Carbon capture and pedogenetic processes by change of moisture regime and conventional tillage in Aridisols

In recent years, conservation tillage has been promoted as a method of increasing the quality of agricultural soils; however, in the Aridisols of northeastern Mexico, this type of tillage is not practical because of the formation of natural crusts. Conventional tillage systems that include different culture practices have been used for six decades to increase the yields. However, little is known of the changes to the soil properties and modifications to the moisture control section. Six agricultural plots representative of 78,000 ha in districts of the state of Tamaulipas, Mexico were studied based on their management: rainfed or irrigated, with or without the incorporation of crop residues and with or without plot drainage. The results show that three moisture regimes occur in the soils according to the irrigation intensity and plot drainage: aridic, ustic and udic. The aridic regime presents the greatest organic carbon stock (58 Mg ha(-1)), stability of aggregates in particles >2 mm in the arable layer and produces sorghum yields of up to 2.5 t ha(-1). In the udic regime, because of plot drainage and the incorporation of crop residue and manure, there is high biological activity; in addition, stability of aggregates is along the whole profile, alkalinisation and redox processes occur, and short-cycle maize yields are up to lot ha(-1). The different management practices for intense production modify the moisture regime but do not modify the organic carbon capture. The pedogenetic processes are related to the management intensity and cause the Aridisols to evolve into inceptisols in less than six decades of agricultural activity; however, only the redox processes are expressed in their classification despite a significant amount of calcitic features. (C) 2015 Elsevier B.V. All rights reserved.