Influence of tomato waste compost ratios on plant growth and fruit quality of cucumber and summer squash

ABSTRACT

Peat-moss (Sphagnum spp.), is currently an expensive material and a nonrenewable resource with variable properties. Therefore, its use should be gradually reduced. Hence, there are numerous attempts aiming to reduce the use of peat-moss as a bulk substrate and to search for high-quality, locally available and low-cost alternatives to peat-moss. Therefore, the main objective of this research is to investigate the effect of partial replacing of peat-moss with tomato waste compost (TWC) on plant growth, productivity, fruit quality, and morphological features of two types of economic cucurbits species under greenhouse conditions. The plants were planted into pots containing different proportions of TWC (0%, 5%, 10%, 15%, 20% and 30%) with peat-moss, sand and clay as growing substrates. The results indicated that the plant height and the leaves number of both plants were significantly influenced by different substrate treatments. TWC ratios of 15% and 20% increased the amount of cucumber and summer squash fruit yield more than the commercial peat media but they had insignificant differences. Also, they were significantly improved fruit quality characteristics, particularly total soluble solid (TSS) and titratable acidity (TA) of crop fruits more than commercial peat-moss treatment.

Implications: Because of the high price of peat-moss and that it is a non-renewable material, farmers resorted to using other alternatives, including green residue compost. Thus, the aim of this work is to reduce the use of peat-moss by replacing it with the use of lokw percentages of TWC. When tomato plant residues return to the soil by converting them into compost, this is a valuable agricultural practice to improve soil fertility and increase the organic matter of the soil as well as increase the source of nitrogen (N) that supports the growth of beneficial microorganisms.

Introduction

Several materials, whether singly or mixed, can be used to produce substrates with physical, chemical and biological properties suitable for growing different crops under various cultural conditions (Diaz-Perez and Camacho-Ferre 2010). Peat-moss is a high-priced material and a nonrenewable resource, is collected from bogs, marshes, and wetlands, which are often fragile ecosystems of great ecological and archeological value (Bustamante et al. 2008). So it is necessary to search for alternative materials to reduce the cost of cultivation. The greenhouse tomato production in Saudi Arabia represents alone, about 50% of the average total tomato production (Morci, Elmulthum, and Hadid 2020). As a result of pruning practice and after crop harvesting, there is a considerable amount of plant wastes remains especially tomato residues that preferable to be recycled (Ministry of Environment, Water and Agriculture 2016). Hence, the recycle and return back of tomato plant residues to the soil by transforming them to compost is a valuable agricultural practice to improve soil fertility and increase soil organic matter as well as increase nitrogen (N) source that supports the growth of beneficial microorganisms (Bougnom et al. 2010; Liu et al. 2013). Several studies with combinations of peat-moss and composts sourced from different organic wastes mixed in different proportions were carried out for various plant species (Do and Scherer 2013). This compost from various organic waste is an excellent and useful partial alternative to peat-moss. It is used to improve soil properties and plant growth in many vegetables and ornamental species (Do and Scherer 2013; Grigatti, Giorgioni, and Ciavatta 2007; Oberpaur et al. 2010). Most of vegetable species are established from transplants grown in seedling trays using various growing media. However, the effects of growing medium on the productivity of vegetable crops, chiefly after transplant are not well known. The importance of growing medium choice, relative to the other production factors, needs to be assessed for greenhouse vegetable production. Therefore, many researchers and farmers have resorted to using compost resulting from the waste of horticultural plants, as most of it is locally produced, especially as an alternative to peat-moss for ornamental plants in potted plants, and for the production of vegetables in greenhouses. It provides the base material for the majority of the commercial pillars used in nurseries, enjoys excellent physical fitness, chemical and biological properties make it ideal to grow horticultural seedlings (Abad, Noguera, and Bures 2001). Also, the use of vegetable fertilizer leads to their safe disposal and thus there are no environmental hazards as well (Atif et al. 2016). Several authors have indicated the feasibility of compost vegetable waste, urban solid waste as seed substrates for the production of horticultural seedlings in nurseries (Castillo et al. 2004; Herrera et al. 2008; Kostov et al. 1996; Perez-Murcia et al. 2006). Therefore, many studies have been conducted with combinations of peat-moss and composts sourced from different organic wastes mixed in different proportions were carried out for various plant species (Do and Scherer 2013). Although some studies focused on tomato plant residues composting (Hesham et al. 2018; Rashwan et al. 2020a, 2020b) but, little attention has been so far paid to assess the agronomic effectiveness of the produced compost (Pane et al. 2015). Consequently, the aim of this study is to investigate the effects of different TWC ratio mixes with peat-moss on plant growth, productivity and fruit quality and morphological features of two economic cucurbits species under greenhouse conditions.

