Valorisation of Biowaste and Aquatic Invasive Plants Through Compost Production for Agricultural Use

This study evaluates the quality of compost produced from household biowaste (CBIO), aquatic invasive plants (CAIP) and a mixture of the invasive plants and biowaste (CBAIP) and the effect of their application on maize yield in comparison with mineral fertilizer (NPK). The composts were produced using Aerobin 400 Composter with aquatic invasive plant harvested from the Owabi dam and solid biowaste collected from households within the Owabi catchment in the Ashanti Region of Ghana as feedstock. A field experiment in a 35 × 19 m plot of maize was conducted with 9 treatments of the different compost produced and mineral fertilizers in a randomized complete block design (RCBD) with 4 replications. The results show that the composts produced have acceptable quality with regards to nutrients (NPK), organic matter (OM), organic carbon (OC), bulk density, porosity, and heavy metal contents (Cu, Zn, Cd, Pb, As, Ni) among other properties. Grain yields following treatment with CAIP (2.06 ± 0.692 tons/ha), CBAIP (2.15 ± 0.668 tons/ha) and CBIO (2.052 ± 0.915 tons/ha) were similar to grain yields from NPK application (2.55 ± 0.611 tons/ha) but significantly higher than the control (1.34 ± 0.500 tons/ha) at 5%. The results show that the different compost types produced have beneficial impacts on maize yields comparable to NPK application. It is, therefore, concluded that aquatic invasive plants and biowaste are suitable feedstock to produce high-quality compost that can be applied to significantly improve grain yields.


Statement of Novelty
With global interest and appeal towards valorisation and advancement of circular bioeconomy concept, there is the need to explore novel and efficient means of utilizing organic materials to promote sustainable consumption and production.This study demonstrates the use of biowaste and aquatic invasive plants as feedstock to produce compost for agricultural use.While the use of biowaste and aquatic invasive plants as feedstock is not entirely new, studies in this area are piecemeal research that often focus on a single invasive plant species as feedstock when in reality many different invasive plants grow together and intermingle.In this study, an unsorted mixed of all invasive plant species in the Owabi dam is used as feedstock, thereby providing a more practical and cost-effective pathway for their valorisation and eliminating of their negative environmental impact.Using the Aerobin composters in this study also result in efficient destruction of the propagule of the invasive plants to prevent regrowth which is a major challenge for studies

