Revista Agropecuária Técnica

5

Authors: MARCELO MATTOS PEDREIRA , JULIMAR SACRAMENTO RIBEIRO

This experiment compared the influence of aquariums with biological filters, composed by crashed rocks, quartz gravel and powdered limestone, with aquariums without biological filter, only with an air stone, in the cultivation of pacamã larvae. The best operation of the aquariums without biological filter was verified by the larger survival values and biomassa. The values of water temperature were similar among aquariums with and without biofilter. The pH and the conductivity were larger in the aquariums with biofilter due to their composition. There was more dissolved oxygen in the aquariums without biofilter, suggesting that limnological parameters have influenced the worst performance presented in the aquariums with biological filter. This experiment demonstrates that the simple employment of a air stone, is already enough to provide good results, and that, some times, the employment of more refined techniques, as the biological filter, if not appropriately used, can cause falls in the performance of the cultivation.

6

Authors: EVERSON CEZAR, MARCOS RAFAEL NANNI, MARCELO LUIZ CHICATI, JOSÉ ALEXANDRE M. DEMATTÊ, RONEY BERTI DE OLIVEIRA

In the present work was accomplished a comparison among three independent risings of soils accomplished by students of Agronomy course of UEM, in Experimental Farm of Iguatemi (EFI). So much for the teams received the cartographic material previously imaged, as well as aerial pictures and images, besides physical and chemical analyses. With those resources, as well as field descriptions, the groups presented the constituted pedologic maps of soil classes and mapping units. The polygons of the representative mapping units were scanned in table scanner and incorporated in a geographical information system (GIS). By means of algorithms of crossing plans of information tables were generated contends the number of soil classes for each accomplished rising and the area among each mapping unit. The results demonstrated so much differences in the number of soil classes found inside the variation in the area of the same class mapped appraised for the three groups. The soil class of larger occurrence was Oxisoil, with 95.5% of coincidence. It was verified that GIS facilitates the comparison among different groups that generate pedologic risings what it can imply processes in the use and handling of the hydrographic basin.

10

Authors: BENO WENDLING, IVO JUCKSCH, EDUARDO DE SÁ MENDONÇA

The land use and management influence direct or indirectly the physical properties of the soil. To test this affirmative, physicals properties of a red latossol (Tipic Haplorthox), located in Capinópolis/MG, were evaluated. Soil samples were collected in august of 2002 under the following treatments: PDs – no tillage (NT) for 4 years with the succession corn (silage)/soybean/corn (silage)/ soybean; PDg – NT for 4 years with the succession corn/corn/corn/soybean; PDtf – NT for 3 years followed by tifton (hay) and soybean in the last year; SC – conventional cultivation with soybean in the last 4 years; and MN – native forest. Orthogonal contrasts were done among the treatments to isolate the effects of: cultivation, no tillage, tifton and silage. It was evaluated the cover of the soil, total organic carbon, soil density, porosity, water retention by the soil and established indices from the relations aeration capacity/total porosity (AC/Pt) and field capacity/total porosity (FC/Pt). The cultivation contributed to the degradation of the physics properties of the soil compared to the native forest. The soil degradation was less under the no tillage than the conventional cultivation, but still much worse than the native forest. The conventional cultivation presented AC smaller than the limit of 0,10 m³/m³, what can cause a deficient microbial activity and problems to the roots breathing. Within the no tillage treatments, the effect of the tifton introduced better potential for improvement of the physical quality of the soil. The indexes of AC/Pt and FC/Pt were sensitive to the adoption of different uses and managements.