Materials and methods

Converting tomato plant residues to compost

Tomato plant residue (stems, leaves, and some green and damaged fruits) were collected, then they were spread out on the ground to dry for 3 days before being chopped and grinded to reach a suitable particle size (≈ 1–2 cm). The residues were mixed with 20% chicken manure, as a nitrogen source, and MC of the mixture was adjusted to be about 60%. Composting was performed in three identical pilot-scale rotary drum bioreactors (200 L each) for 36 days. In the previous work, the temperature, pH and C: N ratio were monitored. Solvita tests for CO₂ and NH₃, Dewar test, germination test and germination index were used to evaluate the maturity and stability of the compost (Rashwan et al. 2020a). The physiochemical and both compost quality parameters (Dewar and Germination Index) and (Solvita-CO₂ and Solvita-NH₃), were indicated that the final compost is mature and has low phytotoxicity. Therefore, according to the results obtained in the previous study, the final compost product is stable and mature and become ready for application as an agricultural substrate or a soil conditioner (Rashwan et al. 2020a).

Peat-moss and peat substitutes (TWC, clay and sand) in various combinations were tested for successful growth of two economic vegetable species (cucumber and summer squash). The experiment was conducted in one of the greenhouses located at the College of Food and Agricultural Sciences, King Saud University, Riyadh, Saudi Arabia.

Experimental design, substrate treatments and cultural practices

The experiment was carried out in big plastic pots (each plot is 30 cm top diameter × 22 cm base × 28 cm deep), in the greenhouse. A mix of commercial peat-moss, sand, clay and TWC were used to form six substrate treatments, which were (% v/v): (1) sand: clay: peat-moss: TWC (2:1:2:0) represent 0.0% TWC, (2) sand: clay: peat-moss: TWC (2:1:1.75:0.25) represent 5.0% TWC, (3) sand: clay: peat-moss: TWC (2:1:1.5:0.50) represent 10.0% TWC, (4) sand: clay: peat-moss: TWC (2:1:1.25:0.75) represent 15.0% TWC, (5) sand: clay: peat moss: TWC (2:1:1:1) represent 20.0% TWC, and (6) sand: clay: peat-moss: TWC (2:1:0.50:1.50) represent 30.0% (Wightman 1999). The six substrate treatments were arranged in a completely randomized design (CRD) with four replicates per treatment (one pot per replication).

Plant materials

Two cucurbits species were used, hybrid cucumber (Cucumissativus var. Xtrem F₁ Seminis, Monsanto Holland BV, The Netherlands) and summer squash (Cucurbita pepo var. Tala F₁ Volo Agri. Group Company, San Luis Obispo Seed, Inc, USA). Healthy and uniform transplants of cucumber and summer squash seeds were sown (0.5 cm depth) one per big plastic pots, contains 10–12 kg growing media filled with the previous six different growth media. Figure 1 shows the layout of the experiment.

Figure 1. Experimental layout, cucumber and summer squash sampling distribution and planting in plastic pots in the greenhouse

Variables determined by the two cucurbits species

Four plants from each crop treatment were used at 60 days after transplanting of seed sowing to measure the following vegetative growth traits: plant height, leave number and stem diameter. The plant height (cm) was measured using a meter from the soil surface up to the top of the plant. The leave numbers of each crop were carefully counted. Stem diameter (cm) was measured near the soil surface using a digital display caliper (Gold tool Digital Caliper, Taiwan). In addition, at harvesting; plant height, leave number, stem diameter, root and leaf fresh and dry weights were recorded. Root and leaf dry weight samples (each about 50 g) were determined by drying at 70°C until constant weight, using a forced-air oven.

