مجله پژوهش آب در کشاورزی
سال سی و پنجم شماره 4 (زمستان 1400)

Pulses have a special position, after wheat and rice, in the Iranian people diet. The growth of these plants is very fast and water stress has an important effect on their yield. The objective of this study was to evaluate the DSSAT Model in simulating the growth and yield of cowpea under different levels of irrigation water. An experiment was conducted as a randomized complete block design (RCBD) with three replications in Kiashahr City, Iran, in the crop seasons of 2017 and 2018. The main treatments included irrigation with management of 40%, 60%, 80%, 100%, and 120% of plant water requirement and the three sub-treatments included irrigation at vegetative or reproductive stages, and full irrigation. In this experiment, the DSSAT simulation model was used to evaluate water efficiency and water balance components. Evaluation of simulated and measured values of grain yield was performed using the parameters of coefficient of determination, t-test, root mean square error (RMSE) and root mean square normalized error (nRMSE). The results showed that the difference between the predicted grain yield and the observed values was acceptable (RMSE=92 and nRMSE = 12.62%). Total biomass was also well simulated (RMSE=130 and nRMSE = 5.91%). Using the measured grain yield and water balance components simulated from the DSSAT model, the water productivity based on evapotranspiration (WPET) was about 33% lower than that based on transpiration (WPT). According to the results, irrigation with 100% water requirement at both vegetative and reproductive stages resulted in the highest transpiration (383mm), and was selected as the optimum irrigation management during the growing season.

Energy efficiency is one of the most important factors for sustainable agriculture. This study explored the energy consumption and global warming potential for puddled transplanted (PTR), un-puddled transplanted, and direct-seeded rice (Oryza sativa L.) (DSR) production systems under sprinkler, flood, and drip irrigation systems in Gorgan City fields, Golestan Province, Iran. According to the results, the average energy input and output for different irrigation systems in puddled transplanted treatment was higher than the other treatments, while the highest input and output energy was related to drip irrigation system (36366 and 249971 MJ.h-1). The highest energy consumption in different irrigation and cultivation systems was related to water and nitrogen fertilizer. The results also showed that energy use efficiency for different systems ranged from 5.05 to 7.35 kg.MJ-1. Energy use efficiency for pressurized irrigation systems was higher in puddled transplanted treatment and for flood irrigation systems was higher in un-puddled transplanted treatment. Also, the energy productivities of different treatments were between 0.1 to 0.24 kg.MJ-1, while the mean energy efficiencies of PTR and un-puddled transplanted treatments did not differ significantly and were more than DSR treatment. The specific energy and net energy for different treatments ranged from 4.29 to 10.2 MJkg-1 and 112784 to 213825 MJ.ha-1, respectively. The puddled transplanted treatment had the highest GWP for all irrigation systems. The largest share of GWP in rice cultivation was related to the use of nitrogen fertilizers, fuels, and machinery. The results of mean comparison of GWP per unit area, weight, input energy, and output energy showed that modern pressurized irrigation systems with un-puddled transplanted cultivation method (due to less input and a yield similar to PTR) can be a suitable method for rice cultivation to reduce energy consumption and global warming potential.

