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1.
Prunings of Calliandra calothyrsus, Grevillea robusta, Leucaena diversifolia and farm yard manure were applied each cropping season at 3 and 6 t dry matter ha−1 to an Oxisol in Burundi. The field plots also received basal applications of nitrogen (N), phosphorus (P) and potassium (K).
Application of the tree prunings or farm yard manure decreased the concentration of monomeric inorganic aluminium (Al) in
soil solution from 2.92 mg Al dm−3 in the control plots to 0.75 mg Al dm−3 in the plots receiving 6 t ha−1
Calliandra prunings. The other organic materials also decreased the concentration of monomeric inorganic aluminium in the soil solution.
The lowered Al concentration led to a corresponding decrease in the percentage Al saturation of the 0–10 cm soil layer from
80% to 68%. Grain yields of maize and beans were strongly inversely related to the percentage Al saturation of the soil. This
confirms that soil acidity was the main constraint to maize and beans production. The yield improvement was mainly attributed
to the ameliorating effects of the organic matter application on Al toxicity. The nutrient content had less effect presumably
because of fertilizer use. In the best treatments, the yield of maize increased from 0.9 to 2.2 t ha−1 and the corresponding beans yield increased from 0.2 to 1.2 t ha−1. A C Borstlap Section editor 相似文献
2.
Earthworm secondary production and N flux in agroecosystems: a comparison of two approaches 总被引:1,自引:0,他引:1
Production was estimated for Aporrectodea spp. and Lumbricus spp. populations in corn agroecosystems with a 5-year history of manure or inorganic fertilizer applications during 1994–1995
and 1995–1996. Earthworm biomass and production were greater in manure than inorganic fertilizer plots, although biomass and
production declined by about 50% between 1994–1995 and 1995–1996 due to unfavorable climatic conditions. Production was highest
during the spring and autumn when soil temperatures were between 4 and 22°C. Production was higher in Lumbricus spp. than Aporrectodea spp. populations due to greater Lumbricus spp. biomass. Aporrectodea spp. production was 3.47–16.14 g ash-free dry weight (AFDW) m–2 year–1, while Lumbricus spp. production was 6.09–18.11 g AFDW m–2 year–1, depending on the fertilizer treatment and the method used to estimate production. However, production estimates from the
instantaneous growth rate method were within 27% of the values calculated using the size-frequency method. Nitrogen flux through
earthworms was used to estimate efficiency quotients. Net production efficiency (P/A) ranged from 0.64 to 0.76, assimilation efficiency (A/C) ranged from 0.1 to 0.3, and gross production efficiency (P/C) ranged from 0.06 to 0.22. Annual N flux through earthworm populations was higher in manure than inorganic fertilizer plots,
and ranged from 2.95 to 5.47 g N m–2 year–1 in 1994–1995 and 1.76 to 2.92 g N m–2 year–1 in 1995–1996. The N flux through earthworms represented an amount equivalent to 16–30% of crop N uptake during 1994–1995
and 11–18% of crop N uptake during 1995–1996. We concluded that the effects of earthworms on N cycling in corn agroecosystems
were substantial, and that N flux through earthworms was influenced significantly by fertilizer amendments.
Received: 20 September 1999 / Accepted: 24 March 2000 相似文献
3.
Effects of carbonized and dried chicken manures on the growth, yield, and N content of soybean 总被引:2,自引:0,他引:2
The present study was conducted to investigate the effects of nitrogen derived from dried or carbonized chicken manure on
growth, nodulation, yield and N content of soybean. 15N labeled chicken manure used in this study was obtained from the droppings of chicken fed on hulled rice grown under field
conditions and fertilized with 15N-labeled stable isotope ammonium sulphate and potassium nitrate fertilizers. Carbonized chicken manure was made by heat treatment
in a muffle furnace in our laboratory. This study was conducted in pots filled with clay loam soil. Results from the study
show that the application of carbonized chicken manure increased soybean seed yield by 23% and 43% for the 50 and 100 kg N
ha−1 rates respectively. Dried chicken manure application increased soybean seed yield by 7% and 30% for the 50 and 100 kg N ha−1 rates respectively. There was no difference in the N manure yield of both manures when applied at the same rate. The percentage
15N recovery was 17.6% and 8.9% for carbonized chicken manure, 19.2% and 10.5% for dried chicken manure at 50 and 100 kg N ha−1 rates respectively at peak flowering stage of soybean growth. We found high total nitrogen yields of soybean at the rate
of 100 kg N ha−1 for both manures. There was a positive relationship between number of nodules and seed yield of soybean. Total N content
also showed positive relationship with number of nodules and seed yield of soybean. We supposed that the higher P content
of carbonized chicken manure is responsible for the higher seed yield and nodule growth compared to dried chicken manure. 相似文献
4.
