Using mushroom farm and anaerobic digestion wastewaters as supplemental fertilizer sources for growing container nursery stock in a closed system

Available online at www.sciencedirect.com

Bioresource Technology 99 (2008) 2050–2060

Using mushroom farm and anaerobic digestion wastewaters as supplemental fertilizer sources for growing container nursery stock in a closed system C. Chong

a,*

, P. Purvis a, G. Lumis a, B.E. Holbein b, R.P. Voroney c, H. Zhou d, H.-W. Liu b, M.Z. Alam a

a

Department of Plant Agriculture, University of Guelph, Guelph, Ont., Canada N1G 2W1 Super Blue Box Recycling (SUBBOR) Corporation, Etobicoke, Ont., Canada M8V 3Y3 Department of Land Resource Science, University of Guelph, Guelph, Ont., Canada N1G 2W1 d School of Engineering, University of Guelph, Guelph, Ont., Canada N1G 2W1 b

c

Received 30 March 2006; received in revised form 12 February 2007; accepted 12 February 2007 Available online 3 May 2007

Abstract Wastewaters from farm and composting operations are often rich in select nutrients that potentially can be reutilized in crop production. Liners of silverleaf dogwood (Cornus alba L. ‘Argenteo-marginata’), common ninebark [Physocarpus opulifolius (L.) Maxim.], and Anthony Waterer spirea (Spiraea · bumalda Burve´nich ‘Anthony Waterer’) were grown in 6 L containers filled with a bark-based commercial mix. Plants were fertigated daily via a computer-controlled multi-fertilizer injector with three recirculated fertilizer treatments: (1) a stock (control) solution with complete macro- and micro-nutrients, electrical conductivity (EC) 2.2 dS m 1; (2) wastewater from a mushroom farm; and (3) process wastewater from anaerobic digestion of municipal solid waste. The wastewaters used in both treatments 2 and 3 were diluted with tap water, and the computer was programmed to amend, dispense and recirculate nutrients based on the same target EC as in treatment 1. For comparison, there was a traditional controlled-release fertilizer treatment [Nutryon 17-5-12 (17N–2P– 10K) plus micro-nutrients topdressed at a rate of 39 g/plant, nutrients not recirculated]. All three species responded similarly to the three recirculated fertilizer treatments. Growth with the recirculated treatments was similar and significantly higher than that obtained with controlled-release fertilizer. Throughout the study, the EC measured in wastewater-derived nutrient solutions, and also in the container substrate, were similar or close to those of the control treatment, although there were small to large differences among individual major nutrients. There was no sign of nutrient deficiency or toxicity symptoms to the plants. Small to moderate excesses in concentrations of SO4, Na, and/or Cl were physiologically tolerable to the species.  2007 Elsevier Ltd. All rights reserved. Keywords: Nutrient recirculation; Wastewater recycling; Fertigation; Container culture; Ornamentals; Woody species

1. Introduction Wastewaters are often rich in nutrients and have been used for irrigation and as supplemental fertilizer sources in a wide variety of agricultural and horticultural production *

Corresponding author. Tel.: +1 519 824 4120x53032; fax: +1 519 767 0755. E-mail address: [email protected] (C. Chong). 0960-8524/$ - see front matter  2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2007.02.047

systems (Gori et al., 2000; Hussain and Al-Saati, 1999 Moore, 1994; Pescod, 1992). Sources of wastewater include municipalities (Allhands et al., 1995; Beltrao et al., 1999; Bouwer et al., 1998; Revel et al., 1999; Sumner, 2000), biosolids and sewage treatment plants (Epstein, 2003), anaerobic digestors (Little and Grant, 2002; Riggle, 1996; Wu and Liu, 1998), composting farms (Jarecki, 2000; Jarecki et al., 2005), and compost leachates and teas (Chong et al., 2005; Gils et al., 2005; Grobe, 2003; Scheuerell, 2003).

0.09 0.04 4.11 3.96 0.35 0.03 5.32 0.32 0.17 0.01 0.47 0.14 0.38 0.03 0.68 0.14 0.51 0.03 0.38 0.09 2.40 0.47 6.60 0.93 862 128 2113 38 194 11 2245 63 5698 1908 2128 949

c

a

b

Each datum is the mean of three samples ± standard error (SE) below each value. Diluted wastewater from mushroom farm. Diluted process wastewater from anaerobic digestion of municipal solid waste.

85 2 6 5 174 2 16 15 821 22 1083 97 29 1 17 1 24 8 137 51 185 3 1813 64 5.3 0.1 18.9 0.1

0.04 0.03 0.02 0.002 0.007 0.003 66 18 31 8 144 12 38 1 95 1 1.4 0.7 0.7 0.3 4 1.2 0.5 0.02 0.9 0.05 8.0a 1.2 SE

Tap watera

Raw wastewater Mushroomb 7.4 SE 0.1 8.7 SUBBORc SE 0.1

0.007 0.003

Cu (mg L 1) Zn (mg L 1) Mn (mg L 1) Fe (mg L 1) Cl (mg L 1) Na (mg L 1) SO4 (mg L 1) Mg (mg L 1) Ca (mg L 1) K (mg L 1) P (mg L 1) NO3–N (mg L 1) NH4–N (mg L 1) EC (dS m 1)

