Evaluation of compost, vermicompost and their teas produced from rice straw as affected by addition of different supplements

Author
Annals of Agricultural Sciences
December 2014, Vol.59(2):243–251, doi:10.1016/j.aoas.2014.11.013
Open Access, Creative Commons license, Funding information

Author 

• M.E. El-Haddad ^a
 
• Mona S. Zayed ^a,,
 
• G.A.M. El-Sayed ^b
 
• M.K. Hassanein ^c
 
• A.M. Abd El-Satar ^b

• aUnit of Biofertilizers, Department of Agric. Microbiol. Fac. Agric., Ain Shams Univ., Shoubra El-Kheima, Cairo, Egypt
• bDepartment of Microbiol. Soil, Water and Environmental Res. Inst., A.R.C., Giza, Egypt
• cCentral Laboratory for Agricultural Climate, A.R.C., Giza, Egypt

Received 14 August 2014. Accepted 3 September 2014. Available online 10 December 2014.

Abstract

Ten treatments were prepared to find out the optimal combinations of different materials to be added to rice straw to produce high quality compost and vermicompost. The effect of addition of N, P and K either in organic or inorganic form as well as addition of bio-accelerator i.e. Trichoderma harzianum NRRL 13019 and Phanerorchaete chrysosporium NRRL 6359 were studied. Another set of the same 10 treatments was prepared by adding earthworm namely Eisenia fetida to each of the plastic bin which containing the pre-composted materials when the temperature steadily reached 30 °C i.e. after finishing the thermophilic phase. The composting process was continued in both sets up to 16 weeks. Tea was prepared using compost and vermicompost which were produced from the four best treatments.

Results revealed that the finished products of compost and vermicompost are free from total and fecal coliforms as well as Salmonella sp. and Shigella sp. The values of tested parameters of compost and vermicompost that produced from rice straw supplemented with cattle dung, organic P and K and fungal accelerator (treatment No. 7) were within the recommended levels of high quality products.

Keywords

Rice straw

Compost

Vermicompost

Eisenia fetida

Compost tea

Vermicompost tea

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Introduction

Egypt is a highly successful producer of rice with average yield of more than 6.5 t ha⁻¹ in 2011/12. Harvesting index of Egyptian rice varieties left up to 60% straw (FAO Rice Market Monitor, 2013). The options for disposal of straw on-farm are limited and include burning as a means of quickly cleaning land for the following crops. The burning causes atmospheric pollution. In addition, incorporation of rice paddy straw stubble into wet soil makes a temporary immobilization of N and methane (CH₄) emission that contributes to greenhouse gases (Dobermann and Fairhurst, 2002). Therefore, the most common practices for recycling rice straw and most of organic wastes are composting and vermicomposting (vermiculture) processes (Ghosh, 2004). Since composting and vermicomposting are of the most promising low-cost technologies to convert agro-industrial contaminant solid wastes into value-added biofertilizer (Misra et al., 2003).

There are many factors influencing the quality of produced compost, which include the pre-processing, particle size and feedstock utilized, the C/N ratio, bio-accelerator, nutrients amendment, pH, aeration, moisture content, temperature, the maturation stage, etc. (Last, 2006).

Vermicomposting is a low cost technology system used for conversion of organic waste into organic fertilizers (Arancon et al., 2004), at which several interactions between earthworms and microorganisms occur in the worm gut (Edwards, 1998). Earthworms can consume practically all kinds of organic matter typically that placed in a compost pile, and they can eat wastes typically equal to their own body’s weight per day. The castings are rich in nitrate, phosphorus, potassium, calcium and magnesium (Misra et al., 2003).

Compost and vermicompost teas are made in a variety of ways; all methods are similar in having water and mature compost or vermicompost, to get their extract. There are different factors affecting the quality of compost tea and vermicompost tea, e.g. compost stability, the quality of water used in producing compost tea, brew time and aeration, additives (Ingham, 2005).

The objective of this investigation is to study the effect of addition of different supplements to rice straw on the general properties of mature compost, vermicompost and their teas.

Materials and methods

Rice straw was collected from Moshtohor, Qalubia Governorate, air dried and fragmented into small pieces (2–5 cm length). The chemical and physical properties of the collected rice straw are presented in Table 1. Analysis was performed by Microbiol. Dept., Soil, Water and Environmental, Res. Inst., A.R.C., Giza, Egypt.

