Practical rain measurement

Watering is a very important thing at the plant nursery stage. Without proper watering, the growth of the seedlings will be disrupted. In the process of watering must pay attention to several things, such as watering time and water discharge. At this time, most independent smallholders do not understand how to use a rain gauge or what is often called an ombrometer. These farmers prefer to use the old way of looking at the state of the soil in the watering process rather than using an ombrometer. In this case, as we know, buying an ombrometer is quite expensive. An ombrometer is a rain gauge which is also often referred to as a rain gauge. This tool is installed in an open place without protection or shade so that rainwater will be caught directly by this tool. The unit used is millimeters with an accuracy of reading up to 0.1 mm. Currently, practical rain gauges that are self-made without using factory machines are still not validated. The purpose of this research is to the results of simple ombrometer (C) accuracy and precision tests compared to Observatory Ombrometers, Ordinary Ombrometers, and Automatic Weather Stations (AWS). The location of the research test was in the oil palm nursery area at the Research and Experimental Garden of the Yogyakarta Community Plantation Academy. Rainfall data were obtained from Nine Practical Rain Gauges (C), Observatory-type Ombrometers (A), Ordinary Ombrometers (B), and Automatic Weather Station (AWS). Statistical methods are used to test accuracy and precision. The results of the C test compared to AWS have a precision value of 95.9% and an accuracy of 88.7%. Comparison of C with A shows a precision value of 99.6% and an accuracy value of 98.3%. The results of testing C against B show a precision value of 99.5% and an accuracy of 97.5%.


Introduction
The availability of water in sufficient quantities is needed in the process of cultivating plants.The availability of water in sufficient quantities needed in the process of cultivating plants [1].This is because water availability is one of the main requirements for supporting plant growth as a medium for carrying nutrients and the most crucial element in the process of developing plant cells [1].
Elaesis Guinensis oil palm is an essential commodity in Indonesia because it is proven to provide welfare to the farmers who cultivate it [1,2].To optimize the yield of oil palm, it is necessary to carry out maximum cultivation starting from the nursery stage to caring for productive category plants.At the nursery stage, optimal watering is something that must be fulfilled [2,3].
Given the importance of watering for oil palm seedlings, it must be considered whether there is a water source that allows water to be obtained easily.Each seedling aged 0 -9 months requires 0.1 -0.25 liters of water for each watering which is done 2x a day, in the morning and evening.For seedlings aged 1230 (2023) 012135 IOP Publishing doi:10.1088/1755-1315/1230/1/012135 2 9-12 months, 3-4 liters of water/day is needed [4][5][6].In this case, it is necessary to pay attention to the state of rainfall so that additional watering can be given as needed [1].
Rainfall is the amount of rainwater that falls in a specific time and area.Rainfall is measured in daily, monthly, and yearly times [4,6].A rain gauge is a tool for measuring rainfall in an area, whether rural, sub-district, or province, which refers to WMO (World Metrological Organization) standards.This practical rainfall gauge, it will be able to help us measure the amount of rainfall that occurs in a certain period of time (real-time) [6].
High and low rainfall affects the amount of watering.If it rains 6 mm in a day, then watering should be done twice a day (morning and evening), if the rainfall is 8 mm then watering is sufficient only once (in the afternoon), if the rainfall is > 10 mm, then watering is not necessary [4,7].To find out the amount of rainfall, measurements are made with a tool called an ombrometer.
Obtaining a rain gauge (Ombrometer) requires a relatively high cost.As attached by the Palm Oil Research Center (PPKS), the latest price for a Darma Yanti CP ombrometer set is IDR 1,800,000, with details of a rain measuring tube IDR 1,200,000.00and a measuring cup IDR 600,000.00.Based on this, we as writers have the idea to make a practical ombrometer or rain gauge by utilizing simple items that can be used based on the actual ombrometer working system, namely, not flowing, not evaporating, and not absorbing [7].
The purpose of this research is to the results of simple ombrometer (C) accuracy and precision tests compared to Observatory Ombrometers, Ordinary Ombrometers, and Automatic Weather Stations (AWS).