Fruit characteristics and total yield

Fruit characteristics represented by fruit dimension (length and width, cm), number and weight (g) were determined. The fruit length and width (cm) was measured using a ruler from the end, up to the top of the fruit. The cumulative numbers of fruits harvested from each plot were recorded by counting the fruits of each crop during the fruiting stage until the end of harvesting (60 days from planting). The weight of each fruit was measured throughout the harvesting period using a digital balance and average fruit weight was recorded. Total yield (kg per plant) was determined as the number and weight of fruits per plant for all pickings (Ahmed and Shalaby 2012).

Fruit quality aspects

Six fruits from cucumber and summer squash per plot were picked coinciding with the commercial harvest for fresh consumption. Then, the fruits were cut into small slices and pooled. Samples were homogenized in a blender and portions of the homogenate were taken to determine the fruit quality. Parts of fruit slices were oven-dried at 70°C to constant weight and the dry weight content (%) recorded. The following fruit quality traits were registered: Vitamin C, total soluble solids (TSS) and titratable acidity (TA). Vitamin C was measured by NaOH (0.1 M) titration and the indophenol method (Horvitz, Hilo, and Reynolds 1970). TSS was determined in fruit juice using a hand held refractometer (PR-101; Palette Series, Atago Co., Ltd., Tokyo, Japan).

Statistical data analysis

All data were statistically analyzed using SAS version 9.0 (SAS Institute, Cary, NC, USA). A revised least significant difference (LSD) test at P ≤ 0.05 was then used to reveal significant differences among the means.

Results and discussion

TWC was evaluated as a new substrate in this study; tomato plant residues (leaves, stems green and damaged fruits) were collected from many farms in Riyadh city, Saudi Arabia. Subsequently, the composting process was carried out in three pilot-scale rotary drum bioreactors at the Educational Farm, Agricultural Engineering Dept., College of Food and Agriculture Sciences, King Saud University, Riyadh city, Saudi Arabia. After maturation and stability of TWC (Rashwan et al. 2020a), it was used as a complimentary growing medium to reduce using the expensive commercial peat-moss medium. The main chemical characteristics of TWC, which were measured in the lab compared with commercial peat-moss, are listed in Table 1.

Table 1. Chemical analysis of tomato waste compost (TWC) and peat-moss

Growing media parameters	TWC	Peat moss
OM (weight % in dry matter)	78.11 ± 0.17	95
Dry matter (%)	44.13 ± 0.14	< 75
Ash content (%)	21.89 ± 0.02	< 5.0
Moisture content (%)	57.00 ± 0.12	40–50
Porosity (%)	62.00 ± 0.81	60–90
pH	8.80 ± 0.03	< 6.0
Electrical conductivity (EC) dS/m	4.53 ± 0.01	< 3.0
C/N ratio	19.13:1 ± 0.89	20:1

Influence of TWC on growth, yield and fruit quality of cucumber and summer squash

To control the fitness of TWC as an acceptable complimentary growing medium for vegetable production, the growth, yield, production and quality characteristics of cucumber and summer quash plants under various ratios of TWC combined with peat-moss substrates were assessed under greenhouse conditions.

Influence of TWC ratios in growing media on plant height

The plant height of cucumber and summer squash was significantly influenced by different growing media treatments. Figure 2 shows the influence of the different TWC ratios in growing media on plant height of cucumber and summer squash plants at harvesting (after 60 days from transplanting and seed sowing date). The pure peat-moss media (0% TWC) significantly had the tallest cucumber and summer squash plants than those grown on other TWC ratios. Taller cucumber and summer squash plants were produced with pure peat-moss treatments (128.5 and 47 cm), respectively, followed by 15% of TWC treatment for cucumber (75.5 cm) and 5% of TWC treatment for summer squash (38.5 cm). On the other hand, increasing the compost ratio up to 30% led to decrease the values of the plant height trait (Figure 2). These results might be owing to plants grown in the pure peat-moss rooted more easily than those grown in the TWC or mineral wool media (Grunert, Perneel, and Vandaele 2008).

