Effectiveness of Bio-Phosphate Fertilizer on Growth Performance and Production of Irrigated Lowland Rice

. Intensive agricultural land with a limiting factor of acidity often has a great degree of phosphate elements but is not accessible to plants. The utilization of bio-phosphate fertilizer (Bio-P) is an eﬀort to enhance the available P for plants to support sustainable agricultural development. This research evaluated the eﬀectiveness of Bio-P on the growth performance and production of irrigated lowland rice. The research was accomplished in Gemolong District, Sragen Regency, Central Java, Indonesia, from May to October 2021. The research was set in a randomized block design corresponded of ten treatments and four replications. The treatment corresponded of fertilization according to the recommended dose, fertilization according to the recommended dose + Bio-P, existing farmers' fertilization + Bio-P, and without fertilization. The data observed included plant growth, yield components, production, and agronomic and economic feasibility assessments. The ﬁndings revealed that fertilization treatment according to the recommended dose + Bio-P and the existing farmers' fertilization + Bio-P did not signiﬁcantly aﬀect plant growth and yield. The extension of 10 kg ha-1 Bio-P with existing farmers' fertilization produced the highest eﬀectiveness value of 3.56 with a proﬁt of IDR 25,400,400 ha-1 and the highest RAE value of 110.25%.


Introduction
Phosphate (P) is one of the nutrients required by plants for growth and development [1,2].Generally, P levels are high in intensive agricultural land due to the continuous application of P fertilizers.However, almost all P is unavailable because soil particles vigorously bind available P, and divalent cations make insoluble P complexes, making P hard for plants to be absorb [3].Phosphorus availability is highly dependent on soil pH, with an optimal pH range of 6.5-7.5, and maximum P availability can be achieved in soils with a pH range of 6.0-6.5 [4].Soils with low pH have relatively high solubility of Al and Fe ions, which can bind P, causing disruption of plant growth [5].
Elemental phosphorus is not lightly lost through leaching because it is bound on the surface of soil colloids, except in very sandy soils [6].The application of organic matter can accelerate P accessibility [7].Adding soil organic matter (SOM) is important for regulating soil P dynamics and making P available to plants [8].Increased P accessibility can occur during the decomposition and mineralization of organic P in organic matter [9].Phosphorus must exist as an inorganic compound before it can be accessed by plants, usually in orthophosphate ions such as H2PO3-, HPO2- [10].Therefore, phosphate-solubilizing microorganisms (PSM) are needed to provide phosphate to plants [11].Phosphate-solubilizing microbes can dissolve P molecules from organic and inorganic P and increase the accessibility of P by plants [12].PSM can increase plant productivity without causing soil damage [13,14].The experimental results of Fitriatin et al. [15] revealed that PSM can increase phosphatase activity and upland rice production by decreasing organic P. PSM utilization is the most environmentally friendly innovation for P nutrition in plants [16].
Inorganic fertilizers can be suppressed by applying PSM, supporting the government's efforts to reduce the budget for fertilizer subsidies, which tend to increase yearly, and supporting sustainable environmental management.Strategies to increase the effectiveness of inorganic fertilizers can be done with site-specific balanced fertilization and NPK 15-10-12.Balanced fertilization involves the use of compound fertilizers with various formulas to achieve nutrient effectivity.This research aims to test the effectiveness of Bio-P fertilizer on the growth and production of irrigated lowlands rice.

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Materials and method

Research site
The research was carried out in Gemolong Village, Sragen Regency, notably one of the rice production centers in Central Java, Indonesia, from May to October 2021.

Experimental design
The research employed a randomized block design with ten treatments and four repetitions (Table 1).The materials utilized in this study included the Cakrabuana rice seed variety, fertilizers (Petroganic, Urea, NPK, and Bio-P), and pesticides, according to recommendations.Rice was planted in each 20 m2 plot upon a distance between plants of 20 cm x 20 cm.The planted rice is maintained so that water remains available, free from pests and plant diseases, and clean from weeds.

