Impact of Composts Based on Poultry Droppings and Phosphate Waste from Togo on Corn Yield (Zea mays) and on the Physicochemical Characteristics of the Soil ()
1. Introduction
Overexploitation of agricultural land, exacerbated by the population explosion, leads to its depletion of nutrients. This phenomenon pushes farmers to resort to chemical inputs, particularly chemical fertilizers. However, the high cost of these chemical fertilizers makes them almost inaccessible to smallholders [1]. In addition, the excessive use of chemical fertilizers presents economic but also environmental problems: it pollutes groundwater, increases soil acidity, degrades its physical structure and reduces organic matter [2]. A decrease in crop yields is also observed a few years after the application of chemical fertilizers. Faced with this situation, the use of organic fertilizers, such as compost, becomes essential. In Togo, compost is the most accessible and least expensive organic fertilizer for smallholders. Several studies ([2]-[5]) have demonstrated that this material constitutes a biofertilizer rich in organic matter (OM), nitrogen (N), phosphorus (P2O5) and potassium (K2O). Composts modify the physicochemical parameters of the soil and their repeated applications increase the organic matter content of the soil [6]-[9]. Iglesias-Jimenez and Alvarez suggest that plants can obtain a high contribution of nitrogen compounds through compost [10]. Improvements in pH have been observed in Kolwezi (DR Congo) after the application of different levels of composts from household waste to acid soils [11]. In this study, it is a question of studying, from agronomic trials, the impacts of four (4) composts developed from poultry droppings and phosphate waste on corn yield (Zea mays L.) and on some physicochemical parameters of the soil.
2. Material and Methods
2.1. Material
2.1.1. The Tools Used
The field tools used during the agronomic trials were: hoes for weeding, planters for making holes, a lopper for cutting shrubs, plastic ropes for making holes in straight lines.
2.1.2. Fertilizers Used during Agronomic Trials
Four composts (A, B, C and D) (Figure 1), made from poultry droppings and phosphate waste (phosphate sludge and sieve rejects) from Togo were used as organic fertilizers during the agronomic trials. The poultry droppings came from the Regional Center of Excellence on Avian Sciences (CERSA) of the University of Lomé while the phosphate waste (phosphate sludge and sieve rejects) came from the Société Nouvelle des Phosphates du Togo (SNPT) which is the natural phosphate washing plant of Togo located in Kpémé (Figure 2). The substrate composition of each compost is mentioned in Table 1 and their physicochemical characteristics are listed in Table 2 [12]. In order to assess the maturity of these composts, the germination rates of corn seeds (Table 3) were studied with these clearly showing their non-phytotoxicity according to the work of abad Berjon et al. [13] which stipulate that when the germination rates of species are greater than 50%, then the composts are considered non-phytotoxic for this species. Chemical fertilizers (NPK and urea) purchased on the market were also used as mineral fertilizers for comparison in these trials.
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Figure 1. Appearance of the different composts obtained after 120 days of the process.
Figure 2. Map showing the collection locations of composting raw materials.
Table 1. Substrate composition of different composts [12].
Swath |
Poultry droppings (FV) |
Phosphate mud (BP) |
Screen Refusal (RC) |
m (kg) |
P (%) |
m (kg) |
P (%) |
m (kg) |
P (%) |
HAS |
170 |
66.7 |
85 |
33.3 |
0 |
0 |
B |
170 |
66.7 |
0 |
0 |
85 |
33.3 |
C |
170 |
66.7 |
42.5 |
16.7 |
42.5 |
16.7 |
D |
255 |
100 |
0 |
0 |
0 |
0 |
m = mass of raw materials and P = percentage relative to the total mass of the pile.
Table 2. Physicochemical characteristics of the composts used [12].
Settings |
Compost A |
Compost B |
Compost C |
Compost D |
pH |
8.8 |
9.1 |
8.2 |
9.7 |
%MO |
20.00 |
19.00 |
18.00 |
39.51 |
%COT |
12.10 |
11.02 |
10.44 |
22.92 |
%N |
1.20 |
1.27 |
1.45 |
2.02 |
C/N |
9.9 |
8.68 |
7.20 |
11.34 |
Ptot (mg/g) |
32.40 |
61.44 |
39.96 |
15.02 |
Pass (mg/kg) |
112.37 |
113.46 |
110.53 |
136.86 |
Ca (mg/g) |
51.12 |
52.26 |
50.44 |
39.50 |
Mg (mg/g) |
7.90 |
9.34 |
9.01 |
9.91 |
K (mg/g) |
12.58 |
10.50 |
13.58 |
30.67 |
Na (mg/g) |
17.79 |
11.21 |
14.07 |
14.13 |
CEC (Cmol /kg) |
78.10 |
69.94 |
73.50 |
80.49 |
Ptot = total phosphorus, Pass = available phosphorus, CEC = cation exchange capacity, COT = total organic carbon.
