(Micro)biological, chemical and physical properties of soils subjected to conventional or no-till management: an assessment of their quality status

In order to evaluate the impact of no-tillage (NT) against conventional-til lage (CT), or the effect of different fertilizers and herbicides, soils rec ently incorporated to agriculture from the El Salado basin river (Buenos Ai res, Argentina) under a corn (1996/1998)-pasture (1998-)rotation were monit ored for several soil (micro)biological, physical and chemical properties d uring the second (1997) to fourth (1999) years from the beginning of the ex periment (1996). The rates of exchange of O-2 and CO2 expressed in terms of kg O-2 or CO2-C per hectare per day, are denoted as qO(2) and qCO(2). They decreased at the end of the corn growth cycle (T2) along with an increase of the respiratory quotient (RQ = qCO(2)/qO(2)), when compared to the time of land preparation (TO), irrespective of the management system. Both, qO(2 ) and qCo(2), increased 8 months after the mixed-grass-legume pasture plant ing (T3) keeping similar RQs with values slightly higher for NT than CT. At T4 (after 20 months of pasture), a 22 and 21% decrease of organic carbon w as registered for NT and CT, respectively, with respect to the beginning of the experiment. A 22% (not significative) and a significative 31% diminish of total nitrogen was observed in the NT and CT systems, respectively. The results obtained are discussed in terms of soil function and sustainabilit y in both management systems tested. (C) 2001 Elsevier Science B.V. All rig hts reserved.