The prototype of the computer-controlled multifertigation injector, also known as the Harrow Fertigation Manager (HFM), was initially designed to fertigate commercial greenhouse-grown vegetables (Papadopoulos and Liburdi, 1989). Purvis et al. (1998) described the original scaled-down model used for recirculating nutrients in our experimental container nursery. The system consisted of a two-tiered stainless steel frame (1.2 m long · 1.4 m high · 0.5 m wide) mounted with 10 electrically-driven, individually-controlled dosimetric injection pumps. Each pump dispensed a separate stock solution of nutrients or acid. The injector housed in-line electrical conductivity (EC), pH, and flow sensors

pH

2.2. The injector

Wastewater

Mushroom farm wastewater was obtained from an onsite aerated tank which collected washwater and operational runoff from growing houses as well as leachates from outdoor compost piles (Money Mushroom, Campbellville, Ont.). Process liquid wastewater was obtained from an anaerobic digestion pilot plant [Super Blue Box Recycling (SUBBOR) Corporation, Guelph, Ont., a subsidiary of Eastern Power Ltd., Toronto, Ont.], which used mixed municipal solid waste as a feedstock to produce biogas for electricity generation (Liu et al., 2002; Vogt et al., 2002). Table 1 shows initial chemical compositions of the wastewaters. Before use, the raw mushroom and SUBBOR wastewaters were diluted with tap water 10 and 20 times, respectively, based on initial chemical analyses (Table 1).

Table 1 pH, EC, and nutrient concentrations of tap water and of both raw mushroom farm and SUBBOR wastewaters

2. Methods 2.1. Wastewater sources

0.03 0.006

B (mg L 1)

There is little definitive scientific information on wastewater usage for container nursery crop production (Gori et al., 2000). Some commercial nurseries capture leachates from container-grown plants in retention ponds and recycle them through the irrigation system (Skimina, 1986; Fain et al., 2000). Monnet et al. (2002) produced roses from treated domestic wastewater using the nutrient film technique. Under greenhouse conditions, Gils et al. (2005) used recirculated turkey litter and leachate solutions prepared from municipal solid waste compost for growing containerized ninebark (Physocarpus opulifolius). It is, however, labor-intensive to recycle wastewater and difficult to achieve an appropriate nutritional balance without the proper fertigation equipment. In our experimental nursery, we have successfully recycled nutrient leachates from container-grown nursery plants by recirculating them with the aid of a computer-controlled multifertigation injector (Chong et al., 2004; Gils et al., 2004; Purvis et al., 2000). The objective of this research was to evaluate and compare mushroom farm and anaerobic digestion wastewaters as supplemental fertilizer sources for growing container nursery crops in our nutrient recirculating system, which was upgraded and re-modified specifically for this research.

2051

0.02 0.02

Mo (mg L 1)

C. Chong et al. / Bioresource Technology 99 (2008) 2050–2060

2052

C. Chong et al. / Bioresource Technology 99 (2008) 2050–2060

Fig. 1. Schematic diagram of the Harrow Fertigation Manager as re-equipped for this research. (Courtesy of Climate Control Systems, Inc., Leamington, Ont.).

and two nutrient blending tubes connected in series. Previous iterations of the model dispensed only one source of recycled nutrients, fresh water, or both (Chong et al., 2004; Gils et al., 2004; Purvis et al., 2000). For this experiment, the system was re-equipped with four large (1300 L) leachate collection tanks, buried into the ground just exterior to the injector system that was housed in an adjoining laboratory (Fig. 1). Each tank was equipped with an EC sensor that protruded into the wastewater or nutrient solution from the middle of a round 2.5 cm thick · 16 cm diameter extruded polystyrene platform which kept the sensor afloat. The solution in each tank was agitated continuously by air directed to the bottom of the tank through vinyl flex tubing from a pump (2500 cc/min Maxima Air Pump, Rolf C. Hagen Inc., Montreal, Quebec). The injector and mixing tanks were connected to a computer via an interface panel which ran version 6.51 of the HFM software program (Climate Control Systems, 2000). This re-configuration of the system allowed separate and sequential recycling of up to four different solutions.

2.3. Plant material and establishment On 14 June 2004, 17–19 cm tall plug-rooted liners of silverleaf dogwood (Cornus alba L. ‘Argenteo-marginata’), common ninebark [Physocarpus opulifolius (L.) Maxim.], and Anthony Waterer spirea (Spirea · bumalda Burve´nich ‘Anthony Waterer’) were potted in #2 (6 L; 21 cm diameter · 21 cm deep) containers and grown initially for 4 weeks with daily hand-watering and once-a-week fertilization with 20-8-20 (20N–3.5P–16.6K) based on the rate of 250 ppm N. The growing medium was 73% bark, 22% peat, and 5% pea gravel by volume. The physical properties of the substrate were: total porosity, 70 ± 0.4%; aeration porosity, 30 ± 0.5%; water retention porosity, 40 ± 0.5%; and bulk density, 0.50 ± 0.01 g cm 3. The initial concentrations of nutrients (mg L 1) measured in saturated paste extracts of the substrate were: NH4–N, 0; NO3–N, 3 ± 0; P, 2 ± 0.7; K, 52 ± 9.8; Ca, 17 ± 0.7; Mg, 9 ± 1.7; Na, 31 ± 9.3; Cl, 44 ± 0.5; SO4, 29 ± 6.9; Fe, 0.95 ± 0.11; Mn, 0.21 ± 0.05; Zn, 0.025 ± 0.005; Cu, 0.025 ± 0.005; B, 0.15 ± 0.01; and Mo, 0.5 ± 0.015. The

Control = stock solution with complete macro- and micro-nutrients; Mushroom = diluted wastewater from mushroom farm; SUBBOR = diluted process wastewater from anaerobic digestion of municipal solid waste. b 16 July–18 August; each datum is the mean over five sampling dates. c 19 August–29 September; each datum is the mean over six sampling dates. * Significantly different from the control value within each period and variable at 99% confidence limit.

