Shoot and Root Decomposition from Different Cropping Systems Under Semiarid Mediterranean Conditions

Improving the management of crop residues is essential for water and soil conservation and for increasing soil carbon (C) and nitrogen (N) levels in dryland agroecosystems. The main objective of the study was to evaluate the decomposition dynamics and C and N released from crop residues from different cropping systems under semiarid Mediterranean conditions. A litterbag experiment was conducted from July of 2020 to June of 2021 to examine the shoot and root decomposition dynamics of different cropping systems; the following systems were selected: V(B), vetch (Vicia sativa) residue decomposition in a barley crop; B(V), barley (Hordeum vulgare L.) residue decomposition in a vetch crop; P(B), pea (Pisum sativum) residue decomposition in a barley crop; B(P), barley residue decomposition in a pea crop; and B(B), barley residue decomposition in a barley crop. After 48 weeks of decomposition, a 45% and 60% of residues mass remaining (MR) was found corresponding to vetch and pea shoot residues respectively, whilst barley MR ranged 77-87% depending on the cropping system. In root residues, the mass decay from legume residues (40-45%) was higher compared to barley residues (17-29%). Exponential decay and linear models explained the residue decomposition observed in our study conditions. Residues C to N ratio and edaphoclimatic conditions played a major role controlling the decomposition. Residue decomposition and C and N release dynamics from different crop residues need to be considered for a transition to more sustainable agroecosystems under Mediterranean semiarid conditions.