Effect of filter press mud (FPM) application on nutrient availability in Aquert and Fluvent soils at Wonji-Shoa Sugarcane Plantation, located at central part of the East African Rift Valley, was studied during the 2003/04 growing season. The rate of FPM application was 0, 60 and 120 ton/h. Field monitoring was made for ninety days. As per the management practice of the Sugar Estate, the Aquert soil was green manured with Crotalarea junceae prior to the treatment application. Soil samples were collected and analyzed every fortnight for organic carbon (OC) and available N. Available P, exchangeable bases, Fe, and Mn content of the soil were monitored at the beginning and end of the experiment. Incorporation of FPM significantly increased the OC content in both soils. Nonetheless, the accumulation of OC was more in Aquert than Fluvent soils, due to the initial higher OC obtained from Crotalatea j., higher clay content and moist condition of the Aquert soil. The application of FPM promoted the available N though the availability of N ion, however, in both soils, the content declined during the first 45 days after application. Gradually, significant increase in the available N was observed (starting from 45th day of application up to the 90th day). This indicates that FPM having C/N ratio of 27 resulted in priming effect. The trend analysis made indicated that proportional increase in available P can be obtained with increasing rate of FPM application, though available K was found to be lower in FPM treated soils. The application of FPM buffered (reduced) the soil pH to 7.6. The highest rate of FPM application (120 ton/ha) slightly improved the soil electrical conductivity (EC). Furthermore, the study indicated that the application of FPM had the ability to reduce the soils exchangeable Na content. Thus, FPM has A. Fantaye

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A study was conducted at Metahara Sugar Estate in Ethiopia to assess effect of vinasse disposal on sugarcane fields. The experiment was laid out in a randomized complete block design with five replications. To simulate the amount of vinasse to be disposed, three levels of potassium chloride (0, 340, and 580 kg ha -1 ) were tested on three different soil types (brown clay loam, black non-vertic clay and black vertic clay). Soil analysis result showed that available K in the soil was ranged from 311-547 ppm. Potassium chloride application on cane fields had nonsignificant (P<0.05) effect for cane and sugar yields. Similarly, non-significant (p<0.05) effect was found for juice K2O and leaf nutrient contents (N, P and K%). Therefore, the level of potassium chloride applied at the proposed vinasse disposal rates didn't affect nutrient uptake, yield, and juice quality in the subsequent crop; thus at Metahara Sugar Plantation, sugarcane fields can be used as disposing site for vinasse. However, long-term effect of vinasse to sugarcane crop and dynamics of K in relation to availability and fixation in the soils of the plantation should be further investigated through vinasse application to sugarcane fields.