Effects of different tillage regimes on soil compaction, maize (Zea mays L.) seedling emergence and yields in the eastern Argentinean Pampas region

Crop establishment depends primarily on the methods used for seedbed preparation and sowing. Our main objective was to evaluate the soil compaction and crop residue effects on maize (Zea mays L) seedling emergence and yields in three tillage regimes: direct sowing (DS), chisel plough (ChP) and mouldboard plough (MP). The current study was performed in the eastern section of the humid subtropical Rolling Pampa region, Buenos Aires State (Argentina) between October 2004 and March 2007. The soil of the study site is a typical Argiudoll. We hypothesised that maize yields are affected by different tillage regimes used for seedbed preparation and that the traffic for the three tillage regimes caused subsoil compaction. The variables measured were: (1) cone index (Cl) in the 0-450 mm depth profile; (2) root dry matter per plant (RDM); (3) dry matter per plant (DMP); (4) seedling emergence (SE); and (5) maize yields (MY). The results showed that in DS, the high soil compaction level causes smaller yields (decrease between 10.7 and 15.2%) compared with the other two tillage systems. SE was slower under ChP and MP compared with DS, but similar results were achieved 18 days after sowing. The highest RDM average values for three growing seasons were observed in ChP and MP (42.3 and 46.1 g plant(-1), respectively) compared to DS (37.1 g plant(-1)). The study produced the following conclusions. Maize yield was directly related to root dry matter per plant, which was affected by soil compaction. The soil Ap horizon needs to be tilled to improve yields. Despite the greater number of tractor passes in ChP and MP, all systems caused subsoil compaction. SE was not affected by plant residue. (C) 2011 Elsevier B.V. All rights reserved.