Peter Sørensen 《Plant and Soil》2004,267(1-2):285-296
About 50–60% of dairy cattle slurry nitrogen is ammonium N. Part of the ammonium N in cattle slurry is immobilised due to
microbial decomposition of organic matter in the slurry after application to soil. The immobilisation and the remineralisation
influence the fertiliser value of slurry N and the amount of organic N that is retained in soil. The immobilisation and the
remineralisation of 15 N-labelled dairy cattle slurry NH4-N were studied through three growing seasons after spring application under temperate conditions. Effects of slurry distribution
(mixing, layer incorporation, injection, surface-banding) and extra litter straw in the slurry on the plant utilisation of
labelled NH4-N from slurry were studied and compared to the utilisation of 15N-labelled mineral fertiliser. The initial immobilisation of slurry N was influenced by the slurry distribution in soil. More
N was immobilised when the slurry was mixed with soil. Surface-banding of slurry resulted in significant volatilisation losses
and less residual 15N in soil. Much more N was immobilised after slurry incorporation than after mineral fertiliser application. After 2.5 years
the recovery of labelled N in soil (0–25 cm) was 46% for slurry mixed with soil, 42% for injected slurry, 22% for surface-banded
slurry and 24% for mineral fertiliser N. The total N uptake in a ryegrass cover crop was 5–10 kg N/ha higher in the autumn
after spring-application of cattle slurry (100–120 kg NH4-N/ha) compared to the mineral fertiliser N reference, but the immobilised slurry N (labelled N) only contributed little to
the extra N uptake in the autumn. Even in the second autumn after slurry application there was an extra N uptake in the cover
crop (0–10 kg N/ha). The residual effect of the cattle slurry on spring barley N uptake was insignificant in the year after
slurry application (equivalent to 3% of total slurry N). Eighteen months after application, 13% of the residual 15N in soil was found in microbial biomass whether it derived from slurry or mineral fertiliser, but the remineralisation rate
(% crop removal of residual 15N) was higher for fertiliser- than for slurry-derived N, except after surface-banding. Extra litter straw in the slurry had
a negligible influence on the residual N effects in the year after application.
It is concluded that a significant part of the organic N retained in soil after cattle slurry application is derived from
immobilised ammonium N, but already a few months after application immobilised N is stabilised and only slowly released. The
immobilised N has negligible influence on the residual N effect of cattle slurry in the first years after slurry application,
and mainly contributes to the long-term accumulation of organic N in soil together with part of the organic slurry N. Under
humid temperate conditions the residual N effects of the manure can only be optimally utilised when soil is also covered by
plants in the autumn, because a significant part of the residual N is released in the autumn, and there is a higher risk of
N leaching losses on soils that receive cattle slurry regularly compared to soils receiving only mineral N fertilisers. 相似文献
5.
Annick Bertrand Danielle Prévost Francine J. Bigras Roger Lalande Gaëtan F. Tremblay Yves Castonguay Gilles Bélanger 《Plant and Soil》2007,290(1-2):173-187
Increased atmospheric CO2 was shown to affect a variety of physiological processes in plants, including photosynthesis and growth with repercussions
on crop yield and nutritive value. Perennial alfalfa (Medicago sativa L.) is a sustainable crop with a deep root system, living in symbiosis with rhizobium for nitrogen (N) fixation. The objective
of the project was to determine the combined effects of elevated CO2 and rhizobial strains on photosynthesis, growth, N fixation, and nutritive value of alfalfa, and on soil microflora. Alfalfa
inoculated with two different strains of rhizobia (Sinorhizobium meliloti strains A2 and NRG34) was grown 2 months at day/night temperatures of 22/17°C under either 400 (near ambient) or 800 (elevated)
μmol mol−1 of CO2. The photosynthetic response of alfalfa to elevated CO2 differed according to the rhizobial strain. At the end of the experiment, elevated CO2 stimulated photosynthetic rates by 50% in plants associated with A2 but there was no significant increase in plants nodulated
with NRG34. Nitrogenase activity (+38%) and shoot growth (+60%) were stimulated under 800 μmol mol−1 of CO2 for alfalfa inoculated with both strains. Root dry weight was significantly higher at 800 μmol mol−1 of CO2 only with strain A2. Fibre concentration decreased in response to elevated atmospheric CO2 in alfalfa inoculated with strain A2 resulting in plant material with greater nutritive value when inoculated with A2 compared
to NRG34. In the soil, elevated CO2 increased the proportion of fungi in the microbial community while decreasing Gram− bacteria. For alfalfa inoculated with rhizobial strain A2, photosynthetic rates, nitrogenase activity, and growth were all
stimulated by increased atmospheric CO2 compared to less consistently positive responses to elevated CO2 when inoculated with NRG34. Our results show that it is possible to identify rhizobial strains to improve plant performance
under predicted future CO2 concentrations with no negative effect on nutritive value.
