Forecasting analysis of harvest area, production and productivity of potato (Solanum tuberosum L.) in North Sumatra Province

North Sumatra Province stands out as a key hub for potato cultivation in Indonesia, with a considerable potato consumption rate driven by its substantial population. This study aims to analyze the trend of harvest area, production, and productivity of potatoes in North Sumatra Province from 2007 to 2021. Additionally, it seeks to project the future trends in harvest areas, production, and productivity for the period 2023-2032 through forecasting analysis facilitated by the SPSS program application. The research employs purposive area sampling to determine the study locations, utilizing secondary data sourced from the Central Agency on Statistics of North Sumatra Province. Finding reveal a positive trend in potato harvest area, production, and productivity from 2007 to 2021. Looking ahead to 2023-2032, the forecast indicates a downward trajectory in potato harvest areas, while potato production and productivity are anticipated to maintain a positive trend in North Sumatra Province.


Introduction
Sustainability can be defined as the capacity to fulfill present requirements without jeopardizing the potential of subsequent generations to satisfy their own needs, considering economic, social, and environmental aspects in a balanced manner while managing natural and social resources wisely [1].
Potato forecasting for sustainable agriculture is a crucial step in efficient and sustainable farming management.By having accurate predictions about potato, farmers can plan resource usage more efficiently, reduce waste, and minimize environmental impact [2].There are several concepts and practices that can be applied in sustainable potato agriculture including crop rotation, variety selection, sustainable soil management, use of organic fertilizers, water management, pest and disease control, crop residue utilization, education and training, monitoring and evaluation, partnership and collaboration, and long-term planning [3].
Potato (Solanum tuberosum L.) is one of the horticultural commodities that has important significance because it acts as an alternative food source in supporting food diversification programs.Food is one of the basic needs that must be met by humans and can't be stopped even for a moment.Over time, the population is increasing, so it will increase the need for food that must be met.Meanwhile, the domestic ability to provide food is limited by the area of land managed by farmers [4].
As with all agricultural commodities, especially those cultivated by farmers, the main problem is production and marketing [5].Challenges in production arising from the inherent dependence on natural factors in agriculture are compounded by risks associated with the overuse of chemical fertilizers, 1302 (2024) 012127 IOP Publishing doi:10.1088/1755-1315/1302/1/012127 2 causing low and unstable land productivity, this can even lead to high opportunities for production failures [6].
North Sumatra Province with a population of 14,562,549 people in 2019, there is a need for 125,238 tons of potatoes annually.However, the available supply of potatoes was only 118,778 tonnes in 2019, resulting in a shortage of around 6,460 tonnes.To meet the needs of potatoes, North Sumatra Province currently relies on supplies from Java Island or through import activities [7].To find out the development of harvest area, production, and productivity of potato can be seen in Tabel 1 below.Based on Table 1 above, it can be seen that the growth of land area, production and productivity of potato plants in North Sumatra has fluctuated for several years from 2007 to 2021.From 2007 to 2015, production and productivity figures of potato plants in North Sumatra increased for eight consecutive years.Meanwhile, from 2016 to 2021, the level of productivity of potato plants in North Sumatra has fluctuated.This is due to the increasing amount of potato production were stable year by year, otherwise the available area has changed from year to year.
Trend is an extended and continous shift in one direction, manifesting a proclivity for either upward or downward movement over an extended period [8].Meanwhile, a trend refers to a prolonged inclination in either an upward or downward direction, derived from the average alteration over time, with a relatively steady and smooth value [9].In addition, forecasting is a combination of art and science in predicting future events by utilizing historical data and making projections using relevant mathematical models [10].
Monitoring the development of production at any given time is essential for government policies on food supply, price control, and farmer's income.Therefore, it is necessary to analyze the trend and to forecast the harvest area, production, and productivity of potato.The results of this research can be used as input in the formulation of future policies.

