Biological response of using municipal solid waste compost in agriculture as fertilizer supplement.

Waste management and declining soil fertility are the two main issues experienced by all developing nations, like India. Nowadays, agricultural utilization of Municipal Solid Waste (MSW) is one of the most promising and cost effective options for managing solid waste. It is helpful in solving two current burning issues viz. soil fertility and MSW management. However, there is always a potential threat because MSW may contain pathogens and toxic pollutants. Therefore, much emphasis has been paid to composting of MSW in recent years. Application of compost from MSW in agricultural land helps in ameliorating the soil's physico-chemical properties. Apart from that it also assists in improving biological response of cultivated land. Keeping the present situation in mind, this review critially discusses the current scenario, agricultural utilization of MSW compost, role of soil microbes and soil microbial response on municipal solid waste compost application. © Springer Science+Business Media Dordrecht 2016.

Introduction

The growing urbanization and industrialization n class="Chemical">han>s led to countless problems in developed as well as in developing countries (Singh et al. 2011a, b; Vaish et al. 2016a, b). There are many pressing issues emerged due to increasing population that eventually poses threat to the agricultural, ecosystems and environmental sustainability either directly or indirectly (Fig. 1). Amidst, the generation and management of Municipal solid waste (MSW) is important as this waste is disposed of unscientifically in low lying area without taking necessary precautions, thus posing risk to the human health and nearby environment (Singh et al., 2011b; Vergara and Tchobanoglous 2012; Srivastava et al. 2015). Therefore, there is an urgent need to manage the MSW in such a way that while managing its quantity and quality, it also helps to sustain the environment (Araujo et al. 2010). Apart from this, the environmental and health standards along with social acceptability should be achieved. However, selection of the most appropriate route for MSW management (MSWM) is always being a matter of concern due to many environmental, technical, financial, social and legislative constraints which are faced by almost all industrially growing nations (Adani et al. 2000; Araujo et al. 2010).

Fig. 1

Impact of increasing population on environmental health

Impact of inn class="Chemical">pan class="Chemical">creapn>an class="Chemical">sing population on environmental health

Usually, waste generated from domestic, commercial, institutional and industrial sectors; and municipal services are included in MSW (Srivastava et al. 2015). MSW can be treated as renewable resource for a variety of valuable products. The organic fraction of MSW provides an excellent opportunity for production of different value added by-products through the biorefinery concept (maximum utilization of waste resource), further fueling the circular bioeconomy (maximizing resource efficiency with least waste generation through which socio-economic and environmental stability is achieved). Recently, Sadhukhan et al. (2016) described an integrated bio refinery concept through utilizing the organics present in the MSW for production of levulinic acid which increased the economic margin by 110–150 %. The byproducts derived from this levulinic platform could further be used for the production of biogas and fertilizer. Similarly, carboxylates can be generated from organic fraction of waste through anaerobic unidentified mixed cultures, that can be efficiently converted into useful bioproducts like acetate, propionate, lactate and n-butyrate which are the product of primary fermentation process (Agler et al. 2011). There are many examples of biorefinery platforms emerged from waste studied in the past that leads to the production of various value added byproducts like biosurfactants, organic acids, antibiotics, industrial enzymes and other possible industrial chemicals etc (Bastidas-Oyanedel et al. 2016). However, these methods require high operational costs, therefore less suitable for developing countries. In addition, organic fraction of MSW can also be used directly in the fields or could be converted into compost that can be used as fertilizer supplements in the fields, which in turn augment crop productivity and produces job opportunities with less negative impacts on the environment. Thus, play a pivotal role in circular economy.

