Utilization of Biogas Slurry from Cow Faces and Palm Oil Empty Fruit Bunches Soaking Water on Indigofera Zollingeriana Productivit y

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Introduction
Forage is one of the important factors in the ruminant livestock business. To increase ruminant livestock production, however, it is need to be supported by quantity and quality provision of adequate forage. One way that can be done to increase greenery is by applying liquid organic fertilizer.
such as manure [1]. The slurry is useful for fertilizing vegetables, fruits and trees/perennials. Biogas slurry has an advantage over manure or compost: it contains nutrients that plants can immediately utilize. There are two kinds of biogas slurry fertilizers: liquid and solid slurry. Biogas slurry contains various nutrients which are very important for plant growth. Macronutrients such as Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca), Magnesium (Mg), and Sulfur (S), and micronutrients such as Iron (Fe), Manganese (Mn), Copper ( Cu), and Zinc (Zn). In addition to nutrients, liquid bio-slurry fertilizer contains amino acids, auxin hormones and cytokinins [2].
The liquid slurry can improve soil properties, produce safe agricultural products, and contain microorganisms that can fertilize the soil, add nutrients, and control soil diseases. [3] Based on the description above, which explains the nutritional content of biogas slurry, the authors wish to research the use of biogas slurry with the input of cow faeces and empty fruit bunches soaking water on the productivity of Indigofera zollingeriana plants such as (plant height, number of leaves, number of branches, stem diameter and leaf width).

Methods
The research method used a completely randomized design (CRD) and consisted of 3 treatments and six replications: P0 = Control P1 = 50% slurry (180 ml/polybags) P2 = 100% slurry (360 ml/polybags) Indigofera seeds were planted in polybags with a capacity of 5 kg and watered every day according to the field capacity in this research, which was 360ml/polybags.

Making biogas slurry
Mixing cow dung with empty palm fruit bunches soaking water in a predetermined amount,then stirred so that a mud-like form with a ratio of 2:1.
Flowing sludge to the digester inlet hole. For the first filling, you need much sludge to fill the volume in the digester.
After the digester is filled with sludge, the gas valve on the digester must be closed so that the fermentation process occurs.
. Discard the first gas produced from day 1 to day 8. From day 10 to day 14, methane gas (CH4) and CO2 gas will form and have begun to decrease in the fermentation On the 14 th day, gas will form, which can ignite a fire on the gas stove and produce a slurry used as fertilizer. Measured once every 14 days.

the number of leaves
Counted all leaves in each treatment. Counted every 14 days.

the number of branches
Calculated by counting all branches that appear on each plant from each treatment. Counted every 14 days.

Stem diameters
Measured rod diameter 10 cm above the ground using a calliper. Measured every 14 days.

Leaf width
Measured leaf width using a tape measure or ruler, measured on the widest leaf in each treatment.
Measured once every 14 days.

Plant high
The effect of slurry dilution on the plant high of Indigofera Zollingeriana Zollingeriana plants resulted significant growth in plant height. As can be seen in Table 1

Number of leaves
The effect of slurry application on the number of leaves of Indigofera Zollinegrianna It can be seen in Table 2 that P2 shows the highest average number of leaves compared to P0 and P1, with an average number of leaves of 592,83. It can be seen from the plant height data (Table   1), and compared with the average number of leaf blades, that taller plants have more leaves. This is presumably due to the nutrient content contained in the soil and the influence of the fertilizer application used to meet plant needs. The process of photosynthesis also depends on the availability of nutrients that can help grow plants; as seen in Table 3, the results of the P0 treatment showed an average number of leaves of 297,33 fewer leaves than in P1 and P2; this was due to the lack of nutrients contained in the soil and there was no effect from the treatment given, because at P0 only given 360 ml/plot water treatment and no slu fertilizer ry biogas. [5] states that the number of leaves shows an increase along with an increase in the concentration of foliar fertilizer. This is related to the role of nitrogen as a component of chlorophyll. Increasing the element of N in plants is associated with the formation of chlorophyll in the leaves, thereby increasing the process of photosynthesis, which spurs the growth of the number of leaves in plants [6].

Number of branches
The effect of slurry dilution on the number of branches of Indigofera Zollinegrianna  [7], [8].

Stem diameters
The effect of slurry dilution on the stem diameters of Indigofera Zollinegrianna Zollingeriana stems. The increase in stem diameter is caused by the presence of N, P, and K nutrients contained in the bio-gas slurry fertilizer. N, P, and K nutrients are absorbed by plants, especially in the vegetative phase. According to [9], N, P, and K fertilizers are needed for plant growth, especially in stimulating plant height formation and stem diameter enlargement.

Leaf width
The effect of slurry dilution on the leaf width of Indigofera Zollinegrianna The results showed that administering a biogas slurry dose of 360 ml/plot or in the P2 treatment resulted in a greater increase in leaf width compared to P0 and P1. The application of biogas slurry fertilizer at a dose of 360 ml/plot significantly affected the P2 treatment. It can be seen in Table   4 that the largest leaf widths were found in P2 with an average leaf width of 1,07 cm; in P1, the average leaf width was 0,90 cm and in P0, the average leaf width was 0,68 cm.
Leaf width increases because leaf growth is quite good and faster. Plants with wider leaf width at the beginning of growth will grow faster because of the ability to produce higher photosynthate compared to plants with lower leaf area. The more leaves, the more photosynthesis occurs. An increase in photosynthesis will produce more and more photosynthate so that the dry weight of the plant will increase by the photosynthate, and the energy produced is used to form and maintain the quality of the leaves [10], [11].

Conclusion
Based on the research that has been done, it can be concluded that treatment with a concentration of 360 ml of biogas slurry/plant plot gave the best effect on plant height, number of leaves, leaf width, number of branches and stem diameter. The higher the dose given, the better the results produced because, the higher the biogas slurry given, the more N content it contains.