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1.
Increasing phosphorus supply in subsurface soil in northern Australia: Rationale for deep placement and the effects with various crops 总被引:6,自引:0,他引:6
Three field experiments involving wheat, lucerne or cotton were established at different sites in the semiarid cropping regions
of northern Australia, to test whether the deep placement of P fertiliser improved P availability, compared to the conventional
practice of placing the fertiliser beside or adjacent to the seed. At Mulga View, near St George in southern Queensland on
a red Kandosol soil with a Colwell soil test value of 19 mg P kg soil−1 in the top 10 cm, there was no response to 10 kg P ha−1 applied in the 5–7 cm layer. However, increasing the depth of placement of 10 kg P ha−1 from 5–7 to 10–15 cm resulted in increased shoot growth and grain yield of spring wheat (Triticum aestivum) by 43 and 30%, respectively. A further grain yield increase of 43% to 3.2 t ha−1 resulted when the deep P rate was increased from 10 to 40 kg P ha−1. At Roma, in southern Queensland, on a grey/brown Vertosol with a Colwell soil test value of 15 mg P kg soil−1, there was no difference in the winter growth of lucerne (Medicago sativa) when P fertiliser had been applied at 5–7 cm depth at rates of 10 and 40 kg P ha−1. Shoot dry matter yields were around 2 t ha−1. However dry matter yields increased significantly to 2.6 and 3.7 t ha−1 when 10 and 40 kg P ha−1, respectively were applied at the 10–15 cm depth. The third experiment was carried out on a grey Vertosol at Kununurra in
Western Australia. Significant increases in the yield of seed cotton (Gossypium hirsutum) occurred when 50 kg P ha−1 was applied at depth (10–15 and 25–30 cm), compared with the conventional placement at 7–10 cm, with maximum yield response
to deep placement occurring with DAP, and the minimal response with MAP. The cotton was grown on raised beds and the crop
was irrigated according to district practice. The response to deep P at all sites was attributed to the rapid drying of the
soil surface layers, reducing the availability of soil or fertiliser P in these layers. The deep fertiliser P remained available
during the growing season and alleviated the P deficiency that appears to be a feature of these soils when the surface layers
become dry. 相似文献
2.
Root growth,macro-nutrient uptake dynamics and soil fertility requirements of a high-yielding winter oilseed rape crop 总被引:2,自引:0,他引:2
P. B. Barraclough 《Plant and Soil》1989,119(1):59-70
Shoot growth, root growth and macro-nutrient uptake by a high-yielding (5t/ha grain) winter oilseed rape crop have been measured.
Maximum rooting density in the top 20cm of soil was 9.4 cm cm−3 and roots reached a depth of at least 1.8 m. Maximum nutrient uptakes were 364 kg ha−1 for N, 43 kg ha−1 for P, 308 kg ha−1 for K, 287 kg ha−1 for Ca and 16 kg ha−1 for Mg. A 30-day drought coincided with the flowering period and root and shoot growth, as well as nutrient uptake rates,
were reduced. Nutrient concentrations in the soil solution necessary to sustain the nutrient fluxes into the root system by
diffusive supply have been calculated. Peak values were in the range 10 μM for P to 87 μM for N, lower than the observed concentrations, and it was concluded that nutrient transport to roots was not a limitation
to uptake by this rape crop. 相似文献
3.
Chris van Kessel 《Plant and Soil》1994,164(1):69-76
Although wheat (Triticum aestivum L.) is the dominant crop of the semi-arid plains of Canada and the western United States, lentil (Lens culinaris Medik.) has become an important alternative crop. Sources and seasonal accumulation of N must be understood in order to identify
parameters that can lead to increased N2-fixing activity and yield. Inoculated lentil was grown in a sandy-loam soil at an irrigated site in Saskatchewan, Canada.
Wheat was used as the reference crop to estimate N2 fixation by the A-value approach. Lentil and wheat received 10 and 100 kg N ha−1 of ammonium nitrate, respectively. Crops were harvested six times during the growing season and plant components analyzed.
