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1.
Dissolved organic carbon loss fluxes through runoff and sediment on sloping upland of purple soil in the Sichuan Basin 总被引:1,自引:0,他引:1
Runoff is a major driver for dissolved organic carbon (DOC) diffusing into aquatic ecosystems. Transport of DOC in runoff is important in the C cycle of soils in an agricultural ecosystem. This study provides a combined dataset on DOC loss pathways and fluxes from sloping upland in the purple soil area of southwestern China. A free-drain lysimeter experiment was conducted to quantify DOC loss through overland flow (2010–2012), interflow (2010–2012) and sediment (2011–2012). Average annual cumulative discharges of overland and interflow were 58.3 ± 3.1 and 289.4 ± 5.4 mm, accounting for 6.8 and 33.8 % of the totals during the entire rainy season, respectively. Average annual cumulative sediment loss flux was 183.5 ± 14.6 g m?2. Average DOC concentrations in overland flow and interflow were 3.44 ± 0.36 and 3.04 ± 0.24 mg L?1, respectively. Average DOC content in sediment was 73.76 ± 4.09 mg kg?1. The relationship between DOC concentration and discharge in overland flow events could be described by a significant exponential decaying function (R = 0.53, P = 0.027). Average annual DOC loss fluxes through overland flow, interflow and sediment were 163.6 ± 28.5, 865.5 ± 82.5 and 9.4 ± 1.5 mg m?2, respectively, and total DOC loss was 1,038.5 ± 112.5 mg m?2. The results suggest that interflow is the major driver of DOC leaching loss on sloping upland. It is shown that interflow is fundamentally important for reducing DOC loss on sloping croplands in the Sichuan Basin and possibly beyond. 相似文献
2.
Nitrogen leaching in an upland cropping system on an acid soil in subtropical China: lysimeter measurements and simulation 总被引:4,自引:0,他引:4
The effect of rainfall and nitrogen (N) input on nitrate leaching in a rain-fed peanut–oilseed rape system on an acidic soil
in subtropical China was investigated in a field lysimeter experiment from 1997 to 2000. Drainage and nitrate leaching were
simulated using the Water and Nitrogen Management Model (WNMM). Nitrate concentrations in the drainage water and nitrate leaching
increased with increasing N application rate. Annual leaching losses ranged from 21.1 to 46.3 kg N ha−1 (9.5–16.8%) for inputs between 0 and 150 kg N ha−1. Growth of oilseed rape decreased the nitrate concentration in the drainage water, but growing N fixing peanuts did not.
Rainfall had a greater impact on nitrate leaching than crop uptake. Nitrate concentrations in the drainage water were relatively
low (1.95–4.33 mg N l−1); this was caused by the high precipitation, the low nitrification rate, and the low residual nitrate in the soil. The loss
of nitrate was low during the dry season (October–February) and in the dry year (rainfall 17% below average) mainly as a result
of reduced drainage. WNMM satisfactorily simulated the inter-monthly variation in drainage and total nitrate leached, with
respective relative root mean square errors of 42.7% and 70.2%, mean modelling efficiencies of 0.88 and 0.67, and mean relative
errors of −3.82% and 21.8%. The modelled annual N losses were only 1–7% less than the observed values. 相似文献
3.
Sarah M. Stackpoole Kevin R. Kosola Beth Ann A. Workmaster Nathan M. Guldan Bryant A. Browne Randall D. Jackson 《Nutrient Cycling in Agroecosystems》2011,91(1):41-54
Even though nitrogen (N) is a key nutrient for successful cranberry production, N cycling in cranberry agroecosystems is not
completely understood. Prior research has focused mainly on timing and uptake of ammonium fertilizer, but the objective of
our study was to evaluate the potential for additional N contributions from hydrologic inputs (flooding, irrigation, groundwater,
and precipitation) and organic matter (OM). Plant biomass, soil, surface and groundwater samples were collected from five
cranberry beds (cranberry production fields) on four different farms, representing both upland and lowland systems. Estimated
average annual plant uptake (63.3 ± 22.5 kg N ha−1 year−1) exceeded total average annual fertilizer inputs (39.5 ± 11.6 kg N ha−1 year−1). Irrigation, precipitation, and floodwater N summed to an average 23 ± 0.7 kg N ha−1 year−1, which was about 60% of fertilizer N. Leaf and stem litterfall added 5.2 ± 1.2 and 24.1 ± 3.0 kg N ha−1 year−1 respectively. The estimated net N mineralization rate from the buried bag technique was 5 ± 0.2 kg N ha−1 year−1, which was nearly 15% of fertilizer N. Dissolved organic nitrogen represented a significant portion of the total N pool in
both surface water and soil samples. Mixed-ion exchange resin core incubations indicated that 80% of total inorganic N from
fertilizer, irrigation, precipitation, and mineralization was nitrate, and approximately 70% of recovered inorganic N from
groundwater was nitrate. There was a weak but significant negative relationship between extractable soil ammonium concentrations
and ericoid mycorrhizal colonization (ERM) rates (r = −0.22, P < 0.045). Growers may benefit from balancing the N inputs from hydrologic sources and OM relative to fertilizer N in order
to maximize the benefits of ERM fungi in actively mediating N cycling in cranberry agroecosystems. 相似文献
4.
