Soluble carbon in oxisol under the effect of organic residue rates

Abstract

SUMMARYThe application of organic residues to the soil can increase soluble organic carbon (SOC) and affect the pH and electrolytic conductivity (EC) of the soil. However, the magnitude of these changes depends on the type of residue and the applied dose. This study aimed to evaluate the effect of increasing C rates contained in organic residue on the pH, EC, water-extractable total carbon (WETC), waterextractable organic carbon (WEOC), and water-extractable inorganic carbon (WEIC) in soil treated with manure (chicken, swine, and quail), sawdust, coffee husk, and sewage sludge. The levels of total C (TC-KH 2 PO 4 ), organic carbon (OC-KH 2 PO 4 ), and inorganic C (IC-KH 2 PO 4 ) extractable by a 0.1 mol L -1 KH 2 PO 4 solution were also quantified in soil under the effect of increasing rates of chicken and quail manures. The following rates of organic residue C were applied to a dystrophic Red Latosol (Oxisol) sample: 0, 2,000, 5,000, 10,000, and 20,000 mg kg -1 . The addition of organic residues to the soil increased pH, except in the case of sewage sludge, which acidified the soil. The acidity correction potential of chicken and quail manure was highest, dependent on the manure rate applied; regardless of the dose used, sawdust barely alters the soil pH. At all tested rates, the EC of the soil treated with swine manure, coffee husk, and sawdust remained below 2.0 dS m -1 , which is a critical level for salinity-sensitive crops. However, the application of chicken or quail manure and sewage sludge at certain rates increased the EC to values above this threshold level. Highest levels of WETC, WEOC, and WEIC were obtained when chicken and quail manure and coffee husk were applied to the Oxisol. The quantities of SOC extracted by KH 2 PO 4 were higher than the quantities extracted by water, demonstrating the ability of soil to adsorb C into its colloids.Index terms: soluble organic carbon, manure, electrolytic conductivity, soil acidity, crop residues, carbon adsorption.( RESUMO: CARBONO SOLÚVEL EM LATOSSOLO SOB EFEITO DE DOSES DE RESÍDUOS ORGÂNICOSA adição de resíduos orgânicos pode aumentar o carbono orgânico solúvel (COS) e alterar o pH e a condutividade elétrolítica (CE) do solo, mas a magnitude dessas variações depende do resíduo e de sua dose aplicada. Objetivou-se avaliar o efeito de doses de carbono pela adição de resíduos orgânicos sobre o pH, a CE, o carbono total extraível por água (CTEA), o carbono orgânico extraível por água (COEA) e o carbono inorgânico extraível por água (CIEA), em solo tratado com estercos (galinha, suíno e codorna), serragem, casca de café e lodo de esgoto. Os teores de C total (CT-KH 2 PO 4 ), C orgânico (CO-KH 2 PO 4 ) e C inorgânico (CI-KH 2 PO 4 ) extraível por solução de KH 2 PO 4 0,1 mol L -1 também foram quantificados em solo sob efeito de doses crescentes de estercos de galinha e de codorna. O solo utilizado foi o Latossolo Vermelho distroférrico (LVdf) e as doses de C-resíduo orgânico constituíram-se de 0, 2.000, 5.000, 10.000 e 20.000 mg kg -1 . A adição de resíduos org...

Early Growth of Coffee Plants and Soil Fertility Properties in Response to Coffee Husk Application

“…The high ion concentrations, e.g., of K + , in coffee husk explain the increase in soil EC by the application of this organic waste (CARMO et al, 2016). Similar results were reported by Higaskikawa, Silva and Bettiol (2010); Pinheiro, Silva and Lima (2014) and Carmo, Lima and Silva (2016), who also observed an increase in the soil EC in response to coffee husk application.…”

Electrical Conductivity and Chemical Composition of Soil Solution: Comparison of Solution Samplers in Tropical Soils

“…Levels of SOC and TSC in the LHd and CXbd samples were much higher than those observed in the RQ solutions. Such results are not uncommon, since the soluble C content in the soil depends on its OM content (Pinheiro et al, 2014). Thus, high contents of C in the LHd (6.5 %) and CXbd (3 %) may explain the higher soluble C content found in the solution of these soils compared to the levels measured in the RQ solutions.…”