During the first 71 days after planting the wheat had a higher daily dry matter and N accumulation compared to lentil. However,
during the latter part of the growing season, daily dry matter and N accumulation were greater for lentil. The maximum total
N accumulation for lentil at maturity was 149 kg ha−1. In contrast, wheat had a maximum N accumulation of 98 kg ha−1 in the Feekes 11.1 stage, or 86 days after planting. The maximum daily rates of N accumulation were 3.82 kg N ha−1 day−1 for lentil and 2.21 kg N ha−1 day−1 for wheat. The percentage of N derived from N2 fixation (% Ndfa) ranged from 0 at the first harvest to 92 % at final harvest. Generative plant components had higher values
for % Ndfa than the vegetative components which indicates that N in the reproductive plant parts was derived largely from
current N2 fixation and lentil continued to fix N until the end of the pod fill stage. At final harvest, lentil had derived 129 kg N
ha−1 from N2 fixation with maximum N2-fixing activity (4.4 kg N ha−1 day−1) occurring during the early stages of pod fill. Higher maximum rates of N2-fixing activity than net N accumulation (3.82 kg N ha−1 day−1) may have been caused by N losses like volatilization. In addition, lentil provided a net N contribution to the soil of 59
kg ha−1 following the removal of the grain. 相似文献
4.
Culm recruitment, standing crop biomass, net production and carbon flux were estimated in mature (5 years after last harvest)
and recently harvested bamboo (Dendrocalamus strictus (Roxb.) Nees) savanna sites in the dry tropics. During the 2 study years bamboo shoot recruitment was 1711–3182 and 1432–1510
shoots ha−1 in harvested and mature sites, respectively. Corresponding shoot mortality was 66–93% and 62–69%, respectively. Total biomass
was 34.9 t ha−1 at the harvested site and 47.4 t ha−1 at the mature site. Harvesting increased the relative contribution of belowground bamboo biomass. Annual litter input to
soil was 2.7 and 5.9 t ha−1 year−1 at the harvested and mature sites, respectively. The bulk of the annual litterfall (78–88%) occurred in the cool dry season
(November to February). The mean litter mass on the savanna floor ranged from 3.1 to 3.3 t ha−1; at the harvested site wood litter contributed 70% of the litter mass and at the mature site leaves formed 77% of the litter
mass. The mean total net production (TNP) for the two annual cycles was 15.8 t ha−1 year−1 at the harvested site and 19.3 t ha−1 year−1 at the mature site. Nearly half (46–57%) of the TNP was allocated to the belowground parts. Short lived components (leaves
and fine roots) contributed about four-fifths of the net production of bamboo. Total carbon storage in the system was 64.4
t ha−1 at the harvested site and 75.4 t ha−1 at the mature site, of which 23–28% was distributed in vegetation, 2% in litter and 70–75% in soil. Annual net carbon deposition
was 6.3 and 8.7 t ha−1 year−1 at harvested and mature sites, respectively. 相似文献
5.
Old growth forest soils are large C reservoirs, but the impacts of tree-fall gaps on soil C in these forests are not well
understood. The effects of forest gaps on soil C dynamics in old growth northern hardwood–hemlock forests in the upper Great
Lakes region, USA, were assessed from measurements of litter and soil C stocks, surface C efflux, and soil microbial indices
over two consecutive growing seasons. Forest floor C was significantly less in gaps (19.0 Mg C ha−1) compared to gap-edges (39.5 Mg C ha−1) and the closed forest (38.0 Mg C ha−1). Labile soil C (coarse particulate organic matter, cPOM) was significantly less in gaps and edges (11.1 and 11.2 Mg C ha−1) compared to forest plots (15.3 Mg C ha−1). In situ surface C efflux was significantly greater in gaps (12.0 Mg C ha−1 y−1) compared to edges and the closed forest (9.2 and 8.9 Mg C ha−1 y−1). Microbial biomass N (MBN) was significantly greater in edges (0.14 Mg N ha−1) than in the contiguous forest (0.09 Mg N ha−1). The metabolic quotient (qCO2) was significantly greater in the forest (0.0031 mg CO2 h−1 g−1/mg MBC g−1) relative to gaps or edges (0.0014 mg CO2 h−1 g−1/mg MBC g−1). A case is made for gaps as alleviators of old growth forest soil C saturation. Relative to the undisturbed closed forest,
gaps have significantly less labile C, significantly greater in situ surface C efflux, and significantly lower decreased qCO2 values. 相似文献
6.
