Residual effects of composted sewage sludge on nitrogen cycling and plant metabolism in a no-till common bean-palisade grass-soybean rotation

Mariana Bocchi da Silva; Liliane Santos de Camargos; Marcelo Carvalho Minhoto Teixeira Filho; Lucas Anjos Souza; Aline Renée Coscione; José Lavres; Cassio Hamilton Abreu-Junior; Zhenli He; Fengliang Zhao; Arun Dilipkumar Jani; Gian Franco Capra; Thiago Assis Rodrigues Nogueira

doi:10.3389/fpls.2023.1281670

Residual effects of composted sewage sludge on nitrogen cycling and plant metabolism in a no-till common bean-palisade grass-soybean rotation

Front Plant Sci. 2023 Oct 20:14:1281670. doi: 10.3389/fpls.2023.1281670. eCollection 2023.

Authors

Affiliations

¹ Department of Plant Protection, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira, SP, Brazil.
² Instituto Federal de Educação, Ciência e Tecnologia Goiano, Rio Verde, GO, Brazil.
³ Center of Soils and Environmental Resources of the Campinas Agronomic Institute, Campinas, SP, Brazil.
⁴ Center for Nuclear Energy in Agriculture, Universidade de São Paulo, Piracicaba, SP, Brazil.
⁵ Indian River Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Fort Pierce, FL, United States.
⁶ Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou, China.
⁷ Department of Biology and Chemistry, California State University, Monterey Bay, Seaside, CA, United States.
⁸ Dipartimento di Architettura, Design e Urbanistica, Università Degli Studi di Sassari, Sassari, Italy.
⁹ Desertification Research Centre, Università Degli Studi di Sassari, Sassari, Italy.
¹⁰ Department of Agricultural Sciences, School of Agricultural and Veterinarian Sciences, São Paulo State University, Jaboticabal, SP, Brazil.

Abstract

Introduction and aims: In the context of increasing population and decreasing soil fertility, food security is one of humanity's greatest challenges. Large amounts of waste, such as sewage sludge, are produced annually, with their final disposal causing environmental pollution and hazards to human health. Sludge has high amounts of nitrogen (N), and, when safely recycled by applying it into the soil as composted sewage sludge (CSS), its residual effect may provide gradual N release to crops. A field study was conducted in the Brazilian Cerrado. The aims were to investigate the residual effect of successive applications of CSS as a source of N in the common bean (Phaseolus vulgaris L. cv. BRS Estilo)-palisade grass (Urochloa brizantha (A.Rich.) R.D. Webster)-soybean (Glycine max L.) rotation under no-tillage. Additionally, N cycling was monitored through changes in N metabolism; the efficiency of biological N₂ fixation (BNF) and its implications for plant nutrition, development, and productivity, was also assessed.

Methods: The experiment consisted of a randomized complete block design comparing four CSS rates (10, 15, 20, and 25 Mg ha^-1, wet basis) to a control treatment (without adding mineral or organic fertilizer) over two crop years. Multiple plant and soil analyses (plant development and crop yield, Falker chlorophyll index (FCI), enzymatic, biochemical, ¹⁵N natural abundance, was evaluated, root and shoot N accumulation, etc.) were evaluated.

Results and discussion: Results showed that CSS: i) maintained adequate N levels for all crops, increasing their productivity; ii) promoted efficient BNF, due to the stability of ureide metabolism in plants and increased protein content; iii) increased the nitrate content and the nitrate reductase activity in soybean; iv) affected urease activity and ammonium content due to changes in the plant's urea metabolism; v) increased N accumulation in the aerial part of palisade grass. Composted sewage sludge can be used as an alternative source to meet crops' N requirements, promoting productivity gains and N cycling through forage and improving N metabolism.

Keywords: biological N2 fixation; cover crops; no-till; organic fertilizer; urban waste.

Grants and funding

The authors declare financial support was received for the research, authorship, and/or publication of this article. This research was funded by the National Council for Scientific and Technological Development (CNPq) (grant # 404815/2021-9). This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (PROAP Program - AUXPE no. 2671/ 2022).