Utilization azolla liquid organic fertilizer with goat manure to enhance organic okra (Abelmoschus esculentus L. Moench) production

Azolla is found abundantly in rice fields in Indonesia, therefor potentially as a source of biological nitrogen derived from natural biological bodies that are renewable. The use of a combination liquid fertilizer from fermented azolla with goat manure which is used as a source of nutrients and to improve soil quality as an effort in developing and implementing sustainable agriculture in cultivation of okra plants, needs to be studied. Okra is a vegetable that has many benefits for health which can be consumed in fresh or processed form. This research was carried out on Faculty of Agriculture, Universitas Sumatera Utara, Medan, from August to December 2022, using a randomsized block design with two factors, the first factor is azolla liquid organic fertilizer (75, 150, 225, and 300 ml/polybag) and the second factor is goat manure (0, 100, and 200 g/polybag). The application of 200 g/polybag goat manure with150 ml/polybag azolla liquid organic fertilizer or 100 g/polybag goat manure application with 300 ml / polybag azolla liquid organic fertilizer in okra plants can substitute the use of inorganic fertilizer for increased yield and environmental preservation.


Introduction
Increasing yields and preserving the environment is the basis for the implementation of sustainable agriculture, organic fertilization to reduce environmental damage and pollution is one of the implementations [1].Utilization of azolla as an organic fertilizer that has the ability to provide nutrients for plants, especially the need for nitrogen elements [2].
Azolla is found abundantly in rice fields in Indonesia, therefor potentially as a source of biological nitrogen derived from natural biological bodies that are renewable [3].Azolla has a wide distribution and is able to fix N2 from the air because it has a symbiotic relationship with Anabaena alga, which can fix nitrogen naturally.Anabaena can fix air nitrogen and will release this nitrogen to its host and the water in the rice field, so that azolla plants as a host grows quickly and reproduces quickly, within 3-5 days azolla's fresh weight doubles.If azolla's inoculum is spreaded with 100 g/ m 2 under normal conditions, it will grow and develop to reach 15-20 tons in 20 days for 1 ha area.The decomposition of azolla is very fast (3-6 weeks) by releasing 56-80% nitrogen into the soil, 10 tons of fresh azolla is equivalent to 50 kg of urea.However, farmers generally do not know the benefits of this azolla plant or how to cultivate and manage into organic fertilizer [4].
Azolla liquid organic fertilizer is a solution from the decomposition or fermentation Azolla sp.plants.Azolla liquid organic fertilizer contains 1.645% nitrogen, 0.071% phosphorus, 2.366% potassium, and 0.089% magnesium [5].Applied 120 ml/L azolla liquid organic fertilizer to tomato significantly increasing number of leaves, plant height, fruit weight per plant, number of fruits, total production, wet pruning weight, dry pruning weight, and harvest age [6].
Goat manure can improve soil aeration, increase the ability of the soil to hold nutrients and water, increase soil buffer, energy source for soil microorganisms and as a source of nutrients [7].Goat manure is often used as organic fertilizer, contains among others 0.6% nitrogen, 0.3% phosphorus and 0.17% potassium [8].The application of 40 ton/ha goat manure has significantly effect, on all variables of corn plant observation [9].
Growing vegetables with organic farming techniques will use natural ingredients without using chemical fertilizers and pesticides.Organic vegetables have advantages over non-organic vegetables, which are healthier, have better taste, are environmentally friendly, and have a higher nutritional content than non-organic vegetables, such as vitamins, minerals, and antioxidants.Okra is a vegetable that has many advantages, especially for health, and can be consumed in fresh or processed form.Young okra content among others; 85.70% water content, 8.30% protein, 2.05% fat, 1.4% carbohydrates and 38.9% calories per 100 grams.
The success of growing organic okra is influenced by the right application of fertilizers.Using organic fertilizers can improve the physical, chemical and biological characteristics of soil media and have an impact on increasing plant growth and production.The use of only manure is not sufficient for plant nutritional needs, therefore it is necessary to add other fertilizers, one of which is liquid organic fertilizer.This study was conducted to determine the effect of azolla liquid organic fertilizer and goat manure application for okra plant growth and production.

