1. A Survey of Phosphorus in the Yaqui Valley, Sonora, Mexico Barbara Cade-Menun Geological and Environmental Sciences Stanford University

2. 1. International Rice Research Institute Soil phosphorus concentrations are of interest environmentally for two reasons: 2. Lake Experiment, Manitoba, 1973 P Added No P

3. Concerns in the Yaqui Valley n High N fertilization n Drought n Increased animal production

4. Research Objective: To assess the concentrations of soil P throughout the Yaqui Valley n To determine if P might limit crop growth. n To determine if land application of manure would be appropriate

5. Obregon Zone 3 Zone 1 Zone 2 Samples collected by D. Lobell July 2001 0-20 cm depth; 5 replicates per field

6. Soil Data by Zone Zone 1 Zone 2 Zone 3 pH 7.57 a (0.016) 7.37 b (0.038) 7.35 b (0.029) Total C 0.074 b (0.001) 0.085 a (0.002) 0.082 a (0.003) Total N 0.984 a (0.014) 0.980 a (0.021) 0.924 b (0.026) CN Ratio 15.61 a (0.249) 13.35 b (0.157) 13.36 b (0.274) Zone 3 Zone 1 Zone 2

7. Soil Texture by Zone Zone 1 Zone 2 Zone 3 Sand 23.1 a (2.15) 15.6 a (3.11) 15.8 a (2.77) Silt 32.3 b (2.49) 36.3 b (2.03) 49.7 a (2.59) Clay 44.8 a (1.63) 47.2 a (3.62) 34.5 b (2.64) Zone 3 Zone 1 Zone 2

8. Soil Data by Zone Zone 1 Zone 2 Zone 3 Ca 7943.9 a (195.1) 5393.7 b (153.4) 4410.6 c (164.8) Fe 42.8 b (1.50) 67.6 a (2.04) 70.8 a (1.61) Al 299.1 c (18.0) 614.4 a (12.8) 397.2 b (20.2) Na 347.8 a (14.6) 323.8 a (14.4) 233.0 b (21.9) Zone 3 Zone 1 Zone 2

9. Total Soil Phosphorus

10. Available Phosphorus (Bray P)

11. P Saturation Index

12. Phosphorus Retention Curves Zone 1 Zone 2 Zone 3

13. Zone 1 Soils and Fertilizers FieldFertilizers Carlos Valenzuela 150 kg NH 3, 100 kg 11-52-0 Luis Arturo Arraya 200 kg Urea Luis Arturo Arraya 200 kg Urea, 200 kg 11-52-0 Cesar V. Gallinaza Seca, 11 t/ha M. Lopez Lava No fertilizer

14. P in Fertilized soils Fertilizers Total P Available P PSI NH 3, 11-52-0 541.80.510.004 Urea, no P 622.01.030.005 Urea, 11-52-0 537.81.340.005 Gallinaza Seca 966.81.340.004 No fertilizer 349.33.970.005 10.0 / 40.00.02 / 0.05

15. Summary of P Research n Soils in Zone 1 (NE) have a low P concentration, with a high P retention capacity n Soils in Zone 3 (NW) are P-saturated, with the potential for P transfer to water

16. Manure application to land? n Manure application to soils in Zone 1 would be a beneficial source of P n Low risk of P saturation from manure application in Zone 1; high risk in Zone 3 n Wide-scale manure application should be carefully monitored

17. Future Research Needed n Evaluate nutrient status of different types of manure n Develop a consistent manure product, (through composting ?) n Establish guidelines for manure storage and application, to avoid environmental risk

18. Policy Perspectives n This information is useful to farmers, regional planners, livestock producers n To be implemented, valley-wide coordination required to collect manure, turn it into a useful product, and monitor manure application

19. Micronutrients Zone1 Zone 2 Zone 3 B 3.69 a (0.103) 3.49 a (0.124) 3.00 b (0.117) Cu 2.41 b (0.094) 2.95 a (0.088) 2.42 b (0.081) Mn 151.4 c (6.06) 205.6 b (5.76) 231.3 a (7.05) Zn 0.98 b (0.094) 1.49 b (0.088) 1.74 a (0.082)

20. Soil Exchangeable Zinc