Figure 2. Influence of different TWC ratios in growing media on plant height of cucumber and summer squash plants at harvesting

Influence of TWC ratios in growing media on plant leaves number

Leaves number of both plants significantly increased under pure peat-moss growing media in comparison with other TWC ratios media at harvesting. Figure 3 shows the influence of the different TWC ratios on leaves number of cucumber and summer squash plants at harvesting (after 60 days from transplanting and seed sowing date). The pure peat-moss media (0% TWC) produced cucumber and summer squash plants with the significantly greater number of leaves, however, there were no significant differences compared with 5% and 15% TWC treatments in cucumber and between 5%, 10% and 15% of TWC in summer squash (Figure 3). On the other side, the higher TWC ratios (20% and 30%) in growing media were significantly worse in terms of number of leaves produced in both crops, probably because of high pH and electrical conductivity (EC) contents of TWC product. A similar trend was obtained in tomato by Al-Karaki (2000) and Romero-Aranda, Soria, and Cuartero (2001) who reported that the value of leave number decrease depending on the stress term, the plant species, and the cultivar involved. On the contrary, Jahromi, Aboutalebi, and Farahi (2012) reported that the increase in compost rate in growing media leads to increase in the number of cucumber leaves.

Figure 3. Influence of different TWC ratios in growing media on leave number of cucumber and summer squash plants at harvesting

Influence of TWC ratios in growing media on plant stem diameter

Cucumber and summer squash plants which grew under 5%, 10%, 15%, 20% and 30% TWC treatments at harvesting had smaller diameters, while those of pure peat-moss treatment were significantly thicker. Figure 4 shows the influence of different TWC ratios in growing media on the stem diameter of cucumber and summer squash plants at harvesting (after 60 days from transplanting and seed sowing date).

Figure 4. Influence of different TWC ratios in growing media on the stem thickness of cucumber and summer squash plants at harvesting

Dry weight partitioning

The differences in partitioning plant parts of both cucumber and summer squash plants were significant within the six substrate treatments. Plants which were grown under higher increase of TWC (20% and 30%) had a tendency for a higher reduction in dry weight (DW) partitioning of the root, leaf and fruit compared to plants under peat-moss or low levels of TWC treatments (Table 2). The root, leaf and fruit dry weights of cucumber and summer squash plants were highly significant reduced by applied by 20% and 30% TWC substrate. Since, both TWC treatments adversely influenced the dry weights of all separated plant parts, as indicated by the lower significant values of root, leaf and fruit dry weights. These results indicated that the development of most plant organs was closely related to the low amount of TWC applied up to 15% TWC. Schulz, Dunst, and Glaser (2014) reported that the addition of low level of compost to the soils increases the nutrient availability for the plants. On the other hand, insignificant differences were detected between peat-moss substrate (0%, TWC) and 15% TWC in their effects on root, leaf and the fruit dry weight of both plants. However, sometimes 15% TWC showed the superior influence, particularly with leaf and fruit dry weight of cucumber and summer squash plants than peat-moss substrate (0%, TWC) (Table 2). This means that 15% TWC was more effective on the leaf and fruit dry weight traits compared to the peat-moss substrate (0%, TWC) treatment. The increased number of leaves induced by the applied peat-moss substrate (0%, TWC) and 15% TWC could lead to stimulated photosynthesis and increased leaf dry mass (Abafita, Shimbir, and Kebede 2014).

