Green Compost Combined with Mycorrhizae and Rhizobia: A Strategy for Improving Alfalfa Growth and Yield Under Field Conditions

Abstract

Alfalfa (Medicago sativa L.) is one of the most important forages and legume crops in the Mediterranean region, where extensive soil exploitation and low soil fertility are among the factor limiting its production. In this study, a field experiment was carried out in the semi-arid area of Morocco, in order to assess the influence of the individual and combined application of autochthonous arbuscular mycorrhizal fungi (AMF), rhizobium strain and green compost supply on alfalfa. Vegetative yield, physiological and biochemical traits were evaluated together with the associated changes in the soil’s physico-chemical parameters. The results show that AMF and rhizobium inoculation combined with compost application induced the greatest effect. This treatment increased the dry matter yield, leaves and nodules number, and AMF infection rate. Moreover, the combined use of these biofertilizers further enhanced stomatal conductance, photosystem II efficiency, photosynthetic pigments (chlorophyll and carotenoids), protein and sugar content along with the nutrients uptake (Phosphorus (P), Nitrogen (N), Potassium (K) and Calcium (Ca)). When compared with the initial soil status, the compost (10 t/ha) combined with AMF and rhizobium significantly improved the organic matter, N and P content, decreased soil pH and increased electrical conductivity. This treatment is also efficient in increasing soil glomalin content. This study demonstrated that the interaction between green waste compost, AMF and rhizobium inoculation could have important implications in alfalfa sustainable agriculture.