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1.
Benjamin Nowak Thomas Nesme Christophe David Sylvain Pellerin 《Nutrient Cycling in Agroecosystems》2013,96(1):79-91
Organic farming systems are often nutrient-limited. Moreover, even if organic guidelines emphasize the reliance on ecological processes and recycling, the trend towards farm specialisation induces an increased reliance on off-farm fertilising materials in arable areas. There is, therefore, a need to better understand the drivers of nutrient inflows on organic farms. Our objectives were to assess the nitrogen (N,) phosphorus (P) and potassium (K) farm-gate inflows through fertilising materials, and the nutrient budget and use efficiency over a large range of organic farming systems. To do this, 56 interviews with organic farmers concerning their nutrient management for the years 2010 and 2011 were carried out in 2012 in three French agricultural districts distributed over a gradient of farming activity. The results showed that the farm-gate fertilising material inflows were strongly related to both the ratio of land under cereal and oilseed crops (proxy of nutrient ‘demand’) and the stocking rate (proxy of nutrient ‘supply’). However, other inflows (biological N fixation, feed use, fodders and straws) increased with the stocking rate, leading to low farm-gate N and K use efficiency (0.2 and 0.7, respectively) on livestock farms compared to arable, stockless farms (1.4 and 3.5, respectively). Such results helped to disentangle the drivers of nutrient use in organic farms compared to previous analyses based solely on farm production typology. 相似文献
2.
A comparative study of farm nutrient budgets and nutrient flows of certified organic and non-organic farms in China,Brazil and Egypt 总被引:3,自引:0,他引:3
Myles Oelofse Henning Høgh-Jensen Lucimar S. Abreu Gustavo F. Almeida Ahmed El-Araby Qiao Yu Hui Andreas de Neergaard 《Nutrient Cycling in Agroecosystems》2010,87(3):455-470
Increased demand for certified organic products has led to an increase in the number of certified organic farms in developing
countries. Knowledge of farmer nutrient management practices on certified organic farms in developing countries is limited.
Thus, the aim of this study was to investigate the impact of the adoption of certified organic agriculture on farm nutrient
flows and nutrient budgets, and evaluate to which degree organic farms comply with organic principles relating to nutrient
management. The study is based on five case studies of different types of certified organic farming systems in Brazil, Egypt
and China. Farm nutrient flows and nutrient budgets for nitrogen, phosphorous and potassium were created for each farm. Four
of the five organic systems studied had nutrient surpluses on the farm budget. The surpluses were of varying magnitude. The
main difference between organic and non-organic farm nutrient flows was the replacement of mineral fertilizers with organic
inputs. However, the magnitude of nutrient flows were generally similar for organic and non-organic farms. Certified organic
farms with positive nutrient budgets had a heavy reliance on external inputs. Continued high dependence on an external supply
of nutrients, which typically originate from mineral sources, poses a significant challenge to organic farmers’ fulfilment
of the principles of organic agriculture. 相似文献
3.
Regional-scale phosphorus flows and budgets within France: The importance of agricultural production systems 总被引:6,自引:0,他引:6
Kalimuthu Senthilkumar Thomas Nesme Alain Mollier Sylvain Pellerin 《Nutrient Cycling in Agroecosystems》2012,92(2):145-159
Large-scale studies at the regional, national and global scales are increasingly needed to assess nutrient flows in agroecoystems
and to identify their drivers. In this study, we aimed to quantify the extent to which regional phosphorus (P) flows and soil
P budget depend on agricultural production systems. Phosphorus was taken as a case study due to its sorbing properties in
soil and to the many questions concerning its future availability. The issue was studied from two different stages: (1) for
the 21 administrative regions of France; and (2) by selecting four contrasting French regions—the Centre region (a crop farming
region), Brittany (an animal farming region) and Lorraine and Aquitaine (mixed farming regions). Phosphorus flows and soil
P budgets were quantified on a yearly basis for the 21 regions from 1990 to 2006, whereas a 5-year average was calculated
for the years 2002–2006 to compare the four selected regions. At the beginning of the study (1990), the calculated P budget
was positive for all regions averaging 17.5 kg P ha−1 year−1 which declined over years to 4.4 kg P ha−1 year−1 in 2006, but huge differences between the 21 regions were observed, confirming the heterogeneity of the regional P flows.