Introduction
One of the oldest and yet widely adopted means of handling organic waste materials globally is composting.Composting is a controlled, aerobic biotechnological process that results in the decomposition of polymeric compounds in organic matter into simpler substances by the activities of microorganisms [1].The main product of this process called "compost" is a dark, humus and stable organic matter with an earthy scent that adds nutrients and improves the chemical, physical, and biological characteristics of soils [2].Generally, the preparation of compost is done as means of nutrient recovery for agricultural use or in some cases as a strategy for safe and more environmentally friendly means of waste disposal [3].There are also other purposes of compost production including as means of bioremediation [4], diseases and weeds control method [5], pollution prevention [6], land reclamation and erosion control [7] among many others.The purpose of compost preparation determines the feedstock use and the quality of the compost produced.
Many different organic materials can serve as feedstock for composting, but the commonly used ones include agricultural waste such as crop residues, animal wastes, food garbage, some municipal wastes, and suitable industrial wastes [2,8,9].There are essential properties of these materials that favour their usage as feedstock for composting including structural composition (cellulose, hemicellulose, and lignin content), elemental composition especially carbon to nitrogen ratio (C/N ratio), and electrical conductivity among other properties [2].High lignin content in the feedstock impedes degradation of the feedstock and therefore hinders the efficiency of the composting process and the quality of compost produced [10].A desirable C/N ratio of 15-30:1 of the feedstock is also important to ensure effective decomposition [11].The selection of feedstock for composting therefore requires an understanding of their quality and suitability for composting.
Besides the quality and characteristics of the materials, environmental factors such as aeration, pH, temperature and moisture level of the medium are also important to the success of composting [12].Producing quality compost, therefore, depends on not only selecting feedstock of desirable properties but also controlling the composting system to achieve optimal conditions.The preponderance of literature has shown that most compost are prepared with a combination of green waste (nitrogen-rich) and brown (carbon-rich) waste [6].Common examples of brown waste used in composting include fallen leaves, straw, woodchips, limbs, logs, pine needles, sawdust, and wood ash whereas the greens generally include fresh food waste, grass clippings, garden trimmings, and fresh leave [13,14].Animal manure such as poultry droppings, cow dung, swine and horse manure are also common feedstocks used for compost preparation [15,16].
The preparation of compost using waste serve an important purpose of environmental protection from pollution, supports agrarian livelihood and can also serve as a source of income for producers [17].The extent to which these benefits are realised depends on the feedstock and the efficiency of composting.In developing countries where municipal services such as waste collection and recycling services are scarce, compost preparation with household biowaste takes the burden of handling waste from households and reduces the risk of environmental pollution [6].Studies have also shown that the preponderance of household solid biowaste in these areas consist of food/kitchen waste, fruit/vegetable and crop residues which are often high in nutrient and promising feedstock for the production of high-quality compost for agricultural use [6,18,19].By composting these materials, therefore, substantial environmental and economic benefits can be envisioned.
Another group of promising feedstocks for quality compost production that has however not been well explored is lignocellulosic waste from harvested nuisance invasive plants [20].In many developing countries around the tropics, invasive plants are common in aquatic environments where they course injurious ecological and economic consequences [21].The most common means of handling these plants often involve harvesting and discarding/dumping which is neither a sustainable nor profitable means of managing them.Economic and ecological benefits can be derived from utilising these invasive plants for the preparation of compost.Invasive plants are generally carbon-rich lignocellulosic materials and as such their potential utilisation as feedstock for compost production is high.Evidence from studies such as that of [22,23] and [24] have shown that invasive plants such as Hydrilla verticillate, Eichhornia crassipes and Pistia stratiotes can be converted to compost of acceptable quality standard for agricultural use.
Despite the proven potential of both household biowaste and invasive plants as feedstock for compost production, they remain underutilised and poorly disposed posing a huge threat to environmental sustainability [25,26].In many developing countries, unsafe disposal of organic waste (biowaste) often leads to water pollution through eutrophication which then leads to the growth of invasive plants and therefore creation of other problems in these areas [27].In Ghana, for instance, the growth and threatening takeover of major water bodies such as the Owabi dam by invasive plants have been linked to indiscriminate disposal of organic waste.In this context, promoting compost production with household biowaste and invasive plants has the potential to address the environmental problem of pollution, and contribute to farming livelihood and income generation.To ensure these practices are adopted, however, require demonstrable evidence of success in the converting of available biowaste and invasive plants to quality compost that supports crop production.This research in response to this problem involves the preparation of quality compost from biowaste and aquatic invasive plants in the Owabi Catchment and determining the effect of the application of the compost produced on grain yield.

Collection of Feedstock
The feedstock for the compost preparation included mixed of aquatic invasive plants consisting of Ceratophyllum demersum (hornwort), Nymphaea odorata (water lily), Polygonum lanigerum, Arthropteris orientalis (water ferns), Typha domingensis (Cattail), Pistia stratiotes (water lettuce) and Cyperus papyrus (nutgrass) as well a mix household solid biowaste that included food/kitchen waste, fruit/vegetable, crop-residue, yard waste.The invasive plants were harvested from the Owabi dam (06° 43′N 01° 40′W) in the Ashanti Region of Ghana, while the household solid biowaste were gathered from households within communities in the Owabi catchment area.The harvesting of the invasive plants was done manually with the aid of simple hand tool including rake and cutlass and carried in canoe with the assistance of Water Laborers at the Owabi dams.The biowaste on the other hand were gathered fresh from households in communities within the Owabi catchment.