Agrin class="Chemical">cun>ltural utilization of MSW is one of the most promising and cost effective options for disposal of MSW (Crecchio et al. 2004; Hargreaves et al. 2008a, b, c; Araujo et al. 2010). It is an important tool for recycling of MSW, which would be otherwise landfilled leads to groundwater contamination, air pollution and many other health problems (Kathiravale and Yunus 2008) (Fig. 2). Agricultural utilization of MSW not only decreases the escalating pressure on land for landfilling, but it also improves soil fertility and acts as a soil conditioner (Singh and Agrawal 2008, 2010). However, there is also possibility of potential threat to the soil fertility as MSW contains different pathogens and pollutants (eg. heavy metals, pesticides and other organic pollutants etc.) (Crecchio et al. 2004; Hargreaves et al. 2008a, b, c). The long term application of MSW in agricultural field may lead to heavy metal accumulation (Lopes-Mosquera et al. 2000), which may enter at elevated level through the progression of food chain (Page et al. 1987; Singh et al. 2011a). Therefore, composting of MSW is more interesting option for recycling of waste.

Fig. 2

Comparison between landfilling/open dumping versus composting of MSW

Comparison between landfilling/on class="Chemical">pen dumping versus composting of MSW

Nowadays, there is a growing interest in comn class="Chemical">posting of MSW, as it decreases the stabilization time of household waste and sewage sludge (Hargreaves et al. 2008a; Carbonell et al. 2011; Fernández et al. 2014; Weber et al. 2014). The quality of compost from MSW depends on numerous factors such as feedstock source and ratio used, toxic compounds, the composting design, maturation length, and procedure that have been adopted during the process of composting (Hargreaves et al. 2008a; Watteau and Villemin 2011). During composting, the quality of carbon (C) in waste stuff drives the decomposition rate. If it is present in readily degradable form like carbohydrate, then will accelerate the process whereas, high proportion of lignin and cellulose will slower down the process of organic matter decomposition (Araujo et al. 2010).

The composting/vermicomn class="Chemical">posting of organic wastes involves lower operating costs because of lower capital and technical requirements (Ruggieri et al. 2009; Galgani et al. 2014). Ruggieri et al. (2009) compared external management cost and composting costs of organic fraction of waste generated from wine industries. They found that an annual savings of €19.56/t can be achieved if composting process is used to manage the waste as compared to the cost involved in external management. Similarly, cost benefit analysis done by Couth and Trois (2012) for MSWM in Africa illustrates that aerated open windrow composting method was better option than controlled landfilling.

In spite of n class="Chemical">pan class="Chemical">having many advantages over other conventional waste management opclass="Chemical">n>tions, composting of MSW is not as much as popularize or in the practice as it deserves. This is due to lack of awareness and inactive policies that need to be changed. Government and local authorities should take initiatives to promote composting/vermicomposting of organic waste. For example, awareness campaigns and incentives for its installation should be provided to spread this technique at decentralized level. Also, involvement of public private partnership (PPP) and community based organization (CBO) should be encouraged to overcome the problem of financial and professionals’ crisis especially in the developing countries (Rathi 2006; Lohri et al. 2014). Apart from that local authority can generate revenue from better tax collection, polluters pay scheme, selling of MSW compost as being performed by Kolkata Municipal Corporation, India (Chattopadhyay et al. 2009).

Therefore, composting of MSW n class="Chemical">pan class="Chemical">has immense pn>otential tpan class="Chemical">hat adds value to the waste and diverts its route from landfills to agriculture fields as fertilizer supplement. Thus, helps in waste recycling and maintaining soil fertility. The present mini-review was aimed to discuss different aspects of agricultural utilization of MSW compost and biosolids including its potential benefits and threats; and soil microbial response.

Potential benefits and threats of MSW compost/biosolids application in agriculture

