|Authors: ||D.D. Poudel, W.R. Horwath, J.P. Mitchell, S.R. Temple|
|Keywords: ||Soil mineral N, potentially mineralizable N, farming systems|
Precise management of soil mineral nitrogen (N) is necessary to optimize the profitability of a farming system and to minimize groundwater pollution by reducing N leaching.
Organic and low-input farming systems are alternatives to conventional systems for sustainable soil fertility.
Little information is available, however, on the effects of these farming systems on soil mineral N availability.
Evaluation of a 4-year rotation of organic (no synthetic fertilizer or pesticide use), low-input (reduced amount of synthetic fertilizer and pesticide use), and conventional (synthetic fertilizer and pesticides applied at conventionally recommended rates) (conv-4) farming systems, and a conventional 2-year rotation (conv-2) on potentially mineralizable nitrogen (PMN) and soil mineral N levels in irrigated processing tomatoes (Lycopersicon esculentum L.) was conducted after 10 years of management.
The organic and low-input systems showed 112% and 36% greater PMN pools than the conventional system, respectively.
However, nitrogen mineralization rate in the conventional system was 100% greater than in the organic and 28% greater than in the low-input system.
Organic and low-input systems showed a small but continuous supply of mineral N during the cropping season, while the conventional systems supplied mineral N as fertilizer pulses.
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