ISSN: 04532198 Volume 62, Issue 03, April 2020 , 2020

Effect Model of Rainfall Intensity and Use to NPK Content on the Run-off

Berlian Gari Amrina1, Riyanto Haribowo2, and EmmaYuliani2

1Master Program in Department of Water Resources, Faculty of Engineering, University of Brawijaya, Malang, Indonesia 2Department of Water Resources, Faculty of Engineering, University of Brawijaya, Malang, Indonesia

Abstract—This research intends to investigate the effect of rainfall intensity and fertilizer use to NPL (Nitrogen, Phosphate, and Kalium) content that also carried away together with run-off. Questionnaire about the application of fertilizwe that is commonly used is distributed to farmers. The modeling is carried out by using yje rainfall simulator of system SK-III Armfield. When the rain is dropped, the run-off will be directly taken as the sample to be tested in the laboratory for knowing the NPK content that is also carried away.The methodology uses linier regression statistical analysis and variance analysis for reaching the aim of research. Result of laboratory test shows that the rainfall intensity and the dose of fertilizer use is influencing tohether to the Nitrogen (R2 = 0.787), Phosphate (R2 = 0.49); and Kalium (R2 = 0.489). Result of variance analysis test indicates that the Nitrogen, Phosphate, and Kalium in run-off is affected by the rainfall intensity and the dose of fertilizer use. .. Keywords— water quality, NPK waste, rainfall intensity, rainfall simulator

1. Introduction Indonesia has long period of rainy season and there is more than six months. This condition needs attention due to regulate an urban region [1]. However, the infrastructure development is carried out for considering the social prosperity of society. Therefore, it is also meant to change the land use. Even though the land use change will cause rainfall that cannot permeate again into on the rainy season [3], so it has the potency to cause surface run-off that will be becoming as flood or pool [4][5][6]. In hydrological cycle, the process of and run-off is one of the urgent processes [7][8].

Recently, the watersheds in Indonesia have the pollution problem due to the excessive human acitivity. Some of the water pollution are come from point or non-point source pollution. Unlike point source pollution, the non point one (NPS) is come from many sources that is spreading from land use activities in the watershed like residence, agriculture, and industry that is predicted has affected river water quality. One of the activities that cab cause the decreasing of water quality is agricultural activity [9].

Irrigation and rainfall can contribute to the pollution mainly the exaggerated fertilizer content [10]. Kaown [11] said that the agricultural activity has proven to produce the high concentration of Nitrate and Phosphate in many places in the world. However, Kim [12] expressed that the intensive agricultural activity by using fertilizer and pesticide has decreased the sirface water quality. Nitrogen, Phosphate, and Kalium are the new nutrient that is very needed for fulfilling the crop demand nutrient [13]. However, the using of nutrient has a number of environmental consequences. Nitrogrn, Phosphate, and Kalium can negatively affect the surface water quality [14]. Non-point source pollution is marked by the random and intermittent event and generally it is affected by many factors like type of soil and fertilizer that is used and the rainfall intensity.

This research intends to analyze the water quality due to the agricultural waste as the non-point source pollution. In further, this research intends to investigate the effect of rainfall intensity and

917

B. Gari, R. Haribowo, and E. Yuliani, 2020 TRKU the dose of NPK fertilizer using to the NPK content that carried away with the run-off. To reach the aim, this research will be carried out with modeling by using rainfall simulator in the laboratory scale.

2. Material and Method

2.1. Research Location This research is conducted in Hydrology Laboratory, Department of Water Resources, Faculty of Engineering, University of Brawijaya, Malang-Indonesia, Media of soil that is used is directly taken from agricultural area of Sumber Brantas Village and then it is moved to the rainfall simulator. The case study is selected in begetable agricultural area in Bumiaji District, Batu City. The area of Sumber Brantas Village is 541.1364 ha and in the height of 1,700 mdpl and the rainfall is high. The vegetables in Sumber Brantas consist of carrot and potato that is as the vegetable which is abundant in rainy season. Map of location is presented as in the Figure 1. .

Figure 1 Map of Sumber Brantas Village

2.2. Research Design The measuring of point source pollutant will has many constraints if it is directly carried out in field. If the sample is tested to the variable of rainfall time or fkood event, it will bw very difficult to be carried out. It is due yo the natural condition that is very uncertainty and it is so dangerous for the researcher himself/ herself. Data that are obtained is primary data from laboratory.that is by using the rainfall simulator with the variation of rainfall and NPK fertilizer content themselves.

