reza saeidi; Hadi Ramezani Etedali; Amir Samadi; Ali Reza Tavakoli
Abstract
Introduction: Rainfed agriculture plays an important role in food production. In Iran, 6 million hectares of cultivated landsare rainfed. Moreover, about10% of raw agricultural products are being produced by rainfed agriculture. Yields of rainfed fields are decreased due to drought in recent years in ...
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Introduction: Rainfed agriculture plays an important role in food production. In Iran, 6 million hectares of cultivated landsare rainfed. Moreover, about10% of raw agricultural products are being produced by rainfed agriculture. Yields of rainfed fields are decreased due to drought in recent years in Iran. Supplementary irrigation is a suitable management to improve and enhance the yield of rainfed agriculture. Determination of appropriate time of supplementary irrigation is necessary in each region. But water allocation for this practice is the main challenge, because water resources are restricted. Therefore, water allocation management between irrigated and rainfedfields could be a viable strategy. Water resources for supplementary irrigation in rainfed fields are saved through deficit irrigation in irrigated lands or from rivers. The purpose of this study is optimum water allocation for supplementary irrigation in wheat and barley farms from rivers to around rainfed fields in Kamyaran region. In this study, supplementary irrigation is considered in three management methods of autumn irrigation, spring irrigation and both of them.
Materials and Methods:Kamyaran is located in Kurdistan province in west of Iran. The area of rainfed field is very vast in this region. Usually, rainfed fields are located in high slop lands and far from water resources in Kamyaran region. Supplementary irrigation is possible in rainfed fields around to water resources and with slope of less than 8%. The area of sub-basins with appropriate situations in Kamyaran region was calculated by geographic information system (GIS). Ratio of wheat to barley in rainfed fields is 3 to 1. Rivers in each sub-basin is the only water resources for supplementary irrigation in Kamyarn region. In this study, the objective function is maximizing net benefit. Also, constraints are total available water volumes in rivers at supplementary irrigations times and rainfed fields with appropriate situation for supplementary irrigation. Decision variable is rainfed area with different irrigation managements (autumn supplementary irrigation, spring supplementary irrigation, autumn+spring supplementary irrigations and rainfed managements). The total costs and income of agricultural production are found in statistical books of agriculture jihad in 2008-2009 growing season.
Results and Discussion: The lands around of rivers with suitable slope are about 30% of rainfed land of Kamyaran. The appropriate rainfed fields in sub-basins of A, B, C, D, E, F and INT were 125.39, 15.52, 18.11, 1111.26, 96.51, 48.13 and 49.55 Km2, respectively. The results of Optimization model showed the supplementary irrigation managements are different in each sub-basin because of different discharge of river in each sub-basin in different months. The optimal supplementary irrigation management for barley rainfed fields is autumnsupplementary irrigation. The yields of barley rainfed fields increase about 90% by autumn supplementary irrigation. The optimal supplementary irrigation managements for wheat are different in each sub-basin, but autumn+spring supplementary irrigations is best managed if water resources will be enough in each sub-basin. Due to restriction of water in rivers at supplementary irrigation time, some of wheat and barley fields remain rainfed in A+B+C and D sub-basin. The results showed minimum and maximum increase of wheat production in D and INT sub-basins are 29 and 134%, respectively. Also production increasing are 87, 112 and 126% in A+B+C, E and F, respectively. Increasing of barley production in the sub-basins of E, F and INT, are 61, 96 and 96%, respectively. Other sub-basins of A+B+C and D remained in rainfed farming. Net benefit increase about 65 and 275% for wheat and barley fields respectively, in 2014. Water productivity in all sub-basins for both wheat and barley is 74.8 and 44.5%, respectively.