Composting of MSW n class="Chemical">pan class="Chemical">has many advantages over inorganic class="Chemical">n>an class="Chemical">fertilizers (IFs) whose uncontrolled use during last few decades has badly affected the soil’s physico-chemical and biological properties (Mathivanan et al. 2012). Though, IFs add nutrients to the soil immediately after application but their long term use may change soil pH and disturb the soil microbial biota. Usually, IF tends to leach or filter away from the plants, therefore requires additional supply that pollutes ground water and also emits greenhouse gases (GHGs). On contrary to this, application of MSW compost augment plants yield and ameliorates soil nutrient profile, microbial activity, soil texture and buffering capacity (Hargreaves et al. 2008a, b, c; Carbonell et al. 2011; Weber et al. 2014; Bouzaiane et al. 2014) (Tables 1, 2). MSW compost is rich in organic matter content, nitrogen (N) and humic substances (mainly humic acid and fulvic acid) (Garcia-Gil et al. 2004). Soil organic matter plays a significant role in maintaining soil quality (Pedra et al. 2007), as it improves soil’s physico-chemical and biological (microbial biomass) properties (Araujo et al. 2010). Besides this, it has high water holding capacity (WHC) and low bulk density (Soumare et al. 2003). Humic acid in MSW compost intensifies the cation exchange capacity (CEC) and buffering capacity of soil (Garcia-Gil et al. 2004). It has been reported by several researchers that repeated application of MSW compost in agricultural land helps in increasing the organic matter content and C/N ratio of soil in comparison to unamended soil (Crecchio et al. 2004; Garcia-Gil et al. 2004; Hargreaves et al. 2008a, b, c). Thus helps in maintaining soil fertility and its productivity. Therefore, the organic fertilizer (like MSW compost) could be considered as a promising and sustainable alternative to inorganic fertilizer in agriculture and horticulture.