2.3. Questionnaire for Farmer Before carrying out the trial in laboratory, there is carried out the interview with the local farmers for obtaining some information about the farmer behavior in using chemical fertilizer. The methodology is survey method by distributing yhe questionnaire on the farmer group. The farmer group consists of 87 persons. The number of person ia used for determining the number of questionnaire sample with the relative error of 1%, For this research, there is used the Isaac and

918

ISSN: 04532198 Volume 62, Issue 03, April 2020 , 2020

Michael and it is obtained the number of respondent is 78 persons. Some information that are obtained from the interviews are as follow: a) Type and merk of chemical fertilizer that is commonly used; b) Content or dose of fertilizer using; c) The treatment to the soil that is fertilized; d) The method of fertilizer using; and e) The government role un controlling the fertilizer using. . 2.4. Media of Soil

Type of soil in this research is taken from yje place where the questionnaire is distributed that is in Sumber Brantas Village, Bumiaji Districtm Batu City-Indonesia. Agricultural soil in this place is taken as the media for carrying out the modeling. The soil sample will be tested for knowing the soil texture. Generally, by knowing the texture is able to know the porosity, durability against water, water availability, easy or difficult to be prepared infiltration rate, consistency, nutrient content, and water demand. The analysis is carried out by hydrometer trial. This trial is used for determining the classification of soil particle that pass the filter no. 300 and the gradation curve, so it can be known what soil type that is used. The classification of soil texture size is presented as in the Figure 2.

Figure 2 Triangle Diagram of Soil Texture Based on the USDA Source: Hardjowigeno [15]

The available composition of soil fraction as the result of Hydrometer analysis is plotted on the soil texture triangle so it can be known the soil type that will be used,

2.5. Experiment Design The modeling is carried out by using rainfall simulator. The slope in the rainfall simulator is set on the condition of 5%. The rainfall intensity that is used is the highest rainfall intensity in the Sumber Brantas Village during the last 10 years that is from 2008 until 2017 in the Junggo rainfall station that is 105 mm. If it is conversed in the laboratory scale is proportional with 2 liter/minute. Then, the rainfall ia also simulated when the intensity is 1.5 litre/minutes, and by the end is 0.5 litre/minute. In every rainfall event, the fertilizing dose is also modelled with 3 variations of fertilizing that are soil withput fertilizer, soil with fertilizer that is suitable with the using rule dose (44.8 gr) and by the end the fertilizer using as the result of questionnaire to the farmer (93.33 gr). The fertilizer that is used in this research is the nitrophoska 15-15-15 or it is known as the trade name: basf fertilizer. In every trial, the run-off due to the rainfall will be drop tp the soil surface. When the soil has already saturated, the water will be run-off. The run-off will be taken as the sample by using bottle. From this modeling, there is obtained 12 water samples that will be analyzed in Environmental Laboratory of PT Jasa Tirta I, Malang City. In the experiment, to know how much the content that is held in soil, so the soil sample is taken and will be analyzed in the 919

B. Gari, R. Haribowo, and E. Yuliani, 2020 TRKU laboratory. The content that will be tested is the content of Nitrogen, Phosphate, and Kalium that is dissolved the run-off. .

2.6. Data Analysis There are some variables for knowing the effect of rainfall intensity and the dose of fertilizer using to the content of Nitrogen, Phosphate, and Kalium. Yo know how big the effect among the variables, so it is needed to ba carried out the statistical test. The statistical test is used the SPSS (Statistical Package for the Social Sciences) and the method is linier regression and bariance analysis. . 3. Result and Discussion

3.1. Soil Type

The result of hydrometer analysis test shows that the soil in the agricultural location in Sumber Brantas has the content composition of soil fraction as follow: gravel: 0.00 %, sand: 48.00 %, silt: 45.08 %, and clay: 6.92 %. Based on the available composition, it indicates that there is loam soil in the research location. Loam soil is as the soil with the composition of sand, silt, and clay in relative balanced amount. The loam soil is assumed as the ideal soil for plantation because it has enough nutrient and humusv bthan sandy soil. The uptake and groundwater drainage is better than silt soil and it is easier prepared than the clay soil.

3.2. Rainfall Intensity The rainfall that is used in the modeling is the maximum rainfall during 2008-2017 in the nearest rainfall station from the Sumber Brantas Village such as Junggo rainfall station, Bumiaji District. The result is presented as in The Table 1. Tabel 1 Maximum Rainfall During 2008-2017 Max rainfall Max rainfall No Year (mm) No Year (mm) 1 2008 87 6 2013 98 2 2009 89 7 2014 96 3 2010 64 8 2015 105 4 2011 100 9 2016 68 5 2012 76 10 2017 87

The maximum rainfall in the last 10 years is 105 mm and it is proportional with 2 liter/minutes in rainfall simulator. The rainfall for the next simulation is 1.5 liter/minute, 1 liter/minute, and 0.5 liter/minute.