Selenium accumulation by sequentially grown wheat and rice as influenced by gypsum application in a seleniferous soil 总被引:2,自引:0,他引:2
A field experiment was conducted for 2 years on an alkaline calcareous seleniferous soil to study the effect of different
levels of gypsum (0.2 – 3.2 t ha−1) applied to wheat only in the first year on Se accumulation by wheat (Triticum aestivum L.) – rice (Oryza sativa L.) cropping sequence. With gypsum application, grain yield of both rice and wheat crops increased by 0.4 – 0.5 t ha−1; the increase in straw yield was 0.4 – 1.1 t ha−1. Significant reduction in Se accumulation by wheat was observed with gypsum application up to 0.8 t ha−1 and its residual effect was evident on the following crops for 2 years. Reduction in Se accumulation varied from 53 to 64%
in wheat grain, 46 to 49% in wheat straw, 35 to 63% in rice grain and 36 to 51% in rice straw with an application of gypsum
at 0.8 t ha−1. A corresponding increase in S concentration was observed. In the gypsum-treated plots, the ratio of S:Se increased by 6
– 8 times in wheat and 3 – 6 times in rice. Reduction in Se accumulation by crop plants through gypsum application may help
in lowering the risk of Se over-exposure of animals and humans that depend on diet materials grown on high selenium soils.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
7.
Mingsheng Fan Xuejun Liu Rongfeng Jiang Fusuo Zhang Shihua Lu Xiangzhong Zeng Peter Christie 《Plant and Soil》2005,277(1-2):265-276
A field experiment was conducted for 5 years to examine the effects of non-flooded mulching cultivation on crop yield, internal
nutrient efficiency and soil properties in rice–wheat (R–W) rotations of the Chengdu Plain, southwest China. Compared with
traditional flooding (TF), non-flooded plastic film mulching (PM) resulted in 12 and 11% higher average rice (Oryza sativa L.) yield and system productivity (combined rice and wheat yields), and the trends in rice and wheat (Triticum aestivum L.) yields under PM were stable over time. However, non-flooded wheat straw mulching (SM) decreased average rice yield by
11% compared with TF, although no significant difference in system productivity was found between SM and TF. Uptakes of N
and K by rice under PM were higher than those under TF and SM, but internal nutrient efficiency was significantly lower (N)
or similar (K) under PM compared to SM and TF. This implies that more N and K accumulated in rice straw under PM. After 5-year
rice–wheat rotation, apparent P balances (112–160 kg ha−1) were positive under all three cultivation systems. However, the K balances were negative under PM (−419 kg ha−1) and TF (−90 kg ha−1) compared with SM (45 kg ha−1). This suggests that higher K inputs from fertilizer, straw or manure may be necessary, especially under PM. After five rice
seasons and four wheat seasons, non-flooded mulching cultivation led to similar (PM) or higher (SM) soil organic carbon (SOC),
total N (TN) and alkali hydrolyzable N (AH-N) in the top 0–5 and 5–12 cm layers compared with TF. SOC, TN, AH-N and Olsen-P
(OP) in the sub-surface layer (12–24 cm) were significantly higher under PM or SM than under TF, indicating that rice under
non-flooded mulching conditions may fail to make use of nutrients from the subsoil. Thus, the risk of decline in soil fertility
under non-flooded mulching cultivation could be very low if input levels match crop requirements. Our data indicate that PM
and SM may be alternative options for farmers using R–W rotations for enhancement or maintenance of system productivity and
soil fertility. 相似文献
8.
Quanxiao Fang Qiang Yu Enli Wang Yuhai Chen Guoliang Zhang Jing Wang Longhui Li 《Plant and Soil》2006,284(1-2):335-350
There is a growing concern about excessive nitrogen (N) and water use in agricultural systems in North China due to the reduced
resource use efficiency and increased groundwater pollution. A two-year experiment with two soil moisture by four N treatments
was conducted to investigate the effects of N application rates and soil moisture on soil N dynamics, crop yield, N uptake
and use efficiency in an intensive wheat–maize double cropping system (wheat–maize rotation) in the North China Plain. Under
the experimental conditions, crop yield of both wheat and maize did␣not␣increase significantly at N rates above 200 kg N ha−1. Nitrogen application rates affected little on ammonium-N (NH4-N) content in the 0–100 cm soil profiles. Excess nitrate-N (NO3-N), ranging from 221 kg N ha−1 to 620 kg N ha−1, accumulated in the 0–100 cm soil profile at the end of second rotation in the treatments with N rates of 200 kg N ha−1 and 300 kg N ha−1. In general, maize crop has higher N use efficiency than wheat crop. Higher NO3-N leaching occurred in maize season than in wheat season due to more water leakage caused by the concentrated summer rainfall.
