Composted Sewage Sludge Enhances Soybean Production and Agronomic Performance in Naturally Infertile Soils (Cerrado Region, Brazil)

Adrielle Rodrigues Prates,Cassio Hamilton Abreu-Junior,Gian Franco Capra,Fernando Carvalho Oliveira,Bruno Gasparoti Miranda,Antonio Ganga,Zhenli He,Arun Dilipkumar Jani,Adônis Moreira,Maria Márcia Pereira Sartori,Orivaldo Arf,Fernando Shintate Galindo,Marcelo Carvalho Minhoto Teixeira Filho,Aline Renée Coscione,Thiago Assis Rodrigues Nogueira

doi:10.3390/agronomy10111677

Abstract

Naturally infertile soils require large amounts of mineral fertilizers to obtain the desired crop yield. In the Cerrado region of Brazil, there is a need to investigate the potential of organic fertilizers to sustainably increase crop productivity and food security. A field study was conducted over two experimental seasons to evaluate the agronomic effectiveness of composted sewage sludge (CSS) as a fertilizer for soybean cultivation in infertile tropical soils. A 4 × 2 + 2 factorial randomized complete block design was applied with the following treatments: (i) CSS: 5.0, 7.5, 10.0, and 12.5 Mg ha−1 on a wet basis applied according to two different methods: whole area (WA) or between rows (BR); (ii) comparison with two alternative treatments: a control with no CSS and mineral fertilizer application, and an area treated with conventional fertilizers only. All the treatments were compared in terms of micronutrient concentrations in surface soil and plant leaves, plant development, crop productivity, and yield. Bi- (ANOVA, correlation matrix, and polynomial regression analysis) and multivariate (PCA, principal factor analysis) statistics were applied to determine statistical differences and relationships/observed variability among the treatments. Results showed that at higher CSS-WA rates: (i) soil and leaf micronutrient concentrations increased; (ii) there was an increase in soybean yield by 12 and 20%, respectively, as compared to control and conventional fertilization; (iii) soybean yield was 67% higher than the mean soybean yields for Brazil. Research outcomes confirm the benefits of CSS application on infertile agricultural soils in the Cerrado region, representing a strong alternative source of micronutrients in the CSS with respect to conventional fertilizers.

Highlights

Sewage sludge (SS) is an organic byproduct derived from wastewater treatment plants (WWTP) that may contain a large amount of organic matter (OM) and plant nutrients, including nitrogen (N), phosphorus (P), and micronutrients [1,2,3]
Comparing the higher soybean yields observed in our study with the mean productivity in Brazil (3300 kg ha−1) during the I harvest period [44], we noted that a yield increase of up to 67% could be obtained with composted sewage sludge (CSS) application with the whole area (WA) method
The results from the field trial of soybean crop in the infertile tropical soils of the Cerrado region showed that CSS application to the whole area (WA) resulted in higher concentrations of B, Cu, and Zn in soil and plant leaves, which are within their optimal range for crop production, avoiding soil deficiencies and/or pollution

Summary

Introduction

Sewage sludge (SS) is an organic byproduct derived from wastewater treatment plants (WWTP) that may contain a large amount of organic matter (OM) and plant nutrients, including nitrogen (N), phosphorus (P), and micronutrients [1,2,3]. While CONAMA encourages SS use in agriculture, there are concerns that have limited SS adoption in Brazil, as evidenced by the fact that less than 3% of SS in Brazil is currently used in agriculture [7]. Such low SS adoption is attributed to the scarcity of research into SS use as a fertilizer or soil amendment in Brazil. The Brazilian government approved a revision of the aforementioned Resolution [10], clarifying there are no further restrictions in the use of composted sewage sludge (CSS) as an organic fertilizer

Objectives

Methods

Results

Conclusion