Phosphorus and Potassium Fertilization Effects on Growth Attributes and Yield of Two Sugarcane Varieties Grown on Three Soil Series.

A two-year field trial was carried out in the seasons of 1997/98 and 1998/99 at Sennar Sugar Company (latitude 13° 33′N and longitude 33° 37′E), to investigate the effect of different levels of potassium (0, 72, and 144 kg K/ha) as K2O and phosphorus (0, 29 and 58 kg P/ha) as P2O5 on the performance of two sugarcane (Saccharum officinarum) varieties (Co 6806, Co 527) and their first ratoon grown on three soil series (Hagu, Nasr, and Dinder). The layout was a randomized complete block design arrangement using three replications. The results indicated that potassium application affected plant density and stalk diameter significantly. The stalk height of the plant cane and its first ratoon was positively affected only late in the season. In the ratoon, the effect was significant early in the season on all growth parameters. The yields of cane and sugar on Dinder series were raised significantly in response to potassium addition in plant cane and ratoon. Potassium increased yield of cane and sugar on Nasr soil and yield of sugar on Hagu soil significantly. Phosphorus addition, on the other hand, reflected a significant effect on stalk height, number of internodes and plant density of plant cane and ratoon early in the season. However, the increase in stalk height and plant density of ratoon continued as the season proceeded. In plant cane, phosphorus application significantly affected sugar yield on Hagu soil. Application of phosphorus to ratoon grown on Dinder and Hagu series resulted in significant increase of cane and sugar yields. Variety Co 6806 gave the best growth and yield compared with Co 527. Soil analysis revealed a depletion of extractable potassium after plant cane harvest. The reverse was true after ratoon harvest from Nasr and Hagu soil series. Soil available phosphorus decreased after cane cropping and increased after ratoon harvest, but both were mostly less than the initial amount before cane planting. [ABSTRACT FROM AUTHOR]