Deep tillage and nitrogen do not remediate cumulative soil deterioration effects of continuous cropping

Abstract

AbstractShort‐term solutions like increasing N fertilization and decompaction with deep tillage (DT) have been proposed to mitigate soil degradation in continuous cropping systems. However, the joint evaluation of these factors in established no‐till systems is limited. This work aims to quantify corn yield losses generated by the cumulative degradation of soil quality of intensified no‐till cropping systems, quantify to what extent yield losses could be mitigated by soil DT and N fertilization, and identify the most important process involved in yield reductions. Eleven experiments were installed during 2014 and 2015, on a typic Argiudoll with different soil quality generated by more than 50 years of contrasting land uses. A split‐plot design was employed; the main plots were for DT (with and without) whereas the subplots were four N rates (0, 60, 120, and 240 kg ha−1). Overall, soil physical quality (SPQ) and carbon losses were associated with yield depletions. An increase in bulk density of 0.1 g cm−3 was associated with a 15.8% yield decrease. Deep tillage improved SPQ and modified water and N dynamics. However, these changes were small, variable, and did not affect corn growth. N fertilization improved yields but did not eliminate differences linked with land degradation and previous crop effects. Soil organic carbon had a better association with yields than bulk density, macroporosity, and penetration resistance. The results of this study highlight the importance of evaluating remediation practices to soil degradation under real conditions, regardless of its greater complexity for interpretation.