Vegetables productions systems are done normally with intense soil tillage causing a strong decline of soil quality. Use of conservation systems can be an alternative to recover this quality. In order to evaluate the effects of such systems on soil organic matter, an experiment has been conducted in randomized blocks design and factorial scheme 3 × 2: three soil management systems (no-tillage; reduced tillage and conventional tillage) and two cover crops (maize single; and intercropping maize with gray velvet bean—Stizolobium niveum); and repeated measures over time. Soil samples were collected before the implementation of the experiment and at the end of each crop cycle until the fifth crop cycle. Carbon associated with humic substances is also determined in 0 - 5 cm, 5 - 10 cm and 10 - 30 cm at the end of the last crop cycle. The SOM content was higher in RT (48.34 g·kg -1 ) than in the CT (39.48 g·kg -1 ) at the end of the fifth crop cycle. SOM content in NT (44.92 g·kg -1 ) was statistically equal to RT and CT, during the same period. In 0 - 5 cm, carbon contents associated to the humic substances present the same behavior of SOM contents in 0 - 10 cm. Probably these results are associated with the capacity of each system to improve superficial contents of SOM stable fractions. It follows that the conservation systems used are alternatives to the cultivation vegetables in order to improve soil organic matter contents.
Machado, P.L.O.A. (2005) Soil Carbon and the Mitigation of Global Climate Change. Química Nova, 28, 329-334. https://doi.org/10.1590/S0100-40422005000200026
Johnson, J.M.F., Franzluebbers, A.J., Weyers, S.L. and Reicoski, D.C. (2007) Agricultural Opportunities to Mitigate Greenhouse Gas Emissions: A Review. Environmental Pollution, 150, 107-124. https://doi.org/10.1016/j.envpol.2007.06.030
Souza, E.D., Costa, S.E.V.G.A., Anghinoni, I., Carvalho, P.C., Andrigueti, M. and Cao, E. (2009) Soil Organic Carbon and Nitrogen Stocks in an Untilled Crop-Livestock Integration System under Different Grazing Intensities. Revista Brasileira de Ciência do Solo, 33, 1829-1836. https://doi.org/10.1590/S0100-06832009000600031
Figueiredo, C.C., Resck, D.V.S. and Carneiro, M.A.C. (2010) Labile and Stable Fractions of Soil Organic Matter under Management Systems and Native Cerrado. Revista Brasileira de Ciência do Solo, 34, 907-916. https://doi.org/10.1590/S0100-06832010000300032
Franzluebbers, A.J. (2002) Soil Organic Matter Stratification Ratio as an Indicator of Soil Quality. Soil & Tillage Research, 66, 95-106. https://doi.org/10.1016/S0167-1987(02)00018-1
Dick, D.P., Novotny, E.H., Dieckow, J. and Bayer, C. (2009) Chemistry of Soil Organic Matter: In: Melo, V.F. and Alleoni, L.R., Eds., Química e Mineralogia do Solo: Parte II—Aplicacoes, Sociedade brasileira de Ciência do Solo, Vicosa, 1-68.
Santos, L.L., Lacerda, J.J. and Zinn, Y.L. (2013) Partitioning of Humic Substances in Brazilian Soils. Revista Brasileira de Ciência do Solo, 37, 955-968. https://doi.org/10.1590/S0100-06832013000400013
Bayer, C, Kick, D.P., Ribeiro, G.M. and Scheuermann, K.K. (2002) Carbon Stocks in Organic Matter Fractions as Affected by Land Use and Soil Management with Emphasis on No-Tillage Effect. Ciência Rural, 32, 401-406. https://doi.org/10.1590/S0103-84782002000300006
Conceicao, P.C., Dieckow, J. and Bayer, C. (2013) Combined Role of No-Tillage and Cropping Systems in Soil Carbon Stocks and Stabilization. Soil & Tillage Research, 129, 40-47. https://doi.org/10.1016/j.still.2013.01.006
Souza, R.F., Figueiredo, C.C., Madeira, N.R. and Alcantara, F.A. (2014) Effect of Management Systems and Cover Crops on Organic Matter Dynamics of Soil under Vegetables. Revista Brasileira de Ciência do Solo, 38, 923-933. https://doi.org/10.1590/S0100-06832014000300024
Moser, E. (2016) Repeated Measures Modeling with PROC MIXED. http://www2.sas.com/proceedings/sugi29/188-29.pdf
Freitas, A.R.F., Presotti, C.V. and Toral, F.L.B. (2005) Alternative Analyses of Repeated Weight Measurements of Beef Cattle. Revista Brasileira de Zootecnia, 34, 2233-2244. https://doi.org/10.1590/S1516-35982005000700010
FAO (2015) World Reference Base for Soil Resources 2014: International Soil Classification System for Naming Soils and Creating Legends for Soil Maps. FAO, Roma.
