Impact of giving vermicompost and goat manure compost to soil N, P, K nutrients, growth and production of mustard greens (Brassica juncea L.)

The excessive and prolonged use of synthetic fertilizers in mustard greens cultivation can lead to soil and plant degradation. To address this issue, alternative methods to enhance soil nutrients, such as incorporating organic fertilizers like vermicompost and goat manure compost, can be employed. This study aims to investigate the effects of applying vermicompost and goat manure compost on soil nutrients (N, P, K), the growth and yield of mustard greens (Brassica juncea L.). Conducted at the experimental field in Medan Selayang and Sumatera Utara Agricultural Technology Research Laboratory from February to May 2020, the research utilized a non-factorial randomized block design (RBD) with various treatments. These treatments included a control group (no fertilizer), recommended dose (goat manure 10 ton/ha + Urea 130 kg/ha) as comparison, vermicompost at 10, 20, and 30 ton/ha, and goat manure compost at 10, 20, and 30 ton/ha. The result indicated that the application of vermicompost and goat manure compost led to increased levels of C-organic, N-total, P-available, K-exchange, the number of mustard greens leaves, and mustard greens production. Vermicompost outperformed goat manure compost in enhancing K-exchange, the number of mustard greens leaves, and mustard greens production. The best treatment is giving vermicompost 20 ton/ha.


Introduction
Mustard greens (Brassica juncea L.) is a type of green vegetable that has high economic value.In Indonesia, mustard greens is one of the most popular vegetables and loved by various groups of people.Mustard greens are widely used as a main ingredient or complementary ingredient in various Indonesian dishes.This causes the demand for mustard greens increase every year.However, this high level of consumption and demand has not been matched by an adequate level of mustard greens production.
According to the Central Statistics Agency, Mustard greens production in Sumatera Utara has decreased, namely 13.10 ton/ha (2019), 12.56 ton/ha (2020), 12.07 ton/ha (2021) and 11.56 ton/ha (2022) [1].Moreover, based on these data, mustard greens production is only around 11-13 ton/ha, while the potential for mustard greens production can reach 25 ton/ha.There are so many factors that can cause non-optimal production of mustard greens, one of which is low soil fertility.Use of organic fertilizers or return crop residues to agricultural land barely done [2].This causes the content of nutrients and organic matter in the soil to be low.
The nutrient element that plays the most role in the growth and production of mustard plants is nitrogen because nitrogen plays a role in the growth of the vegetative parts of the plant.The low nitrogen content in the soil can be overcome by applying urea fertilizer.However, most farmers in Medan Marelan District, which is the central area for vegetable production in Medan City, provide subsidized urea fertilizer without paying attention to the correct dosage [3].They assume that more fertilizer given 1302 (2024) 012008 IOP Publishing doi:10.1088/1755-1315/1302/1/012008 2 cause higher the production of mustard greens, even though excessive application of inorganic fertilizer can cause low efficiency values and in the long-term cause residues that have a negative impact on plants, soil and the environment.
One effort to minimize the residual effects that arise due to the use of inorganic fertilizers such as Urea can be done by using organic fertilizers such as vermicompost.Vermicompost is the result of process decomposing organic material carried out by earthworms.According to the Central Statistics Agency, the amount of organic waste transported in Medan City is 1,230 ton in a day [4].This is potential and can be used as a basic material for making vermicompost.Vermicompost is an organic material that is rich in nutrients and can be used as organic fertilizer and soil conditioner.Vermicompost contains C-organic: 20.43-30.31%,N: 1.80-2.05%,P: 1.32-1.93%,K: 1.28-1.5% with C/N ratio: 11-15 and pH: 6.5-7.5 [5].
Another effort to minimize the residual effects due to the use of inorganic fertilizers such as Urea is to use manure considering that the number of livestock farms in Indonesia is relatively large.One type of manure that can be used is goat manure.According to the Central Statistics Agency, The total population of goats in Sumatera Utara is 819.774goats and the daily production of goat manure is 1.4 kg/head [6].The use of manure is very useful in optimizing natural resources.Goat manure also has potential and can be used as organic fertilizer to add nutrients.Goat manure has a relatively more balanced nutrient content compared to the other manure.Goat manure contains C-organic: 46.51%, N: 1.85%, P: 1.14%, K: 2.49%, with C/N ratio: 11.3 [7].
Based on the description above, the author is interested to do a research about the impact of giving vermicompost and goat manure compost to soil N, P, K nutrients, growth and production of mustard greens (Brassica juncea L.).This study compared vermicompost and goat manure compost with various doses as a substitute for inorganic fertilizer in mustard greens cultivation for sustainable agriculture.

