Showing 6 results for Rainfed
A. Jalalian, J. Givi, M. Bazgir, Sh. Ayoubi,
Volume 10, Issue 4 (1-2007)
Abstract
In Iran, the development of cultivated areas becomes gradually impossible due to ever-increasing population growth and urban area development. Therefore, it is very important to use the existing cultivated lands more efficiently. Land suitability evaluation makes the sustainable use of the lands feasible. The objective of this study was qualitative, quantitative and economic assessment of land suitability in Talandahst area for rainfed wheat, barley and chickpea. Talandasht plain with a surface area of 4500 ha is located southwest of Kermanshah city. The climate is semi-arid with cold winter and moderate summer. The successive stages of this research included soil survey in the field, soil analysis, qualitative and quantitative and economic evaluations of land suitability. In qualitative evaluation of land, climatic, topographic and soil suitability classes were determined according to the degree of the matching. Limitation and parametric methods were used in qualitative evaluation. Quantitative and economic evaluations made based on the observed yield and gross benefit, respectively. Based on qualitative evaluation, the studied area is marginally suitable for rainfed farming of wheat, barley and chickpea. This is due to water deficiency occurring during some stages of the growing cycle. The solution for this problem is supplementary irrigation. In addition to climate limitation, there are also topographic and soil restriction for the growth of the studied crops. On the basis of observed yield, the land units are moderately to highly suitable for rainfed wheat and barley production. Among the three named crops, the most and least profitable ones are chickpea and barley, respectively, and wheat ranks between them.
R Karimizade, B Vaezi, T Hoseyn Por, A Mehraban, H Ghojagh,
Volume 13, Issue 48 (7-2009)
Abstract
Multi-environment trial data are required to obtain stability performance parameters as selection tools for effective cultivar evaluation. The interrelationship among several stability parameters and their associations with mean yield, along with the repeatability of these parameters in consecutive years was the objective of this study. Barley yield data of 18 cultivars, proprietary of Dryland Agricultural Research Institute, evaluated in 12 locations over 2005-2007 in three locations of Iran was used for the combined analysis of variance in three datasets. I: Across locations in a single evaluation year (dataset A), II: Across locations in each of two single evaluation year (dataset B), III: Across all locations in three years (dataset C). For each dataset, cultivar phenotypic variance and other statistics were appropriately partitioned in its components. The interrelationship among the parameters and their associations with mean yield based on Spearman rank correlation was studied in each of the three single evaluation years (dataset A). Rank correlation coefficients were also used as estimates of the repeatability of these stability parameters across two year combinations (dataset B). The parameters 2 σi Shukla and 2 Wi were consistently highly correlated with each other but not with mean yield in all single and pair evaluation years. The parameters bi , 2 Si and CV were consistently highly correlated with each other but not with mean yield in all single and pair evaluation years. Result showed that Shukla variance, Wricke ecovalence, SIPC1 and ASV AMMI stability statistics have high repeatability. Thus it is suggested that more stability statistics especially nonparametric methods be used for determination of repeatability methods.
J. Hamzei, M. Seyedi,
Volume 18, Issue 70 (3-2015)
Abstract
This experiment was carried out at the Agricultural Research Station of Bu-Ali Sina University to study the effect of different tillage methods on bulk density, yield, and yield components of barley (Hordeum vulgare) cultivars under rainfed conditions. Three levels of tillage (CT: conventional tillage, MT: minimum tillage and NT: no tillage) and five barely cultivars (V1: Local V2: AbidarV3: Valfagr V4: Bahman and V5: Makouei) were evaluated in a factorial arrangement in a completely randomized block design with three replications in the growing season of 2010-11. Traits of bulk density plant height, grain yield, yield components, biological yield, and harvest index (HI) were evaluated. The results showed that maximum value of bulk density (1.09, 1.26 and 1.29 g cm-3 for 0-10, 10-20 and 20-30 cm of sampling depth, respectively) was observed at MT treatment. But, there was no significant difference between MT and NT treatments for this trait. In comparison of cultivars, maximum bulk density was achieved with Valfagr cultivar. Using chisel plow (MT treatment) produced maximum plant height (70 cm) and yield components (513 numbers of spike m-2 and 19.2 grain spik-1). Also, among cultivars maximum plant height (72.7 cm) and grain number spike-1 (23.2 grain spike-1) belonged to Valfagr cultivar. Also, results showed that V3×MT treatment had the highest grain yield (3100 kg ha-1). Therefore, the findings of the study recommend using chisel plow (MT treatment) and Valfagr cultivar.
