جستجوی مقالات مرتبط با کلیدواژه "crop management" در نشریات گروه "آب و خاک"

Optimum yield production under rainfed cultivation directly depends on the amount of rainfall and moisture storage in the soil. The tillage system directly influences soil moisture retention as well as the soil’s physical and chemical properties. Selecting the appropriate tillage system can significantly impact crop yields. Oilseeds are particularly important among crops, representing the second-largest food reserve in the world after grains. These products are rich in fatty acids. Today, the oil extraction and production industry is one of the most strategic industries in most countries. Iran has vast arable land and favorable conditions for cultivating oilseeds. However, according to available statistics, over 80% of the country's oil needs are met through imports. Given the increasing demand for higher-quality oil products and the challenges posed by climate issues, such as recurring droughts, cultivating and developing crops with lower water requirements and greater resilience appears to be a promising solution. Implementing effective management practices and appropriate fertilizers aligned with conservation agriculture could help increase crop yields while maintaining and improving long-term soil quality. To explore the potential of oilseed cultivation, an experiment was conducted to examine the effects of tillage and fertilization on the yield and yield components of safflower under rainfed conditions.

This experiment was carried out as split plots based on random complete blocks design, with three replications under rainfed conditions. The treatments included tillage systems (conventional tillage, reduced tillage, and no-tillage) as the main factor and NPK fertilizer (a mixture of urea, triple superphosphate, and potassium sulfate) at four levels of zero, 33, 66, and 100% as a secondary factor. Potassium and phosphorus fertilization and 50% of nitrogen fertilizer were used at the same time as planting, and the remaining 50% of nitrogen fertilizer was used four months after planting. Each block had three main plots; the distance between each block was 3 meters, and between the main plots was 2 meters. In each main plot, four sub-plots were created, and the distance between the sub-plots was 1 meter. The area of the main plots was 21 × 15 meters, and the area of each sub-plot was 4.5 ×15 meters. The amount of seed used for safflower was 25 kg per hectare. The safflower seeds were sown in 5 rows and planted at a distance of 50 cm and a distance between plants of 10 cm. At all stages of planting, maintenance, and harvesting, agricultural management followed the traditional practices of the study area, as performed by the local farmers. The final sampling, or harvesting, was carried out manually at the physiological maturity stage. Before conducting variance analysis, a normality test was performed on the data. In this research, the LSD test was used to compare the mean at the 5% probability level, Excel software was used to draw graphs, and SAS 9.4 software was used to analyze the data.

The research showed that the traits examined, including leaf area index, dry matter content, thousand seed weight, seed yield, and biological yield, were affected by the tillage system, fertilizer, and their interaction effect. The highest safflower seed yield of 195.6 g/m2 was obtained from the fertilizer ratio of 33% and conventional tillage, and the lowest seed yield of 116.2 g/m2 was obtained from no-tillage and no fertilizer use. The results indicated that the conventional tillage system outperformed both reduced tillage and no-tillage systems. In reduced and no-tillage systems, the changes in the leaf area index of the safflower plant were similar, with the 100% fertilizer application under reduced tillage having a more pronounced effect compared to no-tillage. Additionally, in the absence of fertilizer in the no-tillage system, the leaf area index was lower. Fertilizer application increased the plant's biological yield, but its impact was greater under conventional tillage compared to reduced and no-tillage systems. Applying 33% of the required fertilizer in the conventional tillage system resulted in the highest biological yield for safflower, leading to a 94% increase in biological performance compared to the control.

In most of the examined traits, the application of 33 and 66% of the fertilizer requirement caused the best results, and the 100% fertilizer ratio left adverse effects, which indicates the lower fertilizer requirement of this cultivar in the studied conditions compared to cultivars in other regions. Since the research was conducted in rainy years, conventional tillage was better than low tillage. It is suggested that this plant's production amount be evaluated under different irrigation conditions and moisture limitations so that tillage systems and management methods can be examined and selected more carefully.

Given the extensive cultivation of maize in Iran, any initiative aimed at increasing water use efficiency contributes to reducing water consumption and enhancing food security in the country. One of the most influential factors affecting the growth and performance of crops is the impact of climate change. The present study aims to assess the impact of climate change and altering planting dates on the water productivity of maize in Gorgan County. Additionally, water productivity of maize under different irrigation treatments and planting dates is simulated using the WOFOST model for future conditions. The irrigation treatments include 100% (T1), 75% (T2), and 50% (T3) of the plant's water requirements. Hence, statistical SDSM and HadCM3 General Circulation Model were employed to downscale all scenarios of the fifth report for two thirty-year periods, 2020-2050 and 2050-2080. The results showed with increasing of irrigation water stress, the simulation error of irrigation water productivity increased, but no consistent trend was observed. In the period of 2050-2020, the highest irrigation water productivity was predicted in treatment T3 on 23 June, amounting to 4 kilograms per cubic meter, which represents a 1.9% reduction compared to the baseline period. During this period, the lowest irrigation water productivity was projected in treatment T1 on 2 June, amounting to 2.7 kilograms per cubic meter, indicating a 57.3% reduction compared to the baseline. Based on the simulated results, the optimal planting time for corn in Gorgan is on 23 June. With appropriate validation of the planting date, effective management can be implemented to adapt to the negative effects of climate change on corn water productivity. Choosing the best planting time, along with proper management, is an efficient solution in Gorgan to prevent reduced performance due to an inappropriate choice of planting date.