Table 1

MSWC studies and post treatment responses

MSW/organic waste source	Soil type/pH/EC	Initial nutrient profile of soil	Experiment type (pot/field)	Crop	Application rate	Post response of treatments	References
Composted tannery sludge (CTS)/Teresina, Piauí	Fluvisol/6.5/0.63 dS m−1	Soil organic carbon (SOC) was 9.5 g kg−1	Long term/5 year field experiment	Cowpea	0, 2.5, 5, 10 and 20 Mg ha−1	5 Mg ha−1 Composted tannery sludge showed highest values for soil MBC, MBN and soil respiration whereas, DHA activity was highest in 2.5 Mg ha−1 CTS amendment	Araujo et al. (2015)
Municipal waste, Calcutta, India	Alluvial/5.5/0.294 d Sm−1	OC and total N were 13.9 and 1.7 g kg−1 respectively	Factorial completely randomized design	N/A	0, 2.5, 10, 20 and 40 t ha−1	Substantial increase in MBC, soil respiration, urease and phosphatase activity of the soil; no adverse effect at higher dose	Bhattacharyya et al. (2003)
Municipal Solid waste, Kerala, India	Laterite/5.5/WHC was 42.3 %	OC was 1 %, Available Ca and Mg and exchangeable K were 518.3, 14.0 and 185.8 mg kg−1 respectively	Pot	Cassava	0, 2.5, 5, 10, and 20 t ha−1	Available N, residual C and decomposition rate significantly increased with increase in the rate of application of MSWC	Byju et al. (2015)
Mornag, Tunisia	Clayey-loamy/7.64	Total K and Mg were about 5650 and 3380 mg kg−1, respectively. OC 0.93 %; and N 0.12 %	Long term/ 5 year Field	Wheat	MSWC at rates of 40 and 80 Mg ha−1, farmyard manure at a rate of 40 Mg ha−1	Wheat grain yield increased significantly. Similarly, heavy metal concentration and faecal coliform were also rouse. On basis of treatment effectiveness index, the use of MSWC at a rate of 40 Mg ha_1 was recommended	Cherif et al. (2009)
Castel di Sangro, Italy	Clay/8.3	Organic C and total N were 9.7 and 1.36 g kg−1 respectively	Short term/ 2 year field	Sugar beet and durum Wheat rotation	12 t MSW compost ha−1 for sugar beet and 24 t MSW compost ha−1 for durum wheat	Organic C and total N contents, dehydrogenase and nitrate reductase activities of soil increased. Dehydrogenase activity was positively correlated with β-glucosidase activity	Crecchio et al. (2001)
Naples, Italy	Sandy loam/8.1/low CEC (13.1 c mol kg−1),	Total carbonates 520 g kg−1, assimilable P2O5 46 mg kg−1; exchangeable K2O 410 mg kg−1; and NO3-N 35 mg kg−1	Short term/ 2 year field trial	Lettuce	10, 30 and 60 Mg ha−1	In compost and soil, total concentrations of Cu, Cr, Pb and Zn were below European pollutant limits. The recommended dose was 30 Mgha−1	Fagnano et al. (2011)
Valdemingomez Municipal Waste Treatment Plant Madrid, Spain	Sandy loam soil/6.4/0.1 dS m−1	OC and total N were 8.0 and 0.7 g kg−1. Similarly, P, K, Ca, Mg and Na were 0.03, 0.2, 1.5, 0.2 and 0.01 g kg−1 respectively	Short term/plot	Barley	20 and 80 t ha−1	Increased microbial activity in soil; helped in maintaining long term buffering capacity of soil	Garcia-Gil et al. (2000)
MSW Chania, Greece	Clay-loam/7.7/0.1 d Sm−1	Organic matter and total N were 0.22 and 0.08 % respectively. Whereas, NO3-N 34 mg kg−1; and NH4-N 6.55 mg kg−1 respectively	Large pots	Lettuce and Tomato	0, 50, and 100 t ha−1	Inhibition of plants’ growth was recorded with increasing dose of MSWC. Growth inhibition was linked with a sharp decrease in soil NO3-N content	Giannakis et al. (2014)
Municipal food waste Salerno, Italy	Sandy loam/7.9	OC and Total N were 26 and 2.3 g kg−1 respectively. Whereas, available P was 52 mg kg−1	Green house, 3 years of repeated treatments	Tomato, Snap bean and Lettuce	15, 30 and 45 t ha−1	Organic amendment increased soil respiration, fluorescein diacetate hydrolysis, phosphatase and arylsulphatase activities and improve the microbial activity of soil	Iovieno et al. (2009)