The transportation of dissolved organic nitrogen (DON) from croplands to aquatic ecosystems potentially negatively influences water quality. Sustaining crop yields while decreasing the environmental impacts of the DON from nitrogen fertilizer application is a key challenge in sustainable agriculture. However, few field datasets have measured the lateral transportation of DON via hydrological routes under different nitrogen fertilizer applications, particularly in sloping croplands. Using lysimeter plots (8?×?4 m2), we measured DON loss via overland flow, interflow, and soil erosion under different fertilizer applications under a long-term field experiment. There were four treatments, including no fertilizer (CK), mineral fertilizer (NPK), mineral fertilizer combined with swine manure (MNPK), and mineral fertilizer combined with crop straw (CNPK). In comparison to the NPK treatment, the annual DON loss fluxes via overland flow, interflow, and soil erosion for the MNPK treatment were significantly (P?<?0.05) increased by 68.8, 100.6, and 63.7%, respectively. Conversely, this was significantly decreased by 182.6, ??14.1, and 49.4%, respectively, under the CNPK treatment. Correspondingly, the yield-scaled total DON losses for the MNPK and CNPK treatments were significantly increased by 78.8 and ??18.2% compared to the NPK treatment (0.33?±?0.04 kg N t?1 grain). Therefore, long-term continuous manure application is associated with an increased risk of DON environmental pollution. Alternatively, the incorporation of crop straw can be recommended as a means of decreasing DON pollution while maintaining crop yield. 相似文献
5.
Frank Eulenstein Armin Werner Matthias Willms Radosław Juszczak Sandro Luis Schlindwein Bogdan H. Chojnicki Janusz Olejnik 《Nutrient Cycling in Agroecosystems》2008,82(1):33-49
Oxidation of pyrite by nitrate (autotrophic denitrification) was identified as the main cause for sulfate increase in drinking
water wells in an agriculturally used watershed, located in the north of Lower Saxony (Germany). Nitrate, which inducts this
microbial catalyzed process, is drained into ground water predominantly from agricultural fertilization. The increase of sulfate
in the ground water can only be stopped by reducing nitrate leaching into the ground water. To analyze the negative influence
of agricultural fertilization on the quality of ground water different fertilization strategies were deducted for an investigated
area of 890 ha. Calculated on the basis of nutrient balance of soil surface, the current average nitrogen balance in the investigated
area amounts to 91 kg N ha-1 a−1. Farm-gate balance of nutrients is a strong indicator for assessing potential nutrient losses caused by leaching. This indicator
shows comparable accuracy to the calculated nutrient balance of soil surface which demands, however, much more data input
for calculations. Nitrate concentrations in seepage water in 2 m depth layer of the soil from agricultural fields were simulated
with the model HERMES for the whole investigated area (agricultural land + forest). The nitrate concentration in seepage water
was calculated for the whole area on the basis of farm-gate nutrient balance as an annual average, which amounts to 14.0 mg NO3–N l−1 (62 mg NO3 l−1). In order to keep the nitrate concentration of the ground water below the threshold value for drinking water (EU-water directive:
11.3 mg NO3–N l−1 (50 mg NO3 l−1) and to limit pyrite oxidation, different scenarios with simulation studies to optimize fertilization measures were developed.
Only those scenarios which assured reduction of an average nitrate concentration in the drainage water below 11.3 mg NO3–N l−1 (50 mg NO3 l−1) without profit cuts for the farms were analyzed.
相似文献
Janusz OlejnikEmail: |
6.