Materials and methods
This research was carried out on Faculty of Agriculture, Universitas Sumatera Utara, Medan, from August to December 2022, using a Randomized Block Design with two factors, the first factor is Azolla liquid organic fertilizer (P) with a level of P1 = 75 ml/polybag (7.5 L/ha); P2 = 150 ml/polybag (15 L/ha); P3 = 225 ml/polybag (22.5 L/ha) and P4=300 ml/polybag (30 L/ha), and the second factor is goat manure (K) with a level of K0 : 0 g/polybag (0 tons/ha); K1 = 100 g/polybag (20 tons/ha) and K2 = 200 g/polybag (40 tons/ha), The okra seeds used Naila IPB variety (green okra).The planting media used topsoil with 1.17% Nitrogen and 2.19 % Nitrogen goat manure with composition according to the treatment put in10 kg polybag size (40 x 50 cm).Azolla liquid organic fertilizer (Azolla LOF) is made by fermenting azolla that has been given water in a ratio 1: 1, using Effective Microorganisms 4 decomposer bacteria for 7 days and filtered separated pulp and liquid.The liquid is a ready-made Azolla LOF with a content of 0.6% nitrogen, 0.12% P2O5, 0.08% K2O and Ph 6.49, given five times, at the age of 1 week after planting (WAP), 3 WAP, 5 WAP, 7 WAP and 9 WAP, with 2 weeks fertilizing interval and fertilizing dose each administration is 1/5 of the treatment dose.Application is done by watering the planting media.The harvested okra fruits are young fruits.The length of the harvested fruit measures 5 -10 cm.Harvesting is carried out until the plant is 15 WAP old.Data were analyzed with the Duncan Multiple Range Test at α= 5%.

Plant height and leaves number
The highest plants were obtained at the 200 g/polybag goat manure and 150 ml/polybag azolla liquid organic fertilizer treatment combination and the highest leaves number tended to be obtained in the same treatment combination.
The treatment of goat manure and azolla liquid organic fertilizer mutually supports plant growth, where goat manure has organic matter and higher nitrogen than other manure.Goat manure contains 2.19% nitrogen, 2.01% P2O5, and 1.78% K2O.Based on the results of the analysis azolla liquid organic fertilizer contains 0.60% nitrogen total.The application of organic fertilizers increases nitrogen availability because organic fertilizers improve soil chemistry in relation to the decomposition of organic matter, i.e. the change from more complex compounds to simpler compounds.Nutrients in organic fertilizers through the mineralization process can maintain optimal soil levels during the planting period.Some organic substances released during mineralization can act as chelates that help in the absorption of iron and other micro-nutrients therefor can improve plant growth and quality [10].Plants that get enough nitrogen supply will form extensive leaf blades with high chlorophyll content, so that plants can produce assimilate in sufficient quantities to support their vegetative growth.It can also be seen that the15 WAP age of the plant can still be harvest.The relationship between okra plant height aged 13 WAP with goat manure application at the applications of 150 and 225 ml/polybag Azolla liquid organic fertilizer showed a positive linear relationship, while at the dose of 75 and 300 ml/polybag azolla liquid organic fertilizer showed not significant (Figure 1).The relationship between okra plants height aged 13 WAP with the application of Azolla liquid organic fertilizer at the 100 g/polybag application of goat manure (Figure 2) showed a positive linear relationship, where increasing Azolla liquid organic fertilizer dose to 300 ml/polybag will increase plant to 300 ml/polybag will increase plant height.There is a positive cubic relationship at 200 g/polybag goat manure application