Madrid province, Spain	Calcareous Fluvisol/8.3/0.19 d Sm−1	TOC, total N and carbonates were 13.08, 1.4 and 88 g kg−1 respectively; and available P was 25.6 mg kg−1	1 Year field experiment	–	160 Mg ha−1	The application significantly increased MBC while basal respiration, catalase, dehydrogenase and hydrolase activity remained stable throughout the period of application.	Jorge-Mardomingo et al. (2013)
A mixture of separated and shredded organic fraction of house-hold rubbish and garden waste, Beja, Tunish	Not stated/7.95/8	N 0.01 %; C 1.2 %. Zn, Cu, Ni were 70.0, 32.0, 50.0 µg−1	Pot/glasshouse	Wheat	40, 100, 200 and 300 t ha−1	Maximum values of net photosynthetic rate, stomatal conductance, RubisCO activity and biomass gain (78 %) was obtained in 100 t ha−1 (optimal dose) as compare to the control	Lakhdar et al. (2012)
Vegetable, fruit and garden waste compost Ghent University, Belgium	sandy loam/5.7	OC 1.56 %; total N 0.13 %. Total P,K and Ca were 32, 32 and 52 mg, 100 g−1 respectively	Long term/field (9 years)	–	0, 22.5 or 45 t compost ha−1	The amendment had significantly beneficial impact (p < 0.05) on all soil physical properties, apart from soil moisture retention. No significant differences were found in soil physical parameters.	Leroy et al. (2008)
MSW, Huelva province, southern Spain	S1 loamy-clay; and S2, sandy/7.5	S1 Organic matter 1.74 %; and total N 0.096 %. Whereas, In S2, organic matter 1.50 %; total N 0.083 %	Pot	Ryegrass plants	12.5, 25 g kg−1 with Urea 0.27 g kg−1	Positive mineralization was observed but was intense in sandy soil. It is recommended to apply the dose three months before sowing.	Madrid et al. (2011)
Chania, Greece	Sandysoil or SS/8.35/436 µS cm−1; Clayey soil or CS/7.82/744 µS cm−1	In SS, TOC and total N were 4.24 and 0.41 g kg−1 respectively; in CS, TOC and TN were 21.28 and 2.12 g kg−1 respectively	Pot	Spiny chicory	0, 60 and 150 t ha−1	Yield was higher in the sandy than in clayey soil even in absence of compost application; No significant differences were observed in growth and yield between 60 and 150 t ha−1; macronutrients were not affected; bioavailability of Cu, Zn, Fe, Mn, Cr, Ni, Pb, Cd in both soil was increased but content was below toxic level in edible part; sandy soil with 60 t ha−1 is recommended dose	Papafilippaki et al. (2015)
Murcia, Southeast Spain	Silty clay loam/8.5/0.18 Sm−1	TOC 5.41 g kg−1, total N 0.41 g kg−1, total P 0.58 g kg−1, total K 8.10 gKg−1	Long term 8 years plot	N/A	6.5 and 26 kg m−2	Increased natural diversity; Depicted higher values of MBC, soil basal respiration and dehydrogenase activity; enhanced enzymatic activity associated with C, N and P cycle	Pascual et al. (1999)
Composted rice straw, Valencia, Spain	Sandy/9.22–9.34/0.04 d Sm−1 Clay/7.94–8.06/0.21 dS m−1	SOM 0.08 %; N and P were 0.00 % TKN 0.19 % and P 13.8 %	Pot	Barley	Different proportions (w/w) 0.0, 0.2, 0.8, 1.5, 3.0 and 100 % (Clayey soil) 0,1,2,4,6,10,20 and 100 % for sandy soil	Improved soil properties; Recommended dose were 34 Mg ha−1 and 11 Mg ha−1for sandy and clayey soil	Roca-Pérez et al. (2009)
Nova Scotia, Canada	Pugwash sandy loam/6.0	NA	Three year rotation/field	Winter squash	24,48,7219966,12,1819975,10,151998Mgha^-1	Increased the growth and yield; did not contribute to accumulation of extractable heavy metals (HMs) in the soil nor magnification of HMs in leaf tissue	Warman et al. (2009)
Eastern Canada	Sandy loam/5.8	C 16.1 g kg−1, N 1.3 g kg−1, P 90 mg kg−1, K 160 mg kg−1	Three year rotation/field	Potato	21.7,43.8,65.1199611.3,22.6,33.919978.9,22.6,26.71998Mgha^-1	Available N was still the limiting factor even after 3 years; compost mineralization was very slow however it could be safely applied to soil	Warman et al. (2011)