Preparation and Characterization of Feedstock
The feedstock consisting of both invasive plants and biowaste after harvesting were transported in fresh form to the site of compost preparation at the Department of Environmental Science at the Kwame Nkrumah University of Science and Technology (KNUST), Kumasi.To improve the composting process, the feedstocks were shredded to reduce the particle size to 3-5 mm for effective decomposition.Prior to composting, samples of each class of feedstock were taken for laboratory analysis.The invasive plant samples were prepared by shredding and evenly mixing each of the six (6) different invasive plant species.This was necessary to ensure that the samples analyse have an even composition of the different invasive plants that made up the feedstocks.Likewise, the biowaste were also evenly and thoroughly mixed before samples were taken for analysis.In all, nine (9) samples each of the mixed invasive plants, mixture of invasive plants together with biowaste and biowaste alone were taken for laboratory analysis.
The analyses were performed at the Soil Science Laboratory at the KNUST.The parameters analysed included the structural compositions (lignin, cellulose, and hemicellulose content), pH, carbon, nitrogen and potassium content as well as moisture content.The Van Soest Method for neutral detergent fibre (NDF) and acid detergent fibre (ADF) procedure was used to establish the concentration of lignin, cellulose, and hemicellulose in percentage weight in volume (% W/V) basis.The pH of the samples were measured using a pH probe (PHYME Cobros 3 basic unit USB, Germany) while the C and N were determined using an elemental analyser (Model LECO CHN628 and 628S, St. Joseph, MI, USA) following the ASTM D-5291 standard method.Total organic carbon of each sample was determined using a high-temperature combustion process base on standard method (ASTM D7573).The soluble chemical oxygen demand (sCOD) of each sample was measured using mercury-free dichromate method [28] with the sample filtered with a filter of 0.45 mm to remove interference of biological activities.The oxygen uptake rate (OUR) of the samples was also determined using the Standard Method 1683 Specific Oxygen Uptake Rate (SOUR) in Biosolids [29].
The feedstock characteristics obtained from the laboratory analysis are presented in Table 1.The C/N ratio of both the invasive plants, biowaste and their mixture as feedstock were within the desirable range of 1:15-30 [11] although biowaste feedstock has a lower ratio as compared to the invasive plants.The lignin content was higher in the invasive plants than that of the biowaste.The ratio of cellulose to hemicellulose was comparable between the invasive plants and biowaste feedstock with the latter however having a higher content of both cellulose and hemicellulose.The pH of the invasive plants' feedstock is 5.5-8 and that of the biowaste was 6-8.6 indicating both classes of feedstock have desirable pH levels suitable for composting.The organic carbon content was greater than 40% for each feedstock type.Soluble Chemical Oxygen Demand Rate (sCOD) is 114.5 mg/L for the invasive plants alone feedstock, but 126.0 mg/L for the biowaste only feedstock.The Oxygen Uptake Rate (OUR) for the invasive plants only feedstock is 14.4 mg/g VS/day, 15.6 mg/g VS/day for mix invasive plants and biowaste but 17.7 mg/g VS/day for biowaste only feedstock.

Description of Composting System
The compost was prepared in three Aerobin 400 Composters each with a capacity of 400 L mounted at the Department of Environmental Science of the Kwame Nkrumah University of Science and Technology, Kumasi.The Aerobin as shown in Plate 1 is designed for all-year-round aerobic hot composting.The Aerobin 400 Composters is very efficient means of composting with finish compost ready usually within three (3) months.When assembled, the Aerobin 400 measures 740 × 740 mm and stands 1200 mm high.Each Aerobin weighs about 26 kg when empty and up to 400 kg when loaded.The vessel has a moisture recirculation system that helps maintain the correct moisture level of biomass during the composting process.It also has an aeration lung that provides ventilation to the centre of the composting material and thus no digging or turning of the compost is required.In addition to the above, the vessel (Aerobin 200) also has a leachate reservoir at the base of the Aerobin for collecting rich compost tea which can be used as liquid fertilizer.The vessel also has an insulated wall and lid that provide optimum conditions for rapid composting all year round, even in freezing conditions.Preparation of compost using the Aerobin 400 reach high temperature of over 50 °C which kills pathogens, inoculates weeds and their seeds and creates good quality compost in a short period [23].

Compost Preparation Process
To maximize the potential moisture of the material, the compost preparation was done within 48 of collection of the compost feedstock.Three while the feedstock with invasive plants alone reach about 35 °C in the first two weeks.The temperature in each pile were higher than the ambient temperature until week 14 when the temperature levels were equal, an indication that no or very little decomposition taking place at this time.

