Short-Term Decomposition and Nutrient-Supplying Ability of Sewage Sludge Digestate, Digestate Compost, and Vermicompost on Acidic Sandy and Calcareous Loamy Soils

Nikolett Uzinger,Dániel Benjámin Sándor,Eszter Draskovits,István Padra,Zdenko Lončarić,Nóra Szűcs-Vásárhelyi,Márk Rékási,Orsolya Szécsy

doi:10.3390/agronomy11112249

Abstract

Organic waste and the compost and vermicompost derived from it may have different agronomic values, but little work is available on this aspect of sewage sludge. A 75-day pot experiment with perennial ryegrass (Lolium perenne) as the test plant aimed to investigate the fertiliser value and organic matter replenishment capacity of digested sewage sludge (DS) and the compost (COM) and vermicompost (VC) made from it, applied in 1% and 3% doses on acidic sand and calcareous loam. The NPK content and availability, changes in organic carbon content and plant biomass, and the efficiency of the amendments as nitrogen fertilisers were investigated. The final average residual carbon content for DS, COM, and VC was 35 ± 34, 85 ± 46, and 55 ± 46%, respectively. The organic carbon mineralisation rate depended on the soil type. The additives induced significant N mineralisation in both soils: the average increment in mineral N content was 1.7 times the total added N on acidic sand and 4.2 times it on calcareous loam for the 1% dose. The agronomic efficiency of COM and VC as fertilisers was lower than that of DS. In the short term, DS proved to be the best fertiliser, while COM was the best for organic matter replenishment.

Highlights

The application of organic amendments to improve soil properties is a procedure widely used all over the world
Compared to the decreasing trend observed as a function of N doses for the Agronomic efficiency (AE) values, the main difference for the Apparent nitrogen recovery efficiency (ARE) values was the outstanding value recorded in the 3% digested sewage sludge (DS) treatment on both soils
The relatively lower organic carbon (OC), P, and N contents and the higher K content of COM were the result of the addition of green waste [31]

Summary

Introduction

The application of organic amendments to improve soil properties is a procedure widely used all over the world. Sewage sludge utilisation has an increasing range of applications, from agriculture to energy production, building materials, and adsorbents [1,2,3,4]. Sewage sludge acts as an organic amendment, increasing the organic matter content and water capacity of the soil, it has the drawback that it may contain inorganic and organic pollutants [7,8] Another problem is that the organic matter in sewage sludge decomposes rapidly in the soil, so both its beneficial effect on the organic matter content of the soil and its ability to supply nutrients only apply in the short term [9]. These barriers to application can be overcome by sludge treatment processes [10]

Methods

Results

Discussion

Conclusion