Agricultural production systems strongly influenced the P flows through feed, fodder and animal excretion, while P fertiliser
consumption was only partially influenced. As a consequence, both the regional soil P budgets and the magnitude of soil P
inflows and outflows were strongly dependent on the regional agricultural production systems. A balanced soil P budget could
be obtained in crop farming regions, but it strongly relied on P fertiliser use. The animal farming regions continued to accumulate
P in the soil, and further use of P fertilisers in these regions is questionable. Finally, there was no simple rule between
the mixed farming systems and the soil P budget. This study offers some initial elements for understanding the drivers of
mineral P fertiliser use, i.e. the factors governing P fertiliser use by the farmers. It may also contribute to the redesign
of regional farming systems oriented towards more effective use of nutrients at the global scale. 相似文献
4.
Organic farming systems are characterized by the strong regulation of the import of nutrients into the farming system to replace
nutrient losses via sold products. In the present study mineral nutrient flows and balances of P, K and magnesium (Mg) were
analysed for a mixed organic cropping system with dairy husbandry and for a stockless organic farming system. Also the influence
of biogas digestion of farmyard residues (stable wastes, crop residues, etc.) as well as the effect of the import of substrates
for biogas digestion on plant mineral nutrient uptake and farmgate nutrient balances was analysed. The objectives of the current
study were; (1) to study the effects of anaerobic digestion of cattle manure and crop residues on plant mineral nutrient uptake;
and (2) to model nutrient flows and balances related to the input of different kind of substrates for biogas digestion at
the farmgate. Results indicated that slurry digestion did not influence plant P and K uptake. Import of single allowed substrates
for digestion would lead to large imbalances in nutrient inputs compared to withdrawals. Most of the suited substrates for
biogas digestion were associated with large K surpluses and insufficient P returns in comparison to mineral nutrient outputs
via sold animal and plant products. 相似文献
5.
Maintaining sufficient soil phosphorus (P) levels for non-limiting crop growth is challenging in organic systems since off-farm inputs of P are restricted. This study assessed the status of P on organic farms in Europe using soil test results for extractable P. Data was obtained from published literature, unpublished theses, and various national and regional databases of soil test values. Most of the data (15,506 observations) came from field scale soil tests, but in some cases (1272 observations) values had been averaged across a farm. Farm scale and field scale data were analysed separately and the impact of farm type (arable, dairy, grassland, horticulture, mixed, poultry, unknown) was assessed. Soil test results were assigned to P classes from very low (P class 1) to very high (P class 5). The farm scale data came primarily from Norway, Sweden and Switzerland and did not indicate deficiencies in extractable P; 93% of farms fell into class 3 or above. The majority of the field scale data came from Germany and indicated sufficient or higher levels of P availability for arable and grassland systems on 60% of fields; the remaining fields had low or very low available P. Adaptations in organic systems may improve P uptake and utilization efficiency allowing yields to be maintained in the short-term, nevertheless there is cause for concern about the long-term P sustainability of some organic farming systems in Europe. This highlights the need to reassess allowable P inputs in organic farming systems to improve overall sustainability. 相似文献
6.
M. Oyanarte G. Besga M. Rodríguez M. Domingo A. G. Sinclair 《Nutrient Cycling in Agroecosystems》1996,47(3):261-269
Dairy farming is the main agricultural activity of the Basque Country. A dairy farm is characterized as a system with soils and crops, forage, cattle and manure as main components, and in such a system, nutrient cycling is very important to maintain soil fertility and optimize forage production. To quantify nutrient transfers in the cycle, a simple system was developed and has been applied to seventeen farms to examine its ability to achieve a balanced P and K fertilization. These farms have provided data on inputs (fertilizer, feeds, concentrates), pasture and manure management, and outputs (milk production), and soil samples have been taken from farm pastures. Phosphorus and K in excreta and uneaten pasture is used with a relatively high efficiency as suggested by the relatively high efficiency of P and K utilization by the pasture that usually ranges from 70 to 90%. Concentrate feeding (3000 kg cow–1 yr–1) represents one of the main P and K inputs in Basque Country dairy farms, averaging 26 and 66 kg ha–1, respectively. Besides, release of K in the soil through slow liberation from non-exchangeable sites was estimated as 30 kg ha–1. Thus, a high efficiency in excreta recycling would diminish substantially P and K mineral fertilizer needs. Farm nutrient budgets appear to be a convenient tool for determining nutrient shortages and surpluses at farm level, and thus they are considered as a first step to support a better management of maintenance fertilization of permanent pastures. 相似文献
7.