Data collections
The data observed included soil chemical properties before treatment, plant growth, yield components and yield, agronomic feasibility assessment, and the economic feasibility of using Bio-P.Soil chemical properties analyzed were soil acidity (soil pH), C-organic content, N, P, K, and cation exchange capacity (CEC).Plant growth observed were plant height, and amount of leaves at 30, 45, and 60 days after planting (DAP), and amount of productive tillers per plant observed before harvest.Yield components and production parameters included filled and empty grains per panicle, 1000-grain weight and production ha-1.
The Relative Agronomy Effectiveness (RAE) value was used as the foundation for the agronomic feasibility assessment, and the calculation is as follows: (1) Fertilizer uses efficiency occurred if the productivity of the fertilizer treatment tested at a lower dose was the same or greater than that of the standard treatment at a higher dose.Economic feasibility merely considered the variations in how the primary inputs and outputs were produced in its simple benefits analysis [8].

Data analysis
The data obtained were analyzed using IBM SPSS Statistics software version 22, followed by Duncan's least significant difference test.

Soil chemical characteristics
The soil conditions were quite acidic with relatively low C-organic content (<2.0%) (Table 2).The low C-organic content is thought to result from the high intensity of planting without reprocessing rice straw in the field and without adding organic fertilizer.Sudirja et al. [17] reported that organic fertilizers can enhance C-organic content, N-total and N-uptake, and production of rice.The low C-organic content corresponded to low N content (0.18%) (Table 2).Information from local farmers that Urea fertiliser was applied in each growing season, but at a dose below the recommended dosage.The available P status was sufficient, but the total P and Ca contents were high.It was suspected that there was binding between Ca and P, which formed complex compound bonds so that they were not available to plants.

Plants growth
The results of the study showed that the height of the plants did not differ significantly at the recommended doses, recommended doses + Bio-P, or existing farmers' fertilization, but was significantly different when compared to the controls (Table 3).It is presumed that fertilizer application can stimulate plant growth and development, characterized by a consistent increase in plant height from the vegetative phase until harvest.The average increase in plant height with the extension of Bio-P 10-40 kg ha-1 compared to the control was 11.6%.Similarly, adding Bio-P to soil with high P nutrient status did not significantly affect the plant height of some groundnuts during the vegetative and generative phases [19].Applying Bio-P fertilizer at 10-40 kg ha-1 increased the number of tillers per clump at 30 HST and the number of productive tillers before harvest.(Table 3).The addition of 10-40 kg ha-1 Bio-P increased tillers number by 22.3% at 30 DAP and increased the number of productive tillers by 70%.Phosphate is involved in plant tissue proliferation in the generative phase, so the addition of Bio-P is thought to increase the activity of young meristem tissue cells characterized by an increase in the number of productive tillers.This follows the results of Hazra and Santosa [20], who consistently applied 1.00 doses of NPK + 0.75 doses of biological fertilizers and produced more tillers than the controls.Nevertheless, there was no discernible impact on the number of tillers between the treatments of existing farmers' fertilizer + 10 kg ha-1 Bio-P and the recommended fertilization.This was presumably because of the high available P content in both treatments.P availability is influenced by phosphate-solubilizing microbial activity.In soils with a high soil P nutrient status, the microbial activity of phosphate solvent is less or ineffective [21].The activity of phosphate-solubilizing bacteria is more effective when applied to acidic soils, characterized by a high bacterial population; conversely, the bacterial population in slightly acidic soil conditions is relatively low [22].Noted: * Numbers with different letters in each column indicate significant differences based on Duncan's least significant difference test at 0.05.

Yield components and yield
Bio-P added at 10-40 kg ha-1 has been shown to significantly increased the number of filled grains per panicle, 1000-grain weight, and harvested dry grains weight (Table 4).However, significant differences were not found between treatments F3-F6 (recommended fertilizer dose) and treatments F7-F10 (existing farmers fertilizers + Bio-P).Adding Bio-P increased the number of filled grains by 32.2% compared with the control treatment.Massawe and Mrema [23] suggested that using phosphorus fertilizers increased the number of harvested dry grains.The average yield increased by 117%, supported by the number of productive tillers (Table 3) and the weight of filled grains per panicle (Table 4).This follows the research of Meena et al. [24] that using phosphorus fertilizer (60 kg ha-1 P2O5) can increase growth and yield attributes and grain yields.Similarly, a dose of 75 kg ha-1 P2O5 (75% of the recommended dose) positively affected soil phosphatase, P availability, and yield of upland rice in suboptimal soils [15].Noted: * Numbers with different letters in each column indicate significant differences based on Duncan's least significant difference test at 0.05.

