant growth effect of P and Mg application was detected, either alone or in combination with N. The needle nutrient concentrations have been followed along with the annual measurements. An increase in N-concentration was detected after the first growing season in the N treated trees. After five years the Mg concentrations in the needles are lower in these treatments. The one year old needles have concentrations as low as 0.05% Mg. No visible deficiency symptoms have been observed. The field experiment effects demonstrates that N is still the most limiting nutrient under these conditions and that there is a relative large potential for N accumulation in these forest types without negative effects. 相似文献
18.
We developed a model for plant available sulfur (S) in Ohio soils to predict potential crop plant S deficiency. The model
includes inputs of plant available S due to atmospheric deposition and mineralization of soil organic S and output due to
leaching. A leaching index was computed using data on annual precipitation; soil pH and clay content that influence sulfate
adsorption; and pore water velocity based upon percent sand, silt, and clay. There are five categories of S status ranging
from highly deficient to highly sufficient, and the categories are defined based on whether the crop S requirement was 15
or 30kg S ha−1 year−1. The final database derived from the model includes 1,473 soil samples representing 443 of the 475 soil series in Ohio. For
a crop requiring 15kg S ha−1 year−1, most soils (68.6%) were classified as variably deficient, which implies that the response to S fertilization will be variable
but often positive depending on specific crop conditions. For a crop requiring 30kg S ha−1 year−1, 43.2% of soils were classified as variably deficient, but 49.7% were classified as moderately or highly deficient, implying
that a response to S fertilization will usually or always occur. The model predicts crop S status for a single state in the
USA, but with proper inputs, it should be applicable to other areas. 相似文献
19.
Nitrogen deposition, leaching, and retention were monitored in a mature spruce (Picea abies Karsten) dominated mixed boreal forest in eastern Finland. Bulk precipitation, throughfall, stemflow, and percolation through the podzolic soil profile were monitored from 1993 to 1996. Mean annual bulk deposition of total N was 3.83 kg ha-1, of which 33% was NH4 +, 26% was NO3 - , and 41% was organic N. Throughfall+stemflow flux of total N was 2.93 kg ha-1 yr-1. Sixty-four % of NH4 + and 38% of NO3 - in bulk precipitation was retained by tre three canopy. Organic N was released (0.27 kg ha-1 yr-1) from the tree canopy. Nitrate-N was retained and organic N was leached as the water passed through the ground vegetation and soil O-horizon. Ammonium-N and organic N were retained mainly in the E-horizon. The output of total N from the E-horizon was only 5% of the total N deposition in the forest stand during the study period and it was mainly as organic N. The output of inorganic N forms from under B-horizon was seasonal and occurred mainly at spring snowmelt. 相似文献
20.
A field experiment was conducted during 2003–2005 and 2004–2006 at the Indian Institute of Sugarcane Research, Lucknow, India
to study the effect of Trichoderma viride inoculation in ratoon sugarcane with three trash management practices, i.e. trash mulching, trash burning and trash removal.
Trichoderma inoculation with trash mulch increased soil organic carbon and phosphorus (P) content by 5.08 Mg ha−1 and 11.7 kg ha−1 over their initial contents of 15.75 Mg ha−1 and 12.5 kg ha−1, respectively. Soil compaction evaluated as bulk density in 0- to 15-cm soil layer, increased from 1.48 Mg m−3 at ratoon initiation (in April) to 1.53 Mg m−3 at harvest (in December) due to trash burning and from 1.42 Mg m−3 at ratoon initiation (in April) to 1.48 Mg m−3 at harvest (in December) due to trash mulching. The soil basal respiration was the highest during tillering phase and then
decreased gradually, thereafter with the advancement of crop growth. On an average, at all the stages of crop growth, Trichoderma inoculation increased the soil basal respiration over no inoculation. Soil microbial biomass increased in all plots except
in the plots of trash burning/removal without Trichoderma inoculation. The maximum increase (40 mg C kg−1 soil) in soil microbial biomass C, however, was observed in the plots of trash mulch with Trichoderma inoculation treatment which also recorded the highest uptake of nutrient and cane yield. On an average, Trichoderma inoculation with trash mulch increased N, P and K uptake by 15.9, 4.68 and 23.6 kg ha−1, respectively, over uninoculated condition. The cane yield was increased by 12.8 Mg ha−1 with trash mulch + Trichoderma over trash removal without Trichoderma. Upon degradation, trash mulch served as a source of energy for enhanced multiplication of soil bacteria and fungi and provided
suitable niche for plant–microbe interaction. 相似文献