Journal of Agronomy

Year: 2007 | Volume: 6 | Issue: 2 | Page No.: 250-261
DOI: 10.3923/ja.2007.250.261

Effect of Combining Rubber Effluent with Single Super Phosphate (ssp) on Some Soil Chemical Properties and Early Growth of Maize (Zea mays. L)

Robert Ehi Orhue, Frank Ogbonnaya Uzu and Ulamen Agbonsalo Osaigbovo

Abstract: The green house trials were carried out at the Faculty of Agriculture, University of Benin, Benin City, Nigeria to determine the effect of rubber effluent and Single Super Phosphate (SSP) combination on some soil chemical properties, growth and nutrient uptake of maize in an Ultisol. The SSP used was 0-18-0. Five level-0, 30, 60, 90 and 120 kg ha^-1 SSP were combined with 6 levels of rubber effluent (0, 50,000, 100,000, 150,000, 200,000 and 250,000 L ha^-1) in 6x1x5 factorial arrangement in a completely randomized design. Results of the effluent analysis showed that the effluent contains both micro and macro nutrients, slightly acidic pungent in odour and colourless. In the first cropping, soil pH, N, Ca, Mg, K, Na, Fe, Mn, ECEC as well as exchangeable acidity increased when compared with control. The available P and %C were however, reduced when compared with control. In the second cropping, all the nutrient elements declined further after harvesting. The content of N and P increased up to 150,000 L ha^-1 treatment with phosphorus combination. The N, P, K, Ca, Na, Al, Fe, Zn and Mn uptake were also higher at 150,000 L ha^-1 effluent treatment with phosphorus combination Mg uptake was however higher or greater at 150,000 L ha^-1 effluent treatment with phosphorus combinations. The textural status of the soil was not changed throughout the trials. All the treatments were not significantly different from one another in all the growth parameters 2 Weeks after Sowing (WAS). At final harvest, 150,000 L ha^-1 effluent concentration/30 kg ha^-1 of SSP was significantly (p<0.05) better than other treatments including control in plant height, collar girth and leaf area. However, the number of leaves was not significantly different from one another throughout the period of the trials.

Keywords: Rubber effluent, single super phosphate, ultisol and maize

INTRODUCTION

Improving the fertility of the soil has consistently been pinpointed as one of the most critical factors among numerous others in a bid to promote the sustainability of agriculture in Nigeria. The very crucial aspect of improving and maintaining soil fertility is the application of deficient nutrients of which phosphorus is one of the most important. Phosphorus plays a vital role in crop production and so much so that it is considered an amendment because it improves current input like fertilizer, water and labour more efficient (Amapu et al., 2000).

The utilization of phosphate as a source of plant nutrient is influenced by many factors such as fertilizer, soil environment and management. The soil environmental factors that influence phosphorus release and consequently utilization of phosphate when applied to soil are proton buffer, exchangeable calcium, phosphate buffer power, organic matter, soil pH and soil moisture holding capacity (Amapu et al., 2000). Soil pH is known to influence the availability of phosphorus. In most soils phosphorus availability is at a maximum in the pH range of 5.5-7.0 decreasing as the pH drops and also as it goes above 7.0. The ions of calcium and magnesium as well as the presence of carbonates of these metals in the soil cause precipitation of the added phosphorus and its availability again decreases. At low pH values the P retention results largely from the reaction with iron and aluminum and their hydroxides. The controlled application of rubber effluent on soil have been reported to cause changes in soil properties. Yeow and Zin (1981) reported an improved water retention of soil when rubber effluent was applied on the soil. Poon (1982), Lim and P’ng (1983), Lim et al. (1983), Seneviratne (1997) and Orhue et al. (2005) have reported an increased soil pH and soil K, Ca, Mg and organic matter content when rubber effluent was used. The properties of rubber effluent make it an excellent soil conditioner and it could be use to complement synthetic fertilizers. This study therefore seek to evaluate the effect effect of combining rubber effluent with single super-phosphate on some soil chemical properties and growth of maize (Zea mays L.).

