Response of Soil Chemical Properties under Tef ( Eragrostis tef (Zucc.) Trotter) Field to Integrated Application of Lantana camara L. Weed Vermicompost and NPS Mineral Fertilizer

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Introduction
Lantana camara L. weed is mostly native to subtropical and tropical America, but a few species belong to tropical Asia and Africa [1].Tis weed is among the worst weeds of terrestrial ecosystems characterized by tolerance for adverse environmental conditions, high germination rate, and speedy encroachment of lands, all these make the weed an aggressive biological invader [2][3][4].It is the 10th most harmful weed in the world [5].Lantana camara competes with other plants for space, water, and nutrients, and its allelopathic efect stunts the growth of neighboring plants, thus reducing the productivity of crops, pastures, and forest areas [3,6].
Due to all the problems associated with L. camara, researchers have tried to manage and eradicate this invasive weed using mechanical, chemical, and biological methods [3,7].Utilization options such as using L. camara as cellulose [8], ethanol [9], drugs [10], biogas [11], and furniture [3] were also considered as possible ways of managing L. camara invasion.However, not all of these options were economically viable to reduce the ever-increasing biomass of Lantana camara.Instead, vermicomposting of L. camara weed appears to be a feasible way to manage its huge biomass for nutrient recovery by avoiding its allelopathic efect, sequestering carbon, and maintaining soil fertility on a sustainable basis [12].Lantana camara is rich in nutrients, hence vermicomposting can be an appreciated source of nutrients for soil amendments and has a better nutrient availability than traditional composting [13,14].Vermicompost is a nonthermophilic biodegradation product of organic material by the action of vermiworms and microorganisms which is characterized by low mass, requires short processing time and high humus content and reduces infestation of plant diseases when used as fertilizer; it usually has a greater nutrient content than compost and contains plant growth promoting compounds [15][16][17][18] and avoids the problems of nutrient loss and soil toxicity relative to conventional organic amendments [19].Vermicompost is low in cost and an environmentally friendly method of treating organic wastes and controlling invasive terrestrial weeds [20,21].Vermicomposting eliminates the toxicity efect of L. camara and converts it into suitable plant nutrients [12,22].Additional welfare of organic fertilizers is the retention of nutrients from applied chemical fertilizers by protecting against loss through leaching, subsequently making the nutrients available for plants [23].Studies highlighted that vermicompost could replace 25-50% of the recommended chemical fertilizer doses [24].Farmers who use organic fertilizer increase their income by US$132 ha −1 and reduce poverty by 8% compared to farmers who do not use organic fertilizer [25].Recent research revealed that L. camara vermicompost could increase the yield of the tef crop by 26.47% than untreated plots [26].
Indeed, organic fertilizers alone cannot substitute for inorganic fertilizers in the production of high yields [27].As a result, chemical fertilizers of nitrogen (N) and phosphorus (P) have been the primary nutrients applied in the world, even in the study region, Tigray, in the form of urea and diammonium phosphate (DAP), respectively, since the introduction of chemical fertilizers to Ethiopia in 1967.Tey have now been replaced by mineral fertilizers consisting of N, P, and sulphur (S), designated as NPS.Even though the majorly distributed fertilizer at current is NPS, no optimum rate is developed for most pillar crops of the study area.Previous research showed that chemical fertilizers could increase yields by up to 30-50% relative to nonusers of chemical fertilizers [28].Te fnding of Kinfe et al. [26] also revealed that improved tef crop yield was found from the application of 150 kg•ha −1 of NPS fertilizer.However, chemical fertilizers can deteriorate soil's physical and chemical properties, thereby causing nutrient imbalances in the soil [29] and environmental pollution [30].Intensive use of chemical fertilizers often leads to nonsustainable agricultural production and causes a serious threat to soil health [31].Furthermore, farmers have limited access to chemical fertilizers because of unafordable prices and sometimes because of nonavailability in the local market.Conversely, organic fertilizers are afordable and easily accessible to the farmers [20].Terefore, soil fertility management is an effective way to maintain soil fertility, thereby increasing crop production per unit area and creating social and economic acceptance [32][33][34].Research performed on the integrated application of 4 t•ha −1 of L. camara vermicompost and 150 kg•ha −1 of NPS fertilizers revealed better grain yield of the tef crop [26].
In the study area, North Western Tigray region, encroachment of L. camara is occurring in degraded lands and arable, forest, and grazing areas and this is detrimental to the native plants due to its toxic efect [35][36][37].Hence, eforts were made to produce vermicompost from L. camara considering controlling this weed through vermicomposting [38] with the help of Eisenia fetida worms.Tis would simultaneously produce vermicompost and control further expansion of the Lantana camara.Besides, no research has been performed on the use of L. camara vermicompost focusing on its efects on soil chemical properties.Taking all these aspects into consideration, the present study was, therefore, conducted to evaluate the efects of applying various rates of L. camara vermicompost amendment and mineral fertilizer of NPS on diferent soil chemical properties.