Sonoko D. Kimura Shin-Ichiro Mishima Kazuyuki Yagi 《Nutrient Cycling in Agroecosystems》2011,89(2):291-302
This study calculated the carbon (C) input to farmland soils in Japan in an effort to investigate the potential increase in
soil C of farmland soils by proper application of crop residues (straw and root) and manure. The calculation was based on
inventory and activity data obtained from statistics, literature sources and inquiry reports for the year 2005. The total
C resources from crop residues and manure in Japan were 6.1 Tg C year−1 and 2.3 Tg C year−1, of which 4.9 Tg C year−1 and 1.9 Tg C year−1, respectively, were applied to farmland soil. The average C application rate was 1.7 ± 1.6 Mg C ha farmland−1 year−1 and the proportion of manure was 23 ± 26%. One scenario that improved the allocation of manure and crop residue input to
farmland soil increased the average C input to farmland soil to 1.8 ± 1.3 Mg C ha farmland−1 year−1. This agricultural C flow represented only a small percentage of the global warming potential of the whole of Japan. Thus,
management of C resources in the agricultural sector should focus on the sustainable use of soil rather than the C sequestration
potential of soil. To improve the C flow for areas with high C input, the transportation of manure to neighboring municipalities
failed to reduce the excessive amount of manure since those areas are concentrated in only a few regions. Other measures were
required to reduce environmental problems due to the over-supply of manure to farmland soils. For areas with low C input,
the introduction of green manure, changes in cultivation methods, and land use type itself must be considered in relation
to the individual C requirements specific to land use, soil type and climate conditions. 相似文献
7.
Schellberg Jürgen Lellmann Arno Kühbauch Walter 《Nutrient Cycling in Agroecosystems》2006,74(1):41-57
The potential release of nutrients from animal farms into soil, water and the atmosphere is a major concern in agronomy. Farm
gate balances are widely utilised to validate the compatibility of a farming system to the surrounding environment, although
they do not reveal the internal nutrient flow as influenced by production intensity and hence might mask local and spatial
nutrient surpluses or deficiencies. In a three years experiment on Rengen Research Station (Eifel Mountains) of the University
of Bonn (Germany) we examined the entire nutrient cycle of two suckler farm systems without (extensive, system “A”) and with
(intensive, system “B”) nutrient input and with 20 suckler cows on 19 hectare each. Stall and grassland nutrient balance sheets
give insight into sources of nutrient surpluses and losses in the farm compartments. The annual budgets of N in system “A”
were nearly balanced (−18 to 15 kg N ha−1 yr−1) compared to system “B” which calculated 81–120 kg N ha−1 yr−1 surplus due to considerable N input with forage and higher dry matter contribution of white clover leading to higher annual
N2 fixation. The maximum of total annual nutrient flow within the entire systems was 388, 42 and 317 kg ha−1 yr−1 with N, P, and K, respectively. Most of these nutrients circulated with forage and excreta on the pastures. This led to considerable
losses mainly of nitrogen (44–50 kg N ha−1 yr−1) even in the extensive system. The intake, excretion and resulting losses of N were mainly determined by the allowance of
N rich pasture forage and was mostly independent from nutrient input. Compared to the grazing season, stall balances were
similar in both systems and all years and revealed very low surpluses with all nutrients. The authors deduce that internal
nutrient flow analyses should be added to conventional balance sheets, including a ranking of nutrients related to chemical
bond, solubility, volatility and predisposition to losses in the farm’s compartment and environment.
An erratum to this article is available at . 相似文献
8.
María Dolores Hurtado Luis Andreu José María Abril Antonio Delgado 《Nutrient Cycling in Agroecosystems》2011,91(3):255-267
Tile drainage and soil amendments have been found to affect losses of nitrate N from agricultural soils. This work was aimed
at measuring nitrate N losses in a tile-drained marsh soil from SW Spain under traditional fertilization and irrigation practices,
and how these losses were influenced by the application of soil amendments. To this end, a randomised block experiment with
three replications was performed during two consecutive growing seasons—2003 to 2004 with cotton and sugar beet, respectively—involving
four different amendment treatments: (1) control without amendment, (2) phosphogypsum (PG), (3) manure, and (4) sugar factory
refuse lime (SFRL). Flow-weighted (FW) nitrate–N concentrations in drainage water, estimated as the slope of the regression
of the instantaneous nitrate–N flow as a function of drain flow rate, was decreased by PG in some drainage events in the 2003
season and in the four last events of the 2004 season when compared with control without amendment. The increased FW nitrate–N
concentrations in drainage from SFRL in comparison to control in a drainage event of 2003 season, and in the four last events
of 2004, can be explained by the contribution of N present in the amendment. These effects did not account for significant
differences in nitrate–N loss among treatments over the whole season in 2003, when they ranged from 19.3 to 24.9 kg N ha−1, accounting for 6–8% of applied N, nor in 2004, when they ranged from 4 to 6 kg N ha−1, accounting for 3–4% of applied N. The decrease in mean FW nitrate–N concentration after the third drainage event in 2003
was not the consequence of the depletion of total soil nitrate–N because soil mineral N was increased on average by 205 kg N ha−1 during the season. The high N extractions by sugar beet and the subsequent decrease in total soil nitrate–N can contribute
to explain the decrease of mean FW nitrate–N concentrations along the 2004 season. Greater absolute nitrate–N loss in 2003
than in 2004 was explained by the lower efficiency of the furrow irrigation when compared with sprinkler irrigation. Results
also revealed that traditional management of N fertilizer was inadequate: rates applied to cotton were excessive, increasing
the risk of N losses not only during the cotton season, but also at the beginning of the following season. 相似文献
9.