MATERIALS AND METHODS

First cropping: This first cropping experiment was carried out in a greenhouse at the Faculty of Agriculture, University of Benin, Benin City Nigeria. The top soil collected from the floor of Gmelina arborea plantation at a depth of 0-15 cm was composited, air dried and sieved. Two killogram soil samples were weighed into each 180 polythene bags. The experiment was a 6x1x5 factorial design laid out in a completely Randomized Design with 3 replicates. Each replicate had 60 polythene bags with 2 polythene bags for a treatment. Single super-phosphate 0-18-0 was used. Five levels-0, 30, 60, 90 and 120 kg ha^-1 of the single super phosphate were used.

The soil in the polythene bags were polluted with rubber effluent at the rate of 0, 50, 100, 150, 200 and 250 mL (equivalent to 0, 50,000, 100,000, 150,000, 200,000 and 250,000 L ha^-1 effluent treatment), respectively mixed thoroughly and then left for 2 weeks for proper mixing with soil while the phosphate was applied 2 weeks after the rubber effluent application. The soils were moistened with deionized water and then allowed to incubate for another 2 weeks to enable the phosphates react with the rubber effluent and soil. Before the seeds were sown, the soils were also moistened. Four seeds were initially sown and later thinned to one plant per polythene bag. Subsequent watering was carried out every 4 day interval with deionized water. Visual observation and crop performance and data collection on plant height, number of leaves, collar girth and leaf area were measured every 14 day interval for 8 weeks. At 8 weeks the plants were harvested oven dried to constant weight at 70°C for 48 h. Nutrient uptake was also computed using the dry weight and nutrient content (%) (Pal, 1991).

Second cropping: The second cropping was carried out in order to investigate the residual effect of both the phosphate fertilizer and rubber effluent For this second cropping soils of the 180 polythene bags were left to be air-dried for 2 weeks after the first harvest and then sieved to remove crop residue. Thereafter each polythene bag was moistened and re-sown with four seeds. They were thinned to one plant per pot 2 weeks after sowing. Watering carried out as described earlier. Data collections were carried out every 14 day till 8 weeks.

Soil, effluent and maize plant analysis: Soil analysis was carried out before, after pollution and after harvesting of maize plant. The rubber effluent was analyzed before using it to pollute the soil. While the plant analysis was done at the end of the experiment. Particle size analysis was determined by using hydrometer method of Bouyoucos (1951) while the soil pH was determined at a soil to water ratio of 1:1 using a glass electrode pH meter. The pH of rubber effluent was read directly with the pH meter. The electrical conductively of the effluent was read directly from the CIBA-CORNING conductivity meter. The organic carbon content of both soil and rubber effluent was determined by using the chronic acid wet oxidation procedure as described by Jackson (1962). The total nitrogen, available phosphorus, exchangeable bases as well as exchangeable acidity were determined using methods of Jackson (1962), Bray and Kurtz (1945) and Mclean (1965), respectively. The effective cation exchange capacity was calculated as the sum of exchangeable bases and exchangeable acidity. The aluminum, iron and manganese were determined by methods described by Chenery (1955), Mehra and Jackson (1960) and Bradfield (1957), respectively.

RESULTS

Properties of rubber effluent: The physico-chemical properties of rubber effluent (Table 1) indicated that the effluent was slightly acidic colourless and contained N, P, organic carbon, K, Ca, Na, Mg, Fe, Mn and Zn.

Properties of soil used: The property of soil used in the entire trial is shown in Table 2. The soil is moderately acidic. It is classified as Ultisol, Dystric Nitosol, Benin Fasc, grey in colour and texturally sandy (Enwezor et al., 1990). The soil contained organic carbon, N, available P, exchangeable cations, exchangeable acidity, Effective Cation Exchange Capacity (ECEC) as well as trace elements such as Fe, Mn and Zn.