Area Description.
Te feld experiment was conducted at the Shire Soil Research Center site in Beles Tabia (Tabia is the smallest administration unit), Tahtay Koraro district, North Western province of Tigray regional state, Ethiopia (Figure 1), for two consecutive years during the 2016 and 2017 main cropping seasons under rainfed conditions.Te altitude of the district is 1957 meters above sea level.Te dominant soil type in the area is Eutric-Vertic Cambisols [39].Te dominant agricultural practice was mixed crop and livestock farming systems.Te study area is found in a semiarid climatic zone.Te rainfall distribution was monomodal with erratic characteristics.During the study period, the study site received annual rainfalls of 1088.7 and 919.5 mm for the whole years of 2016 and 2017, respectively [40].Te annual mean temperatures were 20.7 and 20.8 °C for the years of 2016 and 2017, respectively [40].

Vermicompost Preparation and Its Chemical Properties.
Fresh stems and leaves of L. camara were collected from areas encroached by L. camara and then chopped into small pieces.To reduce the toxicity efect of L. camara and cow dung on worms, they were frst allowed to air dry for two weeks and then used as vermicomposting materials.During the vermicomposting process, no signs of the toxic efect of L. camara on the organisms were observed, which is why the worms favorably consumed the weeds.Many researchers 2 International Journal of Agronomy have suggested that phenols and lactones which are responsible for the toxic efects of L. camara were broken down during the vermicomposting process.It was also found that the lignin content of L. camara was reduced during the vermicomposting process [12,22].As observed in the present vermicompost study, the ability of Eisenia fetida to convert the feeding raw materials into vermicompost was 70%.Te proportion of L. camara compared to cow dung used during the production of vermicompost was 75% and 25%, respectively.To produce 6 t of vermicompost, 133,254 Eisenia fetida worms were fed on 6.57 t of L. camara biomass and 2.14 t of cow dung biomass.Te worms consumed the biomass and excreted it in a digested form called vermicast or vermicompost.Te vermicompost matured within 45 days and at this period it was collected.Te worms were separated from the vermicompost by sieving.Te worms captured in the sieves were added to other fresh feeding material.Te separated L. camara vermicompost was allowed to dry in the shade before using it for analysis and soil amendment.Dry L. camara vermicompost samples passed through a 2 mm sieve were analyzed for total organic content (TOC), total nitrogen (TN), carbon-to-nitrogen ratio (C : N), total phosphorus (TP), total potassium (TK), pH, and electrical conductivity (EC) (Table 1).Te pH and EC were analyzed through a pH meter and conductivity meter, respectively, in vermicompost water suspension at a 1 : 10 ratio [41].Te total organic content was analyzed by the chromic acid wet digestion method [42] and the macro-Kjeldahl method for the analysis of TN followed by Humphries [43].Te total phosphorus was analyzed by the colorimetric method, molybdenum in sulphuric acid by the vanadomolybdate yellow color method, and TK was analyzed by the fame photometric method [41].Te carbon-tonitrogen ratio of L. camara vermicompost was calculated by dividing the TOC with the TN.