Empresa Brasileira De Pesquisa Agropecu áRIA-Embrapa. (2013) Manual of Methods of Soil Analysis. Rio de Janeiro.
Benites, V.M., Madari, B. and Machado, P.L.O.A. (2003) Extraction and Fractionation of Soil Humic Substances: A Simplified Low Cost Procedure. Comunicado Técnico. http://ainfo.cnptia.embrapa.br/digital/bitstream/CNPS/11578/1/comtec16_2003_extracao.pdf
Akaike, H. (1973) Information Theory and an Extension of the Maximum Likelihood Principle. In: International Symposium on Information Theory, Vol. 2, Anais Academiai Kiado, Budapest, 267-281.
Dal Bello, L.H.A. (2010) Modeling in Experiments Mixing-Process for Optimization of Industrial Processes. PhD Dissertation, PUC-RJ, Rio de Janeiro.
Zikeli, S., Gruber, S., Teufel, C.F., Hartung, K. and Claupein, W. (2013) Effects of Reduced Tillage on Crop Yield; Plant Available Nutrients and Soil Organic Matter in a 12-Year Long-Term Trial under Organic Management. Sustainability, 5, 3876-3894. https://doi.org/10.3390/su5093876
Prasad, J.V.N.S., Rao, C.S., Srinivas, K., Jyothi, C.N., Venkateswarlu, B., Ramachandrappa, B.K., Dhanapal, G.N., Ravichandra, K. and Mishra, P.K. (2016) Effect of Ten Years of Reduced Tillage and Recycling of Organic Matter on Crop Yields; Soil Organic Carbon and Its Fractions in Alfisols of Semi Arid Tropics of Southern India. Soil & Tillage Research, 156, 131-139. https://doi.org/10.1016/j.still.2015.10.013
Ebeling, A.G., Anjos, L.H.C., Pereira, M.G., Pinheiro, E.F.M. and Valladares, G.S. (2011) Humic Substances and Relationship to Soil Attributes. Bragantia, 70, 157-165. https://doi.org/10.1590/S0006-87052011000100022
Brancaliao, S.R. and Moraes, M.H. (2008) Changes in Some Physical Properties and in Humic Fractions of a Nitosol Cropped with a Millet-Soybean Sucession under No-Tillage. Revista Brasileira de Ciência do Solo, 32, 393-404. https://doi.org/10.1590/S0100-06832008000100037
Bezerra, R.P.M., Loss, A., Pereira, M.G. and Perin, A. (2013) Forms of Carbono in Na Oxisol under No-Tillage and Crop-Livestock Integration Systems in the Cerrado, Goias State, Brazil. Semina, 34, 2637-2654.
Carvalho, A.M., Bustamante, M.M.C., Sousa Junior, J.G.A. and Vivaldi, L.J. (2008) Decomposition of Plant Residues in Latosol under Corn Crop and Cover Crops. Revista Brasileira de Ciência do Solo, 32, 2831-2838. https://doi.org/10.1590/S0100-06832008000700029
Piccolo, A. (2002) The Supramolecular Structure of Humic Substances: A Novel Understanding of Húmus Chemistry and Implications in Soil Science. Advances in Agronomy, 75, 57-134. https://doi.org/10.1016/S0065-2113(02)75003-7
Zhang, Z., Hongjun, Q., Mchugh, A.D., Li, H., Wang, Q. and Lu, Z. (2016) Effect of Conservation Farming Practices on Soil Organic Matter and Stratification in a Mono-Cropping System of Northern China. Soil & Tillage Research, 156, 173-181. https://doi.org/10.1016/j.still.2015.10.008