The results of this study indicate that the optimum N rate may be much lower than that used in many areas in the North China
Plain given the high level of N already in the soil, and there is great potential for reducing N inputs to increase N use
efficiency and to mitigate N leaching into the groundwater. Avoiding excess water leakage through controlled irrigation and
matching N application to crop N demand is the key to reduce NO3-N leaching and maintain crop yield. Such management requires knowledge of crop water and N demand and soil N dynamics as
they change with variable climate temporally and spatially. Simulation modeling can capture those interactions and is considered
as a powerful tool to assist in␣the␣future optimization of N and irrigation managements.
Section Editor: L. Wade 相似文献
9.
The present study was undertaken to assess the benefit and compare the functioning of AM fungi on wheat grown conventionally
and on beds. Ten treatment combinations were used, treatments 1 and 2: no fertilizers with and without arbuscular mycorrhizal
(AM) fungi (In vitro produced Glomus intraradices); 3:100% of recommended NPK: (120 kg ha−1 N; 60 kg ha−1 P; 50 kg ha−1 K), and 4 and 5: 75% of recommended NPK dose with and without AM inoculation in a 5 × 2 split-plot design on wheat using
conventional/flat system and elevated/raised bed system. The maximum grain yield (3.84 t ha−1) was obtained in AM fungi inoculated plots of raised bed system applied with 75% NPK and was found higher (although non-
significant) than the conventional (3.73 t ha−1) system. The AM inoculation at 75% fertilizer application can save 8.47, 5.38 kg P and 16.95, 10.75 kg N ha−1, respectively, in bed and conventional system. While comparing the yield response with 100% fertilizer application alone,
AM inoculation was found to save 20.30, 15.79 kg P and 40.60, 31.59 kg N ha−1, respectively, in beds and conventional system. Mycorrhizal inoculation at 75% NPK application particularly in raised bed
system seems to be more efficient in saving fertilizer inputs and utilizing P for producing higher yield and growth unlike
non-mycorrhizal plants of 100% P. Besides the yield, mycorrhizal plants grown on beds had higher AM root colonization, soil
dehydrogenases activity, and P-uptake. The present study indicates that the inoculation of AM fungi to wheat under raised
beds is better response (although non-significantly higher) to conventional system and could be adopted for achieving higher
yield of wheat at reduced fertilizer inputs after field validation. 相似文献
10.
Yuji Isagi 《Ecological Research》1994,9(1):47-55
Gross production and carbon cycling in aPhyllostachys bambusoides stand in Kyoto Prefecture, central Japan, were determined, and then a compartment model showing the carbon stock and cycling
within the ecosystem was developed. Aboveground carbon stock was 52.3 tC ha−1, increasing at a rate of 3.6 tC ha−1 year−1. Belowground carbon stock was 20.8 tC ha−1 in the root system and 92.0 tC ha−1 in the soil. Aboveground net production was 11.2 tC ha−1 year−1. Belowground net production was crudely estimated at 4.5 tC ha−1 year−1. The gross production was estimated at 41.8 tC ha−1 year−1 by summing the amount of outflow to the environment and the increment in biomass. Leaves consumed 13.7 tC ha−1 year−1 by respiration; the rest (41.8−13.7=28.1 tC ha−1 year−1) was surplus production of the leaves and flowed into the other compartments. The amounts of construction and maintenance
respiration of the aboveground compartments were 3.4 and 18.5 tC ha−1 year−1, respectively. The annual amount of soil respiration was 11.2 tC ha−1 year−1. Soil respiration levels of 4.3 and 3.1 tC ha−1 year−1 were estimated for the flow of root respiration and root detritus. The proportion of net to gross production was 37%, which
fell within the range of young and mature forests. A shorter life span of culms, compared to tree trunks, resulted in smaller
biomass accumulation ratio (biomass/net production) in the ecosystem, of 4.66. 相似文献
11.
