Abstract

PAJARES-MORENO, Silvia; GALLARDO-LANCHO, Juan F.; MARINARI, Sara  and  ETCHEVERS-BARRA, Jorge D.. Biochemical indicators of quality in cultivated tepetates of the mexican transvolcanic belt. Agrociencia [online]. 2010, vol.44, n.2, pp.121-134. ISSN 2521-9766.

Tepetates (hardened volcanic tuff located in the Mexican Transvolcanic Belt) conditioned for agricultural use are highly degraded due to poor management practices. The objective of this study was to define biochemical characteristics that can be used as early indicators of the state of tepetate recovery. During the period 2002-2005, experimental plots cultivated since 1986 were subjected to three agronomic management practices: traditional (Tt), improved (Tm) and organic (To). Another two plots plowed in 2002 were treated with traditional (Rt) and organic (Ro) management. As a reference, two plots of tepetates without cultivation were selected (Tv and Td). Soil samples were collected, and the following variables were determined: soil organic carbon (SOC), total N (Nt), microbial biomass C and N (BM), soil respiration (RS), N mineralization, dehydrogenase, β-glucosidase, phosphatase, urease and protease activity, ammonification of arginine, and different metabolic indexes. The tepetates without cultivation, containing little SOC and Nt, had the lowest values of all of the biochemical variables, which increased with years of cultivation, especially with To and Tm management. The highestvalues of BM, RS and enzyme activity were associated with the increase in SOC in To and Tm plots, suggesting improved quality and fertility of these substrates. Therefore, appropriate management of tepetates, with supplements of organic matter or fertilizers with harvest residue cover, promoted better biochemical properties. These variables correlated significantly, indicating the existence of close relationships among the biochemical processes in the tepetates. The biochemical variables studied were useful indicators for assessing changes in quality of the tepetates cultivated under different management systems.

Keywords : enzyme activity; fragipan; metabolic indexes; agricultural management; soil organic matter.

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