Leaching losses of nitrate nitrogen and dissolved organic nitrogen from a yearly two crops system,wheat-maize,under monsoon situations 总被引:6,自引:0,他引:6
Manxiang Huang Tao Liang Zhu Ou-Yang Lingqing Wang Chaosheng Zhang Chenghu Zhou 《Nutrient Cycling in Agroecosystems》2011,91(1):77-89
A large amount of nitrogen (N) fertilizers applied to the winter wheat–summer maize double cropping systems in the North China
Plain (NCP) contributes largely to N leaching to the groundwater. A series of field experiments were carried out during October
2004 and September 2007 in a lysimeter field to reveal the temporal changes of N leaching losses below 2-m depth from this
land system as well as the effects of N fertilizer application rates on N leaching. Four N rates (0, 180, 260, and 360 kg N ha−1 as urea) were applied in the study area. Seasonal leachate volumes were 87 and 72 mm in the first and second maize season,
respectively, and 13 and 4 mm during the winter wheat and maize season in the third rotational year, respectively. The average
seasonal flow-weighted NO3-N concentrations in leachate for the four N fertilizer application rates ranged from 8.1 to 103.7 mg N l−1, and seasonal flow-weighted dissolved organic nitrogen (DON) concentrations in leachate varied from 0.8 to 6.0 mg N l−1. Total amounts of NO3-N leaching lost throughout the 3 years were in the range of 14.6 to 177.8 kg ha−1 for the four N application rates, corresponding to N leaching losses in the range of 4.0–7.6% of the fertilizers applied.
DON losses throughout the 3 years were 1.4, 2.1, 3.6, and 6.3 kg N ha−1 for the four corresponding fertilization rates. The application rate of 180 kg N ha−1 was recommended based on the balance between reducing N leaching and maintaining crop yields. The results indicated that
there is a potential risk of N leaching during the winter wheat season, and over-fertilization of chemical N can result in
substantial N leaching losses by high-intensity rainfalls in summer. 相似文献
10.
Quantification of seasonal soil nitrogen mineralization for corn production in eastern Canada 总被引:1,自引:0,他引:1
Precise estimation of soil nitrogen (N) supply to corn (Zea mays L.) through N mineralization plays a key role in implementing N best management practices for economic consideration and
environmental sustainability. To quantify soil N availability to corn during growing seasons, a series of in situ incubation
experiments using the method of polyvinyl chloride tube attached with resin bag at the bottom were conducted on two typical
agricultural soils in a cool and humid region of eastern Canada. Soil filled tubes were retrieved at 10-d intervals within
2 months after planting, and at 3- to 4-week intervals thereafter until corn harvest. Ammonium and nitrate in the soil and
resin part of the incubation tubes were analyzed. In general, there was minimal NH4+-N with ranges from 1.5 to 7.3 kg N ha−1, which was declined in the first 30 d and fluctuated thereafter. Nitrate, the main form of mineral N, ranged from 20 to 157 kg N ha−1. In the first 20–50 d, main portion of the NO3−-N was in the soil and thereafter in the resin, reflecting the movement of NO3− in the soil, which was affected by rainfall events and amount. Total mineralized N was affected by soil total N and weather
conditions: There was more total mineralized N in the soil with higher total N, and rainy weather stimulated N mineralization.
The relationship between the accumulated mineral N and accumulated growing degree-days (GDD) fitted well into first order
kinetic models. The accumulated mineralized soil N during corn growing season ranged from 96 to 120 kg N ha−1, which accounted for 2–3% of soil total N. Corn plants took up 110–137 kg N ha−1. While the mineralized N and crop uptake were in the same magnitude, a quantitative relationship between them could not be
established in this study. 相似文献
11.