Physio-chemical properties of soil after harvest as influenced by effluent phosphorus combinations in first and second cropping: The physico-chemical properties of soil at harvest in both first and second cropping are shown in Table 2 and 3.

The soil pH increased from 5.10 in control to a mean of between 5.13-6.60 in first cropping (Table 2) with various effluent-phosphorus combinations while in the second cropping (Table 3) the soil pH was raised from 5.10 to a mean of between 5.11 and 6.78. The application of effluent-phosphorus combinations in first cropping reduced the 1.32% carbon in control to a mean of between 1.11 and 1.18% (Table 2). The total N was increased from 0.05% in control to a mean of between 0.41 and 0.83% (Table 2). In the second cropping (Table 3) the carbon was reduced further to a mean of between 0.91 and 1.10% (Table 3). The total nitrogen was reduced to a mean value of between 0.38 and 0.71%. The P level was reduced from 4.71 ppm to a mean of between 0.81 and 3.98 ppm (Table 2) in the first cropping and to a mean of between 0.78 and 3.07 ppm in the second cropping (Table 3).

In the first of cropping, monovalent cations such as K and Na were raised from 0.04 and 0.08 in control to a mean value of between 0.61 and 7.70 Cmo1 kg^-1 1.15 and 4.05 cmo1 kg^-1, respectively whereas the divalent cations such as Ca and Mg were increased from 0.01 and 1.39 cmo1kg^-1 to a mean value of between 3.01 and 6.41 cmo1 kg^-1 and 1.96 and 4.91 cmo1 kg^-1, respectively (Table 2). The exchangeable acidity and Effective Cation Exchange Capacity rose from 0.08 and 1.60 cmo1 kg^-1 in control to a mean value of between 1.60 and 3.20 cmo1 kg^-1 and 9.05 and 23.17 cmo1 kg^-1, respectively (Table 2). The K and Na monovalent cations and Ca and Mg divalent cations were further reduced in the second cropping (Table 3) to a mean value of between 0.48 and 5.12 cmo1 kg^-1, 0.84 and 1.98 cmo1 kg^-1, 2.19 and 4.72 cmo1 kg^-1 and 0.96 and 2.58 cmo1 kg^-1, respectively. The exchangeable acidity and effective cation exchange capacity were reduced to mean value of between 0.08 and 2.91 cmo1 kg^-1 and 6.94 and 20.59 cmo1 kg^-1, respectively (Table 3). In the first cropping (Table 2), trace elements such as zinc, iron and manganese were raised from 0.65 and 0.01, 0.05 ppm, in control to a mean of between 0.58, 1.03 ppm and 0.16 and 0.59 ppm, 0.12 and 0.36 ppm respectively whereas in the second cropping (Table 3), zinc was further decreased to a mean value of between 0.40 and 0.16 ppm.

Iron was reduced to a mean value of between 0.13 and 0.40 ppm while manganese had a mean of between 0.11 and 0.31 ppm. In both first and second cropping, it was however observed that soil texture was not affected by the various rubber effluents phosphorus combination as well as control (Table 2 and 3).

Nutrients content of maize plants treated in first and second cropping: The nutrient content of the maize plant in first and second cropping are shown in Table 4 and 5. The analyses revealed in the first cropping (Table 4) that N, P, Na, Ca, Mg, K, Al, Fe, Mn and Zn had mean value of between 1.64 and 2.45%, 0.078 and 0.136%, 0.032 and 0.040%, 0.058 and 0.116%, 0.069 and 0.631%, 1.039 and 1.631%, 121 and 207 mg kg^-1, 54 and 72 mg kg^-1, 49 and 57 mg kg^-1, 38 and 44 mg kg^-1, respectively whereas in the second cropping (Table 5) the mean nutrient content were between 1.40 and 2.25% for N, 0.075 and 0.098% for P, 0.030 and 0.034% for Na, 0.052 and 0.105% for Ca, 0.060 and 0.232% for Mg, 0.98 and 1.298% for K, 101 and 143 mg kg^-1 for Al, 40 and 64 mg kg^-1 for Fe, 40 and 46 mg kg^-1 for Mn, 34 and 39 mg kg^-1 for Zn.