5.8 5.8 6.4 Period IIc Control Mushroom SUBBOR

a

0.11 0.08 0.09 0.29 0.27 0.29 0.06 0.05 0.04* 0.24 0.25 0.14* 0.28 0.25 0.09* 1.5 1.2 1.1 62 63 106** 43 44 101* 252 237 116* 34 33 28* 120 108 74* 241 243 242 89 89 88 144 141 127* 44 42 42

0.14 0.11 0.11 0.17 0.25 0.23 0.13 0.22 0.17 0.65 0.78 0.74 46 76 118* 30 42 117* 409 237 132* 37 39 31* 105 98 69* 185 177 213* 48 57 122* 105 95* 101 84 58* 64* 2.1 1.9 2.2 6.5 6.5 6.6 Period I Control Mushroom SUBBOR

2.4 2.4 2.3

0.09 0.08 0.27*

0.05 0.22 0.05 0.23 0.27 1.4 <50 <50 <300 24 140 196 27 100 100 2.2 b

Cu (mg L 1) Zn (mg L 1) Mn (mg L 1) Fe (mg L 1) Cl (mg L 1) Na (mg L 1) SO4 (mg L 1) Mg (mg L 1) Ca (mg L 1) K (mg L 1) P (mg L 1) NO3–N (mg L 1) NH4–N (mg L 1) EC (dS m 1) pH Fertilizer treatmenta

Table 2 pH, EC and nutrient concentrations of the target formula and of the three solutions dispensed and recirculated through the computerized injector

After four weeks growth (on 16 July), plants were placed 45 cm apart on 2% sloped aluminum troughs (25 cm wide · 3 cm deep · 5 m), and grown under four separate fertilizer regimes: (1) control fertilizer solution based on a nutrient formula with a targeted EC of 2.2 dS m 1 (Table 2), delivered and recirculated via the injector; (2) recirculated mushroom farm wastewater; (3) recirculated SUBBOR process wastewater; and (4) Nutryon (Polyon) 17-5-12 (17N–2P–10K) 6 month controlled-release fertilizer (CRF) with micro-nutrients (Nutrite, Elmira, Ont.) topdressed at a rate of 39 g/container (nutrients not recirculated). The experiment was laid out as a split-plot design with fertilizer treatments as main plot and species as subplot. There were four main plot replications and four plants of each species per subplot. The control and wastewater solutions, as well as tap water only to treatment 4, were dispensed by the injector through drip emitters at a rate of 1 L per container per day (all species) between 12 July and 18 August (Period I), and 1 L (spirea) or 2 L (dogwood and ninebark) per day between 19 August and 19 September (Period II). A series of inter-connecting troughs directed the leachate from the containers into the in-ground storage-mixing tanks, one for each of the three fertigation treatments 1–3 (Fig. 2). The tanks also collected rainwater runoff from the troughs and/or through the substrates. On 16 July, and at 7–10 days intervals during each period, samples of wastewater-derived and control solutions from the tanks were analysed for pH, EC, NH4–N, NO3–N, P, K, Ca, Mg, SO4, Na, Cl, Fe, Mn, Zn, Cu, B, and Mo, and the values programmed into the computer. Based on these laboratory results, the solution in each tank was recharged to target EC after each fertigation and/or rainfall event. Recharging events also accounted for the concentration of nutrients in the tap water (Table 1), which was initially programmed into the computer file. Monoammonium sulfate was added manually to the tanks in treatments 1 and 2 to augment NH4–N levels at the beginning of both Period I and Period II, since the system did not have an additional injector needed to dispense NH4–N levels from this nutrient source in the amounts required to match those levels in the wastewaters (Climate Control Systems, 2000). At the end of Period I, two plants were harvested from each subplot. The shoots (stems and remaining leaves) were removed at substrate level, dried, and weighed. Samples of the substrate were collected at the 7–12 cm container depth and analysed for nutrients as in the tanks. At the start of Period II, the storage-mixing tanks were emptied, washed, and replenished with fresh solutions. The remaining plants were re-spaced 72 cm apart, and grown on as in Period I. On 29 September plants were harvested

B (mg L 1)

2.4. Treatments and cultural practices

Target formula 6.0

Mo (mg L 1)

pH and EC were 6.3 ± 0.1 and 0.45 ± 0.05 dS m 1, respectively.

2053

0.02 0.03 0.04

C. Chong et al. / Bioresource Technology 99 (2008) 2050–2060

2054

C. Chong et al. / Bioresource Technology 99 (2008) 2050–2060

Fig. 2. A series of criss-crossing aluminium troughs directed leachate from the containers into various in-ground collection tanks. (The tank solutions were recycled by re-routing through the computerized fertigation manager and re-dispensed to the crops.)

and substrate samples taken and analysed, as described above. Normality and homogeneity tests, and analysis of variances were conducted separately on data responses for each period. Means were separated by the LS means procedure. Relationships for each growth parameter versus EC and individual nutrients measured in the substrate at the end of each period were further examined by correlation analysis. 3. Results

cated that trends in top dry weight responses of all three species were similar during Periods I and II. Top dry weights of both dogwood and ninebark were similar with the three recirculated fertilizer treatments, and were significantly taller than those obtained with CRF (Table 3). Spirea top dry weight was similar with all fertilizer treatments. At the end of Period II, height of all species was similar and greater with the three recirculated fertilizer treatments than with CRF, although in Period I only dogwood showed this result (Table 3). In previous investigations most container crops performed better with recirculated fertilizer treatments than with CRF (Chong et al., 2004; Gils et al., 2004).