3.3. NPK content in Run-off

3.3.1. Nitrogen Content The Nitrogen content test indicates that the higher rainfall intensity and dose in fertilizer using will cause the higher Nitrogen content that is dissolved run-off as presented in the Figure 3. However, on the rainfall in amount of 2 litre/minute shows the difference. It is due to the human or tool error. In this research, it will be carried out the statistical test for knowing the relation among variables.

920

ISSN: 04532198 Volume 62, Issue 03, April 2020 , 2020

Without fertilizer

Using rule

Farmer dose

Rainfall intensity (l/minute)

Figure 3 The Relation between Rainfall Intensity and Fertilizer Dose to the Nitrogen Content of Run-off

Nased on the statistical test, the effect of rainfall intensity and fertilizer dose to the Nitrogent content of run-off has the linier regression Y = 2.270 – 0.685 X1 + 0.067 X2 and the determination coefficient is; R2 = 0.787. It means that the rainfall intensity and fertilizer dose is influencing the Nitrogen content of run-off in amount of 78.7% and 21.3% is influenced by the other factor. Based on the variance analysis with the level of significant of 1 or 5 %, the rainfall intensity (X1) and the fertilizer dose (X2) is together significantly influencing the Nitrogen content of run-off (y).

3.3.2. Phosphate Content The result shows that the higher rainfall intensity and fertilizer using dose causes the higher Phosphate content of run-off. There is different with the Nitrogen, the Phosphate content when the rainfall drops with the rainfall intensity of 1 litre/minute indicates the different result and it is presented as in the Figyre 4.

Without fertilizer

Using rule

Farmer dose

Rainfall intensity (l/minute)

Figure 4 The Relation between Rainfall Intensity and Fertilizer Dose to the Phosphat Content of Run-off

Based on the statistical test, the effect of rainfall intensity and fertilizer dose to the Phosphate content of run-off has the linear regression equation as follow: Y = 1.525 – 0.549 X1 + 0.068 X2 with the determination coefficient is R2 =0.49. It means that the rainfall intensity and fertilizer using dose is influencing the phosphate in amount of 49.0% and 51.0% is influenced ny the other factor. Based on the variance analysis with the significant level of 1 or 5 %, the F value is 0.048 or 921

B. Gari, R. Haribowo, and E. Yuliani, 2020 TRKU

4.8%.. It can concluded that the rainfall intensity (X1) and the fertilizer dose (X2) is together significantly influencing the Phosphate content of run-off. . . 3.3.3. Kalium Content The result shows when the soil is not carried out with fertilizer when the rainfall intensity is low as well as very high, the Kalium content is still less than 10 mg/l. However, when there is fertilized, the Kalium content is more than 50 mg/l but it is still less than 2,000 l/mg. It means that the run-off is classified noy dangerous. It is the same as on the Nitrogen content, the Kalium has the different result when the rainfall intensity is 2 litre/minute.

Without fertilizer

Using rule

Farmer dose

Rainfall intensity (l/minute)

Figure 5 The Relation between Rainfall Intensity and Fertilizer Dose to the Kalium Content of Run-off

The result of analytical test about the effect of rainfall intensity and fertilizer dose to the Kalium content of run-off produces the linier regression equation: Y = -20.022 + 9.610 X1 + 2.752 X2 with the determination coefficient is: R2 = 0.489. It means that the rainfall intensity and fertilizer using dose is influencing the Phosphate content of run-off in amount of 48.9% and 51.1% is influenced by the other factor. Based on the variance analysis, the rainfall intensity (X1) and fertilizer dose (X2) is together significantly influenced the Kalium content of run-off (y).

3.3.4. Questionnaire result The questionnaire in this research intends to know the application of fertilizer using. In addition, the aim of the questionnaire is to know how far the government role to make effort in managing to prevent the decreasing of water quality. In amount of 88.46% respondents confess that they do not know the impact of chemical fertilizer yo the environment. Because of the less understanding about it, the farmers do not know the limitation of fertilizer giving. Only 19.23 % of farmers who use the fertilizer is regarding to the suggestion. The more fertilizer using will give the negative impact to the environment. The changes to the environmentally friendly fertilizer are very suggested. However, as much 79.4 % of respondents are not willing to change into environmentally friendly fertilizer. It is due to the government is less in giving the counselling to the local farmers. As much 9.97 % of farmers confess that thet has obtained the counselling from the government. However, the counselling about frequency and the limitation of fertilizer giving is accepted only by 7.69 % of respondents. Besides the government role is less, the consciousness level of the farmers is necessary to be increased. The counselling is only attended by 11.54 % of respondents.