Compost Sampling and Analytical Methods
Compost samples for analysis were taken after the compost were matured and cured.The compost was considered matured when further degradation was no longer taking place as indicated by the fact that the temperature of the medium was equal to the ambient temperature.The sampling was done utilizing the grab sampling technique after the vessels were empty and the compost evenly mixed.All six samples of each compost type were taken for analysis.The samples were analysed for pH, Soluble salt (EC), nutrient content (NPK), organic matter, moisture content, stability, bulk density, porosity, and presence of heavy metals.An electronic pH meter (PHYME cobros 3 basic unit USB, Germany) was used to measure pH while moisture, bulk density was measured using the gravimetric method.Organic matter was measured using the loss-on-ignition organic matter method while conductivity was measured with the Jennway Conductivity meter (Jenway model 4010, UK).
To determine the N content, Total Kjeldahl Nitrogen was used based on standard method [30], phosphorus and potassium were determined using the calorimetric method in line with standard Method 365.1 for the determination of phosphorus by semi-automated colorimetry [31] and Method CN1081764A [32].The atomic absorption spectrometer (AAS) (Varian Spectra 55B) was used to measure the concentration of heavy metals which included copper (Cu), cadmium (Cd), zinc (Zn), lead (Pb), Arsenic (As) and Nickel (Ni) [33].The Chemical Oxygen Demand of the composts were measured periodically using the dichromate method based on the oxygen equivalence of the OM in the sample oxidizable by potassium dichromate (K 2 Cr 2 O 7 ) in 50% sulfuric acid solution [28].A respirometry (CO 2 evolution) test was conducted to determine the stability of the compost using the OECD 301B standard method of CO 2 evolution test [34].The carbon dioxide (CO 2 ) evolution rate for the compost produced are presented in Fig. 2 showing reduction from more than 12 mg/g/day in the first day of composting to below 2 mg/g/day at the end of the composting period.The COD reduction profile is also presented in Fig. 3, with initial values above 800 mg/L to below 200 mg/L at the end of the composting period.

Compost Trial Experiment
A field experiment involving the compost produced was done at a demonstration farm located within the Owabi catchment.Randomized Complete Block Design (RCBD) experimental design was used.The crop used was maize since this was found to be the most commonly grown staple crop in the study area.The experimental plot size was 665 m 2 (35 × 19 m) with a treatment plot size of 12 m 2 (3 × 4 m), 4 replications and nine (9) treatments.The treatment included compost from biowaste (CBIO), compost from invasive plants (CAIP), compost from invasive plants and biowaste (CBAIP), and mineral fertilizer (NPK).The recommended application rate of compost of 4000 kg/ha was used as a treatment for CBIO, CAIP and CBAIP as well as half-recommended rate (2 tons/ha) as treatment and labelled as 1/2CBIO, 1/2CAIP and 1/2CBAIP respectively as treatment.The standard rate of 100 kg/ha of NPK as well as half the recommended rate was also used as treatment.
The planting took place in September 2019 with the treatments applied two weeks after germination.Plant height was measured daily for the first 4 weeks and thereafter measurements were taken weekly.The number of leaves was also taken throughout this period.No-tillage was done before the planting of the maize.The agronomic practices undertaken included weed control with Sunphosate and pest control with a suitable pesticide.Harvesting was done in December 2019 with measurements that included economic yield measurement and biological yield (biomass).The second planting took place in March 2020 at a different plot within the same vicinity, with similar agronomic practices and measurements taken and harvesting done in June 2020.The third planting which was intended to find the residual effects were done in the first experimental plots with no treatment applied.

Field Experiment Measurement
The measurement taken from the experimental fields includes germination rate, plant heights, number of leaves, grains yields and above-ground biomass.The grain yields were measured after the plants were harvested from each plot's area of 4 × 3 cm.The grain yields were measured as the ratio of the weight of dried grain obtained per unit area extrapolated to hectares.Likewise, the above-ground biomass (biomass) was given as the weight of total harvest per unit area extrapolated to hectares.