The N and P content however increased from control up to 150,000 L ha^-1 for various SSP combinations and then declined at 200,000 L ha^-1-phosphorus combinations at first cropping (Table 4) and second cropping (Table 5). In the case of Ca, Mg, K, Na, Mn, Zn, Al and Fe, there were no consistency in the mean values of the nutrient content in both first (Table 4) and second (Table 5) cropping. Generally, the mean values of nutrient content obtained in the first cropping (Table 4) were higher than those of second cropping (Table 5) in the various levels of effluent-SSP combinations.

Nutrient uptake by maize plant in first and second cropping: The nutrient uptake by maize in both first and second cropping as influenced by effluent and phosphorus combination are presented in Table 6 and 7. The data for N and P uptake in first cropping (Table 6) indicated that there were progressive increase from control concentration-phosphorus combinations up to 150,000 L ha^-1-SSP combination and decline gradually. The N mean value was between 364.14 and 1,105.93 mg/plant whereas P mean value was between 17.33 and 61.87 mg/plant. There was no consistency in the Ca, Na K, Al, Mn and Zn uptake in various effluents-SSP combinations in first cropping (Table 6).

Ca uptake however had a mean value of between 12.88 and 51.91 mg/plant, Na had between 7.79 and 18.05 mg/plant, Fe had a mean value between 0.132 and 0.243 mg/plant, Mn had a mean value between 0.111 and 0.234 mg/plant and Zn had a mean value between 0.081 and 0.189 mg/plant, Mg had a mean value between 17.94 and 162.04 mg/plant, K had a mean value between 25.38 and 712.30 mg/plant and Al had a mean value between 0.29 and 0.56 mg/plant in the first cropping (Table 6).

In the second cropping (Table 7), N, P uptake also increased from 0 L ha^-1 effluent-SSP combination up to 150,000 L ha^-1 (30, 60, 90, 120 kg ha^-1 SSP) combination. The mean values of N and P uptake were between 233.56 and 683 mg/plant and 12.16 and 30.06 mg/plant respectively. The Na uptake by maize plant exhibited an increase as from 0 L ha^-1. Effluent-SSP combination up to 150,000 L ha^-1-SSP combination then declined at 200,000 L ha^-1-SSP combinations. The Na mean uptake by maize plant was between 4.86 and 9.71 mg/plant. In the case of Ca, there was an increase in uptake as from 0 L ha^-1 effluent -SSP combination up to 50,000 L ha^-1 effluent-SSP combinations. Thereafter, an increase at 150,000 L ha^-1 effluent-SSP combination was recorded and then decreased again as from 200,000 L ha^-1-SSP combinations. The mean value of Ca uptake was between 8.00 and 31.88 mg/plant. The Mg uptake exhibited a progressive increase from 0 L ha^-1 effluent-SSP combination up to 50,000 L ha^-1 effluent-SSP combinations and then declined inconsistently up to 100,000 L ha^-1 effluent-SSP combination and was raised again at 250,000 L ha^-1 effluent-SSP combination. In the second cropping (Table 7), the N,P,K uptake increased up to 150,00 L ha^-1-various SSP combinations and then decreased at 200,000 L ha^-1-various SSP combination whereas Na, Ca, Mg, Al, Fe Mn and Zn uptake were generally not consistent with various effluent-SSP combination.