The Canadian Government’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged. 相似文献
6.
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
7.
Variations in crop grain and soil N isotope composition (δ15N) in relation to liquid hog manure (δ15N of total N was +5.1‰), solid cattle manure (+7.9‰) and chemical fertilizer (+0.7‰ for urea and −1.9‰ for ammonium phosphate)
applications, and control (no fertilizer application) were examined through a 4-year crop rotation under field conditions.
Canola (Brassica napus), hull-less barley (Hordeum vulgare), wheat (Triticum aestivum), and canola were grown sequentially from 2000 (year 1) to 2003 (year 4). From year 2, hog manure or chemical fertilizers,
but not cattle manure, treatments increased grain N concentrations over the control. Grain δ15N (+0.3 to +2.5‰) of crops applied with chemical fertilizers was lower than those in the other treatments, reflecting the
effects of the N source with a lower δ15N, while the manure treatments tended to increase grain δ15N. The higher grain δ15N of crops applied with hog manure (+5.6 to +8.4‰) than those applied with cattle manure (+2.2 to +4.1‰) reflected the higher
N availability of liquid hog manure (up to 70% as NH
4
+
) than solid cattle manure (99% organic N) and higher potentials for ammonia volatilization loss in hog manure rather than
differences in manure δ15N signatures. Soil total- and extractable-N concentrations and δ15N tended to vary with the application of N sources with different N isotope composition and availability. Our study expanded
the application of the δ15N technique for detecting N source (organic vs chemical) effects on N isotopic composition to field conditions and across
a 4-year rotation, and revealed that N availability played a greater role than the δ15N signature of N sources in determining crop δ15N under the studied conditions.
Section Editor: H. Lambers 相似文献
8.
Optimising the use efficiency of nitrogen (N) derived from different quality organic resources and mineral fertilizers on
sandy soils with <100 g clay kg−1 is a major challenge for smallholder farmers in Southern Africa. The dominant sandy soils have a poor capacity to store and
supply crop nutrients due to low organic matter contents and inherent infertility. A study was conducted in Zimbabwe to determine
the differential N supply effects of different quality and quantities of organic nutrient sources on maize productivity. Crotalaria juncea L., Calliandra calothyrsus Meissn., cattle manure, maize (Zea mays L.) stover and Pinus patula Schiede & Schltdl. & Cham. sawdust which represented high to low quality materials respectively, were each incorporated into
soil at 1.2 and 4 t C ha−1 at Makoholi Experiment Station (rainfall: 450–650 mm yr−1) and tested against a sole mineral N fertilizer and control treatments. In a separate experiment conducted in farmers’ fields
under different rainfall zones of Zimuto (450–650 mm yr−1), Chinyika (650–750 mm yr−1) and Chikwaka (>750 mm yr−1), commonly available organic materials, including manure and composted miombo leaf litter, applied in varying amounts by
farmers were evaluated. Nitrogen release patterns were consistent with differences in resource quality. At 3 weeks after incorporation
into soil at the onset of the rains, C. juncea and C. calothyrsus had released as high as 24% and 13% of added N respectively, compared with no more than 5–6% for the rest of the amended
treatments. Most of the N released was lost through leaching as evidenced by progressive movement of NO3−-N bulges beyond maize rooting depth following major rainfall events. Maize yields were significantly related to the size
of profile mineral N fluxes, with the best linear relationship (R2 = 0.86) obtained with N available in the top 30 cm of soil at maize flowering. High grain yields of ~3 t ha−1 were only achieved with C. juncea applied at 4 t C ha−1, which also had highest NO3−-N leaching losses. Conversely, the same application rate increased N immobilization by 30% and 42% under maize stover and
sawdust, respectively, relative to the control. Results from farmers’ fields showed that organic resources traditionally used
on smallholder farms are invariably of low quality relative to C. juncea and C. calothyrsus. However, they exhibited shorter N immobilization effects than was shown for maize stover and sawdust at Makoholi, suggesting
that pre-application treatments, such as composting, employed by farmers enhance seasonal N benefits from these materials.