Table 2

Comparative assessment of inorganic fertilizer and MSWC/Manure/bio solids on plant response and soil health

Country	Experiment and soil type	Plant	Dose	Post treatment response		Reference
				Inorganic fertilizer	MSWC/Manure/bio solids
Madrid (Spain)	Greenhouse,Loamy sandy soil	Maize	50 Mg ha−1 of MSW compost and 33 g NPK plant−1	Soil pH decreased; Soil organic matter and C were not affected; soil N, Cd and Ni content increased; TFshoot/root for all metals were <1; TFspathes/shoot for Cu and Pb were significantly lower than control soil. No significant differences of TF in other aerial parts of plant. BAFs for all metals were highest in roots and lowest in grains and were also below the phytotoxic level	Soil pH remained same; Soil organic matter and N content slightly increased, C content is not affected; and Cu, Pb and Zn increased in soil. Almost similar trends of TFs and BAFs for all the metals as in case of IF amendment. However, a reduction was noticed for TFspathes/shoot of Zn as well in comparison to control soil	Carbonell et al. (2011)
Nova Scotia, Canada	3-year rotation experiment,Pugwash sandy loam	Squash was grown in 3 year rotation including potatoes and sweet corn	NPK recommended dose; MSW compost was applied at three rates (MSW1, MSW2 and MSW3) in subsequent years based on soil’s P requirement (i) 1st year 24,000, 48,000 and 72,000 kg h−1; (ii) 2nd year 6000, 12,000 and 18,000; (iii) 3rd year 5000, 10,000 and 15,000 kg h−1	Extractable plant nutrients (Na, K, Cu, Zn, S and B) were found in lesser amount as compare to the MSWC. Yield per plant was found maximum as compare to the other amendments. Tissue B, S, Cu and Zn were lowest in NPK and highest in MSW3; Similarly Cd and Mn content in leaf tissue is higher in NPK; No significant differences in tissue N in 3rd year among different amendments	Extractable plant nutrients were found in order of MSW3 > MSW2 > MSW1 > NPK Yield per plant was lesser than IF and order of the productivity in 3rd year was IF > MSW3 > MSW2 > MSW1.Leaf tissue nutrients like P, S, Cu and Zn were found in higher amount except Mg in 1st year as compare to NPK	Warman et al. (2009)
Nova Scotia, Canada	3-year rotation experiment, Pugwash sandy loam soil	Potato and Sweet corn	(i) 1st year NPK 130-145-80 (Kg h−1); MSWC 21.7, 43.4, 65.1 (Mg h−1) (ii) 2nd year NPK 130-90-70 (Kg h−1) MSWC 11.3, 22.6, 33.9 (Mg h−1)	Higher yield was noticed in both the crops as compared to MSWC during 1st year however it was insignificant in all the treatments in 2nd year. Total tuber yield and total marketable ear yield were found maximum in NPK in 1st year, however were insignificant compared to MSWC in 2nd year. Tissue P concentration in potatoes were 2.04 and 3.17 g kg−1, while in sweet corn it was 3.46 and 2.51 g kg−1 in 1st and 2nd year respectively	Lower tissue N compared to IF; No significant differences were found in tissue P among all the treatments in both crops in both years. Tissue P concentration in potatoes ranged from 1.93 to 2.25 and 2.63 to 2.92 g kg−1, while in sweet corn it ranged from 3.20 to 3.32 and 2.32 to 2.61 g kg−1 in 1st and 2nd year respectively. There was no significant difference in soil’s extractable P in both crops in both years in all the amendments including IF	Mkhabela and Warman (2005)
Ludhiana, India	Over 34 years’ field, Sandy loam	Maize–wheat–cowpea (disconti-nued from 2000 onwards	100 % N, 100 % NP, 100 % NPK, 100 % NPK + FYM 100 % NPK (120 kg N, 26.2 kg P and 25 kg K ha−1. FYM at 10 Mg ha−1	Water-soluble carbon, hydrolysable carbohydrates, SMBC, SMBN and dehydrogenase activity, improved significantly as compared to control	Similar trend of SOC was observed as in IF. Maize and wheat grain yield was maximum in FYM at 10 t ha−1 along with recommended NPK. Carbon mineralization is maximum in NPK + FYM. Approximately 1.05 Mg C ha−1year−1 was estimated in 100 % NPK + FYM	Kaur et al. (2008)
Nsukka, Nigeria	Field Sandy loam ultisol	Maize	NPK(20:10:10) 0, 100, 200, 300 kg ha−1, MSWC 0,1000,1500 and 2000 kg ha−1	Yield increased significantly compared to control but was lesser than MSWC; Combined effect of IF and MSWC showed better results than sole application of IF or MSWC in all aspects	Significantly increased yield; leaf area meter, harvest index; MSWC did not showed significant improvement in soil physical properties like bulk density, porosity, aggregate stability and hydraulic conductivity compared to control	Onwudiwe et al. (2014)

MSWC studies and post treatment resn class="Chemical">ponses

0, 2.5, 5, 10 and 20 pan class="Chemical">Mg

pan class="Chemical">ha−1

pan class="Species">Sugar beet and durum

pan class="Species">Wheat rotation

Municipal Waste Treatment n class="Chemical">pan class="Chemical">Plant

Ghent Univerpan class="Chemical">sin>ty, Belgium

Comparative assessment of inorganic n class="Chemical">pan class="Chemical">fertilizer and MSWC/Manure/bio solids on pn>lant response and soil health

Extractable plant nutrients were found in order of MSW3 > MSW2 > MSW1 > n class="Chemical">Npan class="Chemical">PK

Yield per n class="Chemical">plant was lesser than IF and order of the productivity in 3rd year was IF > MSW3 > MSW2 > MSW1.Leaf tissue nutrients like pn>an class="Chemical">P, S, Cu and Zn were found in higher amount except Mg in 1st year as compare to NPK

(i) 1st year Nn class="Chemical">pan class="Chemical">PK 130-145-80 (Kg h−1); MSWC 21.7, 43.4, 65.1 (pn>an class="Chemical">Mg h−1)

Nn class="Chemical">pan class="Chemical">PK 130-90-70 (Kg h−1) MSWC 11.3, 22.6, 33.9 (pn>an class="Chemical">Mg h−1)