Vegetative growth: The vegetative growth parameters measured in first and second cropping were plant height, leaf area, collar girth and number of leaves are shown in Table 8-11, respectively. The results revealed that at 2 WAS the various effluent-SSP combinations including the control were not significantly different from one another in the first and second cropping. As from 4 WAS till 8 WAS the plant height (Table 8), leaf area (Table 9) and collar girth (Table 10) increased progressively from control up to 150,000 L ha^-1(30 kg ha^-1 SSP) combination but declined at treatment combination of 150,000 L ha^-1 (60 kg ha^-1 SSP) in both the first and second cropping. The decline however was not a sharp one but gradual. The treatment combination of 150,000 L ha^-1 (30 kg ha^-1 SSP) was significantly (p<0.05) better than other treatments in plant height (Table 8) from 4 WAS till 8 WAS in first cropping. At 4 WAS in the second cropping treatment 150,000 L ha^-1 (30 kg ha^-1 SSP) was not significantly different from treatment combinations of 150,000 L ha^-1 (60, 90 kg ha^-1 SSP), 200,000 L ha^-1 (120 kg ha^-1 SSP), 250,000 L ha^-1(30, 60, 90 kg ha^-1 SSP) for plant heights.

Also at 6 WAS in the second cropping, plant height (Table 8) was not significantly different from one another at the following treatment combinations of 150,000 L ha^-1(30, 60, 90, 120 kg ha^-1 SSP). Also plant height at 8 WAS in the second cropping (Table 8), the following effluent-SSP combination of 150,000L ha^-1 (30, 60, 90, 120 kg ha^-1 SSP)were not significantly different from one another. The leaf area (Table 9) at 4 and 6 WAS in both first and second cropping as well as 8 WAS in the first cropping, the treatment combination 150,000L ha^-1 (30 kg ha^-1 SSP) was significantly (p<0.05) better than other treatment combination including control. At 8 WAS the treatment combination of 150,000 L ha^-1 (30, 60, 90, 120 kg ha^-1 SSP) were not significantly different from one another (Table 9) in the second cropping. The collar girth (Table 10) was also significantly greater at 150,000 L ha^-1 (30 kg ha^-1 SSP) than other treatment combination including control 4 WAS in the first and second cropping as well as 6 WAS in the first cropping.

In the second cropping at 6 WAS treatment combination of 150,000L ha^-1 (30, 60, 90, 120 kg ha^-1 SSP) were not significantly different from one another but better than other treatment combinations. In the second cropping at 8 WAS these treatment combinations of 150,000 L ha^-1 (30, 60, 90, 120 kg ha^-1 SSP) were not significantly different from one another but better than other treatments. In the number of leaves (Table 11) the various treatment combinations of effluent-SSP combinations including control were not significantly different from one another throughout the period of the trial.

DISCUSSION

The result of effluent analysis (Table 1) when compared with that of Seneviratne (1997) showed that majority of the parameters depends on the source of the effluent. The fact is that most of the effluent whether obtained from the processing of crepe, crumb and concentrate latex contains the basic plant nutrients. The properties of the soil used (Table 2) revealed that the soil is low in fertility which is typical of an Ultisol. This result also agrees with the findings of Agboola and Ogunkule (1993).

The increase in soil pH, N.K, Ca, Mg, Na (Table 2 and 3) is similar to the result of Poon (1982), Lim and P’ng 1983; Lim et al. (1983). The increase in the above mentioned nutrient is due to the nutrient status or properties of (serum) of the effluent as well as the phosphorus applied. This further confirms that combining effluent with phosphorus is not problematic especially when the rate of applications is geared to supply nutrient level corresponding to those in inorganic fertilizer normally applied to promote satisfactory crop performance and that controlled application of effluent combined with phosphorus causes no detrimental changes on soil. Rather it improves soil fertility and has no apparent adverse effect in the environment. Also the gains or beneficial properties of rubber effluent as an excellent soil conditioner makes it to combine very well with phosphorus as a source of nutrients. The decrease in P with effluent phosphorus combination may be due to overlapping of sphere of soil serving as a sink for the dissolution products of adjacent P fertilizer particles, which could have influenced dissolution (Elrasidi and Larson, 1978). The practical consequence of this would be a progressive decline in the agronomic effectiveness of a given quantity of P fertilizer as rate of applications increases (Amapu et al., 2000) and this is primarily due to the build up of products of dissolution on the surface of the fertilizer particles. This result suggests that it is not advisable to rapidly raise the soil P status by the application of large doses of P fertilizer. The decrease percentage carbon is however contrary to the finding of Lim et al. (1983) and seneviratne (1997). Although there was no definite pattern of exchangeable acidity, ECEC, Fe, Mn, Zn, there were slight increase compared with control. The soil texture was never influenced or changed by the effluent-phosphorus combinations.

