Nitrogen balance and gap of a high yield tropical soybean crop under irrigation

Leandro Moraes Zambon; Renan Caldas Umburanas; Felipe Schwerz; Jackellyne Bruna Sousa; Everton Servilho Teixeira Barbosa; Letícia Pacheco Inoue; Durval Dourado-Neto; Klaus Reichardt

doi:10.3389/fpls.2023.1233772

Nitrogen balance and gap of a high yield tropical soybean crop under irrigation

Front Plant Sci. 2023 Sep 27:14:1233772. doi: 10.3389/fpls.2023.1233772. eCollection 2023.

Authors

Leandro Moraes Zambon¹, Renan Caldas Umburanas¹, Felipe Schwerz^{1

2}, Jackellyne Bruna Sousa¹, Everton Servilho Teixeira Barbosa¹, Letícia Pacheco Inoue¹, Durval Dourado-Neto¹, Klaus Reichardt^{1

3}

Affiliations

¹ Luiz de Queiroz College of Agriculture (ESALQ), University of São Paulo (USP), Piracicaba, Brazil.
² Agricultural Engineering Department, Federal University of Lavras (UFLA), Lavras, Brazil.
³ Center of Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba, Brazil.

Abstract

Nitrogen (N) is the most extracted and exported element by the soybean crop. In high yield tropical environments with irrigation, little is known about N accumulation in different soybean plant organs as well as the N balance. The objective of this study was to characterize soybean growth, N accumulation in plant organs, N balance, and N gap in a high yield tropical environment. This study was performed in a homogeneous field, in a soil with low organic matter, with 20 kg ha^-1 of N, under furrow fertilization. Evaluations were performed ten times, temporally distributed from emergence to senescence. The soybean cultivar used was 'RK7518 IPRO' and was sown with row spacing of 0.45 m and a seeding rate of 300,000 plants ha^-1. Plant N partition, N from the biological N fixation (BNF), grain yield, crop harvest index (HI), N harvest index (NHI) with and without root contribution were evaluated. Also, at the grain filling stage the N gap was evaluated from the soil by difference between whole plant accumulated N and the amount of N from BNF. The average grain yield was 6,470 kg ha^-1 and leads to a negative partial balance of N of -33.4 and -42.8 kg_[N] ha^-1 with and without roots, respectively. The N gap from the soil was 231.7 kg_[N] ha^-1. It is recommended to adopt techniques that increase the efficiency of BNF and the soil N accumulation to balance these production systems in the medium to long term.

Keywords: Glycine max; N balance; biomass partitioning; plant nutrition; soil inorganic N.

Grants and funding

São Paulo Research Foundation (FAPESP): Grant no. 2016/06310-0; Coordination for the Improvement of Higher Education Personnel (CAPES): Financial code 001; National Council of Technological and Scientific Development (CNPq): Grant no. 140209/2015 8, to AGRISUS Foundation: Grant no. 2067-17; and Luiz de Queiroz Agrarian Studies Foundation (FEALQ).