Soil Sampling and Analyzed
Parameters.In the frst year, before planting the tef crop, one composite soil sample was collected from the two-year established permanent experimental site at a depth of 0-20 cm using a soil auger.Te sample was used for site characterization.Right after harvesting tef in the second year, 48 samples were taken from each permanent plot to determine the cumulative residual efects of L. camara vermicompost amendment and NPS fertilizer on some selected soil chemical properties.When organic fertilizers are added to the soil, their impact on soil properties is visible when the application is spread over more seasons rather than just one.Te sampling therefore took place as a part of the last two-year experiment.Samples were air-dried, crushed by grinding, and allowed to pass through a 2 mm size sieve for general analysis and a 0.5 mm size sieve for soil organic carbon (SOC) and total nitrogen (TN) analysis.Soil texture was determined using the Bouyoucos hydrometer method [44].Te pH and soil electrical conductivity (EC) were analyzed through a pH meter [45] and conductivity meter [46], respectively, in soil water suspension at a 1 : 2.5 ratio.Soil organic carbon was determined using the wet digestion method [42].Te total nitrogen was measured using the Kjeldahl method as described by Bremner and Mulvaney [47].Te carbon-to-nitrogen (C : N) ratio of soil was calculated as a proportion of SOC to the TN.Plant-available phosphorus (Av.P) was analyzed by employing the Olsen method [48] using ascorbic acid as the reducing agent.Exchangeable cations of calcium (Exc.Ca 2+ ), magnesium (Exc.Mg 2+ ), sodium (Exc.Na + ), and potassium (Exc.K + ), and cation exchange capacity (CEC) of the soil were determined by the ammonium acetate extraction method.Exchangeable sodium percentage (ESP) was determined as a proportion of Exc.Na + to the CEC of the soil (formula (1)).All analyzed results of physical and chemical properties of soil before sowing of the tef crop are summarized in Table 2.
2.5.Data Analysis.Te data on soil chemical properties were subjected to a two-way statistical analysis of variance (ANOVA) using the SAS statistical software program.Before data analysis, the collected data were judiciously checked for normality and homogeneity of variance across separate levels and a combination of L. camara vermicompost and NPS fertilizer treatments.Signifcant diferences between treatments were evaluated using the Fisher's test at the P ≤ 0.05 level of probability.Pearson's correlation coefcient was used to determine the relationship between the diferent soil chemical properties.

Chemical Characteristics of L. Camara Vermicompost
Used in the Experiment.Te pH of L. camara vermicompost used for soil amendment was found with a value of 7.40, that is, almost neutral (Table 1).Confrming the current result, many scholars have informed that most species of earthworms favor a pH value of around 7.0 [51,52].Similar results were also observed by Mahaly et al. [53].Te electrical conductivity of L. camara vermicompost was measured at 1.70 dS•m −1 (Table 1).As shown in Table 2, the EC of soil was higher than the EC of L. camara vermicompost (Table 1).So, adding organic fertilizer into soil having neutral pH and reduced EC might be more benefcial for the fertility of soils, subsequently, suitable condition is created for plant seed germination and soil biological properties [53,54].Te presence of 23% TOC in L. camara vermicompost showed that L. camara vermicompost was mature enough to be used as a fertilizer.As vermicomposting development continued, the TOC content lessened and an efciently matured vermicompost was achieved after 45 days of earthworm activity [53].Analyzed matured L. camara vermicompost had a 1.7% TN (Table 1).Tis current value is 4 International Journal of Agronomy equivalent to the recommended amount of TN (1.6%) of matured vermicompost of distillery sludge waste combined with tea leaf residues at the dose of 80 : 20, respectively [53], and this L. camara vermicompost was favorable to use as a soil amendment.Mostly, TN in the vermicomposting is extended from 1.5% to 2.7% [55].After analyzing the result of L. camara vermicompost, the C : N ratio was recorded with a value of 13.53 (Table 1).Carbon-to-nitrogen ratio is one of the commonly used indicators of vermicompost maturation, and less than 20 C : N ratio indicates that the vermicompost is mature enough to be used as fertilizer [56,57].Te total phosphorus of measured L. camara vermicompost was recorded at 0.82% after 45 days of Eisenia fetida activity (Table 1).After 45 days of vermicomposting of combined L. camara and cow dung biomass, TK was measured at 1.1% (Table 1), which was similar to the fnding of Mahaly et al. [53], who observed 1.2% TK, after 45 days of combined vermicomposting of distillery sludge waste and tea leaf residues at the ratio of 60 : 40, respectively.

