Diversifying crop rotation improves system robustness

Abstract

Agriculture requires a synergetic improvement in production profitability, long-term viability, and environmental health in the presence of abiotic (i.e., uncontrollable weather, input costs, and product prices) and biotic (i.e., weed pressure and disease infestation) stresses. A “robust” agroecosystem can enhance synergetic improvements by alleviating these stresses, but it is unknown how system robustness can be achieved in a systemic manner. Here, for the first time, we demonstrate that crop diversification can significantly enhance system robustness. An 8-year crop rotation study was conducted, in which 3-year crop sequences were repeated for two cycles, with the first cycle from 2010 to 2012 and the second from 2014 to 2016; each cycle began with a wheat (Triticum aestivum L.) crop, and pea (Pisum sativum L.), lentil (Lens culinaris Medik.), and mustard (Brassica juncea L.) were included in the rotation, and chickpea (Cicer arietinum L.), a N2-fixing legume susceptible to weed pressure and the foliar disease Ascochyta blight, was the last crop in each of the two cycles. Crop diversification improved system resistance to biotic stresses, and that chickpea in the diversified lentil-wheat-chickpea system had the lowest weed biomass and foliar disease severity among rotation systems. Chickpea in the diversified pea-mustard-chickpea system recovered from severe weed pressure by the end of the second cycle in 2016. Diversified systems increased resistance and resilience from abiotic stresses and improved the constancy in crop productivity across rotation cycles, compared to the less diversified systems. Quantitative assessments show that the most diversified systems had a 14% advantage in system robustness. We conclude that diversifying crop rotation improves system robustness through enhancing crop resistance to and resilience from biotic-induc ed disturbances and increasing the constancy of crop productivity while facing disturbance.