Organic matter quality and dynamics in tropical soils amended with sugar industry residue

Abstract

SUMMARYSoil organic matter depletion caused by agricultural management systems have been identified as a critical problem in most tropical soils. The application of organic residues from agro-industrial activities can ameliorate this problem by increasing soil organic matter quality and quantity. Humic substances play an important role in soil conservation but the dynamics of their transformations is still poorly understood. This study evaluated the effect of compost application to two contrasting tropical soils (Inceptisol and Oxisol) for two years. Soil samples were incubated with compost consisting of sugarcane filter cake, a residue from the sugar industry, at 0, 40, 80, and 120 Mg ha -1 . Filter cake compost changed the humic matter dynamics in both content and quality, affecting the soil mineralogical composition. It was observed that carbon mineralization was faster in the illitecontaining Inceptisol, whereas humic acids were preserved for a longer period in the Oxisol. In both soils, compost application increased fulvic acid contents, favoring the formation of small hydrophilic molecules. A decrease in fluorescence intensity according to the incubation time was observed in the humic acids extracted from amended soils, revealing important chemical changes in this otherwise stable C pool. Index-terms: humic substances, soil electrical charges, stable carbon, filter cake.(1) Part of the doctoral thesis presented by the first author at the Universidade Estadual do Norte Fluminense Darcy Ribeiro, UENF, Campos dos Goytacazes (RJ

Ten years of application of sewage sludge on tropical soil. A balance sheet on agricultural crops and environmental quality

“…All values referring to SBR and qCO 2 suggested that microbial populations operate in the absence of metabolic stress (Silva et al, 2014). We know that organic matter from SS when applied to soils of tropical regions is rapidly degraded (Busato et al, 2012;Vieira et al, 2014 and the increase of organic matter in the soil over time is very low or zero (Yada et al, 2015, Kirchmann et al, 2017. In the present study, no increase of soil organic matter was observed due to the addition of SS in the first ten years of the experiment (Table 2).…”

Kitchen waste compost increases lettuce growth and shows residual effect on soil fertility

“…Compost presented CEC of 119.0 cmol c kg -1 (Table 1) and, similarly to EC, there is not a reference value for CEC in Brazilian regulations. The CEC in the compost is due to the presence of carboxyl, carbonyl, phenolic hydroxyl, ether and hydroxyl present in the compost (Busato et al, 2012). The observed value for CEC in the compost is higher when compared with the natural CEC in the soils from the Cerrado biome (Lopes & Guilherme, 2016).…”

“…Compost application in the soil increases organic matter and improves soil productivity, since this component is the ultimate source of nutrients and microbial activity. The soil organic carbon preservation after compost addition depends on soil mineralogy (Busato et al, 2012). According to these authors, in weathered soils, some organic fractions, such as fulvic acids, are strongly sorbed by oxides due to their large amounts of carboxylic groups, increasing the residence time of these materials in the soil.…”

Optimizing grass mulch application rate in flue cured tobacco float seedlings for the control of salt injury and improvement of seedling quality

“…The pH reduction results from the addition or retention of organic matter, with organic acid produced from decomposition of plantderived materials. The decomposition of organic matter results in the formation of both organic and inorganic acids (Busato et al, 2012), which cause the basic ingredients of the potting medium, such as calcium, to dissolve and eventually leach out, resulting in lowered medium pH. However, other researchers (Watson and Kupkowski 1991;Greenly and Rakow, 1995) found no change in soil and media pH after applying organic mulches.…”