Table 3. Evolution of corn germination rate as a function of compost and doses.
100% sand |
75% sand + 25% compost |
50% sand + 50% compost |
25% sand + 75% compost |
100% compost |
Germination rate (%) of corn seeds for compost A |
100 |
100 |
87.5 |
87.5 |
75 |
Germination rate (%) of corn seeds for compost B |
100 |
100 |
100 |
87.5 |
87.5 |
Germination rate (%) of corn seeds for compost C |
100 |
100 |
87.5 |
75 |
75 |
Germination rate (%) of corn seeds for compost C |
100 |
87.5 |
75 |
75 |
62.5 |
2.1.3. Reproduction Material Used
Corn (Zea mays L., variety TZEE) was the only crop tested in these agronomic trials, due to its importance as a major food crop in Togo. According to Adewi et al. [14], maize cultivation faces challenges such as soil degradation and unforeseen seasonal variations, which can significantly reduce yields.
2.2. Methods
2.2.1. Period of Agronomic Trials and Test Soil
The agronomic trials were carried out from August to December 2022 on a plot located at the University of Lomé (Togo), at the following geographical coordinates: 6˚10.30'N, 1˚12.70'E, at an altitude of 20 meters. The soil used for this study had been left fallow for more than six years, meaning that this soil had not been subject to any organic or chemical amendment during this time.
2.2.2. Analysis of the Physicochemical Parameters of the Experimental
Soil
Before soil amendment with different composts and chemical fertilizers, soil samples were taken from the 0 to 20 cm layer horizons [15] to determine the following physicochemical parameters: particle size, pH, total organic carbon content (% TOC), total nitrogen content (% N), C/N ratio, total phosphorus (Ptot), available phosphorus (Pass), as well as potassium (K), sodium (Na), calcium (Ca), and magnesium (Mg) contents.
2.2.3. Soil Preparation and Sowing of Corn
On the study soil, a device comprising 18 elementary plots of 2.80 m2 each (2.8 m long by 1 m wide), separated by 0.7 m wide alleys was created (Figure 3). Six treatments were applied on these plots: ST0 (control soil without compost or chemical fertilizers), STA (soil amended with compost A at 10 t/ha), STB (soil amended with compost B at 10 t/ha), STC (soil amended with compost C at 10 t/ha), STD (soil amended with compost D at 10 t/ha) and STEC (soil amended with chemical fertilizers at 200 kg/ha). The composts were applied 3 days before sowing and the chemical fertilizers were applied on the 16th day (NPK) and on the 45th day (Urea) after sowing. Each treatment was repeated three times randomly. Plots were prepared one week before sowing and watered for three days before sowing. Sowing was carried out at a spacing of 60 cm × 40 cm, placing four seeds per pocket. Two weeks after sowing, thinning was carried out to maintain two plants per pocket. Regular weeding was carried out throughout the trial. The crops were watered every two days with 30 litres per plot, or by natural rainfall, until 60 days after sowing, thus ensuring a good water regime.
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Figure 3. Corn sowing plan during agronomic trials.
2.2.4. Harvest and Evaluation
Harvesting took place 110 days after sowing. Grain yield and 1000-grain weight for each treatment were measured. Formula was used to calculate the grain yield of each elementary plot.
: Formula
Yld: yield (in tonnes per hectare);
M: mass of harvested seeds (in tonnes per hectare);
Hs: standard humidity (14% humidity recommended for good seed conservation);
Hc: humidity of seeds at the time of harvest.
2.2.5. Post-Test Analysis
After the agronomic trials, i.e. six months after the application of the different composts, soil samples (depth of 0 to 20 cm) were taken from each elementary plot for analysis. The main physicochemical parameters analyzed on these samples are: particle size, pH, total organic carbon content, fertilizing elements (Ca, Mg, Na, K), total phosphorus and assimilable phosphorus, as well as cation exchange capacity (CEC).