Plant biomass, mineral composition and the amounts of nutrients in the different fractions of the vegetation were determined
for a dense dry deciduous forest growing on light red sands in south-western Madagascar. Complete harvesting and soil coring
were used to determine the above- and below-ground biomass respectively. The above-ground biomass, weighing 118 t ha−1 (dry matter), was mostly (96%) made up of phanerophytes (woody trees and shrubs >25 cm tall). Dead material (litter and dead
wood on the soil surface) represented 13.8 t ha−1. These results fit well into the range of values reported for other tropical ecosystems. The below-ground biomass was 17.8 t ha−1 giving a root/shoot ratio of 0.15. Rooting is superficial. The nutrient concentration in this dry forest on light reddish-brown
sands is, as in other dry forests, considerably higher than that usually found for humid forests. Calcium is the most abundant
element. The plant biomass Ca/K ratio is much higher than that of humid tropical forests. In spite of its high originality,
this Madagascan dry forest has the same behaviour as other dry forests of the world. 相似文献
12.
Conventionally Tilled and Permanent Raised Beds with Different Crop Residue Management: Effects on Soil C and N Dynamics 总被引:1,自引:0,他引:1
B. Govaerts K. D. Sayre J. M. Ceballos-Ramirez M. L. Luna-Guido A. Limon-Ortega J. Deckers L. Dendooven 《Plant and Soil》2006,280(1-2):143-155
Conservation tillage in its version of permanent bed planting under zero-tillage with crop residue retention has been proposed
as an alternative wheat production system for northwest Mexico. However, little is known about the dynamics of C and N in
soils under wheat/maize on permanent beds (PB) where straw was burned, removed, partly removed or retained, as opposed to
conventionally tilled beds (CTB) where straw was incorporated. We investigated the dynamics of soil C and N and normalized
difference vegetative index (NDVI) crop values in zero-tilled PB and CTB after 26 successive maize and wheat crops. Organic
C and total N were respectively, 1.15 and 1.17 times greater in PB with straw partly removed and with straw retained on the
surface, than in CTB with straw incorporated. Organic C and total N were 1.10 times greater in soils with 300 kg N ha−1 added than in unfertilized soil. Cumulative production of CO2 was lower under CTB with straw incorporated than under PB treatments, and CO2 production increased with increments in inorganic fertilizer. The N-mineralization rate was 1.18 times greater than in unamended
soils when 150 kg inorganic N ha−1 was applied, and 1.48 times greater when 300 kg inorganic N ha−1 was added. The N-mineralization rate was significantly (1.66 times) greater in PB where the straw was burned or retained
on the surface than in CTB where the straw was incorporated, but significantly (1.25 times) lower than in PB with straw partly
removed. The NDVI values reached a maximum 56 days after planting and decreased thereafter. The NDVI for unfertilized soil
were similar for CTB with straw incorporated, PB with straw partly removed, and PB with straw retained on the surface, but
significantly lower for PB with straw burned and PB with straw removed. In soils to which 150 or 300 kg N ha−1 was added, NDVI was significantly lower for PB with straw burned than for other treatments. Among other things, this suggests
the utility of rotating maize or wheat with crops whose residues have lower C–N ratios, thus avoiding immobilization of large
amounts of N for extended periods. PB with residue burning, however, is an unsustainable practice leading to low crop performance
and soil and environmental degradation. 相似文献
13.
Toshiyuki Ohtsuka Wenhong Mo Takami Satomura Motoko Inatomi Hiroshi Koizumi 《Ecosystems》2007,10(2):324-334
Biometric based carbon flux measurements were conducted over 5 years (1999–2003) in a temperate deciduous broad-leaved forest
of the AsiaFlux network to estimate net ecosystem production (NEP). Biometric based NEP, as measured by the balance between
net primary production (including NPP of canopy trees and of forest floor dwarf bamboo) and heterotrophic respiration (RH),
clarified the contribution of various biological processes to the ecosystem carbon budget, and also showed where and how the
forest is storing C. The mean NPP of the trees was 5.4 ± 1.07 t C ha−1 y−1, including biomass increment (0.3 ± 0.82 t C ha−1 y−1), tree mortality (1.0 ± 0.61 t C ha−1 y−1), aboveground detritus production (2.3 ± 0.39 t C ha−1 y−1) and belowground fine root production (1.8 ± 0.31 t C ha−1 y−1). Annual biomass increment was rather small because of high tree mortality during the 5 years. Total NPP at the site was
6.5 ± 1.07 t C ha−1 y−1, including the NPP of the forest floor community (1.1 ± 0.06 t C ha−1 y−1). The soil surface CO2 efflux (RS) was averaged across the 5 years of record using open-flow chambers. The mean estimated annual RS amounted to
7.1 ± 0.44 t C ha−1, and the decomposition of soil organic matter (SOM) was estimated at 3.9 ± 0.24 t C ha−1. RH was estimated at 4.4 ± 0.32 t C ha−1 y−1, which included decomposition of coarse woody debris. Biometric NEP in the forest was estimated at 2.1 ± 1.15 t C ha−1 y−1, which agreed well with the eddy-covariance based net ecosystem exchange (NEE). The contribution of woody increment (Δbiomass + mortality)
of the canopy trees to NEP was rather small, and thus the SOM pool played an important role in carbon storage in the temperate
forest. These results suggested that the dense forest floor of dwarf bamboo might have a critical role in soil carbon sequestration
in temperate East Asian deciduous forests. 相似文献
14.
