Sugarcane ratoon fertilization with ammonium carbonate/bicarbonate solutions mixed with potassium and phosphorus salts

The efficiencies of aqua ammonia and ammonium carbonate/bicarbonate solutions mixed with K and P salts were compared to shoot dry matter yield and the profit of N applied from fertilizers by sugarcane. Sugarcane ratoons, cultivar "RB72454", were transplanted to 100 dm³ soil pots and were grown for ninety days. The experimental design adopted was a 2 x 3 completely randomized factorial, with 4 replications. Treatments consisted of supplying N sources mixed or not with KCl and NH4H2PO4. P and K nutrients not included in each treatment were applied at another point, but at the same distance and depth from ratoons than the treatment solutions, to assure the equality of the rates of N, P and K applied to all treatments. Shoot dry matter yield, total N uptake and N recover from the fertilizer solutions were evaluated. This last parameter, was considered as soil N uptake by ratoons of plots, which received only K and P salts. The ammonium carbonate/bicarbonate solutions lead to greater shoot dry matter yield than the aqua ammonia, but they did not differ in respect of the total N uptake and N recover from the fertilizers solutions. The KCl and NH4H2PO4 inclusion to N solutions did not affect the total N uptake and N recover efficiency, to the evaluated N:K and N:P:K ratios.

non conventional fertilizer; fluid fertilizer; nitrogen

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