3.1. Growth 3.2. Dispensed solutions Plants, especially ninebark and dogwood, grew rapidly with the recirculated wastewater-derived and the control nutrient solutions and all species were of marketable size by the end of the experiment. Analysis of variance indi-

3.2.1. EC and pH Confidence interval tests indicated that, during the experiment, the EC of the three dispensed solutions were

C. Chong et al. / Bioresource Technology 99 (2008) 2050–2060 Table 3 Top dry weight and height responses of three container-grown species to fertilizer treatments Treatments

Main plot Fertilizer (F)c Control Mushroom SUBBOR CRF Subplot Species (S) Dogwood Ninebark Spirea Interaction F·S Dogwood

Ninebark

Spirea

Control Mushroom SUBBOR CRF Control Mushroom SUBBOR CRF Control Mushroom SUBBOR CRF

Top dry wt. (g/plant)

Height (cm)

Period Ia

Period I

Period IIb

**

**

32 33 35 24

93 97 95 52

NS 44 44 44 41

Period II **

54Ad 54A 53A 47B

**

**

**

**

27 42 24

90 119 44

55 44 31

65A 60B 32C

*

**

*

29a 28a 30a 19b 44a 50a 48a 27b 23a 21a 26a 26a

99a 103a 100a 56b 134a 141a 139a 63b 47a 47a 46a 37a

56a 57a 57a 48b 43a 44a 45a 44a 32a 30a 30a 31a

NS

a

16 July–18 August 19 August–29 September c Fertilizer treatments: Control = stock solution with complete macroand micro-nutrients; Mushroom = diluted wastewater from mushroom farm; SUBBOR = diluted process wastewater from anaerobic digestion of municipal solid waste; CRF = controlled-release fertilizer. d Means within main plot (fertilizer) or subplot (species) are separated by uppercase letters, A–C; means within interaction (F · S) effects are separated by lowercase letters, a–b. **, * NS Significant at P 6 0.01 and P 6 0.05, and non-significance, respectively.

2055

3.3. Substrate EC measurements in the substrate were similar among the three recirculated treatments (0.6 and 1.2 dS m 1, mean values at end of Period I and II, respectively) but lower with CRF (0.4 and 0.6 dS m 1) (Tables 4 and 5). pH values varied marginally (range 6.9–7.3, Period I; and 6.4–6.9, Period II) and, depending on species, there was a tendency for the lowest values in the control substrate and the highest values with CRF (see Tables 4 and 5). The concentrations of most major nutrients were lowest with CRF and about two to six times higher in Period II than in Period I (Table 4). In Period II, the SO4 levels were moderately (CRF) to substantially (control) higher than recommended for substrates (<80 mg L 1). Concentrations of Na and Cl were also higher than recommended (<50 mg L 1) with the highest values observed in SUBBOR (105 and 110 mg L 1, respectively). Consistent positive correlations were found between top dry weight of each species and EC, as well as with most of each individual nutrients. Similar relationships were observed for height of dogwood and ninebark, but not spirea. We have previously reported similar results between growth and substrate EC, confirming mathematically that plant growth was related to nutrient retention in the medium (Chong and Purvis, 2004). 4. Discussion

b

on target except for in the mushroom tank (1.9 dS m 1) which was marginally but significantly less than in the control (2.1 dS m 1) (Table 2). During Period I, the pH was 0.5–0.6 unit higher than targeted, but similar among the three solutions. During Period II, the pH was higher in SUBBOR nutrient solution (6.4) than in the control (5.8). 3.2.2. Individual nutrients The concentrations of individual dispensed nutrients did not always match targeted values (Table 2). Concentrations of the major nutrients in the wastewaters were lower [NH4– N and Ca (both periods)] or higher [P (both periods); NO3– N and K (Period II)] compared with the control solution. Levels of SO4 were lower than targeted, and similar or lower than that in the control, except in Period I when it was 30% above target. Variations in the concentrations of all micro-nutrients were small and considered to be physiologically inconsequential.

Nutrient-rich wastewaters are broadly available for potential use in plant production systems. However, the principal deterrents against using farm and compost wastewaters in plant culture include nutrient excesses or imbalances and variability in species responses. Generally, nutrients (salts) not readily taken up by plants will accumulate in a closed system (Monnet et al., 2002; Zekki et al., 1996). This, and the presence of too much or too little of one or more nutrients, create imbalances which can cause undesirable side effects. Excess salts may restrict use of wastewater to salt tolerant species since it is often difficult to rectify nutrient imbalances (Jarecki, 2000; Marschner, 1995; Schwarz, 1985). This study has furthered our understanding of the key parameters needed to guide wastewater reuse and the good potential for effective nutrient use in container nursery production. Such reuse can lower water consumption, fertilizer costs, and wastewater treatment and disposal costs, all creating environmental benefits. In the present study, chemical analyses of the wastewaters were conducted initially at various dilutions to determine their fertilizer properties and to devise a strategy for using them in recirculation. The two raw batches contained salt levels that were excessive (EC = 5.3 and 18.9 dS m 1 for mushroom and SUBBOR wastewater, respectively) due to extra-rich concentrations of primary major nutrients, such as K (both sources) and NH4–N (SUBBOR only), and secondary ones such as SO4, Cl, and Na (both sources) (Table 1). These latter nutrients are renowned

2056

Table 4 pH, EC and nutrient concentrations measured in the substrate at the end of Period I Fertilizer treatments

pH

EC (dS m 1)

NH4–N (mg L 1)

NO3–N (mg L 1)

P (mg L 1)

K (mg L 1)

Ca (mg L 1)

Mg (mg L 1)

SO4 (mg L 1)

Na (mg L 1)

Cl (mg L 1)

Fe (mg L 1)

Mn (mg L 1)

Zn (mg L 1)

Cu (mg L 1)