Research site and time
This research was carried out in the experimental field of Medan Selayang District with a height of 32 meters above sea level and the Sumatera Utara Agricultural Technology Research Laboratory.This research began from February to May 2020.

Tools and materials
The materials that used in this research are mustard seeds of the Tosakan variety, Urea fertilizer, vermicompost, goat manure compost and chemicals to support soil analysis.The tools that used in this research are hoes, tape measure, analytical scales, cameras and laboratory tools to support soil analysis.
The research begins with land preparation and made 24 plots measuring 1 m x 1 m.Then ditches are made between the plots with a depth of 30 cm.Initial analysis was carried out on the soil including pH, C-organic, N-total, P-available, and K-exchange.Analysis of vermicompost and goat manure compost includes C-organic, N-total, P-total, and K-total.
The application of vermicompost and goat manure compost is carried out two weeks before planting (two weeks incubation) according to the treatment dose.After two weeks incubation, soil samples were taken in each treatment plot.Soil samples from each treatment plot were analyzed including C-organic (Walkley and Black Method), N-total (Kjeldahl Method), P-available (Bray I Method), and K-exchange (Atomic Absorption Spectrophotometer Method).
The seeds are spread evenly on the seedbed.The seedling media used consists a mixture of goat manure compost and top soil in a 1:1 ratio.Seedlings that are 12 days old or have 3 to 4 leaves are moved to planting holes at a distance of 20 x 25 cm.Stitching is done if a plant does not grow or grows abnormally.
Watering is done every day in the morning and evening.Watering is not carried out if it rains.Weeding is done 2 times or depending on the condition of the weeds.Pest and disease control is carried out using an integrated pest management (IPM) approach.Pests are removed from mustard plants.Meanwhile, disease control is carried out by removing plant parts infected with the disease.
Harvesting is done 33 days after planting.Harvesting is done by taking all the plants and their roots, then weighing them.Production results are written in units of g/m2.
The observed variables in this research are several soil chemical properties namely C-organic, Ntotal, P-available, K-exchange and also some plant parameters namely number of mustard greens leaves and mustard greens production.The Data were analyzed using analysis of variance.If the results from analysis of variance show a significant effect, continued by using the orthogonal contrast test at level 5% and 1%.

Result dan discussion
From the analysis results of vermicompost and goat manure compost can be seen that vermicompost and goat manure compost have the potential to be used as organic fertilizers.Data from the analysis of vermicompost and goat manure composts can be seen in Table 1 below.P2O5 0,55% 0,43% 5. K2O 0,81% 0,70%

C-organic
From Table 2 it can be seen that there is an increase in C-organic along with an increase in the dose of organic fertilizer.The lowest C-organic was found in treatment O (control), which was 2.23%, while the highest C-organic was found in treatment V3 (vermicompost 30 ton/ha) which was 3.81%.The best treatments is giving vermicompost 20 ton/ha because it can increase C-organic up to 3.60% which is not significantly different from giving vermicompost 30 ton/ha.The addition of vermicompost and goat manure compost significantly increased C-organic but was not significantly different between vermicompost and goat manure compost.This increase occurred because the vermicompost and goat manure compost given contained C-organic 30.57% and 27.82%.Both play a role in contributing the C-organic to the soil.This is in line with research by Utami and Handayani which states that the application of organic matter significantly increases soil carbon.Carbon is the largest component of organic matter, so the addition of organic matter will increase the carbon content of the soil [8].

