Biomassa microbiana em diferentes sistemas de manejo do solo e de culturas típicas da região norte do Paraná
Adriana Pereira da Silva
DATA DE PUBLICAÇÃO
The objective of this work was to evaluate the soil microbial biomass (SMB) as a parameter bioindicador of changes in agroecosystem under different soil management and crop rotation systems. The SMB was examined in four different Long-term experiments: In experiment 1: with 26 year-old field experiment established consisting of four systems soil management: (1) no- tillage (NT), (2) conventional tillage [(CT) with disc plough], (3) field cultivator (FC) and (4) heavy-disc harrow (DH) both with a crop sequence soybean [(Glycine max) summer]/ wheat [(Triticum aestivum) winter]. In experiment 2: with 21 year-old field experiment established consisting of eight different crop rotation systems (R) including crops of grains [soybean, maize (Zea mays) and wheat] and cover and green manure [lupine(Lupinus albus), turnip fodder (Raphanus sativus) and black oat (Avena strigosa)], under the no-tillage system. In the experiment 3: with 14 year-old field experiment established consisting of CT (with disc plough) and two NT systems with different period of established both with two crop rotation systems (R) and one crop sequence (S) including crops of grains (soybean, maize and wheat) and the cover and green manure (lupine and black oat). In the experiment 4: with 10 year-old field experiment established consisting of two management of soil, NT and CT (with disc plough), both with three crop rotation systems, including soybean, maize, wheat, lupine and black oat. The analyses were performed during the crop season of summer (2006/2007) and winter (2007). The field experiments were conducted at the experimental station of Embrapa soja in Londrina/PR (North of Parana), Brazil, in soil this site is classified as a Red-Latosol. Evaluations were performece on soil samples collected during soybean and corn flowering and , in the winter during the wheat ripening and turnip fodder, corn and black oat flowering, at 0-10 cm deep. Were have used the modified fumigation-extraction method for the analysis of microbial biomass of C (MBC) and nitrogen (MBN) analysis. The treatments under NT had higher values of MBC and MBN when compared to other systems of soil management in which there was movement of soil (CT, FC and DH), demonstrating that the SMB is favoured in systems with little soil movement. On average, the values were higher in the NT by 45 and 60% for MBC and MBN, respectively, in the collection of summer and up to 41 and 49% respectively, in the collection of winter. The MBN has proved a more sensitive parameter that the MBC not only to indicate changes from the system of soil management, but also changes resulting from the time of deployment of the system of management. The detention of N SMB presented by higher average values of up to 50% when compared to the system NT old (68.0 and 62.7 g μ N g-1 soil dry, summer and winter, respectively) with the system of PC (27, 2 and 34.6 g μ N g-1 soil dry, summer and winter, respectively). In the second experiment in rotations where the rape was used as fodder plant cover in winter, there was more nitrogen immobilization of the soil microbial biomass. The presence of the legume crop rotation systems of the two experiments favored the detention of carbon and nitrogen in the winter. Income from soy beans and maize have been affected by soil management systems, is positively correlating with the higher values of SMB found in the system of NT. On the other hand, there was no influence of systems of rotation / crop sequence of cultures on the incomes of grain.
ACESSO AO ARTIGOhttp://220.127.116.11/document/?code=vtls000147934
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