A study was made over 3 years to find out an optimum rate of Zn application for the maize–mungbean–rice cropping system in
a calcareous soil of Bangladesh. Zinc application was made at 0, 2 and 4 kg ha−1 for maize (cv. Pacific 984, Thai hybrid) and at 0, 1 and 2 kg ha−1 for rice (cv. BRRI dhan33), with no Zn application for mungbean (cv. BARI mung5). Effect of Zn was evaluated in terms of
yield and mineral nutrients contents (N, P, S and Zn). All the three crops responded significantly to Zn application. The
optimum rate of Zn for the maize–mungbean–rice cropping system was found to be 4–0–2 kg ha−1 for the first year and 2–0–2 kg ha−1 for subsequent years particularly when mungbean residue was removed, and such rates for mungbean residue incorporation being
4–0–1 and 2–0–1 kg ha−1, respectively. For all crops, the Zn and N concentrations of grain were significantly increased with Zn application. For
the case of grain-S, the concentration was significantly increased for maize and mungbean, but it remained unchanged for rice.
The grain-P concentration on the other hand tended to decrease with Zn application. For maize, the grain-Zn concentration
increased to 27.0 μg g−1 due to 2 kg Zn ha−1 treatment from 16.5 μg g−1 for Zn control and at higher Zn rate (4 kg Zn ha−1) the increment was very minimum. Another field experiment was performed over 3 years on the same soil to screen out maize
varieties for Zn efficiency. Of the eight varieties tested, the BARI maize 6 and BARI hybrid maize 3 were found Zn in-responsive
(Zn efficient) and the others Zn responsive (Zn-inefficient). 相似文献
15.
The effects on growth, quality and N uptake by turfgrass (Cynodon dactylon L.) during sod production of four fertiliser types applied at three application rates (100, 200 or 300 kg N ha−1 per ‘crop’) under two irrigation treatments (70% and 140% daily replacement of pan evaporation) were investigated. The fertiliser
types were: water-soluble (predominately NH4NO3), control-release, pelletised poultry manure, and pelletised biosolids; and the experiment was conducted on a sandy soil
in a Mediterranean-type climate. Plots were established from rhizomes, with the turfgrass harvested as sod every 16–28 weeks
depending upon the time of the year. Four crops were produced during the study. Applying water-soluble and control-release
fertilisers doubled shoot growth and improved turfgrass greenness by up to 10% in comparison with plots receiving pelletised
poultry manure and pelletised biosolids. Nitrogen uptake into the shoots after four crops (averaged across irrigation treatments
and N rates) was 497 kg N ha−1 for the water-soluble fertiliser, 402 kg N ha−1 for the control-release, 188 kg N ha−1 for the pelletised poultry manure and 237 kg N ha−1 for the pelletised biosolids. Consequently, the agronomic nitrogen-use efficiency (NAE, kg DM kg−1 N applied) of the inorganic fertilisers was approximately twice that of the organic fertilisers. Increasing irrigation from
70% to 140% replacement of pan evaporation was detrimental to turfgrass growth and N uptake for the first crop when supplied
with the water-soluble fertiliser. Under the low irrigation treatment, inorganic N fertilisers applied at 200–300 kg N ha−1 were adequate for production of turfgrass sod.
Section Editor: P. J. Randall 相似文献
16.