Hong-Jie Wang Biao Huang Xue-Zheng Shi Jeremy Landon Darilek Dong-Sheng Yu Wei-Xia Sun Yong-Cun Zhao Qing Chang Ingrid Öborn 《Nutrient Cycling in Agroecosystems》2008,81(3):203-218
Balances of major nutrients such as nitrogen (N), phosphorus (P), and potassium (K) in small-scale farming systems are of
critical importance to nutrient management and sustainable agricultural development. Mass balances of N, P, and K and some
of their influencing factors were studied for two years from July 2003 to July 2005 on small-scale vegetable-farming systems
in two contrasting peri-urban areas (Nanjing and Wuxi) of the Yangtze river delta region of China. This balance approach considered
organic fertilizer inputs (cow manure, pig manure, and human biosolids), inorganic fertilizer inputs (urea, composite fertilizer,
and phosphates), irrigation water, and atmospheric deposition; and considered outputs by vegetables. Input via organic fertilizers
was significant for all element balances in the Nanjing area. Inorganic and organic fertilizer, particularly inorganic fertilizer,
contributed major nutrient inputs to the system in the Wuxi area. Compared with nutrient output by vegetables, there were
significant surpluses of N and P on two vegetable farm systems. Furthermore, N surplus in the Nanjing area was higher than
that in the Wuxi area with an inverse relationship to P surplus. In contrast, the general trend of K balances was negative
on both sites; hence, the nutrient use efficiency was significantly lower for N and P than K. The nutrient imbalance may be
attributed to the differences between fertilizer types and management modes driven by social economic status differences among
farmer households. The large N and P net excess creates an environmental threat because of potential losses to ground or surface
waters, whereas negative K balance creates soil fertility risks. The results highlight researchers’ and farmers’ need to develop
rational fertilization technology to optimize nutrient management on vegetable farmlands to promote sustainable agricultural
development in peri-urban areas. 相似文献
8.
Judged by their negative nutrient balances, low soil cover and low productivity, the predominant agro-pastoral farming systems
in the Sudano-Sahelian zone of West Africa are highly unsustainable for crop production intensification. With kaolinite as
the main clay type, the cation exchange capacity of the soils in this region, often less than 1 cmolc kg−1soil, depends heavily on the organic carbon (Corg) content. However, due to low carbon sequestration and to the microbe, termite
and temperature-induced rapid turnover rates of organic material in the present land-use systems, Corg contents of the topsoil
are very low, ranging between 1 and 8 g kg−1 in most soils. For sustainable food production, the availability of phosphorus (P) and nitrogen (N) has to be increased considerably
in combination with an improvement in soil physical properties. Therefore, the adoption of innovative management options that
help to stop or even reverse the decline in Corg typically observed after cultivating bush or rangeland is of utmost importance.
To maintain food production for a rapidly growing population, targeted applications of mineral fertilisers and the effective
recycling of organic amendments as crop residues and manure are essential. Any increase in soil cover has large effects in
reducing topsoil erosion by wind and water and favours the accumulation of wind-blown dust high in bases which in turn improves
P availability. In the future decision support systems, based on GIS, modelling and simulation should be used to combine (i)
available fertiliser response data from on-station and on-farm research, (ii) results on soil productivity restoration with
the application of mineral and organic amendments and (iii) our present understanding of the cause-effect relationships governing
the prevailing soil degradation processes. This will help to predict the effectiveness of regionally differentiated soil fertility
management approaches to maintain or even increase soil Corg levels.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
9.
Application of reactive phosphate rock and sulphur fertilisers to enhance the availability of soil phosphate in organic farming 总被引:1,自引:0,他引:1
Plant available soil phosphate is frequently deficient for crop and pasture production on organic farms in southern Australia. Improved P management, including developing a fertiliser product conforming to organic farming regulations, is required to sustain and increase production on these farms. Reactive phosphate rock (RPR) and elemental sulphur (S) are natural products. Field and pot experiments were established to measure the impact of ground RPR, and co-treatment of RPR with finely ground S, on available soil phosphate (Olsen P), plant dry matter, and the P concentration (%) and content (kg P ha−1) of the dry matter. Under dry-land field conditions characteristic of cropping regions in southern Australia ( < 600 mm rainfall, organic carbon < 3%), co-treatment of RPR with S was necessary to increase Olsen P, and higher values of Olsen P were generally associated with increased plant dry matter, together with P concentration or P content of the dry matter. The required amount of S was less the more acidic the soil, but greater than reported as being effective in situations of higher rainfall ( > 1,000 mm) and soil organic carbon concentration (OC 11%). It was deduced that the S is probably required to overcome the constraint on dissolution of RPR resulting from frequent periods of low soil moisture. It was concluded that for the south-eastern Australian cropping zone, co-treatment of ground reactive phosphate rock with finely ground elemental S, at ratios (RPR:S) of at least 2:1, depending on soil pH, is required for effective use␣of RPR, even in strongly acidic soil (pHCa < 4.5). It was recommended that ‘organic’ farmers may recover soil P fertility by applying RPR + S fertiliser to the most acidic fields, postponing soil liming, and managing the fields to conserve soil moisture. 相似文献
10.
