Fourteen years of applying zero and conventional tillage, crop rotation and residue management systems and its effect on physical and chemical soil quality

Soil management systems may negatively affect the quality of the soil. Policymakers and farmers need scientific information to make appropriate land management decisions. Conventional (CT)and zero tillage (ZT) are two common soil management systems. Comparative field studies under controlled conditions are required to determine the impact of these systems on soil quality and yields. The research presented studied plant and soil physical and chemical characteristics as affected by different agricultural management practices. i.e. ZT and CT, cropped with continuous wheat or maize in monoculture (M) or in a yearly rotation (R) of these two crops, either with residue retention (+r) or without residues retention (-r), in an experimental field in the Transvolcanic Belt of Mexico after 14 years. The dominant factors defining soil quality were organic C, total N, moisture, aggregate stability, mechanical resistance, pH and EC. The principal component combining the variables organic C, total N, aggregate stability and moisture content showed the highest correlations with final yield (R = 0.85 for wheat and 0.87 for maize). After 14 years of continuous practice. ZTM+r and ZTR+r had the best soil quality and produced the highest wheat and maize yields of average 2001-2004 (6683 and 7672 kg ha(-1) and 5085 and 5667 kg ha(-1), respectively). Removing the residues. i.e. treatments ZTM-r with maize (average 2001-2004: 1388 kg ha(-1)) and ZTR-r and C7R-r with wheat (average 2001-2004: 3949 and 5121 kg ha(-1)), gave the lowest yields and less favourable soil physical and chemical characteristics compared to the other practices. It Was found that zero tillage with residue retention is a feasible management technology for farmers producing maize and wheat in the agro-ecological zone studied, resulting in a better soil quality and higher yields than with the conventional farmer practice (maize monoculture, conventional tillage and residue removal). (C) 2008 Elsevier B.V. All rights reserved.