CO2 Emission and Change in the Fertility Parameters of a Calcareous Soil Following Annual Applications of Deinking Paper Sludge (The Case of Tunisia)

Abstract

<jats:p>The use of deinking paper sludge (DPS) as a fertilizer instead of sending it to landfill could play a role in reducing greenhouse gases and improving soil properties. The objectives of this study were (1) to evaluate the changes in the physical (permeability and structural stability), chemical (particularly soil pH), and biological (microbial metabolic quotient (qCO2), microbial biomass soil CO2 emissions) of a calcareous agricultural soil following two successive annual amendments with three treatments (0, 30, and 60 Mg DPS ha−1—control, DPS30, and DPS60, respectively); and (2) to determine whether the addition of N-fertilizer to these treatments (controlF, DPS30F, and DPS60F, respectively) causes changes to soil fertility. The DPS application increased soil organic matter (+0.80%: DPS60 vs. control; and +0.35%: controlF vs. DPS60F), available phosphorus (+23.14 mg kg−1: DPS60 vs. control; and +14.34 mg kg−1: DPS60F vs. controlF), potassium (+0.6 g kg−1: controlF vs. DPS30F), and calcium (+0.28 g kg−1: DPS60 vs. control). The 60 Mg DPS ha−1 rate improved permeability and structural stability, regardless of the presence or absence of N-fertilizer. On the other hand, the 60 Mg DPS ha−1 rate without N-fertilizer lead to a decrease in total mineralization rate and qCO2, thereby indicating a reduction in CO2 emissions. The rate of 60 Mg ha−1 DPS could be effectively used to enhance the permeability and stability (soil restoration) and mitigate CO2 emissions, whereas the 30 Mg ha−1 rate could be used as fertilizer to improve the fertility of calcareous soils.</jats:p>

Short-Term Effects of Biosolid Application on Two Mediterranean Agricultural Soils and Durum Wheat Yield

“…The use of fertilizing matter like compost, biosolids, or de-inking paper sludge (DPS) is one of the ways to decrease the effects of climate change [2,3]. At the Conference of the Parties in Paris is the 21st (COP21), the reduction target for Tunisia was estimated at 40% of total emissions [2,4]. Despite this, the recycling rate in Tunisia for residues such as DPS is close to 0%, which represents a big loss of organic matter [4,5].…”

“…At the Conference of the Parties in Paris is the 21st (COP21), the reduction target for Tunisia was estimated at 40% of total emissions [2,4]. Despite this, the recycling rate in Tunisia for residues such as DPS is close to 0%, which represents a big loss of organic matter [4,5]. The explanation for this is that in Tunisia this kind of residue is considered dangerous ( JORT No 86 of 27 October 2000), although this classification is not supported by studies.…”

“…DPS is considered non-hazardous in European and Canadian legislation because it is recalcitrant organic matter and contains a lot of nutrients (C, P, K, Ca, and Mg) [6]. The heavy metal content of DPS does not exceed contamination limits [1,5]; this organic matter can be used as a fertilizer and there is no risk of soil contamination if the application rate does not exceed 60 Mg ha −1 [4][5][6].…”

“…This type of organic matter has been used in several applications: restoration of degraded or mining sites [7], crop growth and yield improvement [8], growth improvement of forest tree species such as alder and aspen [9], improvement of the physicochemical properties of acidic soils [5,6,10], and the reduction of greenhouse gases, essentially N 2 O [2,11]. But few studies have involved Mediterranean conditions and especially calcareous soils [4,11]. Recent studies have demonstrated the role of DPS in the improvement of soil fertility, soil carbon storage, and humic substances [2,4,5].…”

“…But few studies have involved Mediterranean conditions and especially calcareous soils [4,11]. Recent studies have demonstrated the role of DPS in the improvement of soil fertility, soil carbon storage, and humic substances [2,4,5]. This leads to the need for in-depth research on the environmental impacts of this amendment on agronomic calcareous soils compared with acidic forest soils and the possibilities of its valorization as an organic fertilizer for agricultural soils and crops.…”