Dr. Eduardo de Sa Pereira was born in Rosario, Provincia de Santa Fe, in 1961. He obtained his degree of Agricultural Engineer in the Facultad de Ciencias Agrarias de la Universidad Nacional de Rosario (UNR). He studied postgraduate studies at the Universidade Estadual Paulista (UNESP) - Faculdade de Ciências Agronômícas - Campus de Botucatu - Botucatu - Sao Paulo - Brasil, where he obtained a Master's degree in Plant Protection. He also obtained his Specialization in No Tillage System in the Facultad de Agronomía de la Universidad Nacional de Buenos Aires (UBA) where he obtained the Specialist of No Tillage System. He studied postgraduate studies at the Universidad Nacional del Sur (UNS) Departamento de Agronomía (CERZOS UNS-CONICET) - Bahia Blanca – Provincia de Buenos Aires where he obtained the Doctorate in Agronomy. He has numerous articles published in national and international magazines, has presented numerous works in National Congresses in the area of Crops and Soil Management. He is in the area of Extension and Technology Transfer with Rural Extension Agency INTA (AER) Coronel Suárez – province of Buenos Aires as Jeff of Rural Extension Agency since 2012
Cover crop (CC) residues protect the soil from erosion and their permanence on the surface is largely influenced by their biochemical constituents. Cover crops (CC) are a necessary tool for the Pampas region to avoid soil degradation after summer crops grown on a year basis, leaving the soil naked during the mild winter (Rimski-Korsakov et al. 2015). In this way, CC may influence soil organic carbon (SOC) contents by providing additional residue carbon to soil (Wang et al. 2010). Nevertheless, reported effects of CC on SOC contents are inconsistent and range from losses (Mazzoncini et al. 2011) to gains (Duval et al. 2016). In this study the dynamics of CC residues decomposition and their effects on soil labile organic carbon fractions were evaluated under controlled (incubation experiment) conditions. Three CC species (oats, Avena sativa L.; vetch, Vicia sativa L.; Persian clover, Trifolium resupinatum L.) and a no CC control (fallow) were evaluated. Shoot residues were applied on the soil surface and incubated for 362-days (with eight sampling times). Particulate organic carbon (POC), total and soluble carbohydrates (CHt and CHs, respectively) were determined in soil samples. Oats and vetch residues decomposed faster than clover, where k valueswere1.3, 1.4 and 1.9 year-1, respectively. At the end of the experiment, the POC concentration was the lower in vetch (1.83 g kg-1) and clover (1.96 g kg-1) than oats (2.21 g kg-1) and fallow (3.00 g kg-1), that's mean a loss between 45-64% of their initial values. Overall, the dynamics of residue decomposition were reflected in changes of CHt contents. The periods of greatest residue decomposition were 0 to 21 days and 130 to 201 days for vetch and oats, respectively which coincides with the greater soil CHt. Hence, this organic fraction is very sensitive to residue decomposition and can be indicators of changes in soil organic matter quality over short periods of time. Changes in soil labile carbon fractions were differentially influenced by residue quality over short periods of time. The lower POC concentrations in CC soils than in fallow soils indicated that despite extra carbon input, mineralization rate was much high in CC affecting also native organic pools. Overall, the dynamics of residue decomposition were reflected in changes of CHt contents, where the periods of greatest residue decomposition corresponded to the higher soil CHt. Hence, this organic carbon fraction is very sensitive to residue decomposition and can be indicators of changes in soil organic matter quality over short periods of time.
Key Words: Particulate organic carbon, carbohydrates, cover crops, biochemical composition