Soil is the basis underlying the food production chain and it is fundamental to improve and conserve its productive capacity. Imbalanced exploitation can degrade agricultural areas physical, chemical and biologically. The objective of this study was to evaluate some soil physical properties and their relation with organic carbon contents of a Humic Dystrudept under conventional tillage (CT) and no-tillage (NT), for 12 years in rotation (r) and succession (s) cropping systems. The experiment was carried out in Lages, SC (latitude 27 ° 49 ' S and longitude 50 ° 20 ' W, 937 m asl), using crop sequences of bean-fallow-maize-fallow-soybean in conventional tillage rotation; maize-fallow in conventional tillage succession; bean-oat-maize-turnip-soybean-vetch in no-tillage rotation; and maize-vetch in notillage succession. The experimental design was completely randomized with four replications. The soil samples were collected in the layers 0-2.5, 2.5-5, 5-10, and 10-20 cm. The following properties were analyzed: soil density, porosity, aggregate stability, degree of flocculation, water retention, infiltration, mechanical strength, and total organic carbon. Soil aggregation in the surface layer (0-5 cm) was better in the no-tillage than the conventional system, related to higher microporosity, organic carbon contents and water retention capacity, indicating that a periodical tillage of this soil is unnecessary. Infiltration was highest in no-tillage with crop succession.Index terms: crop rotation, crop succession, no-tillage, soil management.(

SUMMARYThe impact of pig slurry and poultry litter fertilization on soils depends on the conditions of use and the amounts applied. This study evaluated the effect of organic fertilizers after different application periods in different areas on the physical properties and organic carbon contents of a Rhodic Kandiudox, in Concordia, Santa Catarina, in Southern Brazil. The treatments consisted of different land uses and periods of pig and poultry litter fertilization: silage maize (M7 years), silage maize (M20 years), annual ryegrass pasture (P3 years), annual ryegrass pasture (P15 years), perennial pasture (PP20 years), yerba mate tea (Mt20 years), native forest (NF), and native pasture without manure application (P0). The 0-5, 5-10 and 10-20 cm soil layers were sampled and analyzed for total organic carbon, total nitrogen and soil physical properties such as density, porosity, aggregation, degree of flocculation, and penetration resistance. The organic carbon levels in the cultivated areas treated with organic fertilizer were even lower than in native forest soil. The organic fertilizers and studied management systems reduced the flocculation degree of the clay particles, and low macroporosity was observed in some areas. Despite these changes, a good soil physical structure was maintained, e.g., soil density and resistance to penetration were below the critical limits, whereas aggregate stability was high, which is important to reduce water erosion in these areas with rugged terrain in western Santa Catarina, used for pig and poultry farming.Index terms: biofertilizer, soil quality, soil structure.(1) Received for publication in May 02, 2011 and approved in April 13, 2012 (2)

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The common bean has been considered to have low biological nitrogen fixation capacity; however, this process can be made more effective with molybdenum (Mo) supplementation. The objective of this study was to evaluate the influence of Mo rates on the growth and biological nitrogen fixation by two Brazilian common bean cultivars using the 15N isotope dilution technique. The experiment was performed in 2014 in a completely randomized design arranged in a 5 x 3 factorial scheme, corresponding to 5 rates of Mo (control, 40, 80, 120 and 240 g ha-1), the common bean cultivars Aporé, Ouro Negro and NORH-54 (a non-nodulating common bean cultivar), and three replicates. The application of Mo and the inoculation with rhizobia strains contributed to improving nitrogen fixation and grain weight. The cultivar Ouro Negro showed a higher number and weight of nodules and a higher amount of nitrogen derived from the atmosphere than the cultivar Aporé. The biological nitrogen fixation of Aporé was more dependent on the application of Mo. These results indicated that inoculation with Rhizobium strains and Mo supply effectively contributed to biological nitrogen fixation and improving grain production.