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EFFECT OF ORGANIC FERTILIZERS ON NITRATE ACCUMULATION IN VEGETABLES AND MINERAL NITROGEN IN TROPICAL SOILS OF MOROGORO, TANZANIA
- MARCELINA A BAITILWAKE, SARA DE BOLLE, JOOST SALOMEZ, JEROME P MREMA, STEFAAN DE NEVE
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- Journal:
- Experimental Agriculture / Volume 48 / Issue 1 / January 2012
- Published online by Cambridge University Press:
- 18 August 2011, pp. 111-126
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- Article
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Nitrogen (N) nutrition is a key factor for vegetable growth and yield. However, different rates of nitrogen fertilization may trigger different responses to vegetables. A survey was conducted to investigate the effect of soil fertility management practices on nitrate concentration in vegetables. The survey results were used to plan experiments on the effect of chicken and cattle manures on nitrate levels in Chinese cabbage (Brassica rapa) and amaranthus (Amaranthus cruentus) grown in Tanzania and the patterns of mineral nitrogen in soils under open field conditions. Chicken or cattle manure at 200, 300 kg N ha−1 and 170 250 kg N ha−1 for Chinese cabbage and amaranthus respectively, and control were compared in a randomized complete block design. We observed a higher nitrate content in fertilized Chinese cabbage at day 30 than at day 44 after sowing, ranging from 3243 to 4993 mg kg−1 fresh matter regardless of the N source and rates. Only application of manures at high levels (250 kg N ha−1) induced significantly (p < 0.05) higher nitrate contents in amaranthus at day 28 after sowing, although there was a clear indication of nitrate accumulation even at 170 kg N ha−1 application. Soil NH4+-N + NO3−-N in both Chinese cabbage and amaranthus plots were increased with increasing N application rates and differences between control and amended soils were significant (p < 0.01). There was a positive relationship between NO3− concentration in vegetables and NO3−-N in the rooted top soil layer (0–15 cm). However, higher NH4+ concentrations depressed NO3− build up in crops and a significant negative relationship between soil (NH4+-N)/(NO3−-N) ratio and crop NO3− content was found. It is concluded that low manure application rates result in similar yields to high rates but reduces nitrate accumulation in vegetables and excess mineral nitrogen in soils.
23 - Developing integrated approaches to nitrogen management
- from Part V - European nitrogen policies and future challenges
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- By Oene Oenema, Wageningen University and Research Centre, Joost Salomez, Flemish Government, Cristina Branquinho, Universidade de Lisboa, Faculdade de Ciências, Michaela Budňáková, Ministry of Agriculture of the Czech Republic, Pavel Čermák, Central Institute for Supervising and Testing in Agriculture, Markus Geupel, Federal Environment Agency, Germany, Penny Johnes, University of Reading, Chris Tompkins, Independent consultant, Till Spranger, Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, Jan Willem Erisman, Energy Research Centre of the Netherlands, Christian Pallière, Fertilizers Europe, Luc Maene, International Fertilizer Industry Association, Rocio Alonso, Rob Maas, Netherlands Environmental Assessment Agency, Jacob Magid, Copenhagen University, Mark A. Sutton, Centre for Ecology and Hydrology, Hans van Grinsven, Netherlands Environmental Assessment Agency
- Edited by Mark A. Sutton, NERC Centre for Ecology and Hydrology, UK, Clare M. Howard, NERC Centre for Ecology and Hydrology, UK, Jan Willem Erisman, Gilles Billen, Albert Bleeker, Peringe Grennfelt, Hans van Grinsven, Bruna Grizzetti
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- Book:
- The European Nitrogen Assessment
- Published online:
- 16 May 2011
- Print publication:
- 14 April 2011, pp 541-550
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Summary
Executive summary
Nature of the problem
Reactive nitrogen (Nr) occurs in different forms, arises from a wide range of activities and sources, and leads to environmental impacts over different spatial and temporal scales.
Integrated approaches to N management are anticipated to provide more effective (larger decreases in unwanted emissions) and /or more efficient (less side effects, less costs) policy measures than policy measures based on single sources and pollutant species.
There are many notions of integrated approaches, but as yet little consensus about the best integrated approaches. There is also little quantitative empirical evidence of the performance of these approaches in practice.
The pitfall of integrated approaches is that they may be more complex to agree, leading to a delayed implementation.
Approaches
Based on recent literature and a discussion among experts, the present chapter provides a conceptual framework for developing integrated approaches to N management.
Whilst discussing the framework, various examples of existing partially integrated N management approaches have been considered.
A package of key actions in different sectors is envisaged that, together, should contribute to further developing integrated approaches to N management in the future