N. N. Kouhi Chelle Karan; H. Dehghanisanij; A. Alizadeh; E. Kanani
Abstract
Introduction: Drought is one of the factors that threatens the performance of agricultural products, especially corn in most parts of the world. Under conditions of water scarcity, the effectiveness and efficiency of fertilizer use is reduced, especially if fertilizer application is not consistent with ...
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Introduction: Drought is one of the factors that threatens the performance of agricultural products, especially corn in most parts of the world. Under conditions of water scarcity, the effectiveness and efficiency of fertilizer use is reduced, especially if fertilizer application is not consistent with plant growth. Among fertilizers, nitrogen is one of the most important nutrients for corn, and consumption management of this fertilizer has great importance in order to succeed in increasing the production of corn. Therefore, in conditions of water shortage, balanced and optimal use of fertilizer should be considered to achieve increased yield and water use efficiency.
Materials and Methods: This study was conducted to investigate the effect of drip irrigation regimes and different levels of nitrogen fertilizer on yield and yield components of corn and soil moisture changes at the Shaheed Zendrh Rouh Jupar in Kerman province during the years of 2012-2014. The experiment was arranged as a split-plot design based on randomized complete block design with five irrigation regimes (I1 = 100, I2 = 80 and I3 = 60% ETc) as the main-factor and five nitrogen fertilizer level N1 = 0, N2 = 50, N3 = 100, N4 = 150 and N5 = 200 kg/ha) as sub-factor. According to the Kerman Meteorological Station, this region has a semi-arid climate with warm summers and mild winters. To calculate the volume of water consumed, potential evapotranspiration (ETo) was determined using daily meteorological information and Penman-Monteith method (PM). A sampling method was used to measure moisture at different depths of soil.
Results and Discussion: The results showed that the highest yield was due to I1 treatments with 8.85 t/ha, and there was a direct relation between crop reduction and water requirement reduction at all stages of crop production. High nitrogen application had a negative effect on yield. Typically, in soils that lack nitrogen, corn grain yield increased with nitrogen addition. However, after reaching the maximum yield, nitrogen addition has no effect on increase or yield may reduce. The interactions of different levels of water and fertilizer showed that I1N4 and I3N1 treatments had the highest (10.6 ton/ha) and lowest (1.24 ton/ha) value of corn yield, respectively. The highest and lowest grain yield components (thousand grain weight, number of kernels row, number of kernels per row, cob length, cob diameter) were observed in N1 and N3 I1 treatments, respectively. The highest water use efficiency (1.26 kg/m3) was observed in I2N4 treatment and the lowest (0.068 kg/m3) in I3N1 treatment. The results of this study showed that the remaining moisture content in soil decreased by decreasing amount of irrigation water and nitrogen fertilizer in 20 days after planting. At 75 days after planting, reasons such as severe water shortages during growth, reduced root density, high water requirement at this stage of growing season, and the plants need to nutrients have probably caused the roots to absorb as much as possible of the top three water and nutrient. As a result, the moisture that reaches the last layer is less. The results showed that in the last stages of growth compared to other stages, the plant water requirement is reduced and excess water penetrates the lower layers.
Conclusion According to the results of this study, nitrogen fertilizer at 150 kg/ha with 100% water requirement is the best combination for corn farming in semi-arid climates.
Hossein Dehghanisanij; Elahe Kanani; samira akhavan
Abstract
Introduction: Partitioning of evapotranspiration (ET) into evaporation from the soil (E) and transpiration through the stomata of plants (T) is important in order to assess biomass production and the allocation of increasingly scarce water resources. Generally, T is the desired component with the water ...
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Introduction: Partitioning of evapotranspiration (ET) into evaporation from the soil (E) and transpiration through the stomata of plants (T) is important in order to assess biomass production and the allocation of increasingly scarce water resources. Generally, T is the desired component with the water being used to enhance plant productivity; whereas, E is considered a source of water loss or inefficiency, and is the basis of the management and organization of water resources. The present investigation was carried out with the objectives evaluation of corn evapotranspiration and its components and relationship between leaf area index and components in surface and subsurface drip irrigation systems.
Materials and Methods: The pilot farm were located in the water and soil department of the ministry of agriculture in Karaj, Iran (latitude of 51°38 ˊN and longitude of 35°21ˊ W, 1312.5 m above sea level). For implementation project was placed 8 volume micro-lysimeters in the soil, which were filled with soil excavated from the study site. The soil inside of micro-lysimeter and the soil of the surrounding study had the same physical-chemical characteristics. The corn was irrigated with surface drip (DI) and subsurface drip irrigation (SDI) system, that was installed just prior to planting in 2014 in a field that was planted to sprinkler-irrigated corn. Daily crop actual evapotranspiration (ETc) of each micro-lysimeter was calculated by applying the water balance method and soil evaporation was measured with micro-lysimeters. Finally, plant transpiration was calculated from difference between the actual evapotranspiration value and amount of evaporation from the soil surface. Leaf area index (LAI), was measured, and it was measured with the electronic leaf area-meter, CI – 202 seven times during the growing season. This method provides an indication of the plant growth.
Results and Discussion: The obtained results indicated that actual corn evapotranspiration was 377 and 371.92 mm for surface drip and subsurface drip irrigation systems, respectively. The value of corn evapotranspiration under surface drip and subsurface drip irrigation increased from initial, to middle season stages. The maximum daily values of ETc occurred on 48 days after planting in middle season stages. The total value of transpiration plant was 5.88, 76.82 and 118.21 mmd-1 for surface drip irrigation system and 12.78, 81.31 and 118.95 mmd-1 for subsurface drip irrigation system in the initial, advance, and middle season stages, respectively. Sum evaporation from the soil surface and crop transpiration was 200.81 and 176.02 mm for surface drip irrigation system and 213.04 and 158.81 mm for subsurface drip irrigation system. So, amount of evaporation from the soil surface was 73.02, 65.73 and 37.32 mm for surface drip irrigation system and 65, 58.83 and 34.98 mm for subsurface drip irrigation system in the initial, advance, and middle season stages, respectively. In surface drip and subsurface drip irrigation was allocated approximately 93 and 83 percent of evapotranspiration to evaporation from the soil surface respectively. The minimum daily values of E/ETc were 37 and 34 mm for surface drip and subsurface drip irrigation systems respectively, and occurred in middle season stages. Amount of transpiration was 5.88, 76.82 and 118.21 mm for surface drip irrigation system 12.78, 81.31 and 118.95 mm for subsurface drip irrigation for the initial, advance and middle season stages, respectively. The relationship between T/ETc and LAI was fitted to a polynomial equation with significant correlation coefficients, R2 = 0.95 and 0.89 for surface drip and subsurface drip irrigation systems, respectively. T/ETc started from 0 at sowing, and reached to its maximum at the middle growth stage or when LAI reached to about 3.0. Also, the relationship between E/ETc and LAI was fitted to a polynomial equation with significant correlation coefficients, R2 = 0.97 and 0.88 for surface drip and subsurface drip irrigation systems respectively, and reached to its minimum at the middle growth stage. Also the results showed that subsurface drip irrigation systems have higher biological yield and higher values for plant parameters in compared to surface drip irrigation system that it shows subsurface drip irrigation system due to evaporation reduction, better weed control and direct transport of water to the developmental zone has a significant role in increasing corn yield.
Conclusion: The results of this study indicated that soil evaporation losses in subsurface drip irrigation system had lower than surface drip irrigation system. Also, had higher transpiration in the growth season. This could perform important role on yield of crop. These results should help the precise planning and efficient management of irrigation for these crops in this region.
