JWSS - Journal of Water and Soil Science

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Effect of nitrogen (N) fertilizer levels and its split applications on yield and yield components of rice (Oryza sativa L.) Cv. Khazar was investigated in a completely randomized block design with 3 replications in a paddy light soil at Guilan province, Iran, 2003. In this experiment, six treatments including: T_1-control (no N fertilizer) T_2- 40 kg/ha N (at transplanting time) T_3- 80 kg/ha N (at transplanting, and tillering times) T_4- 80 kg/ha N (at transplanting, tillering, and panicle initiation times) T_5- 120 kg/ha N (at transplanting, and tillering times) and T_6- 120 kg/ha N (at transplanting, tillering, and panicle initiation times) were compared. Results showed that the highest fertile tiller number was obtained in the fifth and sixth treatments with double and triple split applications of 120 kg/h N (236 and 248 m^-2). The highest fertile filled spikelets percentage (84.8%), 1000-grain weight (26.1 g) and grain yield (4.83 t/ha) belonged to the sixth treatment, but grain yield and 1000-grain weight were not significantly differerent in the fourth and sixth treatments with three fertilizing times. This finding may have resulted from the third topdressing application of nitrogen fertilizer in panicle initiation and higher leaf area (44.8 and 45.5 Cm²), leaf greenness (39.4 and 39.9) and leaf nitrogen concentration (31.2 and 33.6 g/kg) during grain filling in the fourth and sixth treatments. Regression analysis also showed that flag leaf greenness (SPAD values at 5 days after flowering) and flag leaf area accounted for about 75% and 78% changes in yield, respectively. In conclusion, triple split application of 80 kgN/ha could be suggested for rice Cv. Khazar in these regions since the yield would be the same as the application of 120Kg/ha N.

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This study was conducted based on a randomized complete block design and a factorial experiment with three replications in regions to investigate the effect of different rates and times of nitrogen on the quantitative properties of safflower. The first factor was different nitrogen rates including 0, 60, 120 and 180 kg ha^-1 , and the  second one was nitrogen application time including seed sowing, rosette and the before flowering stage; these were  1-0-0, 1/3-2/3-0, 2/3-1/3-0 and 1/3-1/3-1/3 with the  Goldasht variety. The results showed that nitrogen rate had a significant effect on all studied traits. Nitrogen application time also had a significant effect on capitulum number and yield at p>0.99 and on the length of plant, nitrogen adsorption, agronomic efficiency and apparent recovery at p>0.95. So based on the results, the recommended consumption of 60 kg/ha N was split into three equal amounts at the time of planting, rosette and flowering or 1/3-2/3-0, in Kerman area.

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Land surface temperature (LST) is used as one of the key sources to study land surface processes such as evapotranspiration, development of indexes, air temperature modeling and climate change. Remote sensing data offer the possibility of estimating LST all over the world with high temporal and spatial resolution. Landsat-8, which has two thermal infrared channels, provides an opportunity for the retrieval of LST using the split- window method. The main objective of this research was to analyze the LST of land use/land cover types of the central part of Isfahan Province using the split- window algorithm. The obtained results demonstrated that the "other" class which had been mainly covered with bare lands exhibited the highest LST (50.9°C). Impervious surfaces including residential areas, roads and industries had the LST of 45°C. The lowest temperature was observed in the "water" class, which was followed by vegetation. Vegetation recorded a mean LST of 42.3°C. R² was 0.63 when regression was carried out on LST and air temperature.