Research Methods
The research location has been purposively selected using the purposive method.The research was conducted in North Sumatra Province which consists of 25 districts and 8 cities.The reason for selecting North Sumatra Province as the research location is because North Sumatra province is known as one of the potato production centres under study and has a significant population.This research uses secondary data collected by researchers from the Central Agency on of Statistics and various related literature relevant to the topic of this research.
To analyze the trend of harvest area, production, and productivity of potatoes in North Sumatra Province (2007-2021), descriptive analysis is used, which involves the presentation of time series data through the use of graphs of visual illustrations, as well as explanations related to the data in the time span 2007-2021 according to the actual situation.
To analyze the second problem, trend analysis is used to estimate the data in the next period.Determination of the trend line using the MSE (Mean Square Error) indicator, the formula is: Description: e = Difference between Y value and forecasting (Yt); n = Number of data The model that has the smallest MSE value is the best.In determining the trend there are 3 trends used, namely [11]: a. Linear Trend, General equation of linear trend: Yt = a + bt (2) Where the values of a and b can be obtained from the equation: Where the values of a and b can be obtained from the equation:

Trend Analysis of Potato in North Sumatra Province
In this research the error value used is MSE with calculations using Microsoft Excel 2010.Based on the analysis results seen in the Table 2. Based on the accuracy value obtained, it can be seen that the best analysis method is using an exponential trend line, where the harvest area has the smallest error or MSE value of 8.40x10^5, production is 3.64x10^8 and productivity is 2.19.The trend analysis results show that harvest area, production, and productivity of potato in North Sumatra Province experienced fluctuating growth but tended to increase.Figure 1 shows that the development of potato harvest area in North Sumatra Province in 2007-2021 fluctuated, but showed an exponential trend that tended to increase with an insignificant increase.Thos shows that the potato harvest area is experiencing a positive trend.Figure 2 shows that the development of potato production in North Sumatra Province in 2007-2021 fluctuated with the highest production in 2021, but showed an exponential trend that tended to increase with an insignificant increase.This shows that potato production is experiencing a positive trend.Figure 3 shows that the development of potato productivity in North Sumatra Province in 2007-2021 fluctuated, but tended to show an increasing exponential trend with an insignificant increase with the highest productivity occurring in 2021.This shows that potato productivity is experiencing a positive trend.

Forecasting Analysis of Harvest Area, Production, and Productivity of Potato in North Sumatra
Province in 2023-2032  Based on Table 3 in the projection of potato harvest area from 2023-2032, there is a decrease every year.In 2023, the estimated potato harvest area is estimated to reach 6,766 ha, while in 2032, the estimate reaches 6,765.77ha.Based on Figure 4, it can be concluded that the projection of potato harvest area in North Sumatra Province in the range of 2023-2032 shows a decrease every year or has a negative trend.Based on Figure 5, it can be concluded that the projection of potato production in North Sumatra Province in the range of 2023-2032 shows an increase every year or has a positive trend.

Forecasting Potato Productivity in North Sumatra
Using the formula that has been obtained, it is possible to estimate potato productivity for the projected year (Y*).So that the following results are obtained: Based on Table 5 in the projection of potato productivity from 2023-2032, there is an increase every year.In 2023, the estimated potato productivity is estimated to reach 20.31 ton/ha, while in 2032, the estimate reaches 28.15 ton/ha.Based on Figure 6, it can be concluded that the projection of potato productivity in North Sumatra Province starts from 2023 to 2032 shows an increase every year or has a positive trend.
Based on the research conducted, it was found that the potato harvest area in North Sumatra Province in 2007-2021 showed a positive trend or an increase.However, in the future, in 2023-2032 based on forecasting calculations, the potato harvest area will experience a negative trend.Although in 2023-2032 the potato area would have decreased, it won't affect its productivity which continues to show an increase or positive trend due to potato production which continues to increase in the future.If the potato productivity shows a positive trend, it can provide various benefits for the environment in the future, including saving water resources, reducing greenhouse gas emissions, diversifying crops, and decreasing pesticide usage [12,13].
In addition to the observed positive trend in potato harvest area in North Sumatra Province from 2007 to 2021, it is crucial to delve into the factors contributing to the projected negative trend in the coming years, specifically from 2023 to 2032.Understanding these factors can aid in developing strategies to address potential challenges and ensure sustainable potato cultivation practices.Perhaps changes in climate, land availability, or economic factors could be influencing this shift, warranting further investigation and proactive measures to mitigate any adverse impacts on the potato industry.
Despite the anticipated decrease in potato harvest area, the promising outlook for potato productivity in the future is a noteworthy aspect.The continuous increase in potato production signifies resilience and adaptability within the agricultural sector.This positive trend in productivity bodes well for environmental sustainability, as highlighted in the research.The benefits extend beyond mere agricultural output, encompassing resource conservation such as water, reduced greenhouse gas emissions, crop diversification, and minimized reliance on pesticides.As we look ahead to the years 2023-2032, focusing on enhancing productivity could serve as a pivotal strategy to harness positive environmental outcomes from potato cultivation in North Sumatra Province.

