نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشیار بخش آبیاری و فیزیک خاک، مؤسسه تحقیقات خاک و آب، سازمان تحقیقات، آموزش و ترویج کشاورزی، کرج، ایران
2 استادیار، بخش آبیاری و فیزیک خاک، موسسه تحقیقات خاک و آب، سازمان تحقیقات، آموزش و ترویج کشاورزی، کرج، ایران
3 استادبخش آبیاری و زهکشی ، مؤسسه تحقیقات فنی و مهندسی کشاورزی ، سازمان تحقیقات، آموزش و ترویج کشاورزی، کرج، ایران
4 دانشیار بخش آبیاری و زهکشی ، مؤسسه تحقیقات فنی و مهندسی کشاورزی ، سازمان تحقیقات، آموزش و ترویج کشاورزی، کرج، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
The objective of this research was to compare the estimated water consumption of watermelon from the NIAZAB System with measured field-applied water and watermelon yield under farmer management. This study was conducted across 146 locations in 28 counties within 9 provinces of Iran in 2017. Furthermore, it aimed to determine the water productivity of irrigated watermelon. The results showed that the average watermelon water consumption using drip irrigation was 4548 cubic meters per hectare in field measurements and 4105 cubic meters per hectare according to the NIAZAB System. For surface irrigation, the applied watermelon water in field measurements and the NIAZAB System was 4512 and 4954 cubic meters per hectare, respectively. The average watermelon yield for drip irrigation was 43114 kg/ha in field measurements and 41760 kg/ha via the NIAZAB System. For surface irrigation, the average watermelon yield was 32701 kg/ha in field measurements and 31362 kg/ha according to the NIAZAB System. The average water productivity for watermelon consumption with drip irrigation was 10.7 kg/m³ using field measurements and 10.5 kg/m³ with the NIAZAB System. The results indicate that the NIAZAB System estimates watermelon irrigation water at the county level with a normalized root mean square error of 11% and a coefficient of agreement of 0.95. The model efficiency coefficient values demonstrate that the model provides acceptable results in determining irrigation water quantity and watermelon water productivity at the farm level across the country. Therefore, the NIAZAB System can be used to estimate the required volume for watermelon irrigation at both the national macro-level and at the farm level.
کلیدواژهها [English]
Given the escalating water crisis in Iran and the critical need to optimize water consumption in agriculture, the utilization of smart systems and modeling tools for accurately estimating crop water requirements has become increasingly vital. This is particularly true for crops with large cultivation areas, such as watermelon. The NIAZAB AB system is a decision making tool designed to estimate crop water needs by leveraging climatic data, plant characteristics, and soil properties. However, it's crucial to assess how well the data from this system aligns with actual on farm water application rates. This comparison is essential for validating the model and analyzing the gap between theoretical management and real world performance. Therefore, matching the estimated watermelon water consumption from the NIAZAB system with the actual water consumed under real farm conditions can play a significant role in identifying the system's efficiency and providing corrective solutions to optimize water use for this crop. This comparison not only determines the system's accuracy in estimating water requirements but can also be used to inform water allocation policies and crop management strategies.
The aim of this study is to compare and evaluate the amount of water used and the irrigation efficiency of watermelon, estimated by the NIAZAB system, with the actual amounts of applied water measured in the field. These field values were collected by the Agricultural Engineering and Technical Research Institute (Baghani et al., 2018) in the form of field designs. In this study, using climatic data, watermelon plant characteristics, soil information, and cropping pattern, the net and gross water requirements of watermelon are calculated from the NIAZAB system and then compared with the actual irrigation water consumption data in the field. The aim of this comparison is to evaluate the accuracy and reliability of the system in estimating the plant's water requirement and to analyze the gap between theoretical and practical water consumption values. This analysis can provide valuable information about the efficiency of the system in real field conditions, and play an effective role in optimizing water resource management, especially for plants such as watermelon. Also, this assessment can be used in macro-policies to reallocate water resources to plants and improve water productivity at regional and national levels.