Soil Physiochemical Properties before Launching the
Experiment.Soil physiochemical analysis results of the experimental site are revealed in Table 2. Te textural class of the experimental site was found with clayey.In addition, the chemical feature i.e., pH was measured with a 6.75 value, which was characterized by a neutral rating [49,50].Tis currently measured pH value falls under the pH ranges between 5.6 and 7, which are suitable for the availability of essential nutrients and crop productivity [58].Te soil organic carbon content of the experimental site was found to be of 0.55% value (Table 2).As stated by Hazelton and Murphy [49], SOC ranking between 0.4 and 0.6% was supposed as very low and accordingly current result of SOC was very low.Moreover, the TN content of the study site was measured with a value of 0.05% (Table 2), which is considered as low rating [49].Due to the experimental site having very low SOC and low TN, tef production could be negatively afected and it is necessary to incorporate fertilizers into such soils.Te soil of the experimental site has a C : N ratio of 11, which is classifed as a normal C : N ratio (10-12) for an arable soil [49].As demonstrated in Table 2, the plant Av.P of the experimental site was found to be of 2.65 ppm.As described by the soil test interpretation of Hazelton and Murphy [49] soils with plant Av.P in the range of 0-5 mg kg −1 was rated as very low, so the current result of plant Av.P was classifed under very low plant Av.P. For the experimental site, the EC of the soil was measured with 2.32 dS m −1 (Table 2), which is classifed under slightly saline soil (2-4 dS m −1 ).Under such conditions of soil EC, the yield of salt-sensitive plants is afected [45,46].Te level of Exc.Na cation of the study site was found to have a value of 0.21 cmol (+) kg −1 , which is considered as low (0.1 to 0.3 cmol (+) kg −1 ) [49].Te Exc.Na percentage of the study site was also determined as having a value of 0.61%, which is nonsodic (0-6%) [49].Te Exc.K content of the soil in the study site was measured at 0.52 cmol (+) kg −1 (Table 2).According to the soil test interpretation of Hazelton and Murphy [49], the current soil result of Exc.K is found in a medium rating (0.3-0.7 cmol (+) kg −1 ), whereas the Exc.Ca content and Exc.Mg content of the soil for the study site were found with 17.49 and 14.91 cmol (+) kg −1 , respectively (Table 2).Based on the ratings recommended by Hazelton and Murphy (45) interpreting soil test results, the Exc.Ca content of the experimental site is found in high ratings (10-20 cmol (+) kg −1 ), while the Exc.Mg value is found in very high categories (>8 cmol (+) kg −1 ).Terefore, Exc.Ca and Exc.Mg of the soils of the experimental sites are appropriate for growing of the tef.Te CEC of the experimental site was measured at 34.30 cmol (+) kg −1 , which is rated as high (25-40 cmol (+) kg −1 ) [49].Te presence of high CEC value might be associated with a high clay content of the soil.As a result, an ideal soil environment was formed for improved nutrient availability and nutrient uptake and consequently supporting better tef growth.