Desirable values for container culture

5.5–7.0

610

610

100–200

6–9

150–200

200–300

70–200

0–80

0–50

0–50

0.3–3.0

0.3–3.0

0.3–3.0

0.3–3.0

**

NS

*

**

**

NS

NS

**

**

**

NS

NS

25 33 49 25

22C 32B 40A 23C

0.17 0.17 0.20 0.17

0.02 0.05 0.03 0.03

B (mg L 1)

Mo (mg L 1)

NS

NS

NS

0.09A 0.03B 0.07A 0.01B

0.01 0.02 0.01 0.01

0.09 0.03 0.07 0.07

0.11 0.01 0.01 0.01

Period Ia **

Control Mushroom SUBBOR CRF Subplot Species (S) Dogwood Ninebark Spirea Interaction F·S Dogwood

c

6.9 7.0 7.0 7.2

0.52B 0.55AB 0.57A 0.36C

0.6 0.5 0.5 0.5

5.1 3.7 3.2 1.0

15C 20B 36A 14C

50B 51B 55A 8C

25 26 22 24

13 14 12 12

97 82 58 50

NS 7.0 7.0 7.0

**

NS 0.5 0.6 0.5

**

NS 39 42 42

NS 23 24 26

NS 12 14 13

**

**

2.8 1.3 5.6

NS 22 21 21

**

0.47B 0.53A 0.50B

63 85 67

30 38 31

26B 32A 29B

NS 0.14 0.18 0.21

NS 0.02 0.04 0.04

NS 0.05 0.05 0.06

NS 0.02 0.01 0.01

NS 0.05 0.05 0.09

NS 0.07 0.02 0.03

NS

NS

NS

NS

NS

NS

NS

NS

NS

NS

NS

NS

NS

*

**

Control Mushroom SUBBOR CRF

6.9b 7.0b 6.9b 7.3a

4.3a 2.5a 3.3a 1.3a

85a 73b 49c 44c

24c 31b 42a 23c

Ninebark

Control Mushroom SUBBOR CRF

7.0ab 7.0b 7.1ab 7.1a

1.4ab 1.8a 1.5a 0.8b

114a 101a 73b 53c

27c 39b 60a 26c

Spirea

Control Mushroom SUBBOR CRF

6.8c 7.0b 7.0b 7.2a

9.8a 6.8ab 4.8bc 1.0c

92a 70b 51c 52c

24b 28b 45a 25b

a

**

**

**

16 July–18 August Fertilizer treatments: Control = stock solution with complete macro- and micro-nutrients; Mushroom = diluted wastewater from mushroom farm; SUBBOR = diluted process wastewater from anaerobic digestion of municipal solid waste; CRF = controlled-release fertilizer. c Means within main plot (fertilizer) or subplot (species) are separated by uppercase letters, A–C; means within interaction (F · S) effects are separated by lowercase letters, a–c. **, * NS Significant at P 6 0.01 and P 6 0.05, and non-significance, respectively. b

C. Chong et al. / Bioresource Technology 99 (2008) 2050–2060

Main plot Fertilizer (F)b

Table 5 pH, EC and nutrient concentrations measured in the substrate at the end of Period II Fertilizer treatments

pH

EC (dS m 1)

NH4–N (mg L 1)

NO3–N (mg L 1)

P (mg L 1)

K (mg L 1)

Ca (mg L 1)

Mg (mg L 1)

SO4 (mg L 1)

Na (mg L 1)

Cl (mg L 1)

Fe (mg L 1)

Mn (mg L 1)

Zn (mg L 1)

Cu (mg L 1)

Desirable values for container culture

5.5–7.0

610

610

100–200

6–9

150–200

200–300

70–200

0–80

0–50

0–50

0.3–3.0

0.3–3.0

0.3–3.0

0.3–3.0

**

NS

NS

**

**

NS

NS

NS

NS

NS

NS

NS

NS

6.5 6.6 6.7 6.9

1.27Ac 1.15A 1.14A 0.64B

0.6 0.9 0.7 0.6

19 25 24 11

30C 34B 45A 24D

118 134 122 16

71 48 36 42

38 25 20 23

332 203 141 101

78 75 105 52

86 86 110 63

0.30 0.26 0.27 0.22

0.10 0.08 0.08 0.07

*

NS 1.15 0.96 1.04

NS 0.6 1.0 0.5

NS 22 19 18

**

*

37A 35A 29B

108 88 97

NS 56 45 47

NS 30 23 26

NS 231 178 173

NS 86 71 75

NS 99 62 97

NS 0.24 0.23 0.31

NS

NS

NS

NS

NS

NS

NS

NS

NS

B (mg L 1)

Mo (mg L 1)

NS

NS

NS

0.13 0.13 0.13 0.03

0.02 0.02 0.02 0.01

0.13 0.08 0.07 0.13

0.03 0.01 0.01 0.01

NS 0.08 0.07 0.09

NS 0.11 0.10 0.10

NS 0.02 0.02 0.02

NS 0.08 0.10 0.10

NS 0.02 0.02 0.01

NS

NS

NS

NS

Period IIa **

Control Mushroom SUBBOR CRF Subplot Species (S) Dogwood Ninebark Spirea Interaction F·S Dogwood