Development of ground vegetation biomass and nutrient pools in a clear-cut disc-plowed boreal forest
Marjo Palviainen Leena Finér Ari Laurén Hannu Mannerkoski Sirpa Piirainen Michael Starr 《Plant and Soil》2007,297(1-2):43-52
Nutrient leaching from forest substrate after clear-cutting and subsequent soil preparation is strongly influenced by the
capacity of ground vegetation to sequester the released nutrients. We studied the rates and patterns of biomass and nutrient
accumulation in ground vegetation growing on ridges, in furrows and on undisturbed surfaces for 2–5 years after disc-plowing
in eastern Finland. The biomass of mosses on ridges remained significantly lower than that in furrows and on undisturbed surfaces.
Field layer biomass on ridges and in furrows was significantly lower than on undisturbed surfaces throughout the study period.
Field layer biomass increased more on ridges than in furrows. Root biomass on ridges and undisturbed surfaces was considerably
higher than in furrows. Five years after disc-plowing, total biomass and nutrient pools for ridges (biomass 4,975 kg ha−1, N 40 kg ha−1, P 5 kg ha−1, K 20 kg ha−1 and Ca 18 kg ha−1) and undisturbed surfaces (biomass 5,613 kg ha−1, N 43 kg ha−1, P 5 kg ha−1, K 22 kg ha−1 and Ca 18 kg ha−1) were similar, but considerably lower for furrows (biomass 1,807 kg ha−1, N 16 kg ha−1, P 2 kg ha−1, K 10 kg ha−1 and Ca 6 kg ha−1). Ridges covered 25% of the area, furrows 30 and 45% was undisturbed surfaces. Taking into account the proportion of each
type of surface, values for the whole prepared clear-cut area were 4,312, 34, 4, 18 and 14 kg ha−1 for biomass, N, P, K and Ca, respectively. Biomass and nutrient pools had not returned to uncut forest levels at the end
of the 5-year study period. The results indicate that mosses and field layer vegetation respond differently to soil preparation,
that the development of biomass on ridges, in furrows and on undisturbed surfaces proceeds at different rates, and that the
biomass and nutrient uptake of ground vegetation remains below pre-site preparation levels for several years. However, ridges,
which are known to be the most susceptible to leaching, revegetate rapidly.
Responsible Editor: Tibor Kalapos. 相似文献
17.
Mark S. Castro Keith N. Eshleman Louis F. Pitelka Geoff Frech Molly Ramsey William S. Currie Karen Kuers Jeffrey A. Simmons Bob R. Pohlad Carolyn L. Thomas David M. Johnson 《Biogeochemistry》2007,84(3):333-348
The objective of this study was to evaluate the nitrogen (N) biogeochemistry of an 18–22 year old forested watershed in western
Maryland. We hypothesized that this watershed should not exhibit symptoms of N saturation. This watershed was a strong source
of nitrate (NO3
−) to the stream in all years, with a mean annual export of 9.5 kg N ha−1 year−1 and a range of 4.4–18.4 kg N ha−1 year−1. During the 2001 and 2002 water years, wet deposition of inorganic N was 9.0 kg N ha−1 year−1 and 6.3 kg N ha−1 year−1, respectively. Watershed N export rates in 2001 and 2002 water years were 4.2 kg N ha−1 year−1 and 5.3 kg N ha−1 year−1, respectively. During the wetter water years of 2003 and 2004, the watershed exported 15.0 kg N ha−1 year−1 and 18.4 kg N ha−1 year−1, rates that exceeded annual wet deposition of N by a factor of two (7.5 kg N ha−1 year−1 in 2003) and three (5.5 kg N ha−1 year−1 in 2004). Consistent with the high rates of N export, were high concentrations (2.1–3.3%) of N in foliage, wood (0.3%) and
fine roots, low C:N ratios in the forest floor (17–24) and mineral soil (14), high percentages (83–96%) of the amount of mineralized
N that was nitrified and elevated N concentrations (up to 3 mg N l−1) in soil solution. Although this watershed contained a young aggrading forest, it exhibited several symptoms of N saturation
commonly observed in more mature forests. 相似文献
18.
