&lt;b&gt;Soil properties and cowpea yield after six years of consecutive amendment of composted tannery sludge

Ademir Sérgio Ferreira De Araújo,Vilma Maria Dos Santos,Luciano Moura Lima,Wanderley José De Melo,Fabio Fernando De Araujo

doi:10.4025/actasciagron.v38i3.28281

<b>Soil properties and cowpea yield after six years of consecutive amendment of composted tannery sludge

Ademir Sérgio Ferreira De Araújo, Vilma Maria Dos Santos + Show 3 more

Open Access

https://doi.org/10.4025/actasciagron.v38i3.28281

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Abstract

This study evaluated soil properties and cowpea yield after six years of consecutive amendment of composted tannery sludge. The compost was applied annually at 0, 2.5, 5, 10, and 20 Mg ha -1 and at the end of the sixth year, the chemical and physical properties of the soil were evaluated using a randomized block design. The Cr, P, K, Ca, Na and organic C contents and the pH and cation exchange capacity increased linearly after six years of compost amendment. The soil bulk density decreased linearly while the aggregate stability index increased after compost amendment. As a consequence of the changes in the chemical and physical properties of the soil, cowpea yield showed a quadratic response to the tannery rates, with an estimated maximum cowpea yield at 8.3 Mg ha -1 . In conclusion, the soil chemical and physical properties improved after six years of composted tannery sludge amendment. However, the soil pH and the Cr and Na contents increased with composted tannery sludge amendment, which influenced the cowpea yield and resulted in a quadratic response to the compost.

Highlights

The tannery industry generates and releases a high volume of solid wastes known as tannery sludge (Santos, Nunes, Melo, & Araújo, 2011)
The soil pH increased after six years of composted tannery sludge (CTS) amendment, which is contrary to the general belief that organic residues decrease soil pH via the production of acids formed during the decomposition of organic matter
The increased soil pH observed in our study may be explained by the high pH and Ca content found in the CTS (Table 1)

Summary

Introduction

The tannery industry generates and releases a high volume of solid wastes known as tannery sludge (Santos, Nunes, Melo, & Araújo, 2011). Tannery sludge may cause environmental pollution if applied in its untreated form to the soil If it is treated before application, it may instead be used to improve agricultural soils (Araújo, Monteiro, & Carvalho, 2007). Following the amendment of composted tannery sludge (CTS), its application to the soil can increase plant yield by supplying additional nutrients, increasing soil pH, and reducing the exchangeable aluminum content (Santos et al, 2011). Because CTS contains high levels of organic matter, it may improve the chemical and physical properties of the soil. In this study, we evaluated the effects of six years of repeated CTS amendment on the chemical and physical properties of soil and investigated cowpea yield in a treated sandy soil

Material and methods

Results and discussion

Conclusion