Back P. J. Valarini1, D. Alves2, F. Guerrero2, R.T.S. Friguetto1, H. Tokeshi3
EMBEAPA, CP69, 13820, Jaguariuna, Brazil1,
Department of Edaphology, Polytechnic University 28040, Madrid, Es.2and
ESALQ, USP, CP9, 13418-900, Piracicaba, Brazil3
Abstract
During 3 months of 1999, the influence of incorporating organic matter
and EE into a sandy saline soil was measured. The treatments tested were
E50 = saline soil + farmyard manure (FYM) 50 ton/ha; E50EM = E50 + effective
microorganisms (EM); CR30 = greed crops residues 30 ton/ha; CR30EM = CR30
+ EM; C = saline soil with no OM. One month before soil treatments and
3 months after incubation soil samples were characterized for FC, pH, EC,
CEC texture, exopolysaccharide, alkaline phosphatase and exteerase enxymatic
activities. The results indicate that the saline soils had low level of
OM, microbial activity (measures by phosphatase and exterase enzymes) due
to low energy balance, alkaline pH, excess of cations (Ca, Mg, Na) low
phosphorus solubility and the unavailable micronutrients for micro-organisms
and plants. When microorganisms (E50EM) were added to the pre-digested
FYM, its microbial activity was increased in the saline soil causing a
much faster humificfation of OM than when only FYM was used. The addition
of OM to the soil provide energy for micro-organisms which when developing,
excrete organic compounds with different functional groups that may immobilize
the various cations existing in the soil, thus making the nutrients accessible
to micro-organisms and plants. In this way, the pH is corrected to neutrality
releasing organic (phenolic, fatty acids), polysaccharide enzymes such
as esterases, alkaline phosphatases and dehydrogenases. This results in
changes in physical-chemical soil properties such as EC, FC, CEC, and OM
decomposition. The higher humification of OM verified mainly in treatment
E50EM reflected on FC and CEC integrated to higher polysaccharide production
and enzyme activities, as corroborated by the higher correlation indices.
This correlation indicates that some biochemical parameters may by early
sensitive indicators of desalinization and improvements in soil structure.
It is concluded that the methodology was efficient and the micro-biological
indicators detected, in an exact an early form, the physical- chemical
changes in the saline soils requires OM as source of energy and stimulation
from micro-organisms to accelerate soil recovery and economic cultivation.