6.7 6.7 6.7

*

*

Control Mushroom SUBBOR CRF

**

6.4c 6.7b 6.7b 6.9a

150a 147a 128a 8b

*

0.33a 0.17a 0.24a 0.24a

0.11a 0.05a 0.07ab 0.10ab

Ninebark

Control Mushroom SUBBOR CRF

6.6b 6.7b 6.7b 6.9a

98b 130a 115ab 7c

0.21b 0.22b 0.36a 0.16b

0.07b 0.06b 0.11a 0.06b

Spirea

Control Mushroom SUBBOR CRF

6.5b 6.7a 6.7a 6.7a

105a 123a 125a 34b

0.36a 0.40a 0.22a 0.27a

0.11a 0.06a 0.12a 0.07a

C. Chong et al. / Bioresource Technology 99 (2008) 2050–2060

Main plot Fertilizer (F)b

a

19 August–29 September Fertilizer treatments: Control = stock solution with complete macro- and micro-nutrients; Mushroom = diluted wastewater from mushroom farm; SUBBOR = diluted process wastewater from anaerobic digestion of municipal solid waste; CRF = controlled-release fertilizer. c Means within main plot (fertilizer) or subplot (species) are separated by uppercase letters, A–D; means within interaction (F · S) effects are separated by lowercase letters, a–c. **, * NS Significant at P 6 0.01 and P 6 0.05, and non-significance, respectively. b

2057

2058

C. Chong et al. / Bioresource Technology 99 (2008) 2050–2060

for buildup in recirculating systems and for causing toxicity problems if not rectified (Zekki et al., 1996). The dilutions chosen for use attempted to retain as much as possible of the NH4–N, P, K, Ca, and Mg, in this order of priority, at concentrations based on the control solution (Table 2), while reducing quantities of SO4, Cl, and Na, low enough to allow for some buildup. Before the start of recirculation, the concentrations of each nutrient were targeted to those of the control with the aid of the computerized injector. Daily nutrient recharge and dispensation were based primarily on target EC of 2.2 dS m 1. Throughout the experiment, the EC values in the three solutions were within or near 10% of each other, a variability that is considered to be quite accurate for this type of equipment (Chong et al., 2004; Gils et al., 2005). While the actual dispensed values of individual nutrients did not always match expected targets, and sometimes did swing widely, similar results are to be expected with this type of equipment and often are not harmful to plants (Purvis et al., 2000; Papadopoulos and Liburdi, 1989). There was evidence of excess SO4 in the control solution in Period I and in the substrate in Period II. This was likely due to the manual addition of extra (NH4)2SO4, and also of Na and Cl especially in the SUBBOR solution (both periods, Table 2) and in the substrate (Period II, Table 4). Salt buildup can be mitigated by periodic flushing of the substrate in situ every 4 weeks (Resh, 1989) and/or by periodic emptying of the tanks (Zekki et al., 1996). In between the two test periods of this study, the tanks were emptied and washed. As Period I was approximately 4 weeks, this would have been insufficient time for significant salt accumulation in the tanks and in the substrate. Fortunately, any excess in salts was moderate and the tanks were emptied and replenished with fresh solutions at the start of Period II. Throughout the study, there were no signs of nutrient toxicity or deficiency. Based on our past experiences with recirculated container-runoff water or fresh nutrient stock solutions, container-grown deciduous nursery plants, as in this study, grew rapidly to salable size (within 9–12 weeks) (Chong et al., 2004; Gils et al., 2004). In contrast, a longer growing period (16–20 weeks) is required when conventional controlled-release fertilizers are supplied as the nutrient source. Periodic flushing of the substrate does not address salt buildup in the recirculating nutrient solution. Thus, in adapting the present system for longer cultivations, we recommend draining and washing the fertigation system periodically to prevent salt buildup. This procedure could be done whenever the wastewater solution is replenished or at regular (e.g. 4 weeks) intervals, based on chemical analysis of the recirculation stream. While this requirement is inconvenient and adds extra cost to production, this precaution provides an extra measure against salt buildup in the recirculation stream. There is little specific information regarding salt tolerance of woody nursery crops (Skimina, 1980). According

to Bernstein et al. (1972), salt tolerance is not necessarily correlated with Na and Cl injury, nor is survival under saline conditions necessarily a good index of salt tolerance. The balance of the cations, Ca, K, Mg, and to some degree NH4 and Na, may be more important than their actual levels. Other factors including species, watering practices and related cultural and environmental factors interact (Davidson et al., 2000). Consequently, plant responses to known salt concentrations cannot be predicted on an absolute basis (Mass, 1986). Reisenauer (1976) indicated that ninebark is salt tolerant to about 355 mg L 1 of Cl, although data by Gils et al. (2005) suggest tolerance near 100 mg L 1 of Cl and near 70 mg L 1 of Na. In the present study, tolerance of the three species to Cl and Na concentrations was near 120 mg L 1, and to SO4 concentrations near 400 mg L 1 (Table 2). In a different recirculating experiment (data unpublished) we replenished compost leachates by topping up at two-week intervals with the same wastewater. Using this procedure, we attempted to grow three containergrown species [forsythia (Forsythia · intermedia Zab. ‘Lynwood Gold’), cotoneaster (Cotoneaster dammeri C.K. Schneid. ‘Coral Beauty’), and sumac (Rhus typhina L.)] supplied solely with recirculated nutrients from wastewater mixtures (SUBBOR + mushroom farm and SUBBOR + turkey litter leachate). However, persistently high Na and Cl levels (125–255 and 144–282 mg L 1, respectively) were a problem. While all species grew best with control stock solution (<65 and <94 mg L 1 Na and Cl, respectively), growth was intermediate (forsythia and sumac) and/or similar (cotoneaster) with the wastewater mixtures compared with CRF. As the fertigation system is computer-controlled, and based on the continuous EC measurements, it is designed to accommodate changes in dilution of the leachate collection tanks such as the introduction of rainfall, as long as the tanks do not overflow. During the present experiment, an undetermined amount of rain water was allowed to collect in the leachate collection tanks, although none of the tanks overflowed. Rainfall of 78, 83 and 0 mm in July, August and September, respectively, was below long-term averages of 90, 93, and 90 mm for the same months. The prevailing temperature was cooler than normal during Period I and warmer during Period II particularly in September. The cool Period I may account in part for reduced release of nutrients from CRF and hence lower performance especially of dogwood and ninebark, the two most rapidly growing species. As a preliminary study to the present research, McLachlan et al. (2004) showed that diluted water extracts from digestates, sampled from progressive stages of anaerobic digestion at the SUBBOR pilot testing facility, Guelph, Ont., were not phytotoxic for seed germination, and some in fact stimulated germination. In stationary hydroponic studies under greenhouse condition, two woody nursery species [forsythia and weigela (Weigela florida Bunge A.DC. ‘Variegata Nana’)] grew well with leachates derived

