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 [email protected]
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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
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
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]
Click to return to Discussion Topics
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]
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]
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]
See paper describing synchronization problem: Gaskell et al. 2007. Soil fertility management for organic crops. http://anrcatalog.ucdavis.edu/pdf/7249.pdf