A review of the effects of tillage systems on some soil physical properties, water content, nitrate availability and crops yield in the Argentine Pampas

R. ALVAREZ, H.S. STEINBACH

SOIL & TILLAGE RESEARCH

ELSEVIER SCIENCE BV

Año: 2009 vol. 104 p. 1 - 15

0167-1987

The Argentine Pampas is one of the most important cropping regions of the World. Conservation tillage systems, and specially no-till, had widespread in recent years, occupying actually around 70 % of the surface devoted to annual crops.  We review results produced in field experiments installed along the Pampas in order to determine the effect of the adoption of these tillage systems on some soil properties and crops yield. It was performed a metanalysis of data from experiments where plow tillage (mould board plow), reduced tillage (chisel plow, disk plow or harrow disk) and no-till were compared. Treatments effects were contrasted by means of paired t tests between groups of paired data. Soil bulk density and cone penetration resistant of the 0-20 cm layer were higher under conservation tillage systems than under plow tillage. The increase of bulk density was greater in soils of initial low bulk density. Neither bulk density increases nor cone penetration changes reached critical threshold for roots development. Aggregate stability and water infiltration rate were also higher in soils subjected to conservation tillage systems than under plow tillage. The improvement of aggregate stability was higher in poorer structured soils. Soil water content during the critical periods of sowing and flowering was generally greater under conservation tillage but, conversely, nitrate nitrogen levels were greater in plow tillage. Soybean (Glicine max (L.)-Merr.) yield was not affected by tillage system, meanwhile wheat (Triticum aestivum L.) and corn (Zea mays L.) yields were lower under reduced tillage and no-till than under plow tillage without nitrogen fertilization. When fertilizers were applied wheat and corn yield differences between tillage treatments generally disappeared. Results shown that the adoption of conservation tillage systems in the Pampas leads to soil improvement but also generates the necessity of increase nitrogen fertilizers utilization to sustain yields of graminaceus crops.