Emissions of nitrous oxide (N2O) from managed and grazed grasslands on peat soils are amongst the highest emissions in the world per unit of surface of
agriculturally managed soil. According to the IPCC methodology, the direct N2O emissions from managed organic soils is the sum of N2O emissions derived from N input, including fertilizers, urine and dung of grazing cattle, and a constant ‘background’ N2O emission from decomposition of organic matter that depends on agro-climatic zone. In this paper we questioned the constant
nature of this background emission from peat soils by monitoring N2O emissions, groundwater levels, N inputs and soil NO3
−–N contents from 4 grazed and fertilized grassland fields on managed organic peat soil. Two fields had a relatively low groundwater
level (‘dry’ fields) and two fields had a relatively high groundwater level (‘wet’ fields). To measure the background N2O emission, unfertilized sub-plots were installed in each field. Measurements were performed monthly and after selected management
events for 2 years (2008–2009). On the managed fields average cumulative emission equaled 21 ± 2 kg N ha−1y−1 for the ‘dry’ fields and 14 ± 3 kg N ha−1y−1 for the ‘wet’ fields. On the unfertilized sub-plots emissions equaled 4 ± 0.6 kg N ha−1y−1 for the ‘dry’ fields and 1 ± 0.7 kg N ha−1y−1 for the ‘wet’ fields, which is below the currently used estimates. Background emissions were closely correlated with groundwater
level (R
2 = 0.73) and accounted for approximately 22% of the cumulative N2O emission for the dry fields and for approximately 10% of the cumulative N2O emissions from the wet fields. The results of this study demonstrate that the accuracy of estimating direct N2O emissions from peat soils can be improved by approximately 20% by applying a background emission of N2O that depends on annual average groundwater level rather than applying a constant value. 相似文献
12.
Effects of mulch,N fertilizer,and plant density on wheat yield,wheat nitrogen uptake,and residual soil nitrate in a dryland area of China 总被引:12,自引:0,他引:12
Yajun Gao Yun Li Jianchang Zhang Wenguo Liu Zhanping Dang Weixian Cao Qin Qiang 《Nutrient Cycling in Agroecosystems》2009,85(2):109-121
Understanding mulching influences on nitrogen (N) activities in soil is important for developing N management strategies in
dryland. A 3 year field experiment was conducted in the Loess Plateau of China to investigate the effects of mulching, N fertilizer
application rate and plant density on winter wheat yield, N uptake by wheat and residual soil nitrate in a winter wheat-fallow
system. The split plot design included four mulching methods (CK, no mulch; SM, straw mulch; FM, plastic film mulch; CM, combined
mulch with plastic film and straw) as main plot treatments. Three N fertilizer rates (N0, 0 kg N ha−1; N120, 120 kg N ha−1; N240, 240 kg N ha−1) were sub-plot treatments and two wheat sowing densities (LD, low density, seeding rate = 180 kg ha−1; HD, high density, seeding rate = 225 kg ha−1) were sub-subplot treatments. The results showed that wheat yield, N uptake, and N use efficiency (NUE) were higher for FM
and CM compared to CK. However, soil nitrate-N contents in the 0–200 cm soil profile were also higher for FM and CM compared
to CK after the 3 year experiment. Wheat grain yields were higher for SM compared to CK only when high levels of nitrogen
or high planting density were applied. Mulching did not have a significant effect on wheat yield, nitrogen uptake and NUE
when soil water content at planting was much high. Wheat yield, N uptake, and residual nitrate in 0–200 cm were significantly
higher for N240 compared to N120 and N0. Wheat yield and N uptake were also significantly higher for HD compared to LD. When
0 or 120 kg N ha−1 was applied, HD had more residual nitrate than LD while the reverse was true when 240 kg N ha−1 was applied. After 3 years, residual nitrate-N in 0–200 cm soil averaged 170 kg ha−1, which was equivalent to ~40% of the total N uptake by wheat in the three growing seasons. 相似文献
13.
Effects of vegetation cover on phosphorus loss from a hillslope cropland of purple soil under simulated rainfall: a case study in China 总被引:8,自引:0,他引:8
Yang Gao Bo Zhu Pei Zhou Jia-Liang Tang Tao Wang Chi-Yuan Miao 《Nutrient Cycling in Agroecosystems》2009,85(3):263-273
Nutrients and sediment lost through runoff to surface and ground water represents a risk to human and environmental health.
