Assessing the biomass yield and nitrogen fixation of Lupinus angustifolius varieties as green manure in Jalisco, Mexico

Abstract

Limited information is available in Mexico regarding the use of Lupinus angustifolius L. as a green manure. This study aimed to assess the effectiveness of six Lupinus angustifolius varieties as green manure in terms of above-ground biomass production, expressed as dry matter (DM), and total nitrogen (N) accumulation at successive harvest dates. Additionally, the study aimed to estimate N2 fixation 110 days after sowing (DAS). The varieties Haags Blaue, Boregine, Borlu, Probor, Sonate, and Boruta were sown during the winter season of 2018-2019 using a randomized block factorial design. The N difference method was employed to estimate N2 fixation, with wheat serving as the reference crop. Data on above-ground biomass production, N concentration, and total N accumulation were recorded at different harvest times: 80, 95, and 110 DAS. The biomass yield of all varieties significantly increased from the first to the last harvest, with the highest yield observed at the final harvest (ranging from 7,632 to 10,200 kg ha-1). The highest total N accumulation from biomass was recorded at the last harvest. On average, the Borlu, Boregine, Haags Blaue, and Boruta varieties accumulated 195.4 kg ha-1 of total N (ranging from 195.6 to 221.2 kg ha-1). The proportion of N derived from the atmosphere (%Ndfa) through N2 fixation averaged 80.09% (ranging from 72% to 93%), resulting in an average N fixation of 160 kg ha-1 (ranging from 106 to 185 kg ha-1) in above-ground biomass. All six varieties demonstrated potential as green manure, considering their above-ground biomass production, total N accumulation, and ability to fix N2.