Phosphorus Fertilizer Reapplication on Sugarcane Ratoon: Opportunities and Challenges for Improvements in Nutrient Efficiency

Abstract

As impaired phosphorus (P) acquisition by sugarcane plants contributes to compromise ratoon longevity, an improved understanding of the role played by P fertilizer reapplication on ameliorating such a limiting condition is critical for sustainable biomass production. A field experiment was carried out to investigate the effects of contrasting P supply on the performance of third and fourth ratoons. Three rates were tested (30, 60 and 90 kg ha−1 of P2O5), in addition to a control without P fertilizer, following evaluation of plant nutritional status, stalk yield, P uptake and fertilizer recovery efficiency. The results revealed that the effects of nutrient reapplication on the studied parameters did not depend on the growing cycle. Therefore, on average of third and fourth ratoons, the maximum stalk yield (75.5 ton ha−1), that was 21.3% greater than the control, was achieved with 54.4 kg ha−1 of P2O5. Furthermore, P fertilization increased leaf P concentration and P uptake, which showed a positive relationship with crop productivity. Fertilizer recovery efficiency did not depend on P rate and ratoon cycle, with an averaged value of 23.1%. Our results revealed the critical role played by improvements of P uptake on ratoon performance. There is an urgent need of augmenting fertilizer recovery efficiency in order to contribute with a more rational input of resources in sugarcane fields.