In order to understand the mechanisms of nutrient and sediment loss under different levels of vegetation cover, we conducted
a simulated rainfall experiment on hillslope cropland in the Sichuan Basin of China. The experiment was performed on a 4.5 m
long × 1.5 m wide × 0.6 m deep plot to analyze the mechanisms of overland flow, subsurface flow, sediment yield, and P loss
for bare soil, and soil with 25, 50, 75, and 90% vegetation coverage. The results showed that total sediment loss and total
bioavailable P (BAP) loss by overland flow decreased with increasing coverage; the rate of P release from fertilizer decreased
with increasing time during a rain event and increasing coverage; and the growth in vegetation shoots and roots improved soil
physical properties around roots, thus increasing P absorbance and the infiltration rate. Hence, we suggest increasing vegetation
coverage to conserve soil and reduce BAP loss by sediments, and paying more attention to groundwater affected by pollutant
transport through subsurface flows. 相似文献
14.
Sampson Agyin-Birikorang Yoana C. Newman Augustine K. Obour Gabriel N. Kasozi 《Nutrient Cycling in Agroecosystems》2012,92(1):91-105
Environmental benefits associated with reduced rates of nitrogen (N) application, while maintaining economically optimum yields
have economic and social benefits. Although N is an indispensable plant nutrient, residual soil N could leach out to contaminate
groundwater and surface water resources, particularly in sandy soils. A 2-year field study was conducted in an established
bermudagrass (Cynodon dactylon) pasture in the Lower Suwannee Watershed, Florida, to evaluate N application rates on forage yield, forage quality, and nitrate
(NO3-N) leaching in rapidly permeable upland sandy soils. Four N application rates (30, 50, 70, and 90 kg N ha−1 harvest−1) corresponding to 0.33, 0.55, 0.77 and IX, respectively, of recommended N rate (90 kg N ha−1 harvest−1) for bermudagrass hay production in Florida were evaluated vis-à-vis an unfertilized (0 N) control. Suction cups were installed
near the center of each plot at two depths (30 and 100 cm) to monitor NO3-N leaching. The grass was harvested at 28 days intervals to determine dry matter yield, N uptake, and herbage nutritive value.
Nitrogen application at the recommended rate produced the greatest total dry matter yield (~18.4 Mg ha−1 year−1), but a modeled economically optimum N rate of ~57 kg N ha−1 harvest−1 (~60% of the recommended N rate) projected an average dry matter yield of ~17.3 Mg ha−1 year−1, which represents >90% of the observed maximum yield. Nitrogen application increased nutritive quality of the grass, but
increases in N application rate above 30 kg N ha−1 did not result in significant increases in in vitro digestible organic matter concentration, and tissue crude protein was
not significant above 50 kg N ha−1. Across the sampling period, treatments with N rates ≤50 kg N ha−1 harvest−1 had leachate NO3-N concentration below the maximum contaminant limit of <10 mg l−1. Conversely, applying N at rates ≥70 kg N ha−1 harvest−1 resulted in leachate N concentration that exceeded the maximum contaminant limit, and suggest high risk of impacting groundwater
quality, if such rates are applied to soils with coarse (sand) textures. The study demonstrates that recommendation of a single
N application rate may not be appropriate under all agro-climatic conditions and, thus, a site-specific evaluation of best
N management strategy is critical. 相似文献
15.
Keiichi Hayashi Naruo Matsumoto Evangeline T. Hayashi Tahirou Abdoulaye Hitoshi Shinjo Ramadjita Tabo Ryoichi Matsunaga Satoshi Tobita 《Nutrient Cycling in Agroecosystems》2012,92(3):289-304
To determine the efficiency of utilization of organic matter in agricultural production, nitrogen flow was estimated within
a village-farm model in the west of Niger, West Africa. Nitrogen was focused on in this study as it is known to be a major
nutrient component of organic matter and one of the limiting nutrients in Sahelian soil. Local practices regarding the use
of organic matter and pertinent information on traditional practices for soil fertility management were determined by interviews
with local farmers. To estimate nitrogen flow in farmlands and consumption in the village through various activities, quantitative
measurements of crop yield and organic amendment were carried out. Data on human and livestock excreta were taken from published
reports. The size and classification of farmlands were as follows: 0.5 ha adjacent farmland, 1.6 ha threshing farmland, 6.0 ha
transported-manure farmland, 5.5 ha corralling farmland, and 86.5 ha extensively managed farmland (EMF). Levels of nitrogen
flow from these farmlands to the studied villages were 0.9, 2.9, 9.6, 15.2, and 94.2 Mg, while the flows to these farmlands
were 14.6, 6.3, 13.7, 17.5, and 26.3 Mg, respectively. Upon calculation of nitrogen balance −8 kg ha−1 year−1 was estimated in EMF, but there was a positive balance in other types of farmland, which ranged from 4 to 262 kg ha−1 year−1, indicating inefficient use of nitrogen in the study area for crop production. The results indicated that nutrient flow in
the study site was unequally distributed and nitrogen was not recycled. Therefore, efforts should be made to establish efficient
utilization of available nutrients by reducing the loss from livestock feed and human consumption. At the same time, more
research is needed to improve the management of EMF. 相似文献
16.
