Eric B. Brennan, Salinas, California
Agricultural Research Service
A Discussion on the Use of Synthetic Nitrogen Fertilizer in
Organic Agriculture
Presented at the Univ. Calif. Coop. Exten. Annual Strawberry Production Research Meeting, February 1, 2018 . Watsonville, California
Brennan Organicwww.youtube.com/user/EricBrennanOrganic
The video for the discussion is available
on YouTube. The next slide has link
watch the video
Eric’s publications are available for free here
Synthetic Nitrogen Fertilizer in Organic?
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video
Let’s TalkDiscussion topics that summarize ideas in the video. Click any of the slides to see an enlarged version and additional information.
PureSynthetic NitrogenFertilizer
‘Repackaged’Synthetic NitrogenFertilizerManure
&slaughter
by-products
Concentrated Animal Feeding Operations
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Problems with Repackaged Synthetic N Fertilizers
1. Expen$ive
2.Too much Phosphorous
3. Challenging to apply
The next 3 slides give more information on this issue.
Click here to view or download a free pdf copy of this paper.
Phosphorous
IN per crop
Phosphorous
OUT per cropBalance after
8 years
Systems Crops Fertilizer Compost Transplants Total
1. No compost + Cover crop* in
4th year
Lettuce 15 0 0.3 16 3
Broccoli 14 0 0.6 15 8
172
2. Compost + Cover crop* in
4th year
Lettuce 15 19 0.3 35 3
Broccoli 14 19 0.6 34 8
449
3. Compost + Cover crop* every
year
Lettuce 15 19 0.3 36 4
Broccoli 14 19 0.6 34 10
* The cover crop was a legume-rye mixture. This table is a simplified version of table 4 in the paper in the previous slide. Compost in system 2 and 3 was made from municipal yard-waste.
448
Phosphorous Budget after 8 Years of Organic Vegetable Production (kg P per hectare)
Notice that there is an excess of P inputs in all systems, but that the situation is worst where compost is applied (i.e. System 2 and 3).
8-1-1 is much better than 4-4-2
% N % P2O5 % K2OClick to return to Discussion Topics
Yes to Pure synthetic nitrogen in organic, but…
Check out this paper for Novel ideas on cover cropping. Brennan, E.B., 2017. Can we grow organic or conventional vegetables sustainably without cover crops? HortTechnology 27:151-161. Click to download a PDF
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1. It’s toxic Sir Albert Howard1873-1947
2. It’s too energy intensive
3. Use legumes to get nitrogen
Arguments against using pure synthetic nitrogenSee paper describing some of Howard’s extreme views: Hershey, D.R., 1992. Sir Albert Howard and The lndore Process. HortTechnology 2:267-269. For a copy email [email protected]
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Interesting paper on this issue: Crews , T.E. and M.B. Peoples, 2004. Legume versus fertilizer sources of nitrogen: ecological tradeoffs and human needs. Agric. Ecosyst. Environ. 102:279-297.For a copy email [email protected]
6
4
1700 1800 1900 2000
8 Billion
Human Population Growth
2
Year
Synthetic nitrogen fixation was developed by Fritz Haber in 1908, and further refined for industrial production of synthetic N fertilizers by Carl Bosch. “.. the lives of around half
of humanity are made possible by Haber-Bosch nitrogen” Erisman et al. 2008. How a
century of ammonia synthesis changed the world. Nature Geoscience 1:636-639. For a copy email: [email protected]
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See this paper for more details in this concept:Du, Z., D. Denkenberger, and J.M. Pearce, 2015. Solar photovoltaic powered on-site ammonia production for nitrogen fertilization. Sol. Energy 122:562-568.*for a pdf copy email: [email protected]
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See paper describing synchronization problem: Gaskell et al. 2007. Soil fertility management for organic crops. http://anrcatalog.ucdavis.edu/pdf/7249.pdf
Out of Sync !
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