The increase in nutrient content of maize plants except N and P (Table 4-6) in the trial was not definite. This may be attributed to the nutrient uptake ability of the maize plant, soil nutrient interaction as well as an indication that the applied effluent-SSP combinations should be at the rates corresponding to crop requirements in the effluent-SSP combinations There is generally a relationship between some of the major elements. The supply of one element can increase, decrease or maintain their percentage in dry matter in leaves (Remison, 1997). These effects are described as antagonistic when the leaf nutrient of an element is reduced by the application of another elements and synergetic when application increases the leaf content of an element. These effects tend to influence nutrient uptake and subsequent nutrient content of plant. The increase in N.P.K, Ca and Fe uptake up to 150,000 L ha^-1 (30 kg ha^-1 SSP) (Table 6 and 7) showed that the effluent-SSP combinations should be applied at crop requirements. The uptake of other nutrients such as Mg, Na, H, Zn, Mn were however not definite.

Thus variation in nutrient uptake may have been influence by certain factors such as temperature, aeration, plant age, concentration of competing ions as well as nutrient interaction in the soil. All these may have differential effects upon nutrient uptake rate and subsequent different nutrient composition (Clinton and William, 1981; Drewes and Blum, 1997; O’conner and Anderson, 1974). Loos et al. (1979) asserted that reduced nutrient uptake in the presence of effluent could occur due to strong adsorption or degradation in the soil and that the extent of adsorption or degradation does not only depend on the properties of the effluent but also on the properties of the site, soil types, kind of soil organisms and climatic conditions.

The increase in the plant height, leaf area and collar growth (Table 8-11) up to 150,000 L ha^-1 (30 kg SSP) combination indicated that the effluent and SSP compliment each other and that the optimum growth at 150,00 L ha^-1 (30 kg SSP) is a matter of crop preference and the depression in height, girth and leaf area as from 150,000 L ha^-1 effluent and various SSP combinations could be due to effluent and phosphorus interactions with other elements in the soil. It was remarkable however; that the plants with SSP alone had the least biomass and least mean height, collar girth and leaf area while that of effluent-SSP combination supported most luxuriant growth.

CONCLUSIONS

This trial no doubt examined the influence of effluent-SSP on physiological, nutrition implication on maize plant as well as on soil chemical properties of an Ultisol. Analyses of the effluent revealed that it contained both micro and macro nutrient elements. The application of effluent-SSP combination had an effect on plant performances by altering some of the soil chemical components thereby affecting the rate of uptake, synthesis and translocation of vital mineral elements in maize plant. The vegetative growth as well as soil nutrient elements was enhanced at 150,000 L ha^-1 effluent (30 kg/ha P) combination. However, maize plant that received higher rate of effluent-phosphorus combination greater than 150,000 L ha^-1 (30 kg ha^-1 SSP) had a declined vegetative growth as well as reduced nutrient elements levels in the soil showing the existence of interaction between effluent and phosphorus with other nutrient elements in soil. Therefore it would be proper from the results to conclude that rubber effluent which contains substantial amount of nutrient element could be used as fertilizer supplement and complement thereby saving the use of inorganic fertilizer. The application of effluent-SSP at rates corresponding to maize crop nutrient requirement can significantly improve the maize crop growth without adverse effect on the crop nutritional status. However more trials should be carried out in both the greenhouse and field over a wide range of time and soils to confirm this fertilizer potential of rubber effluent.

REFERENCES