Successive crops of lettuce fertilized with bovine manure in the presence and absence of mung bean

Using legumes as a green manure is a well-established practice because it adds nitrogen-rich plant material to the soil. This study evaluates successive crops of lettuce fertilized with different doses of bovine manure in the presence and absence of mung bean. Experiments were carried out at the Rafael Fernandes Experimental Farm, Mossoró, Brazil, from August 2015 to January 2016. We applied a complete randomized block design with treatments arranged in a 4 x 2 factorial scheme, with four replications. The first factor consisted of bovine manure at four dosages (1.0, 2.0, 3.0, and 4.0 kg m-2) and the second factor was the presence and absence of green manure (mung bean). We used the "Regina" lettuce cultivar. The following characteristics were assessed: plant height, number of leaves per plant, head diameter, lettuce production, and lettuce dry mass. The lettuce production achieved 87.8 kg/100 m2. The interaction between bovine manure and mung bean did not affect the production characteristics. The use of mung bean as green manure increased the lettuce production significantly, with mean values of 81.4 kg/100 m2 compared to 67 kg/100 m2 in the treatments without mung bean.