Maize yields increased linearly with total N added in these resources in combination with N fertilizer, justifying the high
organic matter loading strategy (e.g. >20 t ha−1 for manure, fresh litter and composted litter) used by farmers who often achieve high crop yields on such coarse sandy soils
in Zimbabwe. 相似文献
9.
Nelson Kelly Lehnert Brözel Volker S. Gibson Susan A. Thaler Robert Clay Sharon A. 《World journal of microbiology & biotechnology》2011,27(3):659-668
Chlortetracycline (CTC), an antimicrobial compound used in animal production, is not sorbed or degraded in the animal, and
may enter the field environment through manure land-spreading. This study determined the influence of a single application
of manure with or without CTC on field soil microbial community characteristics. Manures from swine fed unamended or CTC-amended
rations were applied at 7,000 kg solid ha−1 to a Brandt silty clay loam soil that had no known prior history of manure application. Soil samples taken 1, 7, 28, or 42 days
after treatment (DAT) were analyzed for aerobic culturable counts on R2A agar and most probable number using 2,4-D as sole
carbon source. Soil extracts of 1, 7, and 42 DAT samples were subjected to polymerase chain reaction followed by denaturing
gradient gel electrophoresis (DGGE) analysis of the V3 region of the 16S rRNA gene pool. Gels were analyzed by Neighbor Joining
based on Euclidean distance and Raup–Crick multivariate statistical analysis, and selected bands were extracted to identify
predominant community members. Both manure applications initially changed soil microbial diversity, however, communities appeared
to converge over time, so that no long-term significant effect was detected with this single application. 相似文献
10.
Reversibility of Soil Productivity Decline with Organic Matter of Differing Quality Along a Degradation Gradient 总被引:8,自引:0,他引:8
Joseph M. Kimetu Johannes Lehmann Solomon O. Ngoze Daniel N. Mugendi James M. Kinyangi Susan Riha Lou Verchot John W. Recha Alice N. Pell 《Ecosystems》2008,11(5):726-739
In the highlands of Western Kenya, we investigated the reversibility of soil productivity decline with increasing length of
continuous maize cultivation over 100 years (corresponding to decreasing soil organic carbon (SOC) and nutrient contents)
using organic matter additions of differing quality and stability as a function of soil texture and inorganic nitrogen (N)
additions. The ability of additions of labile organic matter (green and animal manure) to improve productivity primarily by
enhanced nutrient availability was contrasted with the ability of stable organic matter (biochar and sawdust) to improve productivity
by enhancing SOC. Maize productivity declined by 66% during the first 35 years of continuous cropping after forest clearing.
Productivity remained at a low level of 3.0 t grain ha-1 across the chronosequence stretching up to 105 years of continuous cultivation despite full N–phosphorus (P)–potassium (K)
fertilization (120–100–100 kg ha−1). Application of organic resources reversed the productivity decline by increasing yields by 57–167%, whereby responses to
nutrient-rich green manure were 110% greater than those from nutrient-poor sawdust. Productivity at the most degraded sites
(80–105 years since forest clearing) increased in response to green manure to a greater extent than the yields at the least
degraded sites (5 years since forest clearing), both with full N–P–K fertilization. Biochar additions at the most degraded
sites doubled maize yield (equaling responses to green manure additions in some instances) that were not fully explained by
nutrient availability, suggesting improvement of factors other than plant nutrition. There was no detectable influence of
texture (soils with either 11–14 or 45–49% clay) when low quality organic matter was applied (sawdust, biochar), whereas productivity
was 8, 15, and 39% greater (P < 0.05) on sandier than heavier textured soils with high quality organic matter (green and animal manure) or only inorganic
nutrient additions, respectively. Across the entire degradation range, organic matter additions decreased the need for additional
inorganic fertilizer N irrespective of the quality of the organic matter. For low quality organic resources (biochar and sawdust),
crop yields were increasingly responsive to inorganic N fertilization with increasing soil degradation. On the other hand,
fertilizer N additions did not improve soil productivity when high quality organic inputs were applied. Even with the tested
full N–P–K fertilization, adding organic matter to soil was required for restoring soil productivity and most effective in
the most degraded sites through both nutrient delivery (with green manure) and improvement of SOC (with biochar). 相似文献
11.
