Residue removal and tillage interaction effects on soil properties under rain-fed corn production in Central Mexico

Determining the effects of residue removal and tillage systems on surface crop residue accumulation, organic carbon sequestration and nutrient cycling is essential for sustainable land management. This study evaluated the effects of 6 years of conventional and conservation tillage with different amounts of crop residues left on the soil surface on selected soil properties of a Vertisol and an Andisol used for rain-fed corn (Zea mays L.) production in Central Mexico (Apatzingan and Casas Blancas, Mich.). The results showed that conservation tillage. i.e. no tillage (NT) with 100, 66 and 33% of crop residues left on the field, and minimum tillage (MT), significantly increased surface crop residue accumulation on the soil surface. In the 0-50 mm surface layer. organic C, microbial biomass C and N, inorganic and total N. and extractable P were approximately twice higher with NT/100%, NT/66%, NT/33%. and MT than with conventional tillage (CT) and NT/0% treatments. Higher levels of soil organic C, microbial biomass C and N, inorganic and total N, and extractable P were directly related to surface accumulation of crop residues promoted by conservation tillage management. Removal of surface crop residues can seriously reduce production sustainability in climates where stressful conditions occur. In general, the mid-term (6 years) sustainability of Vertisol and Andisol for rain-fed corn production seemed to be enhanced by conservation tillage management. To obtain the benefits of conservation tillage in the sub-humid tropical region of Apatzingan (Vertisols), where organic matter is rapidly oxidized, it is necessary to leave at least 60% of the crop residue on the soil surface, while in the sub-humid temperate region of Casas Blancas (Andisol), where organic matter is oxidized slower, leaving 30% of crop residue is sufficient. (C) 2001 Elsevier Science B.V. All rights reserved.