Under greenhouse conditions at National Center for Research on Cotton (CNPA/ Embrapa), the effects of increasing doses of sewage sludge limited to 50% of dryness (equivalent to 0, 60, 100, 200, 250 and 300 kg N ha-1) were studied on the fiber quality (finess or micronaire, strength, length, length uniformity, short fiber index, elongation, stretching, spinning capability, reflectiveness and color grade) of herbaceous cotton variety BRS 187 8H. The experimental design adopted was a randomized blocks, with six treatments and five replications, resulting in 30 experimental units. Each experimental unit was composed of 90 dm³ plastic pot with 70 dm³ of soil. Significant quadratic effects were obtained with solid sewage sludge doses on the studied variables. The regression analyses estimated the dose of biosolids between 220 to 335 kg N ha-1 for the maximum values of the variables of interest. For maximum fiber resistance value, which is used as base for commercialization of cotton, the dose of biosolid was equivalent to 292 kg ha-1 of N.
sewage sludge; fiber; Gossypium hirsutum L.