Conclusions and Suggestions
Based on the results obtained, in 2007-2021 in North Sumatra Province, the harvest area, production and productivity of potatoes experience a positive trend.Additionally, the projection of harvest area shows a negative trend, while production and productivity continue to experience a positive trend in North Sumatra Province starts from 2023 to 2032.
Into the bargain, it is expected that government and related institutions make a policy that can increase the potato harvest area, especially in areas that are potential enough to influence potato production in North Sumatera.The increase in potato harvest area can provide various benefits to the environment and promote sustainable agriculture including land use efficiency, soil erosion reduction, ecosystem balance improvement, and empowerment of local farmers [14].It is also expected for potato farmers can increase potato production in order to maintain its productivity as one of the potatoes producing centres to meet the needs of potatoes consumption in Indonesia.
c. Exponential Trend, General equation of exponential trend: Yt = a.b t (9) Where:   =   +   (10) The values of a and b are obtained by solving the following equations: a = antilog [ value of Y at a certain value of t a = The intercept value of Y b = Slope value t = A spesific value indicating the time period Province in 2007-2021.The condition of the potato harvest area at North Sumatra Province 2007-2021 can be seen in Figure 1.

Figure 1 .
Figure 1.Trend Graph of Potato Harvest Area in North Sumatra Province 2007-2021 [7] Sumatra Province in 2007-2021.The condition of potato production in North Sumatra Province during the 2007-2021 period can be seen in Figure 2.

Figure 2 .
Figure 2. Trend Graph of Potato Production in North Sumatra Province 2007-2021 [7] Province in 2007-2021.The condition of potato productivity in North Sumatra Province during the 2007-2021 period can be seen in Figure3.

Tabel 4 .Figure 5 .
Figure 5. Forecasting Graph of Potato Production in North Sumatra Province in 2023-2032 [7] Province in 2023-2032.The analysis used through Forecasting analysis through Trend (Long Term Motion) using the Least Squares Method the SPSS program which uses an exponential trend line, using data on the potato productivity of North Sumatra Province in 2007-2021 obtained a trend equation:  * = 16,97 + 1,14^ *

Table 1 .
Potato Harvest Area, Production, and Productivity in North Sumatra Province in 2007-2021

Table 2 .
Selection of the Best Trend Line with MSE (Mean Square Error) value

Table 3 .
Using the formula that has been obtained, it is possible to estimate potato harvest area for the projected year (Y*).So that the following results are obtained: Results of Forecasting Analysis of Potato Harvest Area in North Sumatra 2023-2032 3.2.1.Forecasting Potato Harvest Area of North SumatraProvince in 2023 -2032.The analysis used through Forecasting analysis through Trend (Long Term Motion) using the Least Squares Method the SPSS program which uses an exponential trend line, using data on the potato harvest area of North Sumatra Province in 2007-2021 obtained a trend equation:  * = 6,765.7 + 0.95^ *(13)Source:[7]

Tabel 5 .
Results of Forecasting Analysis of Potato Productivity in North Sumatra Province 2023-2032