Interaction between nitrogen doses and alfalfa (Medicago sativa L.) incorporation in lettuce (Lactuca sativa L.) production

Abstract

Objective: To determine the optimal nitrogen dose combined with alfalfa in the growth, yield, and ion concentration in the sap of the lettuce leaf. Design/Methodology/Approach: We used a completely randomized experimental design, with a 2×5 factorial arrangement and nine repetitions in each treatment. The treatments consisted of five nitrogen doses (200, 250, 300, 350, and 400 kg ha-1) and two soil conditions (with and without alfalfa). Results: Aerial fresh weight (AFW), aerial dry weight (ADW), end-to-end diameter of the shoot (EDS), maximum diameter of the shoot (MDS), shoot weight (SW), and yield were higher when a 200-300 kg ha-1dose of N was applied along with alfalfa. This application had a similar effect to the 300 kg dose of N ha-1, applied without the addition of alfalfa. The concentration of nitrates (NO3-) in the sap decreased with the addition of alfalfa and 200 kg of N ha-1. The concentration of potassium (K+) was higher with or without the addition of alfalfa and 250 kg of N ha- 1. The concentration of calcium (Ca2+) was higher in the plants that received a 400-kg dose of N ha-1, whether alfalfa was included or not. Study Limitations/Implications: The lack of equipment prevented the determination of the nitrogen available in the soil. Findings/Conclusions: The incorporation of alfalfa into the soil is a good alternative to improve lettuce production and reduce the use of nitrogen fertilizers.