Dynamics of nutrients in tropical acid soils amended with paper pulp sludge

Abstract

Paper mill sludge is characterized by high concentrations of organic matter and lime and very low concentrations of heavy metals and organic chemicals. Interest in the recycling of paper mill residuals in developing countries is vital because the use of lime and fertilisers by small farmers is financially prohibitive. The effects of paper pulp sludge and lime on the dynamics of soil nutrients was studied in the laboratory using columns of mixed samples of top soil from three tropical acid soils (Kandiudult). The soil columns were leached over a period of 90 days with de-ionized water in amounts equivalent to the annual rainfall of the sampling site. To assess the amount of nutrient that may become available to plants, NH 4 OAc-EDTA pH 4.65 soil extractant was used. For all soils, application of paper pulp sludge or lime to tropical acid soils generally resulted in an initial flush and increased concentrations of Ca, Mg, SO 4 , dissolved organic carbon (DOC) and inorganic carbon in soil leachates. Compared with liming, application of paper pulp sludge reduced NO 3 leaching. The amount of leached Ca, DOC and inorganic carbon (mainly HCO 3 -) increased substantially with the addition of paper pulp sludge or lime. In relation to nutrients, the most meaningful amendment effect that persisted after leaching was a substantially increased available Ca in the treated soil. In addition to increasing Ca levels, the addition of paper pulp sludge increased the concentrations of leached and available Ca. To sustain yield increase with paper pulp sludge, calculation of the optimum quantity to be returned to the soil should be based on losses of Ca by leaching and by plant uptake.

Effects of warming and nitrogen deposition on the coupling mechanism between soil nitrogen and phosphorus in Songnen Meadow Steppe, northeastern China

“…Much of the research indicates that N deposition promotes net N mineralization in soil, increases the bioavailability of N in soil, and increases the net productivity of plants and the output of litter (Aerts et al, 2006;Sirulnik et al, 2007). Long-term deposition of N will reduce the richness of the plant community and change its composition (Nkana et al, 1999;Prieto et al, 2009). Global change factors such as N, CO 2 and warming frequently limit plant growth, can increase or decrease primary production (Field et al, 1992).…”

Recycling pulp mill sludge to improve soil fertility using GIS tools

“…The secondary sludge also presents values of organic matter lower than the ones detected in other studies (between 49% and 89% according to Nkana et al, 1999 andNunes andCabral, 2000). In the latter, besides the organic matter removal being higher in the secondary treatment (in the liquid phase), the sludge organic content is low due to the subsequent mineralization during sludge storage and treatment.…”

“…Nutrients (nitrogen and phosphorus) in both types of sludge present lower concentrations when compared to the values indicated by several authors (Nkana et al, 1999;Nunes and Cabral, 2000;Foley and Cooperband, 2002;Curnoe et al, 2006;Shipitalo and Bonta, 2008), who pointed to values over 650 mg TP/kg, 5000 mg NH 4 -N/kg and over 10,000 mg TN/kg. However, they are still appropriate to be used in soils for fertilizer purposes, especially the secondary sludge.…”

“…Pulp mill sludge from the paper industry seems to have contents of both organic matter and nutrients (Nkana et al, 1999;Foley and Cooperband, 2002;Jordan and Rodriguez, 2004) which may be considered suitable for organic and nutrient correction of poor soil such as that covered by the Cova da Beira Irrigation System. This kind of application, besides improving soil fertility and waste reuse, may reduce treatment and disposal costs.…”

Aplicação de resíduo de reciclagem de papel em Cambissolo Háplico e seu efeito no solo e no cultivo de plantas

“…O uso desses materiais na agricultura, em substituição parcial ou total de corretivos ou fertilizantes minerais, tem apresentado resultados promissores em diferentes condições (Nkana et al, 1999;Mäkela et al, 2012). As escórias de siderurgia, por exemplo, podem ser utilizadas como corretivo da acidez do solo (Nogueira et al, 2012), potencial que também apresenta o resíduo de processamento de bauxita (Nobile et al, 2011) e o lodo de curtume (Gianello et al, 2011).…”