نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم خاک، دانشکده علوم کشاورزی، دانشگاه گیلان، رشت، ایران
2 بخش خاک و آب. موسسه تحقیقات برنج کشور. رشت. ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Assessment of soil quality and identification of key indicators with their critical limits are very important for maintaining soil functions and rice productivity. The aim of this research was to determine the minimum data set (MDS) based on terrain attributes and to establish critical limits based on rice yield in Langarud, Guilan Province. Composite soil samples (0-30 cm) were collected from three landforms: mountain, alluvial plain, and coastal area. The MDS in each landform were obtained using auxiliary data extracted from DEM, and the Norm values of soil properties. Finally, the integrated quality index (IQI) was calculated for each landform. Available potassium showed the highest correlation with rice yield in the coastal (R2 = 0.87), alluvial plain (R2 = 0.85), and mountain (R2 = 0.90). The lower and upper limits of the IQI for 40% and 80% relative yield were 0.39 and 0.65 in coastal area, 0.56 and 0.76 in alluvial plain, and 0.41 and 0.73 in mountain, respectively. The highest correlation between the soil quality index (SQI) and relative yield (R2 = 0.87) was obtained for mountain. The mapping showed that the low productivity paddy fields are located in the coastal areas, where the SQI is the lowest. This observation is possibly attributed to the coarser soil texture and the proximity to the Caspian Sea. In contrast, paddy fields in mountain exhibited the highest SQI and yield. Therefore, determining the critical limits for MDS is essential for improving management practices and achieving sustainable productivity in paddy fields.
کلیدواژهها [English]
EXTENDED ABSTRACT
Identifying key indicators and determining critical limits of soil quality that affect fertilization levels is crucial. Enhancing the productivity of paddy fields, which is important for ensuring national food security, is impeded by numerous challenges. Systematic evaluation of soil quality can support productivity enhancement. Disregarding this can lead to the ineffective use of chemical fertilizers, which not only fails to increase agricultural productivity but also imposes additional costs, disrupts the balance of nutrients in the soil, and contributes to environmental issues.
The aim of this research was to establish the minimum data set (MDS) based on terrain attributes and norm values of soil indicators and, to identify upper and lower critical limits of the soil quality indicators and soil quality index based on the local rice yields under field condition in Langarud city, Guilan Province.
80 Composite soil samples were collected from three landforms, including mountain, alluvial plain, and coastal area, at depth of 0-30 cm, and 17 physical, chemical, and biological soil properties were measured. The principal components analysis (PCA) method was applied to identify the key soil indicators that better represent the effect on soil quality. The principal components with eigenvalues greater than one were considered for MDS selection. After determining the principal components, variables with high factor loadings in each principal component were separated using the factor rotation method. In order to reduce the number of components and select MDS, Bartlett's test and KMO coefficient were used. A KMO coefficient close to 1 is ideal, and typically, a value exceeding 0.6 is considered appropriate for conducting a PCA. Then, The MDS in each landform were obtained using auxiliary data extracted from the digital elevation model (DEM) and the Norm values of soil properties. Finally, the integrated quality index (IQI) was calculated for each landform. The critical limits of each MDS in different landforms were determined based on linear relationships between MDS indicators and relative yield (RY).
The results showed that clay content, organic carbon, available potassium, soil microbial respiration, and phosphatase were identified as most important MDS influencing soil quality and crop yield in three landforms. Additionally, available potassium showed the highest correlation with rice yield in the coastal (R2 = 0.87), alluvial plain (R2 = 0.85), and mountain (R2 = 0.90). The lower and upper limits of the soil quality index for 40% and 80% relative yield were 0.39 and 0.65 in coastal area, 0.56 and 0.76 in alluvial plain, and 0.41 and 0.73 in mountain, respectively. The highest correlation between the soil quality index and relative yield (R2 = 0.87) was obtained for mountain. The mapping showed that the low productivity paddy fields are located in the coastal areas, where the average soil quality index is the lowest. This observation is possibly attributed to the coarser soil texture and the proximity to the Caspian Sea. In contrast, paddy fields in mountain with the highest average of soil quality index have the highest yield. Therefore, determining the critical limits of MDS as a function of rice yield is crucial for improving management practices and achieving sustainable productivity in paddy fields.
Seyedeh Fatemeh Nabavi: methodology, software, data curation, writing-original draft, formal analysis. Nafiseh Yaghmaeian Mahabadi: conceptualization, methodology, data curation, validation, writing-review and editing, supervision, project administration. Hassan Ramezanpour: writing-review and editing. Mohammad Bagher Farhangi: data curation, validation, writing-review and editing. Shahram Mahmoud Soltani: writing-review and editing. All authors have read and agreed to the published version of the manuscript.
Data is available on reasonable request from the authors.
The authors would like to thank the reviewers and editor for their critical comments that helped to improve the paper. The authors gratefully acknowledge the support and facilities provided by the Department of Soil Science, University of Guilan, Iran.
The authors avoided data fabrication, falsification, plagiarism, and misconduct.
The author declares no conflict of interest.
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