To compare the watermelon water consumption estimated by the NIAZAB system with field-measured applied water quantities, this study utilized field data and direct on-farm measurements. The research's statistical population included watermelon farmers and representatives of agricultural organizations and water resources in selected provinces across Iran. Based on production statistics, nine out of 31 provinces, which accounted for a larger share of the country's watermelon cultivated area, were chosen. These included Razavi Khorasan, Khuzestan, Zanjan, Semnan, Sistan and Baluchestan, Fars, Kerman, Markazi, and Hormozgan provinces. Collectively, these provinces represented approximately 78% of the total watermelon cultivated area in the country (equivalent to 149,780 hectares). In the next step, **28 counties with in the selected provinces, with a combined cultivated area of 42,706 hectares, were chosen as study areas. Subsequently, through purposive sampling, 146 farms within these counties were selected for direct measurement of applied water. Of these, 113 farms used drip tape irrigation, and 33 farms utilized furrow and ridge irrigation methods. Throughout one growing season, the amount of irrigation water was measured directly at each irrigation event. For farms with drip tape irrigation, water consumption was measured using a water meter installed on the irrigation system. For farms with furrow and ridge irrigation, flumes and micromolinette instruments were used to measure the volume of water entering the farm. These measurements were conducted and data recorded for all irrigation turns. After harvesting, the final watermelon yield in each farm was also measured and recorded. In all selected farms, farming operations, including the use of common seeds, fertilizers, pesticides, and pest and disease control, were carried out according to regional customs and standard farmer practices.
A T-test, presented in Chart 3, compared the average applied water for watermelon using drip irrigation in field measurements with the estimated water consumption from the NIAZAB system. The results showed that the average estimated water consumption from the NIAZAB system was 4015 cubic meters per hectare, while field-measured consumption was 4580 cubic meters per hectare. These two averages did not show a significant difference. Although the watermelon irrigation water estimated by the NIAZAB system was less than the measured amount, this difference primarily stems from discrepancies in planting dates and crop phenological stages. For a more robust evaluation, watermelon irrigation water quantities were compared at the county and larger scales. This revealed an 11% normalized error and a 95% agreement index, indicating the system's acceptable efficiency. Therefore, the NIAZAB system can effectively estimate the actual irrigation water for watermelon at the farm level within counties, making it justifiable for estimating actual watermelon irrigation water across the entire country. It's important to note that measuring watermelon irrigation water at the farm level is a time-consuming and costly endeavor. It also depends on the accuracy of measuring instruments and potential human error. Furthermore, factors like plant variety, soil type, nutritional conditions, other environmental stresses, and surrounding environmental factors contribute to this observed error. The 11% normalized error and 95% agreement index are not indicative of poor system performance or inaccurate measuring devices. Instead, every estimation method, measurement technique, variables used, and databases are potential sources of error that contribute to these observed differences.
In this study, watermelon water consumption was investigated using two distinct methods: first, direct measurement data from 146 selected farms across 28 counties in 9 major watermelon-producing provinces in Iran; and second, estimation of water consumption by the NIAZAB (Water Requirement) system. The results indicated that the average measured applied water for drip irrigation in the field was 4580 cubic meters per hectare, while the average estimated water consumption by the NIAZAB system for drip irrigation was 4105 cubic meters per hectare. Furthermore, the weighted average estimated water consumption for drip irrigation from the system was 4057 cubic meters, and the weighted average measured applied water in drip-irrigated fields was 4359 cubic meters per hectare. Considering a total irrigated watermelon cultivation area of 100,000 hectares, the total water consumption nationwide was calculated to be 406 million cubic meters based on the NIAZAB system and 436 million cubic meters based on field data. The difference between these two values was approximately 7, which indicates a relatively good proximity between the system's estimates and actual values. This discrepancy stems from fundamental differences in the computational bases of the two methods. The NIAZAB system calculates crop water requirements using the Penman-Monteith method and applying a crop coefficient (Kc), then estimates water consumption based on the irrigation method and water application efficiency. In contrast, direct field measurements represent the actual volume of water entering the farm, which is influenced by environmental factors, farmer operational conditions, and real-world farm circumstances. The comparison of field-measured applied water with the estimated watermelon water consumption from the "NIAZAB system showed a Normalized Root Mean Square Error (NRMSE) of 15% between the two methods. Additionally, Willmott's index of agreement between the measured and simulated values was found to be 95.1%, demonstrating a high level of concordance between the field data and the system's output.
It is suggested that a similar comparison of irrigation water quantities and determination of water productivity be conducted for other important crops across the country. This would provide authorities with a more realistic estimate of water usage from various national water sources, enabling more informed decision making.
First author: Led the data analysis and writing process of the paper. Second author: Assisted in completing the numerical modeling, data analysis of the model. Third author: Assisted in collecting and analyzing field data in the fields. Fourth author: Assisted in collecting and analyzing field data in the fields.
The data that support the findings of this study are available from the corresponding author upon reasonable request.
This work was part of a research project titled “Establishing a NIAZAB system and determining water consumption of plants” funded by the Soil and Water Research Institute of Iran (SWRI). The authors would like to express their gratitude for their valuable contributions.
The authors avoided data fabrication, falsification, plagiarism, and misconduct.
The authors declare no conflict of interest.
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