Loss of carbon from the soil predicted by first order decomposition model: effect of the breaking down of aggregates and the incorporation of the vegetal cover on the emissions induced by the preparation

• Grant number: 07/57650-6
• Support Opportunities: Regular Research Grants
• Start date: March 01, 2008
• End date: February 28, 2010
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Newton La Scala Júnior
• Grantee: Newton La Scala Júnior
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

Preparation of the soil stimulates the loss of carbon (C) through the increase in aeration, improvement in the temperature and humidity conditions of the soil and through the release of a fraction of the labile organic matter (OM) previously protected by aggregates from decomposition. In this work we present the development of a model capable of explaining the emissions of carbon dioxide (CO2), orthe losses of Cvia emission of CO2 (C-CO2) after soil preparation, in relation to the emissions from the undisturbed plot added to a correction due to the preparation effect. Our hypothesis is that an additional quantity of labile OM, previously protected by the aggregates, is made available through the soil preparation to microbial activity. The model assumes that the level of carbon (C) present in the labile OM follows a kinetic of reduction of the first order. The emission of C-CO2 in the plot where the soil preparation is undertaken will be derived, taking into consideration that this plot possesses a higher quantity of labile OM compared to the undisturbed plot and also taking into account additional labile C introduced into the decay process due to the introduction of the mass of hay into the interior of the soil due to the preparation. Based on this hypothesis, the result is two models. Thus, we are proposing to carry out new experiments in the areas of agriculture where a surface density of residues from the previous maize crop (Zea mays) will be controlled and incorporated into the soil at the time of preparation. The preparation systems tested will be the disk plowing followed by leveler grid, and the moldboard plow followed by leveler grid, to an average working depth of 15- 20 cm. We believe that we can define the effect of the breaking up of the aggregates on the additional emission of CO2 after preparation, distinguishing it from the effect of the incorporation of residues in the soil on these emissions (AU)