N-total
From Table 2 it can be seen that the application of vermicompost and goat manure compost was able to increase N-total.The lowest N-total was in the treatment O (control), which was 0.23%, while the highest N-total was in the treatment U (10 ton/ha goat manure + Urea 130 kg /ha) which was 0.40%, which was significantly different from treatment O, but not significantly different from other treatments.So, vermicompost and goat manure compost was able to replace the use of urea fertilizer in mustard greens cultivation.
Application of vermicompost significantly increased N-total.Application of vermicompost 20 ton/ha can increase N-total up to 0.37%.The increase in nitrogen through the provision of this vermicompost comes from the removal of the remaining worm metabolism during composting.This is in line with Amsath and Sukumaran who stated that the increase in nitrogen content in vermicompost comes from the metabolism of earthworms which are then channeled back into the soil through urine, feces, mucus, and remaining tissue from worms that have died during processing vermicompost production [9].
The application of goat manure compost also had a significant effect on increasing N-total.Applying 20 ton/ha of goat manure compost can increase soil N-total up to 0.32%.The decomposition results in goat manure compost play a role in increasing macro nutrients such as Nitrogen.This is in line with Rosmarkam and Yuwono who stated that decomposition is a process in which organic matter is broken down into simpler components by microorganisms such as bacteria and fungi.In the decomposition process, Nitrogen can be released through the nitrification process by bacteria [10].

P-available
From Table 2 it can be seen that the application of vermicompost and goat manure compost was able to increase the P-available of the soil.The lowest P-available was found in treatment O (control), which was 9.17 ppm, while the highest P-available was found in treatment V2 (vermicompost 20 ton/ha), which was 33.89 ppm.
The application of vermicompost and goat manure compost had a very significant effect on increasing P-available but was not significantly different between the two.Application of vermicompost 20 ton/ha increased P-available up to 33.89 ppm while 20 ton/ha of goat manure compost was able to increase soil P-available up to 28.31 ppm.Vermicompost and goat manure compost have a positive effect on phosphate solubility.This is in line with Damanik et al., which stated that organic matter has an important role in the availability of phosphate in the soil through the weathering process which produces organic acids.Organic acids such as humic, fulvic, malonic and tartaric acids will produce organic anions capable of binding metals such as Al, Fe and Ca in soil solution.This results in the formation of complex compounds that are difficult to dissolve.Through this binding of Al, Fe, and Ca, the ions will be free so that Phosphate becomes available in the soil solution [11].

K-exchange
From Table 2 it can be seen that the application of vermicompost and goat manure compost can increase K-exchange.The lowest K-exchange was in treatment O (control), which was 0.58 me/100g, while the highest K-exchange was in treatment V2 (20 ton/ha vermicompost), which was 2.65 me/100g.Vermicompost is better than goat manure compost in increasing K-exchange.This happens because vermicompost contributes 0.81% K2O, while goat manure compost only contributes 0.70% K2O.
The high potassium in vermicompost is caused by the ability of earthworms to eat and break down organic matter into worm manure which contains potassium.In line with Simamora which states that earthworms have an important role as decomposers of organic matter in the soil which can increase the potassium content in the soil.Worms will consume organic materials and through the digestive process, these organic materials will be converted into total Potassium with the help of enzymes and microorganisms in the digestive tract of worms.The result of this process is vermicompost which contains the nutrient potassium [12].
Supported by Ajangsari who states that when organic matter passes through the digestive tract of worms, some of the Potassium will be converted into a form that is easily soluble by microorganisms in the worm's digestive tract and then the Potassium will be released by micoorganisms into the feces of the worms [13].