Soil carbon storage, litterfall and CO2 efflux in fertilized and unfertilized larch (Larix leptolepis) plantations 总被引:1,自引:0,他引:1
Choonsig Kim 《Ecological Research》2008,23(4):757-763
This study evaluated the effects of forest fertilization on the forest carbon (C) dynamics in a 36-year-old larch (Larix leptolepis) plantation in Korea. Above- and below-ground C storage, litterfall, root decomposition and soil CO2 efflux rates after fertilization were measured for 2 years. Fertilizers were applied to the forest floor at rates of 112 kg
N ha−1 year−1, 75 kg P ha−1 year−1 and 37 kg K ha−1 year−1 for 2 years (May 2002, 2003). There was no significant difference in the above-ground C storage between fertilized (41.20 Mg C
ha−1) and unfertilized (42.25 Mg C ha−1) plots, and the C increment was similar between the fertilized (1.65 Mg C ha−1 year−1) and unfertilized (1.52 Mg C ha−1 year−1) plots. There was no significant difference in the soil C storage between the fertilized and unfertilized plots at each soil
depth (0–15, 15–30 and 30–50 cm). The organic C inputs due to litterfall ranged from 1.57 Mg C ha−1 year−1 for fertilized to 1.68 Mg C ha−1 year−1 for unfertilized plots. There was no significant difference in the needle litter decomposition rates between the fertilized
and unfertilized plots, while the decomposition of roots with 1–2 mm diameters increased significantly with the fertilization
relative to the unfertilized plots. The mean annual soil CO2 efflux rates for the 2 years were similar between the fertilized (0.38 g CO2 m−2 h−1) and unfertilized (0.40 g CO2 m−2 h−1) plots, which corresponded with the similar fluctuation in the organic carbon (litterfall, needle and root decomposition)
and soil environmental parameters (soil temperature and soil water content). These results indicate that little effect on
the C dynamics of the larch plantation could be attributed to the 2-year short-term fertilization trials and/or the soil fertility
in the mature coniferous plantation used in this study. 相似文献
19.
During 1999–2001 the chemical composition and fluxes were measured in rainfall, throughfall, soil solution and stream water
in a remote forested site in the Italian Alps. The analysis of temporal patterns revealed the differential behaviour of nitrogen
and sulphur and suggested that different mechanisms controlled their flux. No important changes in sulphate concentration
and fluxes emerged as the solution passed through the various components of the forest ecosystem, and temporal variations
of SO4 in the soil solution and stream were likely driven by the physical process of dilution. The availability of nitrate and ammonia,
by contrast, was drastically reduced as throughfall water entered the soil and passed through the mineral layers, irrespective
of season. The calculated hydrochemical budget based on throughfall and soil solution N fluxes revealed that ~80% N retention
in the forest soil, corresponding to 12 kg ha−1 yr−1, despite a relatively high N deposition loading (15 kg ha−1 yr−1). Most of the leached nitrogen (90%) was in the organic form. Indicators of the N status of this ecosystem, such as C/N ratio
in solid and solution phase of the soil and N foliage content as well as land use history were examined. Despite the strong
N retention in the forested part of the catchment, the stream water N–NO3 levels were consistently above 10 μg l−1 suggesting that the Val Masino catchment as a whole was less efficient in processing atmospheric N inputs. This contrasting
N behaviour illustrates the role of landscape features, such as the soil cover and vegetation type, that is characteristic
of an alpine catchment. 相似文献
20.
Six pesticides and two spray oils were tested against Polyphagotarsonemus latus. The chemicals were evaluated under laboratory conditions, requiring the development of a novel bioassay method, which is reported here. The pesticide toxicities fell into three distinct groups, namely abamectin, conventional pesticides and oils. The relative pesticide toxicities at the LC50 level were abamectin 4.9×10-8 g ai l-1, endosulfan 1.1×10-3 g ai l-1, fenpyroximate 2.3×10-3 g ai l-1, pyridaben 4.1×10-3 g ai l-1, tebufenpyrad 4.4×10-3 g ai l-1, dicofol 4.5×10-3 g ai l-1, petroleum spray oil 3.4×10-1 g ai l-1 and canola oil 4.1×10-1 g ai l-1. The calculation of the LC99.9 values allows for resistance monitoring in P. latus and the suggested discriminating concentrations are abamectin 1.0×10-4 g ai l-1; endosulfan, pyridaben and dicofol 1.0×10-1 g ai l-1 fenpyroximate and tebufenpyrad 5.0×10-1 g ai l-1. 相似文献