Fruits number and total fruits weight per plant
The highest plants were obtained at the 200 g/polybag goat manure and 150 ml/polybag azolla liquid organic fertilizer treatment combination and the highest leaves number tended to be obtained in the same treatment combination.The largest fruits number and total fruits weight per plant were obtained at at the 200 g/polybag goat manure and 150 ml/polybag azolla liquid organic fertilizer treatment combination which is not significantly difference with at the 100 g/polybag goat manure and 300 ml/polybag azolla liquid organic fertilizer treatment combination.This is also supported by the largest plant height and the highest number of leaves were actually obtained at same treatment.
This shows that to obtain the best production, if goat manure is given with a high dose of 200 g/polybag (40 tons /ha), then azolla liquid organic fertilizer is enough to be given 150 ml/polybag (15 L / ha).But if goat manure is given 20 tons/ha, then Azola liquid organic fertilizer is given with a high dose of 30 tons/ha, so that the nutrients provided by organic fertilizer are available to support vegetative growth and produce more fruit.Application of urea fertilizer in okra plants up to 300 kgs / ha (138 kgs N/ha) significantly increases the number of fruits and the total weight of fruits per plant [11].Fertilizing with 30 tons/ha Azolla liquid organic fertilizer is equivalent to giving 180 kgs N per ha.
The results above show that the use of inorganic fertilizers in okra plants can be substituted by applying organic fertilizers.By utilizing Azolla as an organic fertilizer that has the ability to provide nutrients for plants, especially nitrogen, nitrogen needs for plants can be met not only from inorganic fertilizers and ultimately can reduce the consumption of inorganic fertilizers.This certainly supports efforts in reducing damage to natural and environmental pollution with the continuous use of inorganic fertilizers.In Triputra Region, Northeastern India, Glyricidia leaves are used as organic fertilizer to increase rice productivity [12].Using natural materials such as humic substances is one of the techniques used to save farmers and ecosystems from the adverse effects of inorganic fertilizers [13].
The relationship between okra fruits number with goat manure application at 150 ml/ polybag Azolla liquid organic fertilizer application shows a positive linear relationship where increasing goat manure up to 200 g/polybag will increase the number of fruits (Figure 3).The relationship between okra fruits number with Azolla liquid organic fertilizer shows a positive linear relationship both of at 0 g/polybag and 100 g/polybag goat manure application (Figure 4) where the increase azolla liquid organic fertilizer application up to 300 ml/polybag increases fruits number.The goat manure application up to 100 g/polybag is not enough to support optimal growth, therefor the addition of nutrients from azolla liquid organic fertilizer increases fruits number.This is also supported by plant vegetative growth data.The relationship between total fruits weight per plant with goat manure application at 150 ml/polybag azolla liquid organic fertilizer application shows a positive linear relationship, where increasing goat manure up to 200 g/polybag increases (Figure 5).The relationship between total fruit weight per plant with Azolla liquid organic fertilizer application at both of 0 g/polybag and 100 g/polybag goat manure application shows a positive linear relationship can be seen in Figure 6.

Figure 1 .
Figure 1.The relationship between okra plant height aged 13 WAP with goat manure application in various applications of Azolla liquid organic fertilizer.

Figure 2 .
Figure 2. The relationship between okra plant height aged 13 WAP with Azolla liquid organic fertilizer application at various applications of goat manure.

Figure 3 .
Figure 3.The relationship between okra fruit number with goat manure application in various applications of Azolla liquid organic fertilizer.

Figure 4 .
Figure 4.The relationship between okra fruit number with Azolla liquid organic fertilizer application in various applications of goat manure.

Figure 5 .
Figure 5.The relationship between total fruit weight per plant with goat manure application in various applications of Azolla liquid organic fertilizer.

Figure 6 .
Figure 6.The relationship total fruits weight per plant with Azolla liquid organic fertilizer in various applications of goat man.

Table 1 .
Plant height and leaves number of okra plants with giving azolla liquid organic fertilizer and goat manure aged 13 WA.
Note: Numbers followed by the same letters at same colum show no significant differences in Duncan's Multiple Range Test at α = 5%.

Table 2 .
Fruits number and total fruits weight per plant of okra plants with Azolla liquid organic fertilizer and goat manure.