The land use change as well as changes in climatic parameters such as temperature increase affect many natural processes such as soil erosion and sediment production, floods, and degradation of physical and chemical properties of soil. Therefore, it is necessary to pay attention to different aspects of the effect of these changes in studies and macro decisions of the country. In the present study, the SWAT conceptual model was used to test and analyze the existing scenarios in the Marvast basin. After calibrating the model, the two scenarios were tested. The first scenario is in the field of agricultural management and conversion of gardens to agricultural lands and the second scenario is a 0.5-degree increase in temperature by assuming other conditions are constant. The calibration and validation results of the model with the Nash-Sutcliffe test showed 0.66 and 0.68 respectively, which indicate the acceptable performance of the model in the study area. Then, the results of using two scenarios of land use change and heating, especially in recent years showed the effect of 30 percent of the climate scenario on the increase of flooding in the basin. The scenario of changing the use of garden lands to agriculture in two cases of 20% and 50% change of use of 10% and 12% was added to the flooding of the basin. The results indicate that in similar areas of the study area which is located in a dry climate zone, a possible increase in temperature can have a significant effect on flooding in the basin. However, the indirect impact of the human factor in increasing greenhouse gases and flooding in the basin should not be ignored.

In order to evaluate the effect of humic acid and complete micronutrient fertilizer on growth and economic performance of different bread wheat cultivars, a factorial experiment was conducted on the base of randomized complete block design with three replications in Biranshahr region (Lorestan province) during two years in 2015-16 and 2016-17. The main factors included nutrition at four levels (control, humic acid, complete fertilizer 20-20-20 and humic acid + complete fertilizer 20-20-20) and bread wheat cultivars as sub-factors included (Mihan, Sivand and Alvand). The results showed that the number of spikes per square meter, number of seeds per spike, 1000-seed weight, biological yield, and grain yield and harvest index of wheat cultivars were influenced by the studied factors. The highest economic yield (8296 kg/ha) was obtained in the treatment of humic acid application + complete micronutrient fertilizer in Alvand cultivar. The highest number of spikes per m2 was related to humic acid feeding treatment in Alvand cultivar with an average of 625 spikes per m2. The highest number of seeds per spike was obtained in the treatment with humic acid feeding along with complete fertilizer in Alvand cultivar with an average of 45.2. The highest 1000-seed weight was related to feeding with humic acid + complete fertilizer with an average of 42.0 g. Interaction of humic acid with complete fertilizer in Alvand cultivar has produced the highest biological yield (19156 kg/ha). The highest harvest index (43.6%) was observed in complete fertilizer feeding treatment in Alvand cultivar. Findings showed that the application of humic acid along with chemical fertilizers increases the quality and quantity of agricultural products and maintains the balance of the environment.

In order to evaluate the effect of different crop management methods and irrigation with saline water on evapotranspiration and water use efficiency of Maize, the factorial experiment with randomized complete block design was conducted. This project was carried out in the Agricultural farm of Shahid Chamran University of Ahvaz from March to June 2015. Different crop managements include without crop residues, use of crop residues on soil surface as mulch and mix of crop residues with surface soil layer to 30 cm depth and water irrigation salinity include water salinity of Karoun river (2dS/m), 4.5 and 7 dS/m. The results of variance analysis showed that the effect of salinity, crop management and their interaction effect on evapotranspiration, yield and water use efficiency was significant. Minimum values of ET (387.5mm) and WUE (0.68 kg/m3) were obtained at the salinity level of 7 dS/m. The management of residues use as mulch had the most effect on ET decrease (9%) and yield increase (10%) and So, the maximum WUE (1.10 kg/m3) was obtained at it too. The greatest impact of residues applications mulch and mixing with soil surface layer in increasing of yield (19% and 9% respectively) and WUE (27.6% and 10.6%, respectively) compared to non-use of residues was observed at the salinity level of 4.5 dS/m. Therefore, the use of crop residues particularly as mulch can be recommended as an effective way to reduce the damage of irrigation with saline water.

One way to deal with the water crisis is the use of unconventional waters (such as subsurface waters) with a good crop management. The use of these waters may affect the saturated hydraulic conductivity. But the direct measurement of saturated hydraulic conductivity requires spending a lot of time and cost. A lysimeter experiment was conducted in order to investigate the effect of water table salinity and depth management on saturated hydraulic conductivity and effective porosity and to determine the relation between them. The statistical design was a split-split plot arrangement of a randomized complete block design with three replicates in each treatment. Treatments included 3 levels of groundwater salinity (main plot; S1=