2.2.6. Protocols for Analysis of Physicochemical Parameters
a) Soil granulometry
The particle size was determined with a BETTERSIZER ultrasonic granulometer. Indeed, 1 to 10 g of the soil under study is introduced into an ultrasonic bath containing distilled water and homogenized using a stirrer. After homogenization, the wet sample is conveyed to a reading tank equipped with a screen on which the percentage of each texture is read according to its size.
b) Potential of hydrogen (pH)
The pH is measured on aqueous suspensions according to the AFNOR NF ISO 10-390 standard of November 1994.
c) Total nitrogen (NTK)
Total nitrogen (NTK) which is the sum of ammoniacal nitrogen and organic nitrogen is determined according to the AFNOR ISO 11261 standard of June 1995, as described by Biekre et al. [4].
d) Total phosphorus (Ptot)
Total phosphorus (Ptot) is determined in two steps according to the method of Bustamante et al. [16]. Indeed, ten (10) grams of sample are digested in an acid medium (converting all the phosphorus into orthophosphate), followed by the spectroscopic determination of orthophosphate ions at 660 nm.
e) Total organic carbon (TOC)
Total organic carbon (TOC) was measured following the method of Walkley and Black [17].
f) Fertilizing elements (Ca, Mg, Na, K)
These elements were determined by atomic absorption spectrometry (AAS) after mineralization of the samples with aqua regia, in accordance with the standard method NF ISO 11466.
g) Assimilable phosphorus (Pass)
Available phosphorus (Pass) was measured by the Olsen method. One gram of soil was stirred in 20 ml of 0.5 M sodium bicarbonate for one hour, then filtered and assayed with a UV-visible spectroscope at 660 nm.
h) Cation exchange capacity (CEC)
This parameter was determined according to the Metson method [18].
3. Results and Discussion
3.1. Physicochemical Characteristics of the Experimental Soil
The physicochemical characteristics of the experimental soil before the start of the agronomic trials are presented in Table 4. The analysis reveals that the soil has an acidic pH, less than 7 (pH = 5.50), indicating moderate acidity. This acidity may require adjustment to optimize crop growing conditions. The contents of total organic carbon (TOC) (%TOC = 0.48), total nitrogen (%N = 0.04), total phosphorus (Ptot = 77.55 mg/kg), and available phosphorus (Pass = 2.78 mg/kg) are all relatively low, suggesting that the soil is poor in essential plant nutrients. These results are corroborated by similar studies showing that nutrient-poor soils can limit agricultural productivity [19].
Table 4. Physicochemical parameters of the experimental soil.
Physicochemical parameters |
Measured contents |
Gomgnimbou et al. [15] |
pH |
5.50 |
3.95 |
% Total organic carbon (TOC) |
0.48 |
0.38 |
% Total nitrogen (N) |
0.04 |
0.034 |
C/N ratio |
14 |
11 |
Total phosphorus (Ptot) (mg/kg) |
77.55 |
80 |
Phosphorus assimilable (Pass) (mg/kg) |
2.78 |
2.72 |
Calcium (Ca) (mg/kg) |
136.91 |
- |
Magnesium (Mg) (mg/kg) |
183.89 |
- |
Potassium (K) (mg/kg) |
126.91 |
1348 |
Sodium (Na) (mg/kg) |
345.00 |
- |
Cation exchange capacity (CEC) (Cmol/kg) |
2.93 |
1.98 |
Sand (% sand) |
91.98 |
- |
Silt (% silt) |
6.99 |
- |
Clay (% clay) |
1.02 |
- |
Ptot = total phosphorus, Pass = available phosphorus, CEC = cation exchange capacity, COT = total organic carbon.
The content of nutrient elements, such as calcium (Ca = 136.91 mg/kg), magnesium (Mg = 183.89 mg/kg), potassium (K = 126.91 mg/kg) and sodium (Na = 345.00 mg/kg), is also low. This deficiency of essential plant nutrients is consistent with observations from recent studies, which highlight the importance of proper nutrient management to maintain soil fertility and support crop yields [20]. The soil particle size distribution indicates that it is predominantly sandy (%sand = 91.98). Sandy soils, although well drained, often have limitations in terms of water and nutrient retention. This characteristic is well documented in the literature, which highlights the challenges associated with the management of sandy soils, including their low water-holding capacity and their need for fertilization to improve their productivity [21] [22].
In conclusion, the experimental soil presents characteristics indicating low fertility and potentially problematic acidity. The application of composts as amendments can help to improve these conditions, as previous research has shown [23] [24]. Acidity correction and nutrient enrichment are essential to improve soil fertility and support sustainable agricultural production.
3.2. Influence of Composts on the Chemical Properties of the Soil
Table 5 shows the new physicochemical parameters of the different amended soils.
Table 5. Physicochemical parameters of the treated plots.