Nitrogen export by surface runoff from a small agricultural watershed in southeast China: seasonal pattern and primary mechanism 总被引:1,自引:0,他引:1
The seasonal pattern and primary mechanism of nitrogen (N) export by surface runoff from the Wuchuan subwatershed (WCW), an
agricultural upper watershed (1.88 km2) located in southeast China, were investigated based on extensive streamwater measurements in 2004–2005 under subtropical
climatic conditions. The results disclosed a highly variable but strong linkage between hydrological and anthropogenic controls
and N export. N export via surface runoff presented a significant seasonal pattern caused by changes in rainfall and watershed
N input. Approximately 75% of the annual N export (67 kg ha−1) was flushed by those storm runoff mainly occurred during the wet season (March through September). The WCW dataset of N
concentrations and loads during both baseflow and stormflow implied an interactive effects of anthropogenetic N input and
hydrology conditions: N export was flush-driven in late spring, summer and autumn (wet season), but highly related with soil
N in winter and early spring. Compared to undisturbed watersheds under similar rainfall conditions, WCW exported a considerable
amount of N due to intensive fertilizer application (a mean of 690 kg N ha−1 year−1, commonly as surface applications). This work provides a first characterization of a small agricultural Chinese catchment
under subtropical climates and its associated N export behavior. 相似文献
12.
J. Kipkemboi C. M. Kilonzi A. A. van Dam N. Kitaka J. M. Mathooko P. Denny 《Wetlands Ecology and Management》2010,18(4):471-483
We present the findings of a participatory experiment on integrated aquaculture-agriculture systems (Fingerponds) at the Lake
Victoria wetlands, Kenya. Fingerponds are flood-based lacustrine or floodplain wetland fishponds. The aim of the study was
to explore, within a wetland/floodplain interface environment, the potential of semi-intensive fish production to enhance
the wetland fishery and protect the natural ecosystem from wide-scale, destructive encroachment. The ponds were stocked naturally
by flood water. After flood recession, livestock manure was added to the ponds and the effects of manuring on water and sediment
quality and fish yields were studied. Manuring had positive effects on the nitrogen, phosphorous and chlorophyll a concentrations
of the pond water. Regression analysis results indicated that site, manuring and environmental and climatic variables explained
58–70% of the variation in dissolved nitrogen and phosphorous, and 71% of the variation in chorophyll a. Manuring enhanced the total phosphorus concentration in the sediment but it only had marginal effects on total nitrogen.
Although the net fish yields were highly variable between sites and seasons, ranging from 402 to 1069 kg ha−1, the data showed that manuring was advantageous. The duration of the culture period, site variability and manuring explained
82% of the variation in fish yields. We conclude that Fingerponds fertilized with livestock manure from abutting riparian
subsistence agriculture can improve fish production, enhance food diversity and security and contribute to more efficient
use of papyrus wetlands for food production. This in turn may reduce large-scale conversion of wetlands to agriculture. 相似文献
13.
Evaluation of N2-fixation and nitrogen economy of a maize/cowpea intercrop system using15N dilution methods 总被引:2,自引:0,他引:2
Yields of above ground biomass and total N were determined in summer-grown maize and cowpea as sole crops or intercrops, with
or without supplementary N fertilizer (25 kg N ha−1, urea) at an irrigated site in Waroona, Western Australia over the period 1982–1985. Good agreement was obtained between
estimates of N2 fixation of sole or intercrop cowpea (1984/85 season) based on the15N natural abundance and15N fertilizer dilution techniques, both in the field and in a glasshouse pot study. Field-grown cowpea was estimated to have
received 53–69% of its N supply from N2-fixation, with N2-fixation onlyslightly affected by intercropping or N fertilizer application. Proportional reliance on N2-fixation of cowpea in glasshouse culture was lower (36–66%) than in the field study and more affected by applied N. Budgets
for N were drawn up for the field intercrops, based on above-ground seed yields, return of crop residues, inputs of fixed
N and fertilizer N. No account was taken of possible losses of N through volatilization, denitrification and leaching or gains
of N in the soil from root biomass. N2-fixation was estimated tobe 59 kg N ha−1 in the plots receiving no fertilizer N, and 73 kg N ha−1 in plots receiving 25 kg N ha−1 as urea. Comparable fixation by sole cowpea was higher (87 and 82 kg N ha−1 respectively) but this advantage was outweighed by greater land use efficiency by the intercrop than sole crops. 相似文献
14.