Statistical Analysis
Data for analysis included data on the compost quality parameters/properties as well as data from the field experiment.The analysis of the data was performed using R-studio version 4.1.1.The analysis involves use of both descriptive and inferential statistics.The descriptive statistical analysis involved frequency count and measures of central tendencies (mean, median and mode).The inferential statistical analysis that were performed included a comparison of mean test that included mainly One-Way and Two-way Analysis of variance together with Tukey HSD tests.The one-way ANOVA was employed to compare the average (mean) level of the compost properties across the different compost types.The two-way ANOVA was employed to determine the effect of different fertiliser types, rate of application and interaction effects on crop (grain) yield and above-ground biomass.

Properties and Quality of Compost Produced
In this study, the characterisation was limited to the nutritional composition (NPK), organic matter (OM) and total organic carbon (OC) content, conductivity, moisture content, pH, bulk density, and porosity as well as heavy metals content.These properties have been described in many studies including that of [35,36] and [1] as core properties of compost that ensure the availability of nutrients and improve soil properties favourable for plant growth.The outcome of this study on the nutritional content of the different compost produced are presented in Fig. 4. The results generally confirm [37] assertion that compost has low nutrient content when compared to mineral fertiliser per unit weight.All three (3) types of compost have N composition of 1.8-2.2%db, P of 0.17-0.89%db and K of 0.54 to 0.83% db for the different compost types.The results however show that except for K, the remaining nutrients are proportionally comparable to that of standard compost requirements of about 2% N, 0.5-1% P and about 2% K [38].
The results show with a 1.8% dry basis (db) composition, CBIO has lower nitrogen (N) content than CBAIP and CAIP.Generally, plant-based feedstock such as the CAIP tends to produce compost of lower P content [39].The results confirm this assertion as the CBAIP have a high P of 0.89% relatively compared to 0.17% of the CAIP.The amount of potassium in the composts also varies significantly across the different compost types with the highest in CBIO (0.84%) and the least in CAIP (0.54% db).As [2] have noted, the quality of compost with regard to nutrient values is dependent on the feedstock used.The lowest K (0.54%) was obtained from compost with invasive plants only as feedstock (CAIP) while the highest (0.83%) was obtained from compost from household waste where potassium-rich materials such as banana peels were included.
The results showing organic matter (OM), moisture content (MC) and porosity are presented in Fig. 5. Organic matter content shows the content of organic carbon, water and other ingredients necessary to improve soil structure, nutrient availability, and water holding capacity among others [40].The results show an OM content range of 29.7-55.1% for all the compost types.According to [41] the acceptable OM content of compost is about 30 to 70% db.The OM range of the compost types are comparable to standard compost.It is however noted that OM of CAIP was the lowest (29.7% db) while that of CBAIP and CBIO were more than 50% db, an indication that the OM content was driven by the biowaste feedstock constituent.While high OM is an important indicator of the ability of the soil to hold water, supply nutrients and improve aeration and other properties, a very high OM is often the result of inefficiency in the composting process.As [1] has noted, usually very high OM (> 65%) in compost is an indication that the feedstocks are not thoroughly decomposed which may lead to OM lost after application as further degradation take place.The observed OM ranges of 29.7-55% fall within the optimal range that indicate good quality compost.
The moisture content and porosity of the composts are also presented in Fig. 5.The MC was found to have ranged from 41.67 to 49.3 wt% db while the porosity ranges from porosity of 66.4% to 76.5%.Usually, compost with high moisture content (> 60%) are clumsy and its application on the field become difficult while those with low MC (< 40%) are dusty and may cause respiratory problems.The results of this study show the compost produced were neither too high in moisture nor low.Low porosity (< 30%) of compost can lead to the creation of anaerobic conditions while very high porosity (> 80%) can lead to excess cooling [42].