Settings |
STA |
STB |
STC |
STD |
ST0 |
STEC |
pH |
7.30a |
7.14a |
7.02a |
7.53a |
6.05a |
6.51a |
%COT |
0.66a |
0.72a |
0.78a |
0.80a |
0.50a |
0.54a |
%N |
0.062a |
0.059a |
0.058a |
0.071a |
0.035a |
0.062a |
Ca (mg/kg) |
1643.02a |
703.45b |
1361.49c |
756.20d |
139.69e |
155.76f |
Mg (mg/kg) |
583.07a |
230.92b |
393.05c |
158.97d |
190.42e |
125.45f |
K (mg/kg) |
143.84a |
130.49b |
147.76c |
158.97c |
125.23d |
141.91f |
Ptot (mg/kg) |
802.78a |
686.67b |
732.14c |
526.23d |
111.39e |
116.10f |
Pass (mg/kg) |
35.30a |
24.15b |
34.48a |
45.33c |
2.42d |
38.22f |
CEC (cmol/kg) |
3.36a |
4.61a |
4.03a |
4.90a |
2.56a |
3.35a |
Note: Values with different letters on the same line are significantly different at the 5% probability level. Ptot = total phosphorus, Pass = available phosphorus, CEC = cation exchange capacity, COT = total organic carbon.
Before compost application, the soil pH was 5.5, indicating moderate acidity. After amendment, the pH of soils treated with these composts approached neutrality, ranging from 7.02 to 7.53, while those of the control soil (ST0) and the soil amended with chemicals (STEC), which were 6.05 and 6.51, respectively, were slightly acidic. This trend towards a more neutral pH for soils amended with the different composts can be attributed to the basicity of the composts used, whose pH ranged from 8.2 to 9.7. Nyembo et al. confirmed that the application of composts can effectively restore the pH of an acidic soil by increasing its buffering capacity [25]. The highest levels of total organic carbon (%TOC = 0.80%) and total nitrogen (%N = 0.07%) were observed in soil amended with compost D (STD). Poultry droppings, used to produce this compost, are known to be rich in easily decomposable organic matter, which promotes the release of nutrients into the soil. Dean et al. [26] observed that poultry droppings effectively increased total soil nitrogen levels in the short to medium term. Composts enriched with organic matter, such as poultry droppings, improve soil fertility by increasing carbon and nitrogen content, which is crucial for crop growth. Soil amended with compost D (STD) also recorded the highest cation exchange capacity (CEC) at 4.90 cmol/kg. This increase in CEC is thought to be due to the rich organic matter content of the composts, which improves soil structure and its ability to retain cations. Higher CEC allows the soil to retain essential plant nutrients more efficiently. The best levels of total phosphorus (802.78 mg/kg) and available phosphorus (45.33 mg/kg) were observed in soils amended with compost A (STA) and compost D (STD), respectively. Useni et al. found that composts could improve the levels of available phosphorus in soil, which is crucial for the development of maize plants [11]. The amended soils showed an increase in the levels of calcium (Ca), magnesium (Mg), and potassium (K) compared to the control soil. The soil amended with compost A (STA) recorded the best contents of calcium (1643.02 mg/kg) and magnesium (583.07 mg/kg), while compost D (STD) provided the best contents of potassium (158.97 mg/kg) and available phosphorus (45.33 mg/kg). Composts, rich in nutrients, enrich the soil with these essential nutrients.
3.3. Influence of Composts on the Granulometry of Different
Amended Soils
Table 6 illustrates the particle size distribution of the plots amended with the composts (STA, STB, STC, and STD). Although the general texture of the study soil, initially sandy, was not significantly modified, variations in the proportions of sand, silt, and clay were observed. The proportions of sand in the plots treated with the composts varied from 83% to 88.79%. The soil amended with compost A (STA) showed the lowest percentage of sand (83%) and the highest percentage of clay (%Clay = 8%). Furthermore, the proportions of silt in the amended plots (STA, STB, STC, and STD) varied between 8% and 10.08%, while the control plot (ST0) showed a silt percentage of 6.08%. This increase is probably due to the contribution of organic matter by composts, which enrich the soil with fine particles and promote the formation of silt. The results obtained are in agreement with those of Bouajila and Sanaa [27] who noted an improvement in soil structure after application of manure composts. These changes are beneficial for overall soil structure, as an increase in silt and clay can improve soil stability and its ability to retain water and nutrients. These contributions of silt and clay by the different composts are beneficial to the soil. Indeed, for kantone and Liechtenstein [28], clays and silts constitute formidable reservoirs of water and vital elements for vegetation. In conclusion, although the overall texture of the study soil remained sandy, the composts had a significant impact on the distribution of particles in the soil. The addition of composts, especially those containing phosphate mud, led to an increase in the proportion of clay and silt, which improved the soil texture and its water retention properties.