However, the presence of heavy n class="Chemical">pan class="Chemical">metals (i.e. class="Chemical">n>an class="Chemical">Cd, Cu, Zn, Pb etc.) in MSW compost is always being a matter of concern, as it can accumulate in the soil that can be absorbed by the agricultural crops which may cause variety of human health issues when shifted at high trophic levels through the progression of food chain (Singh and Agrawal 2007; Hargreaves et al. 2008a; Smith 2009; Singh and Kalamdhad 2013; Alvarenga et al. 2015). Moreover, in some cases these heavy metal and excess nutrients percolate through the soil and finally pollutes underlying ground water (Hargreaves et al. 2008a). Garcia-Gil et al. (2000) reported increased concentration of Zn, Cu and Pb in soil amended with MSW compost and found a decreasing trend in the activity of phosphatase and urease possibly due to high heavy metal concentration, while dehydrogenase, catalase and protease were remained unaffected. Although, humic substances in compost act as chelating agent, thus reduces metal solubility but it also depends on pH, salt content and cation exchange capacity (CEC) of the soil (Walker et al. 2003; Lakhdar et al. 2009). In addition, MSW compost sometimes has high salt concentration that can pose negative effect on soil texture and plants grown (Hargreaves et al. 2008a).

Others potential risks of un class="Chemical">pan class="Chemical">sing MSWC is pn>resence of pathogens, and some organic compounds. Although composting is recognized as a suitable treatment used for organic wastes and could inactivate several pathogens (Deportes et al. 1998). However, some previous studies reported that some pathogens, such as Listeria spp., and Salmonella spp., have survived during the composting (Droffner et al. 1995; Sidhu et al. 1999). Similarly, Bibby and Peccia (2013) revealed infectious risk associated with land application of sewage sludge in continental United States and identified 43 different type of human viruses in sewage sludge including high abundance of respiratory viruses (Coronavirus HKU1, Klassevirus, and Cosavirus) with relatively lower presence of Enteroviruses. MSWC may have some organic pollutants due to the presence of household hazardous and industrial wastes (Reinhart 1993). Komilis et al. (2004) evaluated the presence of organic compounds produced during composting of the MSW (food wastes, yard wastes, and mixed paper wastes), and found toluene, ethylbenzene, 1,4-dichlorobenzene, p-isopropyl toluene, and naphthalene being produced in the highest amounts. Likewise, Cincinelli et al. (2012) demonstrated presence of Polybrominated diphenyl ethers (PBDEs) in sewage sludge collected from different effluents of Italy, which may adversely affect soil microbial biota, water cycle and human heath when get accumulated in soil. Apart from that presence of various pharmaceuticals and personal care products (PPCPs) like diphenhydramine, triclosan, carbamazepine, sulfamethazine, florfenicol, levamisole, trimethoprim etc. (Boxall et al. 2006; Prosser and Sibley 2015) and antibiotics like monensin, tylosin, chlortetracycline, virginiamycin, sulfamethazine (Kang et al. 2013; Aust et al. 2008) is well documented in soil amended with biosolids or livestock manure. The plants have ability to accumulate PPCPs and antibiotics (Boxall et al. 2006; Wu et al. 2013; Kang et al. 2013), thus may pose threat to human health.

Difpan class="Chemical">fen>rent legislations pan class="Chemical">have been made for safer land application of compost, organic waste and biosolids to prevent harmful effect on vegetation, soil and human health. Though, it differs among countries mainly in context to organic waste quality and quantities of pollutants that can be subjected to the soil. Table 3 shows permissible level of heavy metals (according to EU and India) and organic pollutants (according to EU) for agricultural utilization of compost. Therefore, quality of MSWC must be examined prior to its application.

