CROP ROTATION IN TOBACCO PRODUCTION: EFFECT ON SOME SOIL PROPERTIES

Abstract

Tobacco cultivation requires numerous agricultural practices, which along with the low
volume of stubble that it leaves, it favors soil physical, chemical and biological
deterioration. The aim of this work was to evaluate, in a soil of Valle los Pericos (Jujuy Province), the effect on edaphic quality of crop rotations carried out in the tobacco
cultivation: monoculture (TM), rotation with grasses (TG), incorporation of green manures
(TV), and also compared these results with those of a low soil disturbance situation (T).
The response of different edaphic variables was studied at two soil depths (0-20 cm and
20-40 cm), in tobacco production plots with different rotations and more than 30 years
under conventional tillage and irrigation. Agriculture caused a decrease of 44 % and 57 %
in the average structural stability at the superficial and deep layer, respectively.
Infiltration rate was five times higher in T. A decrease in all carbon fractions and between
8 % and 11 % of soil pH was observed in cultivated plots. Tobacco production under
irrigation and fertilization showed an increase from 67 % to 100 % in soil electrical
conductivity and more than 300 % in the extractable phosphorus. Crop diversification
generated in superficial layer significant increases of 54 % and 41 % of total and mineral
associated organic carbon content, respectively, while particulate carbon did not change
according to the different agricultural rotations. The superficial and deep carbon of the
microbial biomass was 118 % and 159 % higher, respectively, in TG in relation to the TV
and TM average, while superficial basal respiration was 83 % higher in TG and TV with
respect to TM.