Phosphorus fertilization in low income systems in the humid tropics of Peru

The objetives of two experiments were the assessment of: a.- the possibility of using phosphate rock in direct application for production of acid-tolerant crops, b.- proper P rates for a low-income system, and c.- the possibility of shallow P application. In the first experiment no significant differences were found among phosphorus rates. This could have been the result of soil acidity (50% saturation), which improved the solubility of the rock. In the first rice crop the rototilled treatment yielded significantly more grain than the no-tilled treatment. The second (rice) and third (cowpea) treatments did not show significant differences. For the subsequent crops, the no-tilled treatment yielded better than the rototilled. Phosphate rock was as effective as superphosphate in supplying available P. A total of 13.9 t ha**-1 of rice grain was produced in five harvests in a field just cleared for cultivation, without lime or phosphorus application. The rice crop did not respond to the P application, but the cowpea responded to the application of phosphate rock up to the application of 22 kg P ha**-1. No significant differences among treatments were found in the second experiment for the first three crops (rice-rice-cowpea), but they did were found for the fourth (rice) and fifth (cowpea) crops.

---

• View source