Legumes, such as clover and alfalfa, have long been known for their nitrogen-fixing properties, and a group of University of Kentucky (UK) scientists have discovered a more efficient way for these plants to fix nitrogen.

Through a symbiotic relationship with soil-borne rhizobia bacteria, legumes can fulfill their own nitrogen needs and produce and leave enough in the soil for other plants to use. This reduces the need for topical nitrogen fertilizers, which are costly and can cause environmental pollution.

But not all legumes are the same when it comes to their nitrogen fixation efficiencies. In fact, different environments and bacterial strains can result in legumes fixing little to no nitrogen at all.

Recently, Hongyan Zhu, PhD, a professor in the UK College of Agriculture, Food and Environment, and his team of researchers found two antimicrobial peptides in the model legume Medicago truncatula (barrelclover or barrel medic) that kill certain rhizobial bacteria as the nitrogen fixation process begins. This model legume is closely related to the forage legume alfalfa