Sulfur supply from recycled sources: An effective strategy to improve chickpea productivity and sustainability

Chickpea (Cicer arietinum L.) is a pulse traditionally cultivated in the Mediterranean basin. Interest in its cultivation has recently increased due to social and environmental concerns related to animal-based protein supply systems. Moreover, its inclusion in crop rotations support the provision of ecosystem services associated with legumes cultivation. However, a wider diffusion of chickpea in cropping systems remains constrained by its low productivity. Given that sulfur availability limits nodule metabolism, the use of sulfur fertilizers represent a potential strategy to enhance legume seed yield. This study evaluated the agronomic and environmental performances of two chickpea varieties subjected to three sulfur fertilization strategies (0, 30, and 60 kg S ha− 1 ) under Mediterranean climate conditions over two growing seasons. A Life Cycle Assessment (LCA) was performed to assess the environmental sustainability of recycled sulfur (i.e. gypsum) as a fertilizer. Sulfur fertilizers were obtained from recovered chemical gypsum (CaSO4 x 2 H2O). Both varieties showed a positive yield response to sulfur fertilization at the lower application rate, without further improvements at higher rates. Compared to the unfertilized control, sulfur fertilization increased seed yield and total biomass yield on average by 46% and 49% respectively. The seed yield improvement was mainly driven by more pods per plant (+ 71%). Higher productivity under sulfur fertilization significantly influenced the environmental performances of chickpea. In four impact categories assessed by LCA (Climate Change, Land Use, Energy Resources – fossil fuel, Water Use), the environmental burden per 1 Mg of seed was lower in fertilized treatments compared to the control. Overall, managing chickpea sulfur nutrition through the application of a limited amount of gypsum resulted in a promising strategy to improve both chickpea productivity and sustainability in Mediterranean cropping systems.