T. Lindberg T. A. Bonde L. Bergström R. Pettersson T. Rosswall J. Schnürer 《Plant and Soil》1989,119(1):25-37
An annual cereal, barley, and a perennial grass ley, meadow fescue, were grown in field lysimeters in Sweden and fertilized
with 12 and 20g Ca(NO3)2-N m−2 yr−1, respectively. Isotope-labeled (15N) fertilizer was added during year 1 of the study, whereafter similar amounts of unlabeled N were added during years 2 and
3. The grass ley lysimeters were ploughed after the growing season of year 3 and sown with barley during year 4. The barley
harvest in year 1 removed 59% of the added fertilizer N, while the fertilizer N export by two meadow fescue harvests in year
1 was 65%. The labeled N export decreased rapidly after year 1, especially in the barley, but increased slightly after ploughing
of the grass ley.
The microbial biomass, measured with the chloroform fumigation method, incorporated a maximum of 1.4–1.7% of the labeled N
during the first seven weeks after application. Later on, the incorporation stabilized at less than 1% in both cropping systems.
The susceptibility of the residual labeled N to mineralization was evaluated three years after application by means of long-term
laboratory incubations. The curves of cumulative mineralized N were described by a two-component first-order regression model
that differentiated between an available and a more recalcitrant fraction of potentially mineralizable N. There was no difference
in the amounts of potentially mineralizable N between the cropping systems. The labeled N comprised 5 and 2% of the amounts
of potentially mineralizable N in the available and more recalcitrant fraction, respectively. The mineralization rate constants
for the labeled N were almost twice as high as for the total potentially mineralizable N. The available fraction of the total
potentially mineralizable N was 12%, while twice that proportion of the labeled N was available.
It was concluded that the short-term ley did not differ from the annual crop with respect to the early disposition of the
fertilizer N and the behaviour of the residual organic N. 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.
Summary Balance sheets were computed for total nitrogen and phosphorus in plough layer (0–15 cm) of a Typic Ustochrept soil under
continuous multiple cropping for seven years (1971–72 to 1977–78) with a fixed rotation of pearl millet (Pennisetum typhoideum L.) wheat (Triticum aestivum L.) (Vigna sinensis Savi.) The treatments considered of soil test-based rates of N, P and K, applied both singly and in combinations together with
farm yard manure, sulphur and zinc superimposed over optimum rates (100%) of NPK. Heavy, losses of N (762–899 kg ha−1) occurred in the plots which received high rates of Nviz. 150% of recommended NPK and 100% NPK plus FYM. Application of N alone accelerated N losses whereas addition of P, PK, PKS
to N minimised such losses. Enrichment of P (66 to 198 kg ha−1) occurred in all phosphate-treated plots. A marginal net decrease (29–54 kg ha−1) in P levels was observed in control and N alone treatments. 相似文献
17.
Adjusting fertiliser applications to within-field variations in nitrogen (N) mineralisation during the growing season can
increase yields, improve crop quality, reduce costs and decrease nutrient losses to the environment. Predicting such variations
at a reasonable cost is therefore important. In a 3-year study, Near Infrared Reflectance (NIR) spectroscopy was compared
with soil organic matter (SOM) and clay content as predictors of plant N uptake using cross-validated PLS (Partial Least Squares)
regression models. Plant N uptake was measured as total nitrogen in aboveground plant parts at harvest, in plots without N
fertilisation within three different fields in southern Sweden. NIR spectroscopy and combined clay and SOM content resulted
in equally good estimations of plant N uptake in fields with large variation in SOM content. Cross-validated NIR calibrations
for plant N uptake within fields for separate years resulted in r
2 values of 0.75–0.85 and average cross-validation errors of 11–16 kg N ha−1 for two fields (1 year excluded at one field because of farmyard manure application). No significant improvements were seen
when NIR-spectra, clay and SOM were included in the same model, suggesting that the additional predictive capacity of NIR
over SOM relates to soil texture variations. NIR calibrations also performed poorly in one field where plant N uptake could
not be explained by SOM or clay content. Predictions within fields between years produced r
2 values of 0.56–0.89 and prediction errors of 12–26 kg N ha−1 for one field. These results confirm that N uptake prediction accuracy can be improved by using NIR spectroscopy in fields
with large SOM variations. However, good estimations could not be made between fields, indicating difficulties in creating
more general calibration models for large geographical areas. 相似文献
18.