Number of mustard greens leaves
From Table 3 it can be seen that the application of vermicompost and goat manure compost had no significant effect on increasing the number of leaves at 1 WAT but had a very significant effect at 2 WAT and 3 WAT.At 1 WAT the highest number of leaves was found in treatment V2 (Vermicompost 20 ton/ha), namely 4 pieces.At 2 WAT, the highest number of leaves was in treatment V2 (Vermicompost 20 ton/ha), namely 7.25 pieces.At 3 WAT, the highest number of leaves was in treatment V2 (Vermicompost 20 ton/ha), namely 12.83 pieces.
The increase in the number of mustard greens leaves was affected by the nitrogen contained in the vermicompost and goat manure compost.Vermicompost and goat manure compost in this research contained 2.91% and 2.63% N-total, which can meet plant needs.Nitrogen is a nutrient that plays an important role in supporting plant vegetative growth.In line with Novriani who states that nitrogen is an important nutrient in the formation of amino acids and proteins which are components of the chlorophyll molecule.Therefore, providing sufficient nitrogen will increase the vegetative growth of plants [14].

Mustard greens production
From Table 4 it can be seen that giving vermicompost is better in increasing the production of mustard greens compared to giving goat manure.The lowest production of mustard greens was in treatment O, which was very significantly different from the other treatments.The highest production of mustard greens was in treatment V2, which was very significantly different from treatments O, U, K1, K2, K3 but not significantly different from treatment V3.So, The best treatment is giving vermicompost 20 ton/ha.Application of vermicompost is better than goat manure compost in increasing mustard greens production.The best production was found in the application of vermicompost at dose 20 ton/ha with fresh weight of sample plant is 135.25 g, fresh weight of mustard greens per plot is 2670 g/m 2 and consumption weight of mustard greens per plot is 2492.33 g/m 2 (equivalent to 24,923 ton/ha).This can happen because vermicompost contains macro nutrients such as 2.91% N, 0.55% P, 0,81% K and the growth regulator (auxin) which plays an important role in plant growth and production.
In line with Mahmoud and Ibrahim who stated that the application of vermicompost has the potential to improve the soil chemical properties and the availability of Nitrogen (N), Phosphorus (P), and Potassium (K) [15].Vermicompost also improves soil biological properties by increasing the number of microorganisms in the soil [16].By increasing the number of microorganisms in the soil through the application of vermicompost, there is an increase in the mineralization process of organic matter in the soil, thus increasing nutrient availability for plants [17].Vermicompost also contains biologically active compounds in the form of auxin which have a positive impact on plant root formation [18].Thus, plants can grow and produce higher than the control treatment, goat manure compost treatment and the recommended dose treatment (combination of goat manure plus Urea).
Providing 20 ton/ha of vermicompost and goat manure compost without Urea each was able to increase N-total up to 0.37% and 0.32%, which was not significantly different from giving the recommended dose (combination 10 ton/ha of goat manure plus 130 kg/ha of Urea) which is 0.40%.Providing 20 ton/ha of vermicompost and goat manure compost each also increased the growth and production of mustard greens higher than the recommended dose (10 ton/ha of goat manure plus 130 kg/ha of Urea).Thus, the application of vermicompost and goat manure compost can replace the use of Urea fertilizer in the mustard greens cultivation.This is in line with Prawono and Syafaruddin who stated that replacing inorganic fertilizer with organic fertilizer has met the nutritional needs for plant vegetative growth [19].Supported by Nusantara et al., who stated that vermicompost has positive potential as an alternative to artificial fertilizer to increase kudzu plant biomass production [20].

Conclussion
Providing organic fertilizer (vermicompost and goat manure compost) can increase C-organic, N-total, K-exchange, number of leaves and mustard greens production.Providing vermicompost and goat manure compost can also replace the use of Urea fertilizer in mustard greens cultivation.Vermicompost is better than goat manure compost in increasing K-exchange, number of leaves and production of mustard greens with the best treatment is vermicompost 20 ton/ha.

Table 1 .
Data from analysis of vermicompost and goat manure compost.

Table 3 .
Data number of mustard greens leaves as result from the application of vermicompost and goat manure compost.

Table 4 .
Data production of mustard greens as result from the application of vermicompost and goat manure compost.