Soil microbial biomass under different management and tillage systems of permanent intercropped cover species in an orange orchard

Abstract

SUMMARYTo mitigate soil erosion and enhance soil fertility in orange plantations, the permanent protection of the inter-rows by cover species has been suggested. The objective of this study was to evaluate alterations in the microbial biomass, due to different soil tillage systems and intercropped cover species between rows of orange trees. The soil of the experimental area previously used as pasture (Brachiaria humidicola) was an Ultisol (Typic Paleudult) originating from Caiuá sandstone in the northwestern part of the State of Paraná, Brazil. Two soil tillage systems were evaluated: conventional tillage (CT) in the entire area and strip tillage (ST) (strip width 2 m), in combination with different ground cover management systems. The citrus cultivar 'Pera' orange (Citrus sinensis) grafted onto 'Rangpur' lime rootstock was used. Soil samples were collected after five years of treatment from a depth of 0-15 cm, under the tree canopy and in the inter-row, in the following treatments: (1) CT and an annual cover crop with the leguminous species Calopogonium mucunoides; (2) CT and a perennial cover crop with the leguminous peanut Arachis pintoi; (3) CT and an evergreen cover crop with Bahiagrass Paspalum notatum; (4) CT and a cover crop with spontaneous Brachiaria humidicola grass vegetation; and (5) ST and maintenance of the remaining grass (pasture) of Brachiaria humidicola. Soil tillage and the different cover species influenced the microbial biomass, both under the tree canopy and in the interrow. The cultivation of brachiaria increased C and N in the microbial biomass, while bahiagrass increased P in the microbial biomass. The soil microbial biomass was enriched in N and P by the presence of ground cover species and according to the soil P content. The grass species increased C, N and P in the soil microbial biomass from the inter-row more than leguminous species.Index terms: microbial activity, soil tillage, nutrient cycling, citrus management.

Soil Quality in Relation to Forest Conversion to Perennial or Annual Cropping in Southern Brazil

“…Our results agree with previous studies that soil management affects significant soil properties such as microbial mass and activity (Islam and Weil, 2000;Hungria et al, 2009;Frazão et al, 2010;Balota and Auler, 2011). The microbial biomass measured in FO and NT indicated the same trend as other studies, which show a significant positive effect of decreasing soil disturbance on microbial biomass (Balota et al, 2004;Frazão et al, 2010;Kaschuk et al, 2010).…”

“…Microbial C pools typically decline at a faster rate than soil organic matter, and the C mic :C org percentage will decrease during soil degradation (Islam and Weil, 2000;Anderson and Domsch, 2010;Balota and Auler, 2011), a trend observed in our study. This may allow for a calibrated early soil quality indicator to predict whether soils are accumulating or losing soil C. This relationship also allows comparisons across soils with different organic matter contents.…”

“…The C mic :C org ratio could be an indicator of conversion efficiency of C org into C mic and losses of soil C during decomposition. This indicator may reveal the microbial community capacity to enrich the microbial C pool under conservation management (Islam and Weil, 2000;Balota et al, 2004;Frazão et al, 2010;Kaschuk et al, 2010;Balota and Auler, 2011;Pellegrino et al, 2011). The C mic :C org ratio was higher in FO followed by NT presumably because it maintained more labile organic substrates in the soil, which allowed higher MB-C per unit of soil C org .…”

“…Conventional or plow tillage (CT), uses traditional practices of plowing and disking to prepare the land for sowing. Tillage alters the soil structural stability (Six et al, 2004;Caesar-Tonthat et al, 2011) resulting in losses of soil organic matter (Franzluebbers, 2009) and microbial biomass (Islam and Weil, 2000;Hungria et al, 2009;Frazão et al, 2010;Balota and Auler, 2011).…”

Sistemas intercalares com abacaxizeiro como alternativa de renda durante a formação de cafezais irrigados

“…Coeficientes técnicos e operações para implantação e manutenção de 1 ha de cafeeiro, em diferentes sistemas de cultivo intercalares com abacaxizeiro, do plantio até a primeira produção. (Balota & Auler, 2011), e à possível redução das temperaturas máximas no microambiente de cultivo, o que teria preservado a água e reduzido a alta evaporação, característica do semiárido de Minas Gerais.…”