Abstract

PINO, Amabelia del; REPETTO, Carlos; MORI, Cristina  and  PERDOMO, Carlos. Decomposition Patterns of Manures in Soil. Terra Latinoam [online]. 2008, vol.26, n.1, pp.43-52. ISSN 2395-8030.

In Uruguay manures are extensively used in horticultural production. It is therefore necessary to characterize the nitrogen release capacity of the different materials to be used. The objective of this study was to determine and to compare mineralization patterns of poultry manure, dairy cow manure, and chicken manure (chicken manure and rice hull mixture), added to the soil, evaluating their contribution of N as well as their influence on soil properties and on soil microorganism activity. Soils were incubated for 11 weeks with the tested materials (manure, two levels of KNO₃ and a control without aggregates). All treatments resulted in net N mineralization, which was related to C:N ratio of the manures. Chicken and poultry manures produced more mineral N than cow manure the control in the first 35 days of incubation. The control did not differ from cow manure until the last sampling (58 and 79 days) when cow manure was superior. Manure respiration rates were higher than those of the control or KNO₃, because of the contribution of C by the manures. Manures increased C and N in the microbial biomass. Poultry manure promoted better conditions for microbial growth due to an increase in pH, while KNO₃ created unfavorable conditions (low pH and high electrical conductivity). C and N tended to decrease in soil microbial biomass during incubation except in cow manure. Poultry manure made an important contribution of mineral N shortly after application, with relatively low mineralization rates afterwards. In contrast, cow manure, which did not significantly increase available N during the first 25 days, promoted soil microbial activity on the long term.

Keywords : N mineralization; biomass C; biomass N.

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