Table 3

Permissible limits for land application of toxic elements in organic waste and compost

Heavy metal (mg kg−1)	Limita	Limitb
	pH 5.0 to > 7.0	pH 5.5–8.5
(a)
As	–	10
Cd	3	5
Cr	–	50
Cu	80–200	300
Pb	300	100
Hg	1	0.15
Zn	200–300	1000
Ni	50–110	50

aThe Sludge (Use in Agriculture) Regulations (1989), UK

bMSW Management and Handling Rules (2000), CPCB, India

cEEC-Sludge Rule (2000), European Commission

pan class="Chemical">Pn>ermispan class="Chemical">sible limits for land application of toxic elements in organic waste and compost

aThe Sludge (Use in Agripan class="Chemical">cun>lture) Regulations (1989), UK

bMSW Management and pan class="Chemical">Han>ndling Rules (2000), Cpan class="Chemical">PCB, India

cEEC-Sludge Rule (2000), European Commisn class="Chemical">pan class="Chemical">sion

Land application of MSW compost

Food sen class="Chemical">cun>rity is a major concern in present scenario due to continuous increase in population growth. Thus, puts pressure on agricultural productivity. Nowadays, inorganic fertilizers and pesticides are used in frequent manner in agricultural lands. Similarly, excessive withdrawal of water and clearing of forests have taken place that poses several threats to the environment (Fig. 1). Land degradation resulting from unsuitable land management is a major environmental and agricultural challenge, which is attributed to low nutrient availability and loss of organic matter leading to decreased productivity (Tejada et al. 2009; Duong et al. 2013). In order to revert the declining trend of agricultural productivity and to restore the degraded soils, fertilizer application is requisite (Goyal et al. 1999). However, extensive use of inorganic fertilizer without any organic supplements poses risk to soil health (i.e. soil’s physicochemical and biological properties) and the environment (i.e. water pollution) (Fig. 1). Therefore, application of organic fertilizer such as compost, vermicompost and manure are now becoming more popular that support sustainability to the system.

Agricultural utilization of MSW compost

Nowadays, much attention n class="Chemical">pan class="Chemical">has been pn>aid to agripan class="Chemical">cultural utilization of MSW compost, as it helps in managing twofolds’ problem i.e. soil pan class="Chemical">fertility management (Weber et al. 2014) and MSWM (Srivastava et al. 2015). Application of MSW compost in agricultural land usually poses positive effect on the productivity of a wide variety of cropland vegetables (Warman et al. 2009; Fagnano et al. 2011; Papafilippaki et al. 2015; Mkhabela and Warman 2005; Chrysargyris and Tzortzakis, 2015), and also in hydroponic system (Haghighi et al. 2016). Mkhabela and Warman (2005) evaluated effect of MSWC on potatoes and sweet corn and found that this compost was a good source of P for both vegetables. Recently, Haghighi et al. (2016) conducted an experiment to assess the ability of MSWC to improve the growth of tomato under hydroponic system. The authors found that 25 % of MSWC added to hydroponic solution increased the numbers of fruits as compared with the control.

pan class="Chemical">Pn>aspan class="Chemical">cual et al. (1999) demonstrated tpan class="Chemical">hat application of organic fraction of MSW compost on arid soil for eight years showed positive response on the activity of enzymes involved in C, N, P cycles as well as on C biomass, suggesting that it might be a suitable option for restoration of degraded land. Similarly, Papafilippaki et al. (2015) assessed response of MSW compost on spiny chicory grown in two type of soils (sandy and clayey) at Chania, Greece. The chemical properties of both soil were (i) Sandy soil: TOC 4.24 g kg−1; TN 0.41 g kg−1; available P 15.78 mg kg−1 and DTPA heavy metals content for Fe, Mn, Cu, Zn, Pb, Ni were 1.80, 4.19, 1.98, 1.82, 0.22 and 0.44 ppm respectively; (ii) Clayey soil, TOC 21.28 g kg−1, TN 2.12 g kg−1, available P 19.45 mg kg−1 and available heavy metal content for Fe, Mn, Cu, Zn, Pb, Ni were 2.11,7.41, 0.82, 0.55, 0.34 and 0.68 ppm respectively. MSWC had much higher concentration of NPK in comparison to soil and DTPA heavy metal content for Fe, Mn, Cu, Zn, Pb, Cd, Cr and Ni were 141.5, 8.48, 6.78, 54.14, 11.04, 0.27,