Soil Organic Carbon (SOC).
Diferent organic fertilization management practices signifcantly afect SOC (P < 0.0001), and there were no signifcant diferences in the SOC between the diferent doses of sole chemical fertilizers and at the interaction of organic and chemical fertilizers (Table 3).Application of L. camara vermicompost led to a signifcant increase in the soil of SOC, and the highest SOC was measured at 6 t•ha −1 of L. camara vermicompost, while the lowest was in untreated plots.Tis may be due to the delayed carbon decomposition rate with the highest rate of L. camara vermicompost, but fast mineralization in the lower L. camara vermicompost rates, and this current fnding was similar to the report of N'Dayegamiye et al. [59].Soil organic carbon content obtained from the application of 6 t•ha −1 was signifcantly greater by 51.82% than that of the untreated plot.Before experimenting, the initial SOC was 0.55% (Table 2), which is rated as very low, while after treating the soils with the highest rate of L. camara vermicompost, moderate SOC (1%-1.8%)was observed [49].
Te organic part fraction of vermicompost is up to 50% of its total weight as reported by Hervas et al. [60].Te results of L. camara vermicompost analysis revealed that the TOC content in this material was 23%, and this TOC is higher than the organic content of soil before treatment, and due to this, L. camara vermicompost has the potential to supply organic carbon to the soil.Tis is why plots treated with L. camara vermicompost amendment were found to have improved SOC.Approving the current fnding, Mengistu et al. [24], Azarmi et al. [61], and Baghbani-Arani et al. [62] have observed improved SOC with higher rates of vermicompost.Correspondingly, Kim and his colleagues [63] found improved SOC from short-term amending of soil with organic amendments.Improved SOC from the highest rate of L. camara vermicompost in the clay textural soil is probably due to carbon protection from mineralization.In soils with a high clay content, nutrient immobilization occurs as nutrients from fertilizers added to the soil are retained in the micro-aggregate sites of clay texture soils [64].Adding a high amount of compost to the soil plays an International Journal of Agronomy important role in improving the organic matter in the soil [65].Tree-year successive fertilization of soils with compost boosted SOC compared to the untreated one [66].Liu et al. [67] found considerably greater SOC from soils receiving farmyard manure.Te vermicompost efect was robust where no chemical fertilizer was added [68].

Soil Reaction (pH).
Interaction application of L. camara vermicompost amendment and NPS mineral fertilizer, and at their separate application had not exerted a signifcant efect on soil pH (Table 3).Te unchanged soil pH after the experiment could be due to the short-term residual efect of nutrients that are unable to change the intrinsic bufering capacity of the soil, especially the soil pH.Tis is because the bufering capacity of the study area soil is high and short-term vermicompost application did not cause any change in soil pH.Soils having clayey textural classes and high cation exchange capacity will acidify slowly compared to sandy textural soils [49].Terefore, the shortterm addition of organic fertilizers to the soil did not change the soil pH [63,65].[75].While more plant Av.P was measured in cases where NP fertilizer and farmyard manure were applied together, less plant Av.P was found in the plots where NP fertilizer and farmyard manure were applied separately [67].An increase in plant Av.P was observed in plots where organic and inorganic fertilizers were added together [76].Likewise, separate incorporation of L. camara vermicompost amendment into soils led to signifcant changes in plant Av.P (Table 4).Considerably, the highest plant Av.P was recorded from plots treated with 6 t•ha −1 of L. camara vermicompost, but the lowest plant Av.P was found under plots without L. camara vermicompost treatment.Plant Av.P for 6 t•ha −1 of L. camara vermicompost was about 2.43 times higher than that of the untreated plot.An increasing pattern of plant Av.P was exhibited with an increasing trend of L. camara vermicompost application rates.Te addition of L. camara vermicompost to soils possibly improves the availability of P through microbial mineralization of the L. camara vermicompost.Another reason why P availability increases from the application of organic fertilizers is due to an efective reduction of P sorption and an increase of P solubility by the organic acids found in L. camara vermicompost amendment.An improved Av. P could be attributed to the addition of organic fertilizer that directed to the relocation of soil-fxed P to the labile pool and release in soil solution [77].Having high TN and plant Av.P in the soil of the tef feld is due to L. camara vermicompost containing a variety of nutrients such as N, P, K, Ca, Mg, S, and other trace nutrients.Similarly, Zhao et al. [69], Paula De Souza et al. [78], and Demir [79] found enhanced Av.P after treating soils with vermicompost.Bacterial mineralization of vermicompost could have increased Av.P [80].After the addition of biochar or compost to soils, an enhanced soil P was measured [81].Correspondingly, the two-year consecutive application of 6

Soil Electrical Conductivity (EC)
International Journal of Agronomy  International Journal of Agronomy sole chemical fertilizer levels increased the plant Av.P from 9.09% to 46.66% versus unfertilized plots (Table 4).Here, the highest plant available P was obtained from plots treated with 200 kg•ha −1 , yet the lower value was measured from untreated plots.

