Deliverables/Results:

1. Soil testing at wheat sowing showed residual fertilization effects of previous seasons on nitrate-N, Bray 1 P, and sulfates-S.
2. After seven years of experimentation, wheat yields in the continuous Check treatment show the depletion of N, P, and S reserves, reaching only 36% of the yield obtained in the continuous NPS treayment.
3. Spikes per m² and grains per m² were significantly related to grain yields.
4. Considering precipitations from June to November, average water use efficiencies were of 6.1, 10.2, 10.4, 15.8, 16.0 and 16.8 kg/ha per mm, for the treatments Check, PS, NS, NP, NPS and Complete, respectively.
5. Average responses to N, P, S, and other nutrients was of 2100, 1930, 102 and 321 kg/ha, respectively. In the three sites, there was a significant response to NP, and at one site to other nutrients. No responses to S were observed in this season.
6. Considering the 28 sites under wheat along the 5 seasons evaluated in the Nutrition Network, significant relationships were established between grain yields and soil nitrate-N at sowing + fertilizer N, 130-140 kg/ha allow to reach grain yields of 4000 kg/ha.
7. A critical level of 15-20 ppm Bray 1 P was determined.
8. Responses to S were not related to sulfate-S availability at planting.

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