The bulk density of the composts were also determined and the results show range of from 423.3 k gm −3 to 527.2 kg m −3 with the highest recorded by CBAIP and the lowest by CBIO (Fig. 6).The bulk density of the composts which was lowest (423.3 kg m −3 ) in CBIO, and the highest of 527.2 kg m −3 in CAIP were generally within an acceptable range of 420 to 655 kg m −3 that supports soil structure, aeration and solute movement [43].This is further evident by the porosity of 66.4-76.5%.It is important to note that the highest bulk density and lowest porosity were recorded in the CAIP which was largely due to the uniformity in the materials for this compost type (invasive plants) as compared to CBAIP and CBIO with heterogenous sizes and types of materials as feedstock.
Other important properties and characteristics of the composts produced including conductivity (EC) in dS m −1 and pH are presented in Fig. 7 and Table 2 respectively.The results show that EC ranges from 3.5 to 5.75 dS m −1 with the highest recorded in CBAIP while the least was record by the CBIO.Also, CBIO recorded a significantly different pH from that CAIP and CBAIP.High EC (> 7 dS m −1 ) can potentially be injuries for plants while low EC (> 7 dS m −1 ) could also deny plants of sufficient nutrients in the form of soluble solid Sullivan et al.The EC of the composts ranging from 3.8-5.75dS m −1 can be said to be ideal for plant growth.
Usually, plant-based feedstock compost has a pH that is moderately acidic to moderately alkaline [44] but the CAIP Fig. 5 The organic matter (OM), moisture (MC) contents and porosity (Po) of compost from the different feedstocks (CAIP, CBAIP and CBIO).N.B.Bars with different letters in the same cluster are different at 5% from the Tukey HSD test Fig. 6 Bulk density of Composts.N.B.Bars with different letters are different at 5% from the Tukey HSD test was found to be slightly more alkaline (pH of 8.2-9.9) as presented in Table 2. Most compost ends up with a pH that is slightly alkaline due to the mineralisation of nitrogenous compounds in the feedstock to form ammonia and ammonium, especially at the mesophilic stage leading to an increase in pH [45].This is observed in the case of CAIP with a pH of 8.2-9.9.Low pH on the other occurs usually due to the formation of fatty acids especially the saturated type which do not often get decomposed through the composting process [46].Most compost without the problem of saturated fatty acid formation has a pH of 7.2 to 8.3 [47] as seen in the case of CBAIP.This type of compost may be unsuitable for acid-loving plants but generally acceptable for most crops.Among the important properties and characteristics of the compost produced include the amount of heavy metals present.Compost with high heavy metal content may be unsuitable for plant growth due to their effect on soil properties but more importantly because of the possibility of contamination and bioaccumulation along the food chain [48].The relevant heavy metals content analysed in this study included arsenic (As), zinc (Zn), copper (Cu), cadmium (Cd), lead (Pb) and nickel (Ni).The results showing the concentration of these invasive plants in the different compost types are presented in Fig. 8. From the results, it is noted that the range of As content in the composts were 0.486-0.833mg kg −1 while that of Cd were 0.727-2.467mg kg −1 .The heavy metal in the highest concentration in the compost were Cu and Zn with a respective range of concentrations of 116.3-273.7 mg kg −1 and 114.6-243.9mg kg −1 .
While it is impractical to expect compost to have no heavy metal, many general standards exist giving thresholds within which many heavy metals are less problematic.
A study by [49] also opined that immobilisation of some heavy metals may occur during composting, however with a decrease in mass and volume of the compost feedstock, the concentration of the heavy metals may turn to be higher in the final product.Globally acceptable threshold for Pb is 100-200 mg kg −1 , Cd is 1.5-10 mg kg −1 , Cu is 100-150 mg kg −1 , Ni is 50-120 mg kg −1 , Zn is 400-1300 mg kg −1 and As is 10 mg kg −1 [50].The results show that the different compost types have heavy metal concentrations within acceptable threshold except for Cu content in CBIO which was 273 mg kg −1 .High Cu in compost (soil) may inhibit enzyme activities and cause toxicity to plants, animals and even humans due to bioaccumulation with food chains [51].Evidence from some studies however suggests that the moderately high Cu content in compost does not impede soil enzyme activity [52].A recent study by [53] also concluded that high Zn and Cu did not adversely affect crop performance in terms of seed germination, growth and yields.It is therefore expected that the relatively high Cu in CBIO has no detrimental effects on crop performance.