Almeida JS Lima F Ros SD Bulhões LO de Carvalho LM Beck RC 《Nanoscale research letters》2010,5(10):1603-1610
The improvement of the rutin photostability and its prolonged in vitro antioxidant activity were studied by means of its association
with nanostructured aqueous dispersions. Rutin-loaded nanocapsules and rutin-loaded nanoemulsion showed mean particle size
of 124.30 ± 2.06 and 124.17 ± 1.79, respectively, polydispersity index below 0.20, negative zeta potential, and encapsulation
efficiency close to 100%. The in vitro antioxidant activity was evaluated by the formation of free radical ·OH after the exposure
of hydrogen peroxide to a UV irradiation system. Rutin-loaded nanostructures showed lower rutin decay rates [(6.1 ± 0.6) 10−3 and (5.1 ± 0.4) 10−3 for nanocapsules and nanoemulsion, respectively] compared to the ethanolic solution [(35.0 ± 3.7) 10−3 min−1] and exposed solution [(40.1 ± 1.7) 10−3 min−1] as well as compared to exposed nanostructured dispersions [(19.5 ± 0.5) 10−3 and (26.6 ± 2.6) 10−3, for nanocapsules and nanoemulsion, respectively]. The presence of the polymeric layer in nanocapsules was fundamental to
obtain a prolonged antioxidant activity, even if the mathematical modeling of the in vitro release profiles showed high adsorption
of rutin to the particle/droplet surface for both formulations. Rutin-loaded nanostructures represent alternatives to the
development of innovative nanomedicines. 相似文献
17.
C. Wilson M. Undi M. Tenuta D. Tremorin L. Coppi D. Flaten K. M. Wittenberg K. H. Ominski 《Nutrient Cycling in Agroecosystems》2011,91(2):155-171
Liquid hog manure (LHM) is used to improve productivity of grasslands in western Canada. However, application of manure to
meet crop N requirements can result in excessive accumulation of P, especially in grazing systems. A three-year study was
carried out to assess the impact of timing of liquid hog manure application and harvest strategy on nutrient utilization and
accumulation by grasslands in southeast Manitoba. Liquid hog manure was applied annually at a full rate of 142 ± 20 kg available
N ha−1 in spring (Single application) or as two half rate applications of 70 ± 6 kg available N ha−1, one in fall and one in spring (Split application). Two harvest strategies, haying and grazing, were employed to export nutrients
from grasslands. Spring-applied manure averaged 8.9% dry matter, 5.7 g total N L−1, 1.5 g total P L−1, and 2.1 g total K L−1 and fall-applied manure from the same source averaged 3.9% dry matter, 4.4 g total N L−1, 0.7 g total P L−1, and 2.2 g total K L−1. Manure application based on grass N requirements resulted in at least two times more P and K applied than recommended for
Manitoba grasslands. Nutrient (N, P, and K) export from grasslands was five times higher when grass forage was harvested as
hay than through grazing. Average nutrient utilization when forage was harvested as hay was 153 kg N ha−1, 18 kg P ha−1, and 123 kg K ha−1 and was higher in the years with increased precipitation. Grazing was not effective in removing nutrients from grasslands
as indicated by lower N, P, and K utilization efficiency (% applied nutrient) in grazed (30% for N, 7% for P, and 18% for
K) relative to hayed (75% for N 32% for P, and 103% for K) paddocks. Nutrient accumulation was impacted by a combination of
harvest strategy and timing of manure application. Both single and split applications increased soil extractable nutrients,
but soil extractable nutrients were higher in grazed relative to hayed paddocks following single manure application. After
3 years of manure application, the amount of Olsen-P (62 kg ha−1) exceeded that required for optimal forage growth. However, soil levels did not exceed the soil Olsen-P regulatory threshold
(60 mg kg−1) that restricts manure P applications in Manitoba. An analysis of P balance, for this particular soil, indicated that a surplus
of 18.9 kg manure P ha−1 (in excess of forage P exported as hay or weight gain) increased the soil Olsen-P concentration by 1 mg kg−1. Nutrient utilization and accumulation will be impacted by timing of manure application and harvest strategy employed as
well as amount of precipitation received during the growing season. 相似文献
18.
