2017 ASHS Annual Conference

Mango (Mangifera indica) is major fruit tree crop of the tropics and subtropics, particularly in Asia, where it is among most economically important fruit crops. Mango has very limited production in temperate Mediterranean climates and currently the only US states producing the fruit are California, Florida, and Hawaii. This study focuses on the improvement of organic mango production in the Coachella Valley of Southern California, where the dry/hot desert climate and sandy soil presents a significant challenge for producers. Recent reviews on mango crop management and physiology indicate that the best prospect for improving mango production must involve a holistic approach that considers the specific climate and edaphic environment. The specific goals of this study are to 1) improve soil fertility and 2) increase mango fruit yield. To reach these objectives, sulfur burners were installed in water reservoirs to alleviate the alkaline soils of the Coachella Valley and improve tree nutrition. In addition, a combination of cover crops – including alfalfa (Medicago sativa) and Sudan grass (Sorghum × drummondi) – and biochar soil amendments were used to manage nutrient cycling and enhance soil fertility. Biochar is a type of charcoal made from carbon-rich waste products (e.g. wood pellets, tree trimmings, and municipal waste) that can water/nutrient use efficiency and yield as well as increase soil populations of beneficial microorganisms. To observe these differences in soil microbial communities, DNA was extracted from soil, sequenced, and analyzed using QIIME. Results indicate that alfalfa cover crops and biochar work synergistically, shifting towards more beneficial microbial communities to improve soil fertility, mango tree health, and ultimately fruit yield in this Southern California orchard. Mangos produced in the Coachella Valley fit in to a niche market due to their harvest timing and lack of quarantine restrictions. Therefore, improved organic production in Southern California could add great value to this crop.