Fifteen years of no till increase soil organic matter, microbial biomass and arthropod diversity in cover crop-based arable cropping systems

The physical, chemical and biological properties of soil may be modified by tillage, fertilization and cover crops. However there is little knowledge on long-term effects on soil properties, notably under Mediterranean climate. Moreover, biological indicators such as micro-arthropods can be used for a cost-effective analysis of soil biodiversity. Here, we studied physical and biological properties of a sandy loam soil in central Italy under a 4-year rotation of maize–durum wheat–cover crop–sunflower–durum wheat–cover crop during 15 years. We analysed the effects of two tillage systems, conventional tillage (CT) and no-tillage (NT); two N fertilization rates, without N and medium N level; and three soil covers: cash crop residue as control, Brassica juncea and Vicia villosa. Results show that no tillage increased soil organic matter content in the upper 10-cm layer (3.31%) compared to the conventional tillage (2.19%). No tillage also improved structure stability and lowered bulk density in the same soil profile. No-tillage systems showed higher soil microbial biomass (+71%) and respiration (+44%), and a higher abundance and diversity of micro-arthropods. We conclude that no tillage is an effective measure to improve the physical and biological quality of soil in Mediterranean conditions. No-tillage positive effect can be enhanced by the right choice of N fertilization and cover crop cultivation. Bio-indicators such as micro-arthropods can be very predictive of soil habitability by organisms.