Departing from the historical background of scientific interest in soil fertility and sustainable agricultural production in sub-Saharan Africa, a review is conducted of nutrient budget studies carried out in semi-arid West Africa at scales ranging from individual fields to the sub-continent. For both, nitrogen and phosphorus, the comparison discloses largely diverging balances calculated for similar agro-ecosystems. In a first step, the modes of calculation of the nutrient budgets are examined. It is demonstrated that the calculations used in the different studies differ by the variables and biophysical processes taken into account, and by the choice of spatial scales as well as related time scales. One important discrepancy between approaches is whether and to which extent nutrient flows are internalized when upscaling. The extent to which the impact of individual and communal management, especially of pastoral and forestry resources, on nutrient flows is accounted for is a second cause of divergence. Moreover, it was observed that nutrient budgets tend to be increasingly negative as the spatial scale of the study increases from farm to sub-continent. This unexpected trend is traced back to the lack of internalization of nutrient flows when upscaling. The complexity of the scale patterns of nutrient flows and that of the interactions and the tradeoffs in the effects of management calls for the use of models to calculate nutrient budgets. Therefore, in a second step, examples of a static model, a multiple-goal linear programming model and a decision rules model were reviewed, all of which include the calculation of nutrient flows and balances and which were applied to West-African farming systems. The models are analyzed for their way of dealing with the critical issues of spatial and temporal scales and the impact of resource management on nutrient flows, taking into account that they have different objectives and were designed for different spatio-temporal scales. To conclude, suggestions were made for strengthening the use of models as tools enabling ex-ante testing of alternative agricultural technologies and policies that could improve soil nutrient balances in semi-arid sub-Saharan Africa. 相似文献
11.
Departing from the historical background of scientific interest in soil fertility and sustainable agricultural production in sub-Saharan Africa, a review is conducted of nutrient budget studies carried out in semi-arid West Africa at scales ranging from individual fields to the sub-continent. For both, nitrogen and phosphorus, the comparison discloses largely diverging balances calculated for similar agro-ecosystems. In a first step, the modes of calculation of the nutrient budgets are examined. It is demonstrated that the calculations used in the different studies differ by the variables and biophysical processes taken into account, and by the choice of spatial scales as well as related time scales. One important discrepancy between approaches is whether and to which extent nutrient flows are internalized when upscaling. The extent to which the impact of individual and communal management, especially of pastoral and forestry resources, on nutrient flows is accounted for is a second cause of divergence. Moreover, it was observed that nutrient budgets tend to be increasingly negative as the spatial scale of the study increases from farm to sub-continent. This unexpected trend is traced back to the lack of internalization of nutrient flows when upscaling. The complexity of the scale patterns of nutrient flows and that of the interactions and the tradeoffs in the effects of management calls for the use of models to calculate nutrient budgets. Therefore, in a second step, examples of a static model, a multiple-goal linear programming model and a decision rules model were reviewed, all of which include the calculation of nutrient flows and balances and which were applied to West-African farming systems. The models are analyzed for their way of dealing with the critical issues of spatial and temporal scales and the impact of resource management on nutrient flows, taking into account that they have different objectives and were designed for different spatio-temporal scales. To conclude, suggestions were made for strengthening the use of models as tools enabling ex-ante testing of alternative agricultural technologies and policies that could improve soil nutrient balances in semi-arid sub-Saharan Africa. 相似文献
12.
