Mechanical harvesting leaves in its wake a considerable amount of straw in the field, which can be effectively utilized to improve the soil condition and sugarcane yield. However, there is no specific information as to the quantity of straw mulch required to achieve such effects and as to whether it can be used in other sectors for bioelectricity and ethanol production. The aim of this research was to evaluate the effect of removing different amounts of straw from the field and its impact on the yield and industrial quality of sugarcane ratoons. The experiment was carried out on Rhodic soil where six treatments were evaluated including 0 %, 25 % (5 Mg ha-1), 50 % (10 Mg ha-1), 75 % (15 Mg ha-1), 100 % (20 Mg ha-1) straw on the soil surface and burned sugarcane (where 100 % of the straw was burned). The influence on yield and industrial quality was calculated using total soluble solids, Pol (Apparent sucrose content), apparent purity, total sugars, reducing sugars and fiber. Shifting the harvesting system from burned cane to growing under straw mulch improved crop yield as well as favoring sugar contents during water deficit conditions. The straw left on the soil did not affect industrial quality in any way during the trials; however, under drought conditions, treatments with 50 and 75 % of straw resulted in a 76 % higher yield compared to burned sugarcane, and 29 % more than the 0 %, 25 % to 100 % treatments of straw mulch thus favoring higher sugar production. The removal of 50 % of the straw caused no damage to the sugarcane crop.

Background and Aims Crop rotation systems and rhizobial inoculation are strategies to increase yield through organic matter addition and modulation of microbial diversity, yet the extent to which these agricultural practices change soil Bradyrhizobium populations, soybean grain yield and economic benefits to farmers are unclear. Thus, this study aimed to evaluate the interaction between crop rotation and inoculation of soybean (Glycine max) cultivated in two contrasting soils (clayey and sandy soil) on biological nitrogen fixation (BNF) components, grain yields and profits. Methods Field experiments with a three-year crop rotation system were carried out to compare effects of inoculation soil chemical attributes, the of bradyrhizobia most probable number (MPN) and diversity, soybean nodulation, grain yield and economic value. Results The crop management system did not affect the soil MPN of bradyrhizobia, which was altered by the soil sampling time, with higher values during the postharvest period for the summer crops. In clayey soil, soybean nodulation was influenced by crop rotation. The grain yield of inoculated soybean in clayey soil was higher than that in sandy soil. Conclusion The soybean response to inoculation is influenced by cropping history. Crop rotation and inoculation of soybean is a strategy for improving BNF components, grain yields and profits. Over time, diversified production systems with crop rotation and inoculation with nitrogen-fixing bacteria will make great contributions to environmental and economic sustainability.

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