Total Soil Nitrogen (TN)
. Te total soil nitrogen was signifcantly afected by separate application of L. camara vermicompost, but not in the case of integrated application of L. camara vermicompost and NPS fertilizers and sole NPS fertilizer (Table 5).Te highest TN was recorded from the sole application of 6 t•ha −1 of L. camara vermicompost versus untreated plots and 2 t•ha −1 of L. camara vermicompost.Vermicompost amounts of 6 t•ha −1 and 4 t•ha −1 showed no signifcant diferences.Contents of TN in the L. camara vermicompost amendment incorporation plots increased signifcantly by 50% and 100% versus unfertilized plots.Tis study found that L. camara vermicompost incorporation enhanced TN.In the untreated plot, very low TN (<0.05%) was measured, while in plots that received L. camara vermicompost, the level of TN altered to low ratings (0.05%-0.15%) [49].In the present research, an increased soil N was found, which may be due to the mineralization of L. camara vermicompost amendment by soil microbe.Tis is possibly due to plants using the readily available nutrients from chemical fertilizers, but nutrients slowly released from organic fertilizers remained in the soil as residuals.Having high TN and plant Av.P in the soil of the tef feld is due to L. camara vermicompost containing a variety of nutrients such as N and P, including K, Ca, Mg, S, and other trace nutrients.Organic amendments ofered an increased soil nutrient due to the mineralization of N from the application of organic fertilizer [77].When the C : N ratio is between 12 and 25, a suitable condition is created for N mineralization and this supports N use efciency and improved crop yield production [59,82].A small amount of C : N ratio in the organic fertilizer stimulates mineralization processes, subsequently increasing N in the soil [83,84].A carbon-tonitrogen ratio greater than 30 has a low N because of N immobilization by soil microorganisms during mineralization and subsequently, crop production is reduced [85].Lim et al. [14] and Zakir et al. [86] studied that adding organic materials to soils improves the organic matter content of the soil, at the same time soil was enhanced with nutrients of N, P, and K.In supporting the current study, Tekulu et al. [87] found enhanced residual soil N from groundnut crop residue.Adding vermicompost to the soil provides better soil N than soil without vermicompost [88].A consistent increment of soil N was generated from the addition of an increased pattern of vermicompost amendments [79,87,89].

Carbon-to-Nitrogen Ratio (C : N).
Individual separate utilization of L. camara vermicompost amendment has a signifcant (P < 0.0001) infuence on soil C : N ratio, and it is not in the case of integrated application of L. camara vermicompost and NPS fertilizers and sole NPS fertilizer (Table 5).Te highest C : N ratio was recorded from a plot treated with 6 t•ha −1 of L. camara vermicompost, however, the lower one was measured from an untreated plot.A somewhat signifcantly higher C : N ratio of 11.58% was obtained for 6 t•ha −1 of L. camara vermicompost relative to the unfertilized plot.Yet, 6 t•ha −1 and 4 t•ha −1 of L. camara vermicompost levels did not reveal signifcant diferences.An upward trend in the C : N ratio was revealed for the increasing application rate of L. camara vermicompost amendment.When the C : N ratio is in the range of 12-25, suitable conditions are created for soil health, N uptake, and crop production [59,82].Higher C : N ratio with the application of the highest rate of L. camara vermicompost indicates sequestration of carbon in the soil.When the C : N ratio is greater than 30, the N nutrient is locked up by soil microorganisms during mineralization and subsequently crop production is reduced, and the N requirement of the crop is fulflled through supplementation of N fertilizer and this could also stimulate organic material mineralization [85,90].As the depth of the soil horizon increases, mineralization of organic carbon gradually decreases and hence accumulation of organic carbon occurs [59].Soil treated through the application of cow manure compost along with biochar resulted in an enhanced C : N ratio due to a greater C : N ratio in biochar [91].