Conclusions:This study showed supplementary irrigation management increased the yield and net benefit in rainfed fields of Kamyaran sub-basins. Resultsshowed about 30% of rainfed land of Kamyaran, are suitable for supplementary irrigation. The results of optimization models showed total increase of wheat production in A+B+C,E, F, D and INT sub-basins are 87, 112, 126, 29, 134%, respectively. Also increase of barley production in the sub-basins of E, F and INT, are 61, 96 and 96%, respectively. The result showed production increase about double in Kamayaran region. Also, net benefit increase about 65 and 275% in wheat and barley fields respectively.It has been suggested in A, B, C sub-basin, autumn supplementary irrigation of wheat, in E, F and INT sub-basins, autumn and spring supplementary irrigation for wheat and autumn supplementary irrigation for barley and in D sub-basin, autumn and spring supplementary irrigation for wheat.
leila jalali; J. Bazrafshan; A.R. Tavakoli
Abstract
Introduction: There have been several indices for agricultural drought monitoring such as Palmer Drought Severity Index (PDSI), Crop Moisture Index (CMI) and Reconnaissance Drought Index (RDI). These indices model the general conditions of soil moisture as a function of climatic parameters such as temperature ...
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Introduction: There have been several indices for agricultural drought monitoring such as Palmer Drought Severity Index (PDSI), Crop Moisture Index (CMI) and Reconnaissance Drought Index (RDI). These indices model the general conditions of soil moisture as a function of climatic parameters such as temperature and rainfall and they are not appropriate to any specific crop. Crop- Specific Drought Index (CSDI) is among few indices which directly take into account evapotranspiration for drought monitoring. This index is defined based on the ratio of actual evapotranspiration (ETa) to potential evapotranspiration (ETp). Literature review of agricultural drought monitoring in Iran reveals that was mainly used Reconnaissance Drought Index (RDI) and in some cases Drought Severity Index Palmer (PDSI) which have less associated with the growth or performance of the specific crop or not. In this paper, a Crop Specific Drought Index (CSDI) model was evaluated for rain-fed wheat in a cold-temperate climate. Then, it’s correlation with RDI was assessed.
Materials and Methods: In this study, using 9 years of data of meteorology, soil, and crop yield and phenology, a CSDI model has been calibrated and validated for rain-fed wheat. A two-layer model of daily soil water balance was used to CSDI calculation. The first layer is the current root growth zone which its depth increases with time. The second layer is between the first layer and maximum depth of root growth which its depth decreases by root growth and the thickness of this layer becomes zero when the root growth is Maximum. Actual daily Evapotranspiration (ETa) was calculated based on two-layer model of daily soil water balance. For this, we used the moisture content of the first layer (active), potential evapotranspiration and daily rainfall values. The statistical indices of error analysis like RMSE, MAE and Index of Agreement was used for assessment of CSDI model. Then, to investigate the correlation possibility of crop specific drought severity, Reconnaissance Drought Index (RDI) was used which is based on two variables of potential evapotranspiration and precipitation. In fact, RDI considers the precipitation as a factor of moisture input and the potential evapotranspiration as a factor of moisture exhaust.
Results Discussion: At Kermanshah station high coefficient of determination (0.95), relatively high index of agreement (0.747), and low error values (RMSE =0. 098 and MAE =0. 068) was obtained. Sensitivity coefficients during vegetative and productivity stages were obtained 1.31 and -0.0542, respectively. As a result, crop yield at vegetative stage severely affected by aridity stress while at productivity stage there was no sensitivity. In fact, water demand supply is vital at vegetative stage .Range of RDI at Kermanshah station was between 1.13 to -2.59. This threshold is the condition between "moderately wet" and "extreme drought". Correlation between the two index was started from March (R2 =0. 467) and persisted to September (R2 =0. 717). But the highest coefficients of determination were related to July to august (0. 738). Although CSDI didn’t affect by drought stress during October to February, it affected by moisture of March onward. RDI incorporating precipitation and potential evapotranspiration is one of the most recent developments for the assessment of drought severity through drought indices. That is why this index is chosen to investigate the relationship with CSDI. Actually, both indices get evapotranspiration factor in the agricultural drought monitoring. Based on the results, there is a good correlation between two indices. Since the CSDI is relay on ETa to ETp ratio and RDI is based on the P/ ETp ratio, it can be concluded that there is a possible to replacement of ETa with rainfall (R) in the CSDI equation.