Nutrient budgets may be useful tools for nutrient management of crops especially if they estimate the nutrient fluxes available
from a variety of sources including organic and inorganic fertilizer, crop residues and soil organic matter. The aim of the
present study was to develop a budget of available nutrients by determining the contribution of mineralized nutrient fluxes
and fertilizer input relative to nutrient losses and removal in harvested products in the overall N and P balances. N and
P inputs and outputs and available N and P fluxes in the soil were estimated for 3 consecutive maize crops where inputs and
outputs were altered by NP fertilizer, compost and stubble removal on a Rhodic Kandiustox. A sensitivity analysis of calculated
and measured nutrient budget items was conducted to identify the main factors affecting the accuracy of the nutrient balance
calculations. Mineral fertilizer rate was the major factor for maize nutrient budgets as shown by its contribution to N and
P balances. Without mineral fertilizer application, soil organic matter (SOM) mineralization was the most important within-season
nutrient input. In the case of N, shoot uptake was the main output followed by denitrification. Phosphorus adsorption by the
soil was the major P output from the available pools followed by shoot uptake. SOM mineralization maintained the pools of
available N and P if stubble of the previous crop was returned. Mineral fertilizer application, which produced surplus balances
of N and P, would however, be needed to attain high yield, even with stubble return. The available N and P from compost were
not significant inputs in the nutrient balances until year 3. Total N and resin extractable P in soil after five crops supported
the calculated nutrient balances indicating the importance of available nutrient fluxes in calculating N and P balances. 相似文献
13.
Effects of setup of centralized biogas plants on crop acreage and balances of nutrients and soil humus 总被引:1,自引:0,他引:1
An increasing number of biogas plants (BGPs) based on digestion of dedicated energy crops have been implemented in Germany.
The objectives of this study were to assess the changes in (1) the acreage of different crops (silage maize, cereals, etc.)
related to the setup of the BGP, (2) nutrient flows and budgets (N, P, K) due to the implementation of the BGPs, and (3) to
assess the effluent N in the overall crop N supply. Data from 14 farmers before the setup of the BGPs were compared with data
after implementation. Due to the setup of the BGPs, the acreage of silage maize greatly increased and there were significant
negative effects on the weighted soil humus budgets, no effects on the weighted mean N and P budgets, and a negative trend
regarding the K budgets. Results concerning the N release from organic manuring to maize crops showed that one third of the
farmers considerably over-fertilize maize, indicating an underestimation of short- and long-term N supply of manure N. The
implementation of centralized BGPs established very intensive nutrient cycles and, in the long-term higher risks of nutrient
losses and environmental pollution are expected. One very effective measure to compensate for negative effects on the soil
humus budgets and nitrate leaching is an enlargement of cover cropping, which will also offer economic revenue by providing
aboveground biomass for digestion. If the amounts of effluents returned to a single farm or field are not adapted to the nutrient
composition of the substrates delivered to the BGP, large nutrient imbalances can result. An effective measure to get a better
allocation of the available nutrients is a solid-liquid separation of the effluents, enabling a more targeted allocation of
the nutrients. 相似文献
14.
K. D. Shepherd E. Ohlsson J. R. Okalebo J. K. Ndufa 《Nutrient Cycling in Agroecosystems》1995,44(2):87-99
There is much current interest in the potential role of agroforestry in the mitigation of nutrient depletion in Sub-Saharan Africa. Using data from farm surveys and trials, a static model of N and P flows was constructed for a standard farm system, representative of typical subsistence farms in humid parts of the East African Highlands. The model was used to explore the possible impact of improved agroforestry systems on nutrient budgets, to identify priorities for research.Soil nutrient balances in the standard farm system were - 107 kg N and - 8 kg P ha–1 yr–1. Agroforestry systems did not significantly reduce the N deficits except when a high proportion of the total biomass was returned to the soil, rather than removed from the farm. Agroforestry increased N input through biological N fixation and deep N uptake, but this was offset by a larger nutrient removal from the farm in harvested products, which increased from 38 kg N in the standard system to 169 kg N ha–1 yr–1 in an intensive dairy-agroforestry system. Agroforestry did not increase P inputs, and harvested P increased from 6 kg P in the standard farm system to 29 kg P ha–1 yr–1 in the dairy-agroforestry system. Thus, moderate P inputs, of 20 kg P ha–1 yr–1 were required to maintain soil P stocks.N leaching from the field was the most significant nutrient loss from the farm system, with a range of 68 to 139 kg N ha–1 yr–1. The capture of subsoil N by deep-rooted trees in agroforestry systems substantially increased N-use efficiency, providing 60 kg N ha–1 yr–1 in the dairy-agroforestry system. The budgets were sensitive to N mineralization rates in subsoils, N losses from soils and manures, and effectiveness of deep-rooted plants in subsoil N capture, for which there is little data from the region. Therefore, high priority should be given to research in these areas.The current model can not account for important feedback mechanisms that would allow analysis of the long-term effects of nutrient budgets on nutrient availability and plant productivity. Dynamic models of farm nutrient budgets that include such interactions are needed to further assess the sustainability of farming systems. 相似文献
15.