C. Chong et al. / Bioresource Technology 99 (2008) 2050–2060

from municipal solid waste and spent mushroom compost, but not with raw SUBBOR wastewater due in part to a slime buildup which appeared to stifle the roots. Similar results were observed even after the SUBBOR wastewater was pretreated by ultrafiltration (Xin, 2006). In contrast, two turfgrass species [creeping bentgrass (Agrostis palustris Huds.) and Kentucky bluegrass (Poa pratensis L.)] thrived in the raw solutions and showed enhanced root growth, compared with control solutions formulated with traditional fertilizers (Michitsch et al., 2003). The turfgrasses also thrived in a containerized sand/peat mixture under growth room conditions and in field plots when supplied with nitrogen (primarily NH4–N) at recommended or lower amounts solely from SUBBOR wastewater (Michitsch, 2004). In addition to buildup of certain nutrients in a closed system, decreased growth might be due to phytotoxicity of specific compounds such as organic acids, phenols or herbicides (Mathers, 2002; Skimina, 1986). It may be that nutrient exchange sites in potting media have importance with wastewater mixtures of higher strength or of more variable composition. In the present study, good growth response was observed with all three species and there was no sign of detriment to the plants. Small to moderate buildup in concentrations of SO4, Na, and Cl were physiologically tolerated by all three species. This closed-loop growing system was effective for growing container nursery crops using recycled wastewater. 5. Conclusion This investigation provides new scientific-based information about wastewater usage in crop production, and introduces a novel and alternative approach for use. The results demonstrate that with appropriate dilution, rebalancing, and dispensing of the wastewater nutrients via a computerized fertigation injector, both mushroom farm and anaerobic digestion process wastewater can be used effectively as a supplementary source of nutrients for growing container nursery plants in a nutrient recirculating system. Chemical analyses of the wastewater are required to determine its fertilizer properties before use, and for monitoring during usage. The computerized HFM fertigation injector, re-modified for this project, dispensed and recirculated nutrients and wastewater relatively accurately based on EC, although individual nutrients did not always match target values. Wastewater usage reduces dependency on synthetically prepared fertilizers and provide environmental benefits by diverting wastewater that would otherwise be discharged into the environment. Acknowledgements Financial support was provided by SUBBOR, a subsidiary of Eastern Power Ltd., the Natural Sciences and Engineering Research Council (NSERC), and the Ontario Ministry of Agriculture and Food (OMAF).

2059

References Allhands, M.N., Allick, S.A., Overman, A.R., Leseman, W.G., Vidak, W., 1995. Municipal water reuse at Tallahassee, Florida. Transactions of the ASAE 38, 411–418. Beltrao, J., Gamito, P., Guerrero, C., Arsenio, A., Brito, J.C., 1999. Grass response to municipal wastewater reuse as compared to nitrogen and water application. In: Anac, D., Martin-Prevel, P. (Eds.), Improved Crop Quality by Nutrient Management. Kluwer Academic Publishers, Maryland, pp. 263–265. Bernstein, L., Francois, L.E., Clark, R.A., 1972. Salt tolerance of ornamental shrub and ground covers. Journal of the American Society for Horticultural Science 97, 550–556. Bouwer, H., Fox, P., Wasterhoff, P., 1998. Irrigating with treated effluent. Water Environment and Technology 10, 115–120. Chong, C., Lumis, G., Purvis, P., Dale, A., 2004. Growth and nutrient status of six species of nursery stock grown in a compost-based medium with recycled nutrients. HortScience 39, 60–64. Chong, C., Purvis, P., 2004. Nursery crop response to substrates amended with raw paper mill sludge, composted paper mill sludge and composted municipal waste. Canadian Journal of Plant Science 84, 1127–1134. Chong, C., Yang, J., Holbein, B.E., Liu, H.-W., Voroney, R.P., Zhou, H., 2005. Rooting cuttings hydroponically in compost tea and wastewater. Combined Proceedings of the International Plant Propagators’ Society 55, 15–19. Climate Control Systems, 2000. Fertigation Manager user manual version 6.31 and 6.51. Climate Control Systems, Leamington, ON. Davidson, H., Mecklenburg, R., Peterson, C., 2000. Nursery Management Administration and Culture, fourth ed. Prentice-Hall, Upper Saddle River, NJ. Epstein, E., 2003. Land Application of Sewage Sludge and Biosolids. Lewis Publishers, New York. Fain, G.B., Gilliam, C.H., Tilt, K.M., Olive, J.W., Wallace, B., 2000. Survey of best management practices in container production nurseries. Journal of Environmental Horticulture 18, 142–144. Gils, J., Chong, C., Lumis, G., 2004. Container nursery stock response to recirculated nutrients. Acta Horticulturae 630, 219–224. Gils, J., Chong, C., Lumis, G., 2005. Response of container-grown ninebark to crude and nutrient-enriched recirculating compost leachates. HortScience 40, 1507–1512. Gori, R., Ferrini, F., Nicese, F.P., Lubello, C., 2000. Effect of reclaimed wastewater on the growth and nutrient content of three landscape shrubs. Journal of Environmental Horticulture 18, 108–114. Grobe, K., 2003. Golf courses find value in compost tea programs. BioCycle 44 (10), 22–23. Hussain, G., Al-Saati, A.J., 1999. Wastewater quality and its reuse in agriculture in Saudi Arabia. Desalinatino 123 (2/3), 241–251. Jarecki, M.K., 2000. Evaluation of compost leachate as a source of irrigation water and nutrients in field and hydroponic experiments. Ph.D. thesis, University of Guelph. Jarecki, M.K., Chong, C., Voroney, R.P., 2005. Evaluation of compost leachates for plant growth in hydroponic culture. Journal of Plant Nutrition 28, 651–667. Little, C.M., Grant, A.A., 2002. Making integrated anaerobic digestion projects a reality. BioCycle 43 (7), 64–68. Liu, H.-W., Walter, H.K., Vogt, G.M., Vogt, H.S., Holbein, B.E., 2002. Steam pressure disruption of municipal solid waste enhances anaerobic digestion kinetics and biogas yield. Biotechnology and Engineering 77, 121–130. Mass, E.V., 1986. Salt tolerance of plants. Applied Agricultural Research 1, 12–26. Mathers, H., 2002. Novel methods of weed control in containers. HortTechnology 13, 28–34. Marschner, H., 1995. Mineral Nutrition of Higher Plants. Academic Press, San Diego, TX. McLachlan, K., Chong, C., Voroney, R.P., Liu, H.-W., Holbein, B.E., 2004. Assessing the potential phytotoxicity of digestates during

