Effect of tillage systems and permanent groundcover intercropped with orange trees on soil enzyme activities

Abstract

The objective of this study was to evaluate the effect of different soil tillage systems and groundcover crops intercropped with orange trees on soil enzyme activities. The experiment was performed in an Ultisol soil in northwestern Paraná State. Two soil tillage systems were evaluated [conventional tillage (CT) across the entire area and strip tillage (ST) with a 2-m strip width] in combination with various groundcover vegetation management systems. Soil samples were collected after five years of experimental management at a depth of 0-15 cm under the tree canopy and in the inter-row space in the following treatments: (1) CT-Calopogonium mucunoides; (2) CTArachis pintoi; (3) CT-Bahiagrass; (4) CT-Brachiaria humidicola; and (5)

Changes in soil quality associated with tillage system applied

“…Also, arylsulfatase (silt soil-0.82**, 0.95**; sandy loam soil-0.87**, 0.99**) and FDA (silt soil-0.96**, 0.99**; sandy loam soil-0.78**, 0.60*) showed strong correlations with microbial biomass C and N at both studied soils (Tables 1, 2). This indicates that enzyme activities were associated with active microorganisms in soil which are the major source of soil enzymes (Balota et al, 2011). Similar results were obtained earlier by Gajda et al (2012).…”

“…4). Similarly to the results discussed by Melero et al (2010) and Balota et al (2004Balota et al ( , 2011, the fact that size of MBC and MBN pools was considerably bigger in both soils under conservation tillage systems RT and NT, as compared to TT, demonstrated the differences in soil organic matter (OM) quality induced by tillage system disturbances and an amount of plant residues incorporated into studied soils.…”

“…The significantly higher activity of AS (2-3 times) were observed in the upper layer of both soils (0-15 cm) under conservation tillage system, especially in NT, than that observed in TT soil. As was mentioned above, the much higher levels of AS activity measured in soils under RT and NT tillage than the ones under tillage with plough used were probably related to a larger input of organic C in RT and /or NT soil via plant residues, which are a basic reservoir of sulfate esters, the main substrate for this group of enzymes (Balota et al, 2011). In general, higher AS activity was measured in the silt soil with a higher clay particles content and fertility level, as compared to the sandy loam soil (Fig.…”

“…The enzyme activities were significantly intercorrelated, as observed in previous studies of eg Green et al (2007), which suggest that tillage and crop rotations systems have similar effects on the activities of those enzymes involved in C, N, P and S cycling in soils. The obtained high correlations between analyzed enzymes and total soil organic C indicate likely that organic C provides a better environment for stabilizing and protecting extracellular enzymes through the association with organic and inorganic colloids, and thus supporting a greater microbial biomass and its activity (Balota et al, 2011). Also, arylsulfatase (silt soil-0.82**, 0.95**; sandy loam soil-0.87**, 0.99**) and FDA (silt soil-0.96**, 0.99**; sandy loam soil-0.78**, 0.60*) showed strong correlations with microbial biomass C and N at both studied soils (Tables 1, 2).…”

“…Thus, arylsulfatase (AS) activity is dependent on sulfate content and nutrient content in soil. AS activity is usually the enzyme with the lowest levels in soils (Balota, 2011) 2010). The levels of activity of AS varied from 7.7 to 26.7, and 5.5 to 17.3 mg PNP g -1 of soil h -1 in a silt soil and sandy loam soil, respectively (Fig.…”