Reza Sokouti
Abstract
Crop growth in natural habitats is the result of the biological function of various factors. Soil is the most influential factor on the yield potential of a habitat that can lead to the soil fertility and yield degradation. This study aimed to determine the relationship between crop yield and soil properties ...
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Crop growth in natural habitats is the result of the biological function of various factors. Soil is the most influential factor on the yield potential of a habitat that can lead to the soil fertility and yield degradation. This study aimed to determine the relationship between crop yield and soil properties used to calculate the soil quality indicators in the semi-arid rangelands of Shohada-Valley as an example in West Azerbaijan Province The slope aspect with four directions, slope classes with five classes and vegetation layers were overplayed to prepare working units of 1:50,000 scale. Physical, biological and chemical properties of soil samples from 0-30 cm of topsoil were determined through required analysis. Landscape Function Analysis (LFA) was done and yield of dominant species was calculated in maximum flowering time by direct collection method. Effective soil properties on plant production were determined using Principal Component Analysis (PCA) and the mathematical relations between crop yield and soil parameters was computed by stepwise multiple regression. Results showed that mean values of soil landscape index is 0.8, stability index was equal to 76.9, the permeability index was 57.1 and the nutrient index was equal to 69.1 in 28 map units. The average of total production was calculated 1535.24 kg /ha of dry matter. Three components having a latent root above one, explained about 78 percent of the variance using factor analysis,. The outcome variables for evaluating soil quality index, organization index, nutrient cycling index, salinity and bulk density, were determined. A significant correlation of 63% was achieved between soil quality indicators and crop production,. Using soil quality index a coefficient of determination of 64 percent was computed after applying a mathematical crop production model Mean Bias Error of -0.02, error of 8% and the efficiency of the model of 0.66, provide a suitable application for interpretation function of rangelands. Therefore, resulted model is suitable for estimating range production in semi-arid and cold semi-arid steppe habitats.
Reza Abdi; Mehdi Yasi; Reza Sokooti Oskoui; Ehsan Mohamadi
Abstract
Determination of environmental flow in river systems and other watery ecosystems is a new science in Iran and other developing countries. This paper evaluates the ecological requirement in a typical river by different hydrological and eco-hydrological methods. In this study, environmental requirement ...
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Determination of environmental flow in river systems and other watery ecosystems is a new science in Iran and other developing countries. This paper evaluates the ecological requirement in a typical river by different hydrological and eco-hydrological methods. In this study, environmental requirement of Zarrinehrood river (located in North West of Iran), from downstream of Bukan dam up to Urmia lake (near to 140 km), was estimated by four methods: Tennant, Tessman, Desktop Reserve Model (DRM) and FDC Shifting using the hydrometric data of Sariqamish station. According to results, the amounts generated from FDC Shifting method are more proper because of considering the ecological management qualification. Therefore, 16.7 CMS (equals to 33% of mean annually flow) was obtained as average environmental requirement of Zarrinehrood river in ecological management class C (maintains minimum ecological term in river). Also, monthly distribution of recommended environmental flow was compared with monthly flow of Sariqamish hydrometry station. The critical period for the river is during August to October. In this period, the monthly flow of 12.6, 11.6 and 6.3 m3s-1, are required to flow downstream in order to preserve the river life.