Table 2. Root, leaf and fruit dry weights of cucumber and summer squash plants as affected by TWC substrate treatments

Crop	Cucumber			Summer squash
TWC (%)	Root DW (%)	Leaf DW (%)	Fruit DW (%)	Root DW (%)	Leaf DW (%)	Fruit DW (%)
0	10.77^A	51.40^B	5.00^A	18.60^A	14.63^AB	13.70^AB
5	8.73^B	49.93^B	4.97^A	10.20^B	11.00^D	13.10^B
10	8.89^B	44.99^C	4.80^A	8.93^C	14.45^B	13.80^AB
15	10.00^A	89.26^A	5.10^A	9.60^BC	15.15^A	14.90^A
20	8.33^B	28.41^D	3.60^C	5.80^D	13.43^C	9.30^C
30	2.26^C	23.08^E	4.20^B	5.00^E	8.60^E	8.00^C

Notes. Means within columns followed by the same letter did not significantly different at P ≤ 0.05 according to LSD. DW: Dry weight.

Generally, treatments with moderate amounts of TWC ratios up to 15% produces beneficial effects on plant growth due to the increase in the bulk density of the growing media, and to the decrease in total porosity and amount of readily available water in the pots (Abafita, Shimbir, and Kebede 2014; Grigatti, Giorgioni, and Ciavatta 2007). Such changes in the physical properties of the substrates might be responsible for the better plant growth with the lower doses of TWC. As it was proposed that high level of TWC ratio has inhibiting effects on cucurbits plants growth and development and the applied TWC substrate has a high pH (8.80, Table 1), therefore, it does not seem that the application of high level of 20% and 30% TWC would result in better economic results than that of the 15% TWC ratio. Many authors (e.g., Abad, Noguera, and Bures 2001; Diaz-Perez and Camacho-Ferre 2010) indicated that most greenhouse crops grow better in substrates with a pH ranged from 5.0 to 7.0. Therefore, according to the findings of our present study, it can be suggested that using TWC substrate up to 15% level, is optimum and economic for producing cucumber and summer squash.

Fruit characteristics and total yield

Fruit characteristics and total yield of cucumber and summer squash plants are presented in Tables 3 and 4. TWC culture media had a significant effect on length, width, number and weight of cucumber and summer squash fruits (P < .05). Treatment TWC (15%) had higher values of length, width, number and weight of fruits than other treatments followed by peat-moss substrate (0% TWC). On the other hand, the amount of cucumber and summer squash total fruit yield per plant in different substrates had significant differences at the 5% level. The higher amount of total fruit yield related to moderate TWC media (15%) had significant differences in higher rates of 20% and 30% treatments. However, the amount of cucumber and summer squash yield in 15% TWC was higher than the commercial peat-moss media, but they had insignificant differences (Tables 3 and 4). Higher fruit yields obtained with moderate rate (15%) of TWC imply that the optimal nutrient level was not attained at very low or high plant residue rates (Togun, Akanbi, and Adediran 2004).

Table 3. Cucumber fruit characteristics and total fruit yield per plant as affected by different TWC substrate treatments

	Fruit characteristics				Total yield per plant (g)
TWC (%)	Length (cm)	Width (cm)	Number	Weight (g)
0	14.80^B	2.90^A	8.50^AB	149.50^AB	1.20^A
5	14.70^B	2.30^C	7.25^AB	142.50^AB	1.03^AB
10	14.00^C	2. 50^B	7.00^AB	143.25^AB	1.00^AB
15	16.00^A	3.10^A	9.00^A	179.25^A	1.39^A
20	12.50^D	2.30^B	6.00^B	84.25^B	0.98^B
30	12.20^D	2.00^C	4.25^C	26.25^C	0.64^C

Notes. Means within columns followed by the same letter did not significantly different at P ≤ 0.05 according to LSD.

Table 4. Summer squash fruit characteristics and total yield per plant as affected by different TWC substrate treatments

	Fruit characteristics				Total yield per plant (g)
TWC (%)	Length (cm)	Width (cm)	Number	Weight (g)
0	12.70^A	3.52^B	12.25^A	295.50^AB	3.62^AB
5	10.80^B	2.28^BC	10.50^AB	191.75^ABC	2.01^ABC
10	10.70^B	2.55^BC	10.75^AB	168.25^BC	1.81^BC
15	13.30^A	3.80^A	13.00^A	327.25^A	4.25^A
20	10.50^B	2.06^E	7.75^B	123.50^C	0.957^C
30	10.10^B	1.99^E	5.00^C	67.50^C	0.405^C

Notes. Means within columns followed by the same letter did not significantly different at P ≤ 0.05 according to LSD.