H. Asadi, M. Aligoli, M. Gorji,
Volume 20, Issue 78 (1-2017)
Abstract
This study aimed to investigate the dynamic changes of rill erosion and evaluate the ability of Hairsine-Rose model in estimation of sediment concentration. The experiments were carried out at the Soil and Water Conservation Research Station of Tehran University in Kuhin, Qazvin. Four flow rates were tested at three slopes in trapezoidal hand-made rills of 3 m long and 5 cm base width. Outflows were sampled periodically to determine changes in sediment concentration. The experiments were repeated in early autumn and mid spring. Sediment concentration showed a dynamic change with time which was affected by flow rate, slope and season. The sediment concentration was high in the first few minutes of the experiment but over time, dropped and finally reached a more or less stable state. The effects of flow rate and slope were more detectable on sediment concentration at the early unsteady conditions than at the final steady conditions. Though the temporal trends were similar, the sediment concentration was generally higher in autumn than in spring. Hairsine-rose model showed a better performance at lower flow stream powers but generally over predicted sediment concentration showing a systematic error probably due to model formulation.
Dr. S. Akhavan, N. Delavar, Dr. A. M. Mehnatkesh,
Volume 21, Issue 2 (8-2017)
Abstract
The aim of this study was to investigate the climate change impacts on some factors affecting rainfed wheat growth such as effective rainfall, planting date and length of growing season in four stations located in Chaharmahal and Bakhtiari province. Firstly, it is necessary to predict future (2046-2065) climatic conditions. For this purpose, the output of HADCM3 general circulation model was used under three scenarios of A1B, A2 and B1. The data were downscaled by LARS-WG model. After simulating the climatic parameters in mention period, the effective rainfall during the wheat growing season was calculated by Food and Agriculture Organization method. Also, the optimum planting date was defined according to the date of the first rain (at least 10 mm in case of continuing for next days). The wheat's growth stages were determined by Growing Degree Days method. The results indicated a rise in temperature for four stations. On average, it is expected that the annual temperature increase by 1.8°C compared with the baseline period (2010-1990). Total annual precipitation in Shahrekord, Koohrang and Borujen will decrease 2.2, 7.8 and 3.6 per cent respectively. About Lordegan it will increase by 2.7 per cent. Also, the results showed that in three stations of Shahrekord, Koohrang and Borujen, the amount of effective rainfall in November will increase compared to baseline, but in Lordegan it will reduce. So, in the first three stations, in most years, planting date was obtained earlier than baseline, but in Lordegan it was later than baseline. The Length of growing season will reduce in Shahrekord, Borujen and Lordegan stations, 12 days on average and in Koohrang about 13 days.
A.r Vaezi, Kh. Sahandi, F. Haghshenas,
Volume 28, Issue 3 (10-2024)
Abstract
Water erosion can be affected by land use change and soil degradation by agricultural activities. This study was conducted to investigate the effects of land use change in poor pastures on soil physical degradation and water erosion in semi-arid regions. Experiments were performed in 42 soil samples taken from seven areas covering the two land uses: poor pasture and rainfed agriculture, which have different soil textures (clay loam, silty clay loam, sandy clay loam, silt loam, loam, sandy loam, and sandy loam). The physical characteristics of soils were measured in the samples of both types of land use and its changes were expressed as physical degradation of the soil. The soil's susceptibility to water erosion was measured under simulated rainfall with 50 mm h-1 intensity for 60 min. The results showed that the land use change in pastures leads to the physical deterioration of soils; so bulk density, porosity, macropore, field capacity, saturated point, aggregate size, and aggregate stability were degraded with a rate of 28, 22, 41, 11, 5, 62, and 63 percentages. The structural characteristics of soil (aggregate size and stability) had the highest physical deterioration due to the land use change in the pastures. The change in land use change greatly increased the sensitivity of soils to water erosion. A significant relationship was found between the susceptibility of water erosion and the soil's physical degradation. The soils with coarser and more stable aggregates have higher physical degradation by the land use change and in consequence show more susceptibility to water erosion.