Elisée Ouédraogo Leo Stroosnijder Abdoulaye Mando Lijbert Brussaard Robert Zougmoré 《Nutrient Cycling in Agroecosystems》2007,77(3):245-256
A field experiment was conducted in Gampela (Burkina Faso) in 2000 and 2001 to assess the impact of organic and mineral sources
of nutrients and combinations thereof in optimising crop production in till and no-till systems and to assess the economic
benefit of these options. The study showed that under conditions of rainfall deficiency, the use of a single organic resource
at an equivalent dose of 40 kg N ha−1 better secured crop yield than the application of an equivalent amount as urea-N, while a combination of organic resources
and fertiliser was better in increasing crop yield than the application of the same N amount in the form of urea. In a year
of rainfall deficiency, a mix of organic resources and fertiliser in both till and no-till systems increased crop water use
efficiency, with the result that the farmer was able to purchase only half of the normal quantity of N fertiliser to obtain
a higher yield that he would have done when all of the N was supplied in the form of urea. Under conditions where soil N is
deficient, an economic benefit was achieved when urea was combined with easily decomposable organic material (e.g. sheep dung);
mixing the urea at a dose of 40 kg N ha−1 with maize straw was not sufficient in alleviating the negative interaction due to the enhanced N immobilisation. The results
demonstrate that the use of N fertiliser alone was risky and that a higher yield, with the accompanying economic benefit,
was scarcely achieved under the prevailing rainfall conditions. The application of soil and water conservation measures can
contribute greatly to increasing the economic benefit of mineral, organic or combined organic and mineral-derived nutrient
application under semi-arid conditions. 相似文献
16.
Kurt Möller 《Nutrient Cycling in Agroecosystems》2018,112(2):147-164
The management of specialised organic crops for vegetable and fruit production require the use of imported fertilizers. A wide range of fertilizers is currently available to organic farmers. These include bulky organic materials with a relatively low nutrient concentration commonly used as base dressing (e.g. composts, solid animal manures) and complementary commercial organic fertilizers with relatively high nutrient concentrations to adjust nutrient supply to crop requirements (e.g. feather meal, hoof and horn meal, vinasse, meat and bone meal, etc.). Nutrient imbalances are a major threat affecting the long term sustainability of horticultural and fruit cultivation systems. Major reasons for these imbalances are the biased element composition of base as well as complementary fertilizers in relation to the nutrient offtakes via harvested products. Gaseous nitrogen losses during manure management and gaseous as well as leaching nitrogen losses after application are major reasons for such nutrient imbalances, as they lead to a relative increase in the concentration of other elements. Conceptual weaknesses in the fertilizer approach in organic farming exist, namely the preferred application of slow release nitrogen fertilizers often rich in phosphorus. This review suggests that the current soil fertility approaches based on application of solid fertilizers and simultaneously a low rate of N inputs via N2 fixation do not foster balanced nutrient levels. The key challenge is to design cropping systems with a higher share of N inputs via biological N2 fixation, and to find fertilizers with a nutrient stoichiometry better suited to match the overall specific offtakes of fertilized crops. 相似文献
17.
During recent decades the problem of the sulphur cycle in the agroecosystem has become increasingly urgent due to the improvements in agricultural technologies and reduction of environmental pollution. The extremely moist climatic conditions prevailing in Lithuania predetermine rather significant losses of sulphur by leaching and also its negative balance. Thus, sulphur deficiency may become a limiting factor in crop productivity in both organic and intensive cropping systems. This paper summarises the results of investigations on sulphur migration and balance in Luvisols carried out from 1994–1998 under both cropping systems. In an intensive cropping system with programmed mineral fertilization the yield of all crops was 54% higher compared to the organic one, where only manure was applied. Liming, used as a means of chemically improving soil, not only neutralizes soil acidity, but also its sulphureous regime. The amount of mobile sulphur in soil is reduced by up to 7–8 times by this treatment. This reduction is even more evident in intensive cropping systems. Mineral fertilization is the main means of regulating nutrient balance. The balance of N and P was negative in organic cropping systems. In contrast, it was positive under the conditions of intensive cropping. Neither the organic nor the intensive cropping systems ensured a positive sulphur balance. The average annual sulphur deficit was 91 kg ha–1 in intensive cropping systems and rose even to 142 kg ha–1 in organic cropping systems. In order to avoid sulphur deficiency as a factor limiting crop productivity and to ensure a positive balance of sulphur in agroecosystems, additional usage of S-rich fertilizers is a necessary condition for rationally farming Lithuanian acid soils. 相似文献
18.