2060

C. Chong et al. / Bioresource Technology 99 (2008) 2050–2060

processing of municipal solid waste by anaerobic digestion: Comparison to aerobic composts. Acta Horticulturae 638, 225–230. Michitsch, R.C., 2004. Nutritive value and agricultural/horticultural uses of intra-process wastewater generated from anaerobic digestion of organic wastes. M.Sc. thesis, Department of Land Resource Science, University of Guelph. Michitsch, R., Chong, C., Voroney, R.P., Holbein, B., Liu, H.-W., 2003. Use of spent mushroom compost leachate for growing turf and nursery species in hydroponic culture. Mushroom World 14 (3), 21–23. Monnet, F., Vaillant, N., Hitmi, A., Vernay, P., Coudret, A., Sallanon, H., 2002. Treatment of domestic wastewater using the nutrient film technique (nft) to produce horticultural roses. Water Research 36, 3489–3496. Moore, J., 1994. Coping with wastewater: Management strategies and information sources. In: The United States Golf Association (Ed.), Wastewater Reuse for Golf Course Irrigation. Lewis Publishers, Chelsea, MI, pp. 193–201. Papadopoulos, A.P., Liburdi, N., 1989. The Harrow Fertigation Manager – a computer controlled multifertigation injector. Acta Horticulturae 260, 255–265. Pescod, M.B., 1992. Wastewater treatment and use in agriculture. Food and Agriculture Organization of the United Nations, Rome, Italy. Purvis, P., Chong, C., Lumis, G.P., 1998. A new computer controlled multifertilizer injector for recycling nutrients and water run-off in nurseries. Combined Proceedings of the International Plant Propagators’ Society 48, 150–152. Purvis, P., Chong, C., Lumis, G.P., 2000. Recirculation of nutrients in container nursery production. Canadian Journal of Plant Science 80, 39–45. Reisenauer, H.M., 1976. Soil and plant tissue testing in California. Bulletin 1879, Division of Agricultural Sciences, University of California. Resh, H.M., 1989. Hydroponic Food Production, fourth ed. Woodbridge Press Publ. Co., Santa Barbara, CA.

Revel, J.C., Morard, P., Bailly, J.R., Labbe, H., Berthout, C., Kaemmerer, M., 1999. Plants’ use of leachate derived from municipal solid waste. Journal of Environmental Quality 28, 1083–1089. Riggle, D., 1996. Anaerobic digestion for MSW and industrial wastewater. BioCycle 37 (11), 77–81. Scheuerell, S., 2003. Understanding how compost tea can control disease. BioCycle 44 (2), 20–25. Schwarz, M., 1985. The use of saline water in hydroponics. Soilless Culture 1, 25–34. Skimina, C.A., 1980. Salt tolerance of ornamentals. Combined Proceedings of the International Plant Propagators’ Society 30, 113–118. Skimina, C.A., 1986. Recycling irrigation runoff on container ornamentals. HortScience 21, 32–34. Sumner, M.E., 2000. Beneficial use of effluents, wastes, and biosolids. Communications in Soil Science and Plant Analysis 31 (11/14), 1701– 1715. Vogt, G.M., Liu, H.W., Kennedy, K.J., Vogt, H.S., Holbein, B.E., 2002. Super blue box recycling (SUBBOR) enhanced two-stage anaerobic digestion process for recycling municipal solid waste: Laboratory pilot results. Bioresource Technology 85, 291–299. Wu, Y.Z., Liu, K.J., 1998. An introduction to the state of research and development of biogas in rural areas of China in recent years and discussion on improvement of old biogas technology. Biogas Technology and Utilization Research, 1–13 (in Chinese). Xin, X., 2006. Use of coagulation as a pretreatment to improve membrane filtration performance for high-strength wastewater from municipal solid waste anaerobic digestion. M.Sc. thesis, School of Engineering, University of Guelph. Zekki, H., Gauthier, L., Gosselin, A., 1996. Growth productivity and mineral composition of hydroponically cultivated greenhouse tomatoes, with or without nutrient solution recycling. Journal for the American Society of Horticultural Science 12, 1082–1088.