Effect of Compost Fertilizer Treatment on Yield Of Maize
For agricultural purpose composts, the most convincing and demonstrable evidence of quality is determined by the extent to which the application of the compost contributes to enhancing crop performance.The mechanism through which the application of compost improves crop output is usually in relation to their contributions to improving soil health and fertility [54].Against this backdrop, the effect of the different compost and NPK fertilizer treatment on output parameters of maize namely yields (tons/ha) and biomass (tons/ ha) are analysed.The results in Fig. 9 show the response of yields of maize to treatment with the different composts and NPK mineral fertilizer treatment.The results in Fig. 10 also show the response to a different rate of treatment or  fertilizer application (full = recommended rate; half = half the recommended rate and none = control) while Fig. 11 show the interaction effect of fertilizer type treatment and rate of application.
From the results, it is noted that the average yields from treatment with each compost type (CAIP = 2.06 tons/ha, CBAIP = 2.15 tons/ha, CBIO = 2.05 tons/ha) and NPK were significantly higher than the yield of 1.34 tons/ha without treatment (control).No difference is observed with regard to average yields of maize from the different fertilizer treatments.The result of this study thus supports the assertion that the application of compost produced from biowaste and aquatic invasive plants improves the average grain yields of maize.Compost from different feedstocks with different properties are expected to have different effects on crop output with the highest quality compost expected to have the highest crop output [55].This study however found no difference with regard to average grain yields from CAIP, CBAIP and CBIO applications indicating that the compost types have comparable effects on crop yields.The study also found no difference between grain yield from composts application and mineral fertilizers (NPK).This show that the composts produced are of comparable effect to the application of NPK mineral fertilizer.
An important consideration in compost and fertilizer application is the rate of application.A lower application rate reduces the cost of inputs but can potentially compromise output.An optimal rate of application minimises the input costs at the same time maximises yields [56].For this reason, the effect of applying each compost type at the recommended rate (full) of 4 tonnes ha −1 and mineral fertilizers of 100 kg ha −1 and half recommended rate (2 tons ha −1 for compost and 50 kg ha −1 for NPK) were compared.The results as shown in Fig. 10 demonstrated that recommended (full) rate applications resulted in higher yields (2.65 ± 0.59 tons ha −1 ) than that of half recommended rate (1.75 tons ha −1 ) and control (1.34 tons ha −1 ) at 5%.No difference exists between the control and half-recommended fertilizer rate application.This show that there is no benefit in applying the half-recommended rate of either compost or the NPK.The interaction effect of fertilizer types of application and rate of application as presented in Fig. 11 is not significant.This means effect of the treatment on yields is not dependent on the rate of application.
With above-ground biomass as the output, a significant difference was found between CBIO and NPK applications compared with CAIP, CBAIP and the control.Above-ground biomass from CAIP and CBAIP application were not different from that of the control but the average biomass from the use of recommended application rate (5.79 × 10 3 tons ha −1 ) was higher than the application of  half recommended rate and control.This result means that CAIP and CBAIP applications offer no biomass benefits over the control.This also means that if the intended output from the maize production is above-ground biomass, then CBIO and NPK should be applied for higher yields.The difference in biomass is attributable to the significant difference in some properties of the composts produced.For instance, organic matter (OM) content in the CBIO were significantly higher than that of CAIP and CBAIP which perhaps accounted for the difference in performance with regard to above-ground biomass.The effect of the application of either fertilizer as well as the rate of application resulted in no difference in harvest index and an indication of no imbalance in biomass to grain yield ratio across the different fertilizer treatment.
The results also show significant differences in the comparison of total above-ground biomass of the crops following in response to the different treatments (CAIP, CBAIP, CBIO and NPK).As seen in Fig. 12, biomass from NPK application of 5.7 tons ha −1 and that from CBIO application of 4.8 tons ha −1 were higher than the average biomass from other fertiliser applications and the control.The results show biomass from CAIP and CBAIP application were not different from that of the control.Likewise, in Fig. 13, it is noted that the average biomass from the use of recommended application rate (5.92 tons ha −1 ) was higher than the application of half recommended rate and control.No difference exists between biomass yield from the halfrecommended fertiliser application rate and control.The interaction effect of fertiliser types and application rate on biomass yields is not significant (Fig. 14).

