[Control of the phosphorus deficiency and the toxicity of aluminium in the rotation of potato - maize - rice in an ultisol of Yurimaguas]

abonos fosfatados aluminio aluminium chaulage clay soils encalado fertilidad del suelo fosfato mineral liming oryza sativa peru phosphate fertilizers phosphate naturel rock phosphate soil soil fertility soil toxicity sol sol argileux solanum tuberosum suelo suelo arcilloso toxicidad del suelo zea mays