In 1981 a two-year field plot experiment was established to assess the effects of quantities (0, 7.5, 15, 30, 60 and 120 t
ha−1) of fresh kelp (Macrocystis integrifolia) on crop growth and nutritional response and chemical properties of a fine-textured soil. Soil was analyzed for NO3−N, NH4−N, electrical conductivity, pH, Cl and exchangeable cations (K, Mg, Ca, Mn and Na). The plots were planted to beans (Phaseolus vulgaris) in the first year and peas (Pisum sativum) in the second year. Marketable bean yields increased in the first year with kelp applications up to 60 t ha−1, with yields, emergence and flowering being reduced by the 120 t ha−1 application. Soluble salts (EC) and Cl concentrations in the soil eight days after application increased linearly and sharply
with increasing quantities of kelp. Increased K concentration and moisture content, characteristics of plants growing in a
salt-stressed soil environment, were measured. A subsequent companion greenhouse experiment confirmed that the reduced bean
emergence and growth with 120 t ha−1 applications of kelp were primarily due to soluble salts. The only growth effects upon peas in the second year was a slight
reduction in leaf plus stem yields with increasing applications of kelp. 相似文献
19.
Green manure application may benefit subsequent crops not only by improving nitrogen (N) fertility but also via non-nutritional
mechanisms. The quantification of the latter effect, however, is complicated by the confounding effect of N fertility. Two
experiments were conducted in controlled environments to partition the yield response of barley to green manure between N
and non-nutritional effects. Each experiment included a factorial of fertilizer N application rates and green manure application
rates. The fertilizer was labelled with 15N to facilitate discrimination between N sources. Approximately 24% of the N applied in green manure was assimilated by barley
after 45 days (Experiment 1) and 32% was recovered by barley grown to maturity (Experiment 2). Apparent recovery of green
manure-N by barley was not appreciably affected by fertilizer application. Regression analysis of the relationship between
dry matter yield and plant N uptake demonstrated that yield responses to green manure application were not entirely attributable
to improved N fertility. For a given amount of N assimilated by the crop, yields were higher in green manure-amended treatments
than in those receiving no green manure. In barley grown to maturity, barley response to N and non-nutritional effects were
estimated to be 5.3 and 2.2g pot−1, respectively. The relationship between dry matter yield and N uptake is suggested as a method for distinguishing nutritional
and non-nutritional yield responses. This approach assumes that no other nutrient is limiting growth. The presence of non-nutritional
benefits observed in this study demonstrates that the agronomic value of green manure is not limited to N release and casts
doubt on the assumptions inherent to calculation of fertilizer equivalents.
Contribution 3879132
Contribution 3879132 相似文献
20.
Organic matter and nitrogen in the unharvested fractions of grass swards in relation to the potential for nitrate leaching after ploughing 总被引:1,自引:0,他引:1
The amounts of organic matter in the stubble, litter, root and soil macro-organic matter fractions of two swards of perennial
ryegrass that had received normal applications of either fertilizer or cattle urine were, on average for the four fractions,
about 3000, 500, 11,500 and 8,800 kg ha−1. The swards had been established 8 or 15 years previously and each was sampled at intervals over a period of about one year.
The amounts of N contained in the four fractions were, on average, 68, 12, 249 and 240 kg ha−1, a total of 569 kg N ha−1.
With other swards, increasing rates of application of fertilizer N were found to have little effect on the amounts of organic
matter in stubble and roots. Concentrations of N in the organic matter of the stubble and roots, however, increased significantly
with increasing rate of fertilizer application, though, with stubble, moderate rates of application had little effect.
Assessments based on these data, together with other published information, indicate that the amount of N mineralized from
the combined stubble, litter, root and macro-organic matter fractions during the first year after ploughing may range from
about 40 kg to at least 360 kg N ha−1 depending on the age of the sward and its recent management. The amount mineralized is likely to increase with age of sward,
with increasing rate of fertilizer N and with utilisation by grazing rather than cutting. 相似文献