Conclusion: Many indices and indicators are available to assist in the quantitative assessment of drought severity, and these should be evaluated carefully for their application to each region or location and sector. This paper presents a CSDI model which compared with RDI. Based on the results of this analysis, CSDI model was performed well in high values of coefficients of determination and Index of Agreement, and low values of errors. Therefore, the CSDI seems to be a reliable index to assess agricultural drought. Furthermore, it is observed a reliable relation between CSDI and RDI during crop growth period. Due to good correlation of CSDI and RDI, it can be proposed to replacement of rainfall (R) instead of ETp in the CSDI equation.
Hamid Reza Salemi; Ali Reza Tavakoli
Abstract
Introduction: Water crisis as a majorlimitation factor for agriculture, like other arid and semiarid regions exists in Isfahan province which is located in the central part of the Zayandehrud River Basin (ZRB). Rice appears to be the far-most profitable crop but at the same time it has a major impact ...
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Introduction: Water crisis as a majorlimitation factor for agriculture, like other arid and semiarid regions exists in Isfahan province which is located in the central part of the Zayandehrud River Basin (ZRB). Rice appears to be the far-most profitable crop but at the same time it has a major impact on basin scale water resources, especially affecting downstream farmers. In the study area (ShahidFozveh Research Station), the water resources for agricultural production face heightened competition from other sectors like industry and domestic use. This necessitates considering different crops, altered agricultural systems and innovative methods that can reduce the water requirements for the irrigation of rice. The Alternative Wetting and Drying (AWD) seems to be an effective method reducing water use for rice crops and possibly save the water for downstream users. There have been no qualitative evaluations of rice production under deficit irrigation practices in Isfahan area. This study sought to determine, under study area conditions, the quantities of water irrigation used with AWD practices, the resulting water productivity (WP) and the effects of alternative irrigation management on yield, quality indices and rice production performance.
Materials and Methods: The ZRB (41,500 km2) is a closed basin with no outlet to the sea. The research was conducted in the Qahderijan region of Isfahan province, which is located in the central part of the ZRB. The ShahidFozveh Agricultural Research Station (32°, 36’ N, 51°, 36’ E) is located at the altitude of 1612 m above the sea level. In order to improve WP and illustration of the impact of various levels of flooding depth on grain yield and quality indices at rice production, a field experiment (3000 m2) was conducted at ShahidFozveh Research Station for 2 years arranged in a split plot design with three replications. It will be necessary to use different scenario of water flooding depth management to achieve the highest irrigation application efficiency and WP. The treatments included: three levels of irrigation managements I1: permanentflooding under 3.5 cm water during growth period, I2: permanent flooding under2.2cm water during growth period and I3: 0-1.5cm. (AWD) were considered as main plots and eight advanced rice cultivars (Geredehmahali, Zayandeh-rud, Sazandegi , Hasani, 67-97, 67-113, 67-47 and 67-72) as sub plots. The treatments were compared based on grain yield and quality indices for irrigation management and rice varieties including: amylose content (AC), Gelatinization temperature (GT) and gel consistency (GC). Production (grain yield), quality indices, the consumption water, WP and cultivars reactions to different irrigation management were evaluated in different treatments. The soil of the experimental area, according to USDA Soil Taxonomy 1994 is of FINE CLAYEY. At the soil depth of 1m, soil salinity (6.2 dS.m-1), water salinity (3.9 dS.m-1), and soil moisture at saturated capacity (48 Vol. %) at the field site were measured or experimentally obtained in the Isfahan Soil and Water Laboratory. The results were subjected to an ANOVA to analyze the effects of the treatments and their interactions using PROC GLM (SAS 9.1, SAS institute Ltd., USA). Duncan’s multiple range tests at 0.05 probability level was used for paired mean comparison.
Results and Discussion: Results showed that water flooding depth treatments had significant effect on gel consistency, geletination degree and WP (P0.01). Significant differences (P0.01) were noticed in Gelenation degree, gel consistency, grain yield, WP among the cultivars. Also cultivars have significant effect (P0.05) on amylose contents. The highest magnitude of WP was calculated 0.91kg.m-3for (I3) followed by Zayandehrud, 67-113 and Sazandegi with 0.86 and 0.85, respectively. Maximum WP obtained from AWD irrigation management and Zayandehrud rice variety, its amount was 9.1kg.mm-1. At this treatment with 33.4 percent reduction of irrigation water, have resulted only 11.1 percent decreased of paddy grain yield. Results showed that it is not necessary to maintain the rice field submerged in whole growth period. Considering the importance of water flooding depth optimization as the main scope in arid and semi-arid lands of Iran, (I3) is recommended.