Soil Cation Exchange Capacity (CEC).
Diferent separate individual applications of L. camara vermicompost amendment, as well as NPS fertilizer have signifcant efects on CEC (P < 0.0001; P � 0.008), respectively, but there was no signifcant diference in soil CEC between diferent interactions of L. camara vermicompost amendment and NPS chemical fertilizer (Table 5).Soil CEC was highest under 6 t•ha −1 of L. camara vermicompost, while the lowest was in untreated plots.Te two-year successive application of sole L. camara vermicompost levels increased the soil CEC from 42.11% to 63.67% versus the untreated plots.It was obvious that the chemical fertilizer efect on CEC was somewhat less than the efect of L. camara vermicompost as the nutrients of chemical fertilizers are readily available and uptaken by crops, but, in the case of organic fertilizer, they release their nutrients slowly and remain unutilized by the crops during the cropping season.Te largest reason for any change of soil CEC was L. camara vermicompost fertilizer; this is due to organic fertilizers resulting in the addition of some essential cations to the soil.Having high CEC in the soil of the tef feld is due to L. camara vermicompost containing a variety of nutrients such as N and P, including K, Ca, Mg, Na, S, and other trace nutrients.Lantana camara vermicompost produces functional groups and has a high proportion of fne particles and organic matter, which are responsible for surface charges, and this in turn increases the number of exchange sites for mineral nutrients.Confrming the current result, Mahmoud and Ibrahim [92] and Demir [79] have found an improved CEC of the soil after the addition of vermicompost to barley feld and sodium-afected soil, respectively.Tis current work is in agreement with the research of Ghanbari and Khajoei-Nejad [93], who revealed that the application of cattle manure compost along with biochar signifcantly increased soil CEC.Vermicompost improves the efciency of mineral fertilizers by preventing them from losses [26].Similarly, Mengistu et al. [24] found the highest CEC of soil with the application of 15 t•ha −1 of vermicompost, whereas the smallest CEC was measured from the untreated plots.Having better exchangeable Ca and Mg, as well as efective cation exchange capacity of compost resulted in an improved soil exchangeable cations [81].

Correlation among Measured Soil Chemical Properties.
Te Pearson correlation result showed that there was a nonsignifcant correlation of soil reaction with EC, SOC, Av.P, TN, EC, and C : N ratio (Table 6).Tis fnding implies that unchanged soil pH after treatment of L. camara vermicompost did not have any relationship with other soil chemical properties which were promisingly changed after L. camara vermicompost addition.Soil EC has a signifcant and moderate positive correlation with the soil chemical properties of plant Av.P, SOC, TN, and C : N ratio.Strong positive correlations were observed between soil EC and CEC.Plant Av.P was moderately correlated with SOC and TN, while a strong correlation was observed with CEC and C : N ratio.Te correlation results also showed a strong and signifcant relationship between SOC, CEC and TN (Table 6).Tis current result is in line with the fndings of Cao et al. [94] and Dhaliwal et al. [95], who reported that SOC and TN were positively correlated.Tere was other evidence by Bekele et al. [96], who reported a positive and signifcant association between TN and soil organic matter with r � 0.89 at P � 0.001.Similar to the present fndings, Tamene et al. [97] reported a positive and signifcant correlation between soil TN and SOC (r � 1; P � 0.001).Tis is due to soil organic matter being the major source of SOC and TN.Cation exchange capacity was also found strongly correlated with TN at r � 0.8 and P ≤ 0.001.Soil organic carbon, TN, and CEC were strongly linked with the C : N ratio of the soil (Table 6).A positive and signifcant correlations between SOC, EC and Av.P, TN, C : N ratio and CEC are due to vermicompost serving as the main source of various nutrients consisting of C, N and P as well as K, Ca, Mg, S and other trace elements.Consistent with the present results,