The improvement in quantitative characteristics of cucumber and summer squash yields as a result of using peat-moss (0% TWC) or 15% TWC might be due to the enhancement of vegetative growth traits e.g., plant height, leaf number plant, and dry weight of plant organs, in these treated pots (Sabreen, Ibraheim, and Mohsen 2015; Sarhan et al. 2011). Increased leaf number and dry weights respond into an increased photosynthetic capacity of the cucumber plant, thereby enhancing plant growth and fruit development (Nair and Ngouajio 2010). These results may be related to sufficient physicochemical conditions in both peat-moss and 15% TWC that was affected by better supplement of water and nutrient elements for plants (Ghehsareh and Kalbasi 2012). In general, sufficient conditions with available bulk density and porosity in either peat-moss or TWC (15%) media caused good support of water and nutrient elements for plants, resulting in good growth with high fruit yield (Ghehsareh and Kalbasi 2012; Kumar and Goh 1999; Olympious 1992). On the other hand, the highest ratio of TWC treatment of 30% significantly decreased fruit dimension, fruit number, average fruit weight and total yield. A lower total fruit yield of 30% TWC plants was attributed to a clear reduction in the fruit number and average fruit weight of both cucurbits crops (Tables 3 and 4). Therefore, the productive response of the cucurbits plants to peat moss and 15% TWC substrate may focus on the induction of better growth conditions until fruit ripening (Pane et al. 2015).

Fruit quality aspects

Results presented in Table 5 indicate that peat-moss substrate (0% TWC) treatment significantly affected vitamin C content. However, 15% and 20% TWC treatments significantly affected total soluble solids (TSS) and titratable acidity (TA) of cucumber and summer squash fruits (Table 5). The results showed that the TSS values for summer squash fruit (7.10–8.20%) are double than those reported by Sabreen, Ibraheim, and Mohsen (2015), who found that the TSS of summer squash fruit were ranged from 3.88% to 4.33%.

Table 5. Quality aspects of cucumber and summer squash fruits as affected by different TWC ratios substrate treatments

Crop	Cucumber			Summer squash
TWC (%)	Vitamin C mg/100 g FW	TSS (%)	TA (%)	Vitamin C mg/100 g FW	TSS (%)	TA (%)
0	633.60^A	7.10^C	0.310^D	880.00^A	6.27^D	0.600^C
5	387.20^D	7.35^BC	0.670^B	581.00^D	6.85^C	1.100^BC
10	422.40^C	7.50^B	0.640^BC	759.00^B	7.92^B	1.100^BC
15	616.00^B	8.20^A	0.750^A	799.00^B	8.91^A	1.375^A
20	352.00^E	8.10^A	0.740^A	704.00^C	9.00^A	1.300^AB
30	211.20^F	7.93^A	0.590^C	686.00^C	8.73^A	0.900^C

Notes. Means within columns followed by the same letter did not significantly different at P ≤ 0.05 according to LSD, FW: Fresh weight, TSS: Total soluble solids, TA: Titratable acidity.

Generally, our results agree with those of Taiwo, Adediran, and Sonubi (2007) and Aminifard et al. (2013) who determined that compost applied at different concentrations improved TSS of tomato and pepper fruits. The maximum TSS and TA were produced at TWC 15% and 20% treatments, while the minimum TSS and TA values were obtained under peat-moss (0% TWC) treatment. Hence, increased TA by TWC 15% and 20% could be due to that, in order to maintain the carbon to nitrogen ratio (C:N) in the plants supplied with compost, the extra carbon may have been used for the production of organic acids like citric acid and malic acid, which are responsible for the acidity of fruit (Taiwo, Adediran, and Sonubi 2007). Thus, our data confirmed previous workers that compost increased levels of organic acids in fruits (Aminifard et al. 2013).