Conclusion: During the two years of conduction of an experiment in ZRB with clay texture and mild saline water with the three (3) irrigation treatments imposed on the rice crop. The highest WP was achieved for (I3) followed by Zayandehrud, 67-113 and Sazandegi, respectively. It was found that the AWD irrigation management, despite its lower yield than other irrigation treatments, increased water productivity. Thus, this treatment is desirable therefore highly recommended for agricultural rice production in arid region.
Ali Reza Tavakoli; H. Asadi
Abstract
Introduction: Two of the main challenges in developing countries are food production and trying to get a high income for good nutrition and reduction of poverty. Cereals and legumes are the most important crops in the rainfed areas of the country occupying the majority of dry land areas. Irrigated production ...
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Introduction: Two of the main challenges in developing countries are food production and trying to get a high income for good nutrition and reduction of poverty. Cereals and legumes are the most important crops in the rainfed areas of the country occupying the majority of dry land areas. Irrigated production systems had a main role in food production in the past years; but unfortunately, in recent years, with high population and competition of industry and environment with agricultural sectors, getting adequate irrigation water is difficult. The main purpose of this study is to determine the best option of crop agronomic management. Rainfed agriculture is important in the world; because this production system establishes %80 of the agriculture area and prepares %70 of the food in the world. In the Lorestan province, production area for rainfed barley is 120,000 ha and the amount produced is 120000 ton (approximately 1009 kg per ha). The purposes of this study were to evaluate cost, benefit and profit of rainfed barley production, economical and non-economical substitution of treatments in different agronomic management, study of sale return, cost ratio, determining break-even of price and comparing it with the guaranteed price of barley and estimating the value of water irrigation.
Materials and Methods: This research was carried out by sample farmers (12 farmers) on rainfed barley at the Honam selected site in the Lorestan province during 2005-07. At on-farm areas of the upper Karkheh River Basin (KRB) three irrigation levels were analyzed (rainfed, single irrigation at planting time and single irrigation at spring time) under two agronomic managements (advanced management (AM) and traditional management (TM). Data was analyzed by Partial Budgeting (PB) technique, Marginal Benefit-Cost Ratio (MBCR), and economical and non-economical test. For estimation of net benefit the following formula was used:
(1)
Where:
N.B: Net income (Rials/ ha) , B(w) : Gross income, C (w) : Cost of production,
YG: Crop yield (kg/ ha), PG : Price of crop(Rials/kg), YS: straw yield (kg/ ha PS : Price of straw (Rials/kg), C1: Total fixed cost without cost of water and irrigation (Rials/ ha), Pw: Price of water and irrigation (Rials/ m3) and W: Amount of water and irrigation (m3/ ha).
Changes of incomes and changes of costs for every treatment in different crop managements were used as follows:
(2)
(3)
Where j and j+1 show existence and substitution crop managements.
In order to determine the price of irrigation water, total cost including pump and electromotor, semi deep well, power instrument, maps, pipe transport and implementation network, other primary cost and operation cost were used. The analysis period for the instruments (pump and electromotor, maps, implementation network) was 20 years and for the semi deep well was 30 years. In this study, total cost was referred to the present value with %15 discount rate by uniform series formulas. Then, the water was used in the farm. The price of water was determined. Capital recovery formula is as follows:
(4)
Where:
A: Annual value of primary investment costs, P: Primary investment costs for irrigation system, i: Discount rate and n: analysis period.
Results and Discussion: According to the results, the price of water and irrigation at the research region based on its components and under 15% and 25% interest rates were obtained to be 213 and 338.1 Rials per cubic meters, respectively. The barley grain yield and its net benefit under advanced management were more than that obtained under traditional management.