Conclusion
Te experiment revealed that soils of the study area have signifcantly improved chemical properties except pH after treatment with L. camara vermicompost.Accordingly, most of the soil chemical properties measured responded promisingly to the application of L. camara vermicompost alone.Only plant Av.P was found to be improved in all treatment factors.Apart from plant Av.P and soil CEC, application of NPS fertilizer alone had no signifcant efect on other soil properties.Since chemical fertilizers contain readily available nutrients, they ensure rapid plant growth, increase crop yield, and leave almost no nutrient residue in the soil.From the result, it was obvious that the critical factor for enhancing the diferent soil chemical properties was L. camara vermicompost amendment.Overall, improved soil fertility in the study area was observed when the soil was treated with the highest dose of L. camara vermicompost.Since the toxicity of L. camara is eliminated by vermicomposting, L. camara vermicompost has been proven to be an ideal nutrient for plants and improves the chemical properties of soil residues.Terefore, utilization management of invasive weeds of L. camera through vermicomposting could minimize the environmental harmfulness of L. camera, and at the same time, contributes essential soil amending material of vermicompost.Hence, vermicompost produced from L. camera could amend soil fertility.From this approach, sustainability and environmental harmonization are achieved through converting harmful weeds to vermicompost technology.Based on the fndings, it is recommended that with utilization management of invasive terrestrial weeds through vermicomposting could minimize extensive encroachment of terrible weeds, and simultaneously sustainable utilization of vermicompost as a soil fertility enhancer is used.

Table 2 :
Initial soil properties of the study area.
NA, not applicable.
L. camara vermicompost and zero NPS, 6 t•ha −1 L. camera vermicompost and 100 kg•ha −1 NPS fertilizer, 6 t•ha −1 L. camara vermicompost and 150 kg•ha −1 NPS fertilizer and 4 t•ha −1 L. camara vermicompost and 200 kg•ha−1 [72]ication of L. camara vermicompost amendment had brought signifcant (P < 0.0001) efect on the EC of soil, but not in the case of combined application of L. camara vermicompost amendment and NPS fertilizer, and sole NPS fertilizer (Table4).Te lowest EC was measured in plots without L. camara vermicompost; whereas the largest EC was found from the application of 6 t•ha −1 of L. camara vermicompost, but this is signifcantly identical with 4 t•ha −1 L. camara vermicompost.Average soil EC increased from 1.57 to 2.03 dS•m −1 with a pattern of increasing L. camara vermicompost application rate (0-6 t•ha −1 ).Increased soil EC with an application of L. camara vermicompost can be explained by the presence of cations released during the decomposition of L. camara vermicompost, which aligns with Azarmi et al.[61], Zhao et al.[69], Babu et al.[70], Nada et al.[71], and González et al.[72].Te reason for the EC rise in the highest dose of L. camara vermicompost could be due3.3.4.Plant Available Phosphorus (Av.P).Te combined application of L. camara vermicompost and NPS fertilizers signifcantly afected plant Av.P (Table4).Signifcantly, the highest plant Av.P was measured from plots that received a combined application of 6 t•ha −1 of L. camara vermicompost and 200 kg•ha −1 of NPS fertilizers, however, the plant Av.P contents were very similar to plots receiving 6 t•ha −1 −1 ) and NPK (10 : 40 : 20 kg•ha −1 ) improved plant Av.P versus plots that received only NPK fertilizer (20 : 80 : 40 kg•ha −1 )

Table 3 :
Efect of L. camara vermicompost and NPS fertilizers on soil organic carbon and soil reaction.

Table 4 :
Efect of L. camara vermicompost and NPS fertilizers on electrical conductivity and plant-available phosphorus.
Te numbers indicated by ± are standard deviations.Mean ± standard deviations with the same letters are not signifcantly diferent at P ≤ 0.05 using Fisher's LSD.VC � vermicompost; CV � coefcient of variance; NS � nonsignifcant; LSD � least signifcant diference; P � probability level.

Table 5 :
[98]t of L. camara vermicompost and NPS fertilizers on soil total nitrogen, carbon-to-nitrogen ratio, and cation exchange capacity.�0.81) for VC * NPS NS Te numbers indicated by ± are standard deviations.Mean ± standard deviations with the same letters are not signifcantly diferent at P < 0.05 using Fisher's LSD.VC � vermicompost; CV � coefcient of variance; NS � nonsignifcant; LSD � least signifcant diference; P � probability level.International Journal of Agronomy Zhou et al.[98]found a positive and signifcant correlation between soil SOC, TN, Av.P, EC, and CEC after soil amendment with organic fertilizers.