Table 1. Chemical and physical characteristics of rice straw and cattle dung.

Characteristics	Rice straw	Cattle dung
pH (1:10)	6.56	7.35
EC (1:10) (dS/m)	2.63	4.40
Bulk density (kg/m3)	50.00	750.00
Moisture content (%)	10.00	60.00
Dry matter (%)	90.00	40.00
Organic matter (OM %)	99.50	43.10
Organic carbon (OC %)	57.71	25.00
Total nitrogen (TN %)	0.50	2.00
NH4+-N (mg/kg)	17.50	43.74
NO3−-N (mg/kg)	8.75	11.67
C/N ratio	115.4:1	21.5:1
Ash (%)	0.50	56.90
Total phosphorus (%)	0.36	0.65
Total potassium (%)	0.89	0.45

Organic additives

Fresh cattle dung was collected from a private farm in Moshtohor, Qalubia Governorate. It was used as organic nitrogen source to adjust the C/N ratio of the rice straw. The chemical and physical properties of cattle dung are presented in Table 1. Analysis was performed by Microbiol. Dept., Soil, Water and Environmental Res. Inst., A.R.C., Giza, Egypt.

Rock phosphate (18% P₂O₅) was provided by Al-Ahram Company, Giza Governorate. It was used as a source of phosphorus. Feldspar (12% K₂O) was provided by Al-Ahram Company, Giza Governorate and used as a source of potassium. The general characteristics of the rock phosphate and Feldspar are presented in Table 2. Analysis was performed by Microbiol. Dept., Soil, Water and Environmental, Res. Inst., A.R.C., Giza, Egypt.

Table 2. Chemical and physical characteristics of rock phosphate and feldspar.

Characteristics	Rock phosphate	Feldspar
pH (1:2.5)	7.49	8.50
EC (1:5) (dS/m)	2.61	0.53
Moisture content (%)	3.00	0.95
Dry matter (%)	97.00	99.05
Total nitrogen (TN %)	0.015	0.025
Total phosphorus (%)	11.20	0.01
Total potassium (%)	0.55	11.62

Inorganic additives

Ammonium sulfate (20.6% N); Super phosphate (12% P₂O₅) and Potassium sulfate (48% K₂O) were kindly provided by Soil, Water and Environmental. Res. Inst., A.R.C., Giza, Egypt.

Biological accelerators

Pure cultures of Trichoderma harzianum NRRL 13019 (as cellulose decomposer) and Phanerochaete chrysosporium NRRL 6359 (as lignin decomposer) were kindly provided by Microbiol. Dept., Soil, Water and Environmental Res. Inst., A.R.C., Giza, Egypt.

These cultures were used as compost activators in order to improve the quality of the compost. Each strain was grown individually in potato dextrose broth medium for 6–7 days in shaking incubator (150 rpm) at 28 °C.

Eisenia fetida used in this study was kindly provided by the Station of Using Earthworm Technology to Recycling of Organic Wastes Under Egyptian Conditions in the Central Laboratory for Agricultural Climate, Ministry of Agriculture and Land Reclamation, Agricultural Research Center, Egypt.

Experimental techniques

Ten treatments were prepared by thoroughly mixing the rice straw with different additives. Treatments were arranged in piles according to the components of each pile. The C/N ratio of the rice straw was adjusted to be 30:1 either by adding cattle dung in the treatments 7, 8, 9 and 10 or by adding ammonium sulfate in treatments 1, 3 and 5. Meanwhile, rice straw in treatments 2, 4 and 6 was left without adjusting the C/N ratio. The composting process was continued up to 16 weeks. Fungal inoculant was added to the pile at the rate of 5 L per ton of rice straw, before starting the composting process, as a biodegradable agent. The inoculant consists of dual cultures of each of Trichoderma harzianum NRRL 13019 (0.321 g.d.w/100 ml) and Phanerochaete chrysosporium NRRL 6359 (0.2608 g.d.w/100 ml) at ratio 1:1.