Relative agronomy effectiveness
Fertilization treatments according to the recommendation, NPK recommendation + Bio-P, and existing farmer fertilization + Bio-P did not show a significantly different effect on production (Table 5).Farmers' existing fertilization + Bio-P 10 kg ha-1 gave the highest production increase of 117% compared to the control (-), and gave the highest RAE value of 110.25% or an increase of 10.25% from the recommended NPK fertilization (Table 5).This increasing production was supported by the number of productive tillers (Table 3) and the highest yield components of the other treatments (Table 4).Noted: * Numbers with different letters in each column indicate significant differences based on Duncan's least significant difference test at 0.05.

Economic feasibility of bio-p fertilizer
The combination of NPK and Bio-P treatments at various doses is expected to provide information on the economic effectiveness of increased production and the economic value  of lowland rice farming.Based on the results, the cost of rice production ranged from IDR 6,660,000-IDR 10,130,000 ha-1 season-1 (Table 6).The highest costs were incurred in the treatment with 40 kg ha-1 Bio-P, followed by the treatment with 30 kg ha-1 Bio-P, while the lowest costs were incurred for the control treatment.The difference in production costs was caused by the difference in the amounts of Urea, NPK, and Bio-P used.Rice production ranged from 3.724-8.412t ha-1.The highest yield was obtained in treating farmers' existing fertilization + 10 kg ha-1 Bio-P, and the lowest yield was achieved without fertilization (control).The results indicate that adding Urea, Phonska, and Bio-P can increase rice production, following the research of Redda et al. [25], increasing the dose of P fertilizer can increase rice yield.Herve et al. [26] also reported that the highest production (5.82 t ha-1) was obtained at the highest dose of NPK fertilizer.In contrast to the research by Redda et al. [25], the highest upland rice production (4.540 t ha-1) was obtained at a higher dose of Urea (69 kg ha-1) compared to P2O5 fertilizer (23 kg ha -1).This difference is due to differences in soil fertility and nutrient availability.
The price of harvested dry grains was IDR 4,200 kg-1; the highest revenue from rice farming was IDR 34,330,400 obtained from the existing fertilization treatment + 20 kg ha-1 Bio-P with a profit of IDR 24,400,400 ha-1.The treatment without fertilization resulted in the minimum profit of Rp 14,640,800 ha-1.Even though the benefits received differed between treatments, all treatments provided positive benefits, as indicated by the economic effectiveness value of fertilization >1 (2.04-3.56).Thus, all treatments could be alternatives for developing rice farming at the study site.
The value of the economic effectiveness of NPK and bio-urine fertilization in South Sulawesi was also greater then >1 [27], whereas the value of economic efficiency in D.R. Congo varies between 0.476-1.549[28].These results indicate that revenue from expected production was greater than the costs incurred.Variations in the economic effectiveness of fertilization in rice farming reflect variations in production costs and the output obtained.

Conclusion
The treatments of existing farmers' fertilization + 10 kg ha-1 Bio-P produced the most effectiveness value of 3.56 with a profit of IDR 25,400,400 ha-1 and the top RAE value of 110.25% compared to other fertilization treatments.
We would like to express our gratitude to the Assessment Institute of Agricultural Technology Central Java for helping to fund and facilitate the research activities.
Additionally, we would like to thank Yuni Kamal and Sutrisno for helping with data collection in the field.

Table 2 .
Soil chemical properties at the study location in Gemolong, Sragen, Central Java, Indonesia, 2021.
[18]d: * The criteria for assessing soil analysis results were based on the Technical Guide 2nd.Edition: Chemical Analysis of Soil, Plants, Water, and Fertilizers by Eviati and Sulaeman[18].

Table 3 .
Growth of irrigated lowland rice plants treated with Bio-P fertilizer in Gemolong, Sragen, Central Java, Indonesia, 2021.

Table 4 .
Yield components and yield of irrigated lowland rice treated with Bio-P fertilizer in Gemolong, Sragen, Central Java, Indonesia, 2021.

Table 6 .
Simple profit analysis on Bio-P fertilizer effectiveness on irrigated lowland rice in Gemolong, Sragen, Central Java, Indonesia, 2021.