Conclusion

The results of using a different TWC ratio mix with peat-moss for growth, yield and quality of cucumber and summer squash indicated that the plant height of cucumber and summer squash plants was significantly influenced by different substrate treatments. Taller cucumber and summer squash plants were produced with pure peat-moss treatments (128.5 and 47 cm), respectively, followed by 15% TWC treatment for cucumber (75.5 cm) and 5% TWC treatment for summer squash (38.5 cm). On the other hand, increasing TWC ratio up to 30% led to decreasing values of plant height. However, 40% TWC caused plant mortality. The leaf area of cucumber and summer squash was also influenced by the ratio of TWC in the growing media. Leaves number of the two cucurbits species significantly increased under pure peat-moss growing media in comparison with other TWC media. The greatest number of leaves on cucumber and summer squash plants achieved with 0% TWC, however, there were no significant differences compared with 5% and 15% TWC in cucumber and between 5%, 10% and 15% of TWC in summer squash. According to the plant stem diameter, cucumber and summer squash plants resulted from 5%, 10%, 15%, 20% and 30% TWC had a smaller stem diameter, while those of peat-moss treatment were significantly thicker. Regarding total fruit yield per plant and fruit quality aspects, the moderate TWC substrate (15%) increased amount of cucumber and summer squash fruit yield more than the commercial peat media but they had insignificant differences. Also, it improved fruit quality characteristics, particularly TSS and TA of cucumber and summer squash fruits more than commercial peat-moss treatment.

Acknowledgment

The authors extend their appreciation to the Deanship of Scientific Research at King Saud University for funding the work through the research group project No. RGP-VPP-134.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Deanship of Scientific Research at King Saud University [Research group project No. RGP-VPP-134].

Notes on contributors

Mohamed A. Rashwan

Mohamed A. Rashwan Assistant Professor, Department of Agricultural Engineering, College of Food and Agricultural Sciences, King Saud University, Saudi Arabia. Assistant Professor, Department of Agricultureal and Biosystems Engineering, Faculty of Agriculture, Alexandria University, Alexandria, Egypt. I did postdoctoral studies at University of Alexandria, I hold a doctorate from Kagoshima University, Japan, in 2005 in the field of agricultural engineering. I am interested in working in environmental engineering fields such as compost production and greenhouse cooling. I also have an interest in solar energy and its uses in agriculture. I supervise a number of Master's theses. I have published and judged many research papers and authored many books in the field of agricultural engineering.

Fahad Naser Alkoaik

Fahad Naser Alkoaik Environmental engineering professor and head of department of agricultural engineering, college of food and agriculture Sciences, King Saud University. The main investigator of a project titled “Design and feasibility study of farm scale composting unit for the sustainable utilization of horticultural wastes in the production of alternative growth substrates for vegetables in greenhouses“. Supervising Master's and Doctoral students. Review many research papers, and attending many national and international conferences.

Mohamed Ibrahim Morsy

Mohamed Ibrahim Morsy Assistant Professor, Department of Agricultural and Biosystems Engineering, Faculty of Agriculture, Alexandria University, Egypt. He did postdoctoral studies at University of Alexandria, he hold a doctorate from Department of Civil Engineering and Geodesy, Techniche Universitat Darmstadt, Germany, in 2011 in the field of agricultural engineering. he is interested in working in environmental engineering fields such as properties of rice straw cementitious composite. He also has an interest in solar energy and its uses in agriculture. He supervises a number of Master's students. He has published many research papers and authored many books in the field of agricultural engineering.

Ronnel Blanqueza Fulleros

Ronnel Blanqueza Fulleros is working as a technician in the laboratory, where he makes various laboratory experiments and measurements and helps in writing scientific papers.

Mansour Nagy Ibrahim

Mansour Nagy Ibrahim works as a technician in the laboratory, where he conducts various laboratory experiments and helps in writing scientific papers and analyzing the results.