Material and Methods
The research at Kebun Penelitian dan Percobaan (KP2) of the Yogyakarta Plantation Community Academy.The tools used in this study were two ombrometers, an observatory ombrometer (A) and an ordinary ombrometer (B) with an ombrometer mouth area of 100 cm 2 [8], nine water measuring devices or called a simple ombrometer (C) made using a plastic bottle and funnel with a size of 11.3 cm, The mouth area of the ombrometer is 100 cm 2 [9], and the volume of the tube is 50 mm.A pole is one meter high to place the ombrometer in the field and the Mertani brand Automatic Weather Station (AWS).The research through the preparation, field survey, and analysis stages.The preparation stage is to make nine simple ombrometers using plastic bottles and funnels.ombrometer placed according to standard rules [8,10].All tools placed in the field with a height of 1 meter above the ground.The survey phase in the area is collecting rainfall data for several days, in the morning at the same time [6].The analysis phase carried out 1) conversion of rainfall values into millimeters (mm), 2) analysis and calculation of statistics for testing the accuracy and precision of the tool.

Result and Discussion
A simple-made ombrometer or practical rain gauge has a funnel whose size specifications are the same as the Ombrometer Observatory's size specifications.A functional rain gauge has a tube/tub to collect raindrops which are collected for a 24-hour period.The 500 ml bottle capacity is equivalent to 50 mm of Rainfall.The results of a simple ombrometer are shown in Figure 1.Based on the ombrometer C rainfall measurement results, there are differences in measurements.A comparison of ombrometer C measurements with A and B is presented in Table 2.The average difference between C and A ombrometer rainfall measurements is 0.36 mm.The average difference between ombrometer C and B rainfall measurements is 0.51 mm.The measurement results show that the measurement results of ombrometer C are closer to ombrometer A than ombrometer B. The results of the rainfall catch between the artificial Ombrometer compared to the Observatory Ombrometer and the Ordinary Ombrometer show a slight difference, namely 0.4 millimeters and 0.5 millimeters.An Artificial Ombrometer / Practical Rain Gauge can be made using tools and materials that are easily available and can still meet the Ombrometer rules, namely not absorbing, not evaporating, not flowing, and can accommodate rainfall for 24 hours, and the results can be measured using a measuring cup.
The measurement results of ombrometer C are closer to ombrometer A than ombrometer B. That is in line with the results of the accuracy and precision tests presented in table 3, table 4, and table 5.The results of simple ombrometer test calculations (C) compared to AWS yield a precision value of 95.9% and 88.7% accuracy.These results indicate a high error value.The AWS system works by weighing rainwater.This system effectively reduces evaporation because it immediately counts as soon as the rain falls on the scale.Whereas ombrometer C on day 6 had a higher error rate than on days 4 and 6.Compared to Ombrometer A, the results of simple ombrometer test calculations (C) yielded a precision value of 99.6% and 98.3% accuracy.The % error comparison value for A is the smallest compared to AWS and B, which is 1.7%.This value is in line with the results of the average difference in rainfall measurements C compared to A of 0.36 mm.The calculation results of a simple ombrometer test (C) compared to Ombrometer B produce a precision value of 99.5% and an accuracy of 97.5%.The % error value for comparison at A is the smallest compared to AWS and B, which is 2.5%, more significant than the comparison with A. This result is in line with the calculation of the difference in average rainfall measurements C to B, which is 0.5 mm; this value is more excellent compared to C to A.
Based on the % error value, the C error rate compared to the highest error rate tool compared to AWS is 11.3%, B is 2.50%, and the lowest is in A, which is 1.7%.Based on the precision value, the highest level of precision compared to A is 99.6%, B is 99.5%, and AWS is 95.9%.Based on the measurement accuracy test, the highest accuracy level compared to A is 98.3%, B is 97.5%, and AWS is 88.7%.Based on these results, it shows C precision and a high degree of accuracy in the measurement results for the manual ombrometer class.

Conclusion
The results of the rainfall catch between the artificial Ombrometer compared to the Observatory Ombrometer and the Ordinary Ombrometer show a slight difference, namely 0.4 millimeters and 0.5 millimeters.An Artificial Ombrometer / Practical Rain Gauge can be made using tools and materials that are easily available and can still meet the Ombrometer rules, namely not absorbing, not evaporating, not flowing, and can accommodate rainfall for 24 hours, and the results can be measured using a measuring cup.
The results of the C test compared to AWS have a precision value of 95.9% and an accuracy of 88.7%.Comparison of C with A shows a precision value of 99.6% and an accuracy value of 98.3%.The results of testing C against B show a precision value of 99.5% and an accuracy of 97.5%.

Figure 1 .
Figure 1.View of a simple ombrometer

Table 2 .
Results of comparison of measurement variations (mm) of tools A, B, and C.

Table 3 .
Simple ombrometer test results (C) compared to AWS.

Table 4 .
Simple ombrometer test results (C) compared to Ombrometer A.

Table 5 .
Simple ombrometer test results (C) compared to Ombrometer B.