In this paper the role of organic manure in intensified farming systems in the SAT of West-Africa is discussed. Different aspects are treated: its function as a source of plant nutrients, its effects on soil physical and on soil chemical properties. It is concluded that often the major effect is through increased nutrient supply, but that in combination with chemical fertilizer — particularly nitrogen — it serves to counteract the negative effects of these fertilizers, particularly acidification and the increased removal of nutrients other than the one applied in the fertilizer.Insufficient organic material appears to be available to realize the required production increase and prevent the negative effects of nitrogen fertilizers. However, application of chemical fertilizer alone can lead to sustainable production systems provided export and losses of all nutrient elements are sufficiently compensated and acidification is avoided by using the correct type of nitrogen fertilizer, possibly in combination with liming. 相似文献
19.
Research on soil fertility decline in tropical environments: integration of spatial scales 总被引:1,自引:0,他引:1
Soil nutrient depletion is increasingly regarded as a major constraint to sustainable food production in tropical environments. Research in the recent past focused on different scales, but few attempts were made to link them. In this paper, two cases are elaborated in Central America (CA) and Sub-Saharan Africa (SSA), in which the integration of different scales has been studied. Soil nutrient depletion has been calculated for fields, and has then been aggregated to farms, regions, and subcontinents. Key problems on aggregation of field nutrient balances to farms include nutrient flows between fields. Aggregation of farms to regions requires a generalization of individual farms into a farm typology. Aggregation of regions into subcontinents implies that the farm typology concept can mostly not be maintained, resulting in a generalized calculation based on national soil, climate and land use data bases. The field-farm step proved complicated for SSA due to the occurrence of a wide variety of nutrient flows between fields, whereas in CA these flows were much less pronounced; the farm-region step turned out to be manageable for both CA and SSA as farm typology adequately covered observed variation; the region-subcontinent step proved difficult for CA due to the considerable variation in management and input levels in farming systems, whereas this was less the case in SSA. The study shows that integration of spatial scales is constrained by both data availability (the tropical parameter crisis) and by scale-specific variability. 相似文献
20.
K. K. Hazra M. S. Venkatesh P. K. Ghosh A. N. Ganeshamurthy N. Kumar N. Nadarajan A. B. Singh 《Nutrient Cycling in Agroecosystems》2014,100(1):95-110
Given inherent qualities like N-fixation, P-solublization and nutrient recycling pulses remain the most preferred option for diversification of cereal-based rotations. A long-term experiment was used to assess the effect of including pulses in rice–wheat rotation on soil–plant nutrient dynamics under inorganic and organic nutrient management. Results revealed that pulses were equally responsive to organic and inorganic nutrient management while, growth of cereals especially wheat was restricted severely under organic production system due to low nutrient input. The annual input (kg ha?1) of N (103.6–160.8) and P (25.9–34.7) under organic treatment was almost ½ of the recommended inorganic rate, while organics supplied higher K and S. Under organic management, the apparent balance of all the nutrients was negative whereas, inorganic fertilization resulted in positive balance of N, P and Zn. Long-term inclusion of pulses in rice–wheat rotation significantly increased soil organic C and available nutrients thus, increased the nutrient uptake by cereals. Mungbean inclusion in rice–wheat rotation significantly (P ≤ 0.05) increased uptake of N (23.0 %), P (32.9 %) and K (21.1 %) by rice crop. Continuous inorganic fertilization enriched soil available N, P, Zn and B. While organic management maintained higher SOC, available K and S over inorganic treatment. Thus, the study suggested that under organic management N and P nutrition is limiting factor for cereals and needs inorganic supplementation. The study also indicates the need for including pulses in conventional rice–wheat system for optimum nutrient acquisition and long-term soil health management. 相似文献