The prepared ten treatments could be summarized as follows:

Treatment 1	Rice straw + ammonium sulfate + superphosphate + potassium sulfate
Treatment 2	Rice straw
Treatment 3	Rice straw + T. harzianum and P. chrysosporium 1:1 + ammonium sulfate + superphosphate + potassium sulfate.
Treatment 4	Rice straw + T. harzianum and P. chrysosporium 1:1
Treatment 5	Rice straw + T. harzianum and P. chrysosporium 1:1 + rock phosphate and feldspar 1:1 + ammonium sulfate
Treatment 6	Rice straw + T. harzianum and P. chrysosporium 1:1 + rock phosphate and feldspar 1:1
Treatment 7	Rice straw + cattle dung + T. harzianum and P chrysosporium 1:1 + rock phosphate and feldspar 1:1
Treatment 8	Rice straw + cattle dung + rock phosphate and feldspar 1:1
Treatment 9	Rice straw + cattle dung + T. harzianum and P. chrysosporium 1:1.
Treatment 10	Rice straw + cattle dung

Vermicompost preparation

The rice straw supplemented by different additives was aerobically decomposed either by native microorganisms or by both the native ones in conjunction with introducing fungal strains as bio-accelerators. When the thermophilic phase is finished, and the temperature reached 30 °C, E. fetida was introduced to each set of the plastic bin, containing the pre-composted material.

Preparation of compost tea and vermicompost tea

Preparation of tea was carried out using compost and vermicompost produced from treatments 1, 3, 7 and 8. Tea was prepared by soaking mature compost or vermicompost in tap water at ratio 8:1, then 50 ml sugarcane molasses and 100 ml yeast extract 10⁵ cfu/ml were added and the mixture was aerated for 3 days using pump model SE-304, made in Germany, output: 2 × 2 OL/min and pressure: 0.01 MPa.

Physical and chemical determinations

The moisture % was calculated as a percentage for compost and vermicompost according to the method described by Page et al. (1982).

Bulk density (kg/m³) was determined in compost and vermicompost using the core method according to Vomocil (1965).

The pH of compost, vermicompost, compost tea and vermicompost tea was determined in compost–water suspension (1:10) according to Jodice et al. (1982).

Electrical conductivity (EC) measurements were run in (1:10) compost and vermicompost water extracts according to the method described by Richards (1954).

Organic matter content was determined in compost and vermicompost materials as reported by Jackson (1973). While organic matter of compost tea and vermicompost tea were determined according to Black et al. (1965).

Total nitrogen, phosphorus and potassium were determined in compost, vermicompost, compost tea and vermicompost tea using the methods described by Jackson (1973).

NH₄⁺ and NO₃⁻-N were determined in compost, vermicompost, compost tea and vermicompost tea according to the methods outlined by Page et al. (1982).

The Chemical Oxygen Demand (COD) in compost tea and vermicompost tea was determined using Walkley and Black method as described by Page et al. (1982).

The Biological Oxygen Demand (BOD) value was measured in compost tea and vermicompost tea according to the method described by Clair et al. (2003).

Statistical analysis

The obtain data were statically analyzed using Statistical Analysis System (SAS, 2006). Tukey’s Multiple Range Test (HSD) was used to test significance between means at level 0.05 according to Snedecor and Cochran (1991). The general characteristics of mature compost and vermicompost were analyzed by one-way analysis of variance. While the data of compost tea and vermicompost tea were analyzed by two-way analysis of variance.

Results and discussion

General characteristics of mature compost as affected by addition of different supplements to rice straw

Data presented in Table 3 show that C/N ratio of the tested treatments could be categorized into two groups. The first group includes the treatments 2, 4 and 6 where the C/N ratio of these treatments in the finished product were too high when compared to the recommended range for good compost as reported by Cabanas-Vargas and Stentiford (2003). These treatments are characterized by the absence of nitrogen source, either in inorganic (ammonium sulfate) or organic (cattle dung) forms. The second group included the treatments 1, 3, 5, 7, 8, 9 and 10, all of them received nitrogen source either inorganic (ammonium sulfate) or organic form (cattle dung). The C/N ratio of these treatments is in the recommended range of good compost, being 21.3, 20.6, 21.1, 17.0, 17.2, 17.0 and 18.1 respectively. The treatments 7 and 9 showed the best C/N ratio as compared to the others, being 17.0.

Table 3. Properties of mature compost as affected by different treatments of rice straw.

Treatments	Tested parameters

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