Table 6. Soil granulometry.
Different amended soil |
%sand |
%silt |
%clay |
STA |
83 |
9 |
8 |
STB |
88 |
8 |
4 |
STC |
85 |
8.52 |
6.48 |
STD |
88.79 |
10.08 |
1.19 |
STEC |
90.58 |
5.58 |
3.84 |
ST0 |
92.26 |
6.08 |
1.66 |
3.4. Influences of Composts on Corn Grain Yield
Table 7 presents the corn grain yields obtained with the different compost treatments. Although the differences are not significant at the 5% level, the plots amended with the composts (STA, STB, STC, STD) show higher yields than the control plot, with values ranging from 2.53 t/ha to 4.05 t/ha, compared to 1.8 t/ha for the unamended soil. This improvement in yield can be attributed to the richness of the composts in essential nutrients such as carbon, nitrogen, phosphorus, calcium and potassium. Compost D (STD), in particular, produced the highest yield (4.05 t/ha). This superior performance is probably due to the high organic matter content of compost D, which provides a gradual and continuous release of nutrients necessary for corn growth. For Kitabala et al., the contribution of doses of compost of compost to the soil improves its fertility and quonsequently crops yelds [29]. Our results are in agreement with those obtained by Tamakloe et al., who reported a yield of 2.40 t/ha for maize on soil amended with household waste composts [30]. However, the yield observed in our study is significantly higher, which can be explained by the higher nutrient composition of our composts. The work of Mrabet et al. [31] has clearly demonstrated that the presence of compost in the soil significantly influences corn yield in terms of weight. Compost D, with its high organic matter concentration and high nutrient levels, is consistent with these observations, highlighting the importance of balanced compost composition to optimize corn yields. Furthermore, the results of this study are also supported by the work of N’dayegamiye et al. [32], who noted significant increases in corn yields after amending soils with composts rich in potassium, nitrogen, phosphorus, and then organic matter.
Ultimately, although the yield differences between treatments were not statistically significant, the addition of composts appeared to improve corn grain yield compared to unamended soil. The variations observed between the different composts highlight the importance of the nutritional quality of composts in optimizing agricultural yields.
Table 7. Corn grain yield according to treatments.
Treated soils |
Yield (t/ha) |
STA |
3.70 ± 0.51a |
STB |
2.53 ± 0.34a |
STC |
3.93 ± 0.29a |
STD |
4.05 ± 0.57a |
ST0 |
1.82 ± 0.26a |
STEC |
4.01 ± 0.22a |
Note: Values assigned the same letters in the same column are not significantly different at the 5% probability threshold.
3.5. Influence of Composts on the Weight of 1000 Corn Grains
Table 8 presents the weights of 1000 corn grains obtained with the different compost treatments. The results show that the weight of 1000 grains varies between 221.95 ± 2.62 g and 240.10 ± 13.10 g for the amended soils, while the control soil has a weight of 217.85 ± 3.15 g; the soil amended with chemical fertilizers has a weight of 235.26 ± 9.32 g. The composts used in this study contain various essential nutrients, such as organic matter and mineral salts, which are beneficial for the growth of corn plants. The values observed for the weights of 1000 grains are higher than those reported by Zoumboudré et al. who found an average weight of 172 g for corn grains grown with pruning manures [33]. This improvement in nutrient availability leads to heavier grains, as shown in our study. These results highlight the importance of composts in optimizing corn production.
Table 8. Weight of 1000 corn grains according to treatments.
Treated soils |
Weight of 1000 grains (g) |
STA |
221.95 ± 2.62a |
STB |
228.90± 16.83a |
STC |
228.10 ± 13.10a |
STD |
240.10 ± 13.44a |
ST0 |
217.85 ± 3.15a |
STEC |
235.26 ± 9.32a |
Note: Values assigned different letters in the same column are significantly different at the 5% probability level.
4. Conclusion
This study investigated the short-term impacts of composts made from poultry manure and phosphate waste from Togo on soil physicochemical properties and maize yield. The results show that compost treatments improved soil parameters, including increasing pH and cation exchange capacity, total organic carbon (TOC), and total nitrogen (NTK) compared to those of the control soil (ST0). The best corn seed yield (4.05 ± 0.57 t/ha) and the highest 1000 grain weight (240.10 ± 13.44 g/1000 grains) came from the treatment with compost D (STD). The soil amended with compost A showed a notable increase in the proportion of clay. Ultimately, in view of the analyses, it can be said in general that the composts produced are of good quality and can validly replace chemical fertilizers if their production is done in large quantities.