In traditional management, the mean barley grain yield for treatments including rainfed, Single irrigation (SI) - planting and SI spring were estimated to be 1572, 2487 and 2670 kgha-1, respectively. The mean profit for rainfed barley production for treatments including rainfed, SI-planting and SI spring were estimated to be 1270.2, 2314.2 and 2607 (Thousand Rial.ha-1), respectively. In advanced management, the mean barley grain yield for treatments including rainfed, Single irrigation (SI) -planting and SI spring were estimated to be 2270, 3444 and 2853 kgha-1, respectively. The mean profit for rainfed barley production for treatments including rainfed, SI-planting and SI spring were estimated to be 1987, 3465.4 and 2519.8 (Thousand Rial.ha-1), respectively. In the research site, the mean net benefit of rainfed barley under sowing and spring single irrigation and AM, increased by about 173% and 98.4%, respectively.
Conclusion: The results showed that the substitution of AM-SI planting treatment instead of other treatments was non-economical. On the other hand, in this substitution, decreasing of profit is more than decreasing of cost. Finally, at Honam site, recommended management include: AM + planting SI, AM + spring SI, and rainfed AM, respectively.
A.R. Tavakoli
Abstract
The main purpose of rainfed farming is increasing the water productivity by applying suitable agricultural management including single irrigation (SI) and panting time for wheat varieties. In order to study the SI optimization and determination its optimal program, a field experiment was conducted as ...
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The main purpose of rainfed farming is increasing the water productivity by applying suitable agricultural management including single irrigation (SI) and panting time for wheat varieties. In order to study the SI optimization and determination its optimal program, a field experiment was conducted as split-split plot based on a randomized complete block design with three replications for different wheat varieties at main station of Dryland Agricultural Research Institute (DARI), Maragheh, Iran, during two crop seasons of 2000-2004. The treatments included three panting time, three SI and five wheat varieties (V1=72YRRGP, V2=Fenkang 15/Sefid (seed white), V3=Turkey, 13//F9.10/Maya”S”, V4=Azar2, V5=double cross shahi). On based of water productivity indices, rain water productivity (RWP), irrigation water productivity (IWP), and total water productivity (TWP) optimal program of single irrigation scenarios was 100mm at early, 75mm at normal and 50mm at late sowing date. V3 wheat variety was better than other varieties. At this single irrigation program, maximum single irrigation water productivity (11.3 – 21.3 kg.mm-1) in producing grain yield and stabilized wheat production were obtained
H. Ramezani; B. Nazari; A.R. Tavakoli; M. Parsinejad
Abstract
Abstract:
Deficit irrigation technique can be used for produce more yield for every unit of irrigation water, and cause to increase crop economical benefit. Main purpose of deficit irrigation is high water use efficiency with decreasing in irrigation sufficiency. In this research potential of CROPWAT ...
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Abstract:
Deficit irrigation technique can be used for produce more yield for every unit of irrigation water, and cause to increase crop economical benefit. Main purpose of deficit irrigation is high water use efficiency with decreasing in irrigation sufficiency. In this research potential of CROPWAT model in deficit irrigation management for two crops, wheat and barley in Karaj climate was studied. The results of reliability index such as RMSE and CRM with about are 9.8-17.2 percent and 0.32-0.51 value respectively, showed that the model in both crops underestimated the yield reduction compared with actual data. Negative values of EF index achieved for both crops with 14 days irrigation interval show inefficiency of model in yield reduction predicting in this irrigation interval. This difference was more obvious in deficit irrigation treatments. Considering only drought stress and neglecting other stresses -such as salinity- is the most important limitation of CROPWAT model. Model crop coefficients could also caused differences between actual data and model results. This study shows that application of CROPWAT model without calibration of crop coefficients and soil characteristics would be result in significant errors and this is should be considered. In this study water use efficiency for studied crops were achieved in the range of 1.3-2.3 Kg/m3 and maximum values of that was in 20% deficit irrigation. Applying optimum deficit irrigation management could have considerable role in increasing water use efficiency.
Keywords: Water use efficiency, Yield reduction, Production function, CROPWAT