4. Conclusion Based on the regression statistical analysis and variance analysis, the rainfall intensity and fertilizer using content is influencing the Nitrogen (N), Phosphate (P)m and Kalium (K) content. The result shows that the rainfall intensity and fertilizer dose to the Nitrogen content of run-off has big

922

ISSN: 04532198 Volume 62, Issue 03, April 2020 , 2020 enough effect. It is expressed by the determination coefficient: R2 =0.787 and the variance analysis with the level of significance of 1% and 5% is significantly accepted. The effect to the Phosphate and Kalium content is not too high with the determination coefficient as floow: R2 = 0.49 and 0.489. However, the result of variance analysis is 4.8 % and 4.9 % with the lwvwl of significance: 5%. However, because the determination coefficient is still less than 70%, it is suggested to carried out the further research for strengthening the result. The determination coefficient of Kalium content is low, may be the pH neutral and the high basa saturation of Kalium is tied by Ca. The bigger change capacity of cation increases the soil ability for holding K so it decreases the potency of .

5. References [1] Suripin, “Sistem drainase kota yang berlanjutan [Sustainable urban drainage system]”, Yogyakarta, Andi, ISBN 979-731-137-6 pp. 183, 2004.

[2] T. Ozteken, “Estimation of the Parameters of Wakeby Distribution by a Numerical Least Square Methods and Applying it to the Annual Peak Flows of Turkish Rivers”, Journal of Water Resource Manage 25, 2011: 1299-1313

[3] L.M. Limantara, M. Bisri, and R. Fajrianto, “Optimization of water usage at irrigation area of pakis-malang rehency-indonesia by using linear programming”, International Journal of Engineering and Technology, Vol. 7{4}, 2018: 6432-6436

[4] M. Bisri, L.M. Limantara, L. Prasetyorini, and D. Chasanawati, “Application of the Kineros model for predicting the effect of land use on the surface run-off. Case study in Brantas sub- watershed, Klojen District, Malang City, East Java Province of Indonesia”, Journal of Water and Land Development, No. 35, 2017, p. 3–9. DOI: 10.1515/jwld-2017-0062.

[5] \B.Z. Tung, Y.K. Yeh, K. Chian and J.Y. Chuan, “Storm Resampling for Uncertainty Analysis of a Multiple-Storm Unit Hydrograph”, J. Hydrology, 194, 1987: 66-384.

[6] L.M. Limantara , “The Limiting Physical Parameters of Synthetic Unit Hydrograph”, World Applied Sciences Journal, Vol 7(6), 2009: 802-804

[7] L.M. Limantara, “Evaluation of Roughness Constant of River in Synthetic Unit Hydrograph”. World Applied Sciences Journal, Vol. 7(9), 2009: 1209-1211

[8] D. Priyantoro and L.M. Limantara L.M.. “Conformity evaluation of synthetic unit hydrograph (case study at upstream Brantas sub-watershed, East Java Province of Indonesia”, Journal of Water and Land Development. No. 35, 2017, p. 173–183. DOI: 10.1515/jwld-2017-0082

[9] H. Haiying and H. Guoru. “Moitoring of Non-Point Source Pollutions from an Agriculture Watershed in South China:, Water, 6, 2014, p. 3828-3840; doi:10.3390/w6123828

[10] B. Chimwanza, P. P. Mumba, B. H. Z. Moyo and W. Kadewa, “The impact of farming on river banks on water quality of the rivers”, Int. J. Environ. Sci. Tech, Vol. 2, No. 4, 2006, p. 353-358.

[11] Z. Inheng, T. Shen, L. Minghua, Y. Wan, L. Jianbo, and J. Li, “Research on non-point source pollution spatial distribution of Qingdao based on L-THIA model”, Journal of Mathematical and Computer Modelling 54, 2011, p. 1151–1159. ELSEVIER

[12] N. M. Chong, Y. C. Chen, and C. N. Hsieh, “Assessment of the quality of stormwater from an industrial park in central Taiwan”m Environmental Monitoring and Assessment, vol. 184, 2012, p. 1801–1811..

923

B. Gari, R. Haribowo, and E. Yuliani, 2020 TRKU

[13] Sumitomo and Nemerow, “1970 dalam Kepmen KLH 115, Th 2003 Pedoman PenentuanStatus Mutu Air”, Kementrian Lingkungan Hidup. 2004.

[14] B. Lila, K. Renica, and R.J. Jati, “Pengaruh Penggunaan Pupuk Di Lahan Pertanian Terhadap Kualitas Air Pada Saluran Tersier Di Kawasan Rasau Jaya III”. Program Studi Teknik Lingkungan Jurusan Teknik Sipil Fakultas Teknik Universitas Tanjungpura, Pontianak, 2015

B. Lila, K. Renica, and R.J. Jati, “Pengaruh Penggunaan Pupuk Di Lahan Pertanian Terhadap Kualitas Air Pada Saluran Tersier Di Kawasan Rasau Jaya III”. Program Studi Teknik Lingkungan Jurusan Teknik Sipil Fakultas Teknik Universitas Tanjungpura, Pontianak,

This work is licensed under a Creative Commons Attribution Non-Commercial 4.0 International License.

924