Carbon and nitrogen in the soil under different uses and managements and your modelling by the Century / Carbono e nitrogênio no solo sob diferentes usos e manejos e sua modelagem pelo Century

AUTOR(ES)

Beno Wendling

DATA DE PUBLICAÇÃO

2007

RESUMO

Every change in the use and management can induce alterations in the C and N stocks of the soil. In this sense, this study was carried out to verify those alterations in the different use and management systems, as well as the capacity of the Century model to simulating those alterations, by comparing the measured stocks with the simulated ones. In Paracatú county-MG, in an agrosylvopasture system with eucalypts and rice, soybean and brachiaria on the first, second and from the third year in the interlines, respectively, it was verified that this system negatively affects C and N of the soil on the initial years, but recovery signs observed after the sixth year begin to be significant on the 10th year. In this system, the use of labile fractions different from that usually used for calculation of the C management index (IMC) were also tested, in which the C fraction extracted with H2SO4 3M/L and C of the particulate free light fraction showed good potential for this purpose, because their results were similar to the usual method that uses KMnO4 to extracting C. In Sete Lagoas county-MG, however, the superiority of the no-till planting in relation to the conventional cropping in maize and soybean crops was observed, mainly in the more-labile fractions that respond more prematurely to the management changes. This superiority was also verified, when using the Century model Century, that simulated stocks similar to those measured in the field. Also in pinus plantation in Sete Lagoas county, the simulations with the Century model showed that the stocks of C and total N and their respective compartments are reduced on the initial years, but they are recovered as the crop begins to incorporate organic material into system through the fall of the needles, as well as through the roots. In Colonel Pacheco county-MG, the Century model satisfactorily simulated the stocks of C and total N, which is proven by the similarity between the simulated and measured stocks. In this same place, for the brachiaria, the values measured and simulated by the Century model showed the use of the chemical fertilization considerably increases the stocks of C and N in the soil. In the crop of the maize for silage, lower stocks were also observed in relation to other crops (sugarcane, tifton and brachiaria) caused by intensive revolving of the soil and removal of the maize aerial part and vegetables previously cropped.

ASSUNTO(S)

compartimentos modelagem carbon compartments ciencia do solo matéria orgânica carbono organic matter modelling

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