Guillaume Vilain Josette Garnier Céline Roose-Amsaleg Patricia Laville 《Nutrient Cycling in Agroecosystems》2012,92(1):35-50
The denitrification process and the associated nitrous oxide (N2O) production in soils have been poorly documented, especially in terms of soil profiles; most work on denitrification has
concentrated on the upper layer (first 20 cm). The objectives of this study were to examine the origin of N2O emission and the effects of in situ controlling factors on soil denitrification and N2O production, also allowing the (N2O production)/(NO3
−–N reduction) ratio to be determined through (1) the position on a slope reaching a river and (2) the depth (soil horizons:
10–30 and 90–110 cm). In 2009 and 2010, slurry batch experiments combined with molecular investigations of bacterial communities
were conducted in a corn field and an adjacent riparian buffer strip. Denitrification rates, ranging from 0.30 μg NO3
−–N g−1 dry soil h−1 to 1.44 μg NO3
−–N g−1 dry soil h−1, showed no significant variation along the slope and depth. N2O production assessed simultaneously differed considerably over the depth and ranged from 0.4 ng N2O–N g−1 dry soil h−1 in subsoils (the 90–110-cm layer) to 155.1 ng N2O–N g−1 dry soil h−1 in the topsoils (the 10–30-cm layer). In the topsoils, N2O–N production accounted for 8.5–48.0% of the total denitrified NO3
−–N, but for less than 1% in the subsoils. Similarly, N2O-consuming bacterial communities from the subsoils greatly differed from those of the topsoils, as revealed by their nosZ DGGE fingerprints. High N2O-SPPR (nitrous oxide semi potential production rates) in comparison to NO3-SPDR (nitrate semi potential reduction rates) for the topsoils indicated significant potential greenhouse N2O gas production, whereas lower horizons could play a role in fully removing nitrate into inert atmospheric N2. In terms of landscape management, these results call for caution in rehabilitating or constructing buffer zones for agricultural
nitrate removal. 相似文献
19.
Long-term simulations of nitrate leaching from potato production systems in Prince Edward Island,Canada 总被引:1,自引:0,他引:1
LEACHN was employed to simulate nitrate leaching from a representative potato production system in Prince Edward Island (PEI),
Canada and enhance the understanding of impacts of potato (Solanum tuberosum L.) production on groundwater quality. The model’s performance on predicting drainage was examined against water table measurements
through coupled LEACHN and MODFLOW modeling. LEACHN was calibrated and verified to data from tile-drain leaching experiments
of potato grown in rotation with barley (Hordeum vulgare L.) and red clover (Trifolium pratense L.) during 1999–2008. Long-term simulations using the calibrated model were performed to evaluate the effects of climate
and N fertilization for the potato crop on nitrate leaching. The modeling suggests LEACHN can be an effective tool for predicting
nitrate leaching from similar cropping systems in PEI. Both measurements and simulations showed nitrate leaching primarily
occurred during the non-growing season when crop uptake diminishes, and nitrate from mineralization and residual fertilizer
coexists with excessive moisture from rainfall and snowmelt infiltration. Annual average nitrate leaching following potato,
barley and red clover phases was predicted to be 81, 54 and 35 kg N ha−1, respectively, and the corresponding leached concentrations were 15.7, 10.1 and 7.3 mg N l−1. Increased N input for potato alone increased nitrate leaching not only during potato phase but also during the rotation
crop phases. To reduce the risk of nitrate leaching, practices should be developed to minimize nitrate accumulation in soil
both during and outside of the growing season and in both the potato and the rotation crop phases. 相似文献
20.
A new and simple differential pulse polarographic method for the analysis of wine has been established. With this method,
it was possible to determine simultaneously six trace elements in wine. There was no need for time consuming extraction and
separation procedures with danger of contamination. The polarogram of wet digested wine was taken initially in pH 2 acetate
buffer and Pb, Cd, and Zn were determined by standard additions. Ethylene diamine tetraacetic acid (EDTA) was added and pH
was increased to six by addition of NaOH. Fe and Cu were determined subsequently. The ammonia buffer, pH 9.5, was identified
as the best medium for separation and determination of Ni and Zn. The quantities of trace elements were found as Cu 290 ± 20 μg L−1, Fe 8960 ± 50 μg L−1, Pb 148 ± 17 μg L−1, Cd 16 ± 8 μg L−1, Zn 460 ± 25 μg L−1, and Ni 78 ± 17 μg L−1. 相似文献