Conclusion
The production of compost from organic waste materials can address the problem of waste management and at the same time contribute to improving crop production.Demonstrably evidence of the ability to produce compost with high quality from available feedstocks and improvement in agricultural productivity is required to promote such practices, especially in developing countries.The evidence from this study shows that various aquatic invasive plants, as well as household  biowaste as feedstock, resulted in compost with high quality and acceptable levels of nutrients (NPK), OM, OC, MC, bulk density, porosity, and heavy metal (Cu, Zn, Cd, Pb, As, Ni) among other properties.This means that biowaste and invasive plants can be used to produce compost of high quality.
The application of the compost made from invasive plants (CAIP), a mixture of invasive plants and biowaste (CBAIP) and compost from biowaste only (CBIO) resulted in maize grain yield levels higher than control and comparable to NPK application.This also means compost produced using aquatic invasive plants and biowaste as feedstock can be used to improve agricultural productivity.

Plate 2
(3) of the Aerobin 400 Composter were used to prepare three (3) classes of co-compost, one with only the invasive plants (CAIP), one with only the mixed household solid biowaste (CBIO) and the other mixture of invasive plants and biowaste (CBAIP).The feedstocks were weight before loading into the three (3) different Aerobins.For the Aerobin with only invasive plants (CAIP), the total weight of the feedstock that filled the vessel was 97.1 kg, that with biowaste (CBIO) contained 98.4 kg of biowaste whereas that of the mixed invasive plants and biowaste (CBAIP) was 194.6 kg (comprising 112.6 kg of biowaste and 82 kg of invasive plants).The composters were tightly closed after filling with the feedstock and watering.A 5 litter plastic container was attached to each of the leachate reservoirs to collect the leachates.The output of the CAIP compost was 52.2 kg indicating 46.2% mass reduction; the CBAIP compost output weigh 79.5 kg indicating mass reduction of 59% while the CBIO compost output weigh 66.5 kg indicating mass reduction of 46.3%.The relatively high mass reduction is a result of the high moisture content of the feedstock.The compost process and output are presented in Plate 2.The composting process was monitored for temperature, pH, and maturity on each composter vessel over the entire duration of the compost preparation.A fast response compost thermometer (ReoTemp Instrument Corporation, San Diego, CA) was used to measure the temperature within each composting vessel at 10 inches, 20 inches and 30 inches with averages recorded per each measurement daily.The pH were also measured and recorded with a hand-held Kelway soil pH sensor (Kel Instruments Co., Inc., Wyckoff, NJ) throughout the composting period.The moisture content was measured using ''feel'' test which involve taking a handful of compost and squeezing it to see if it feels like a moist sponge.The first round of composting lasted for 98 days from July 1, 2019, while the second round lasted for 91 days.The temperature profile of the compost production are presented in Fig.1.The temperature in the Aerobin with biowaste feedstock reach over 55 °C in the first two weeks, that with a mixture invasive plant and biowaste reached 46 °C, Composting Process and Final Output of Compost from Different Feedstock.NB: CAIP Compost produced using only invasive plant feedstock, CBAIP Compost produced using invasive plants and biowaste, CBIO Compost produced from only biowaste 1 3

Fig. 1
Fig. 1 Temperature trend for different composting time Fig. 2 Carbon dioxide evolution rate (mg/g/day)

Fig. 7
Fig. 7 Conductivity of compost produced (CAIP, CBAIP and CBIO).N.B.Bars with different letters are different at 5% from the Tukey HSD test

Fig. 9
Fig. 9 Yields levels from different fertilizer treatment

Fig. 11
Fig. 11 Interaction effect of fertilizer types and rate of application on yields levels

Fig. 12
Fig. 12 Biomass level at different fertilizer application

Fig. 13 Fig. 14
Fig. 13 Biomass at different rate application of compost and NPK

Table 2
Concentration of heavy metals in the compost produced (CAIP, CBAIP, CBIO).N.B.Bars with different letters in the same cluster are different at 5% from the Tukey HSD test: * values are in 100