The use of organic waste in the form of biochar in order to ameliorate soil is a novel approach in the management of organic waste. In previous studies, researchers mostly focused on the amount of biochar that was added to the soil. However, the aim of this study was to investigate the characteristics of biochars prepared from different feedstock (wheat straw, vermicompost and apricot firewood) and the interaction effects of amounts and particle sizes of biochars on yield and water use efficiency (WUE) of winter wheat. In a factorial experiment with a randomized complete block design with three replications, the effects of these three biochars in the amount of 0.5% (R1), 1.5% (R2) and 3% (R3) with a particle size of ≤0.5 (S1), 0.5-1 (S2) and 1-2 (S3) mm were evaluated in two consecutive cropping years. The studied biochar were added to the soil only in the first year to a depth of 0-15 cm. A control plot was considered in each replication. The interactions of experimental factors (except interaction effect of year and biochar amount) on yield and WUE were significant. Comparison of average yield and WUE in each type of biochar showed that, in the first and second year, wheat straw biochar treatment of R3 S2 had the highest yield (5,200 kg ha-1 and 6664.3 kg ha-1, respectively) and WUE (1.6 kg m-3 and 2.1 kg m-3, respectively). In the first year, in vermicompost biochar treatments, the highest yield (4517.7 kg ha-1) and WUE (1.4 kg m-3) were observed in the R2 S3. In the same year, in apricot wood biochar, treatment R3 S3 had the highest yield (3871.7 kg ha-1) and WUE (1.2 kg m-3). In the second year, in vermicompost treatments, the highest yield (6615.7 kg ha-1) and WUE (2.04 kg m-3)  was observed in the R3 S2 and, in the same year, in apricot wood biochar treatments, the highest yield (5263.7 kg ha-1) and WUE (1.6 kg m-3) was observed in the R2 S3. The highest yield and WUE (in the two years) was observed in wheat straw biochar with the R3 S2. These results showed that in addition to the type of biochar, the interaction of the amount and size of biochar particles had a decisive effect on increasing the yield and water use efficiency of wheat.

The crisis of water scarcity is the main reason for the reduction of crops and the lack of human food needs in the countries located in arid and semi-arid regions. One of the methods used to increase the yield and water productivity is the use of low irrigation and magnetized water technology. The purpose of this study was to investigate the effect of regulated deficit irrigation with magnetized water on quantitative and qualitative characteristics of pea (Pisum sativum L.). The present research was performed on a farm located in Aghuzbon Village, Mazandaran Province, Iran. The experiment was performed as a factorial experiment in a randomized complete block design with three replications. The control treatment included full irrigation (FI) at all stages of the plant growth with normal water (non-magnetized). The main factor included non-magnetized water (W1) and magnetized water (W2), and the sub-factor included irrigation levels (I1=100%, I2=80%, and I3= 60% of crop water requirement). For irrigation, the trickle irrigation system with tape pipes was used. The results showed that the effect of irrigation water type and irrigation level as well as their interaction on parameters of pod per plant, seed per pod, grain yield, and water use efficiency were significant (p<1%). The highest pods per plant, seed per pod and grain yield in W2I1 treatment were 13.2, 7.5, and 8.472 t. ha-1, respectively, and the highest water use efficiency was observed in the W2I3 as 3.7 kg.m-3. On average, irrigation with the magnetized water increased grain yield and water productivity by 8.6% and 8.7%, respectively, compared to the non-magnetized water treatment. Also, the effect of type of irrigation water and irrigation level on oil, oil yield, protein, protein yield and germination time had a significant effect at 1% probability level, but had no significant effect on the ripening time. Also, 20% increase in irrigation level from I3 to I2 and from I2 to I1 in non-magnetized water treatment caused increase of the grain yield by 14.5% and 18%, respectively, while in magnetized water treatment, yield increased by 14.2% and 13.6%, respectively. The fastest germination time was related to W2I2 with 10.3 days after planting. In general, it can be concluded that irrigation with magnetized water can be a good way to increase yield, improve quality characteristics, and increase water use efficiency of green pea plant.

Due to the importance of rice cultivation, especially in Mazandaran Province, it is necessary to plan carefully for the optimal use of water resources in the province in the agricultural sector, especially rice, to reduce water demand for rice production. For this purpose, an experiment was conducted in the form of a complete block-design with three replications and four treatments using Tarom Hashemi cultivar, during the 2021 crop year in the Rice Research Institute of Iran-Amol. Treatments included conventional planting with flood irrigation (T1) and drip irrigation (T2), transplanting in un-puddled bed with drip irrigation (T3) and direct seed cultivation in dry bed with drip irrigation (T4). The results showed that the cultivation method was effective on yield, plant height, water consumption and irrigation water, water productivity and water use efficiency and was statistically significant at 1% and 5% level of probablity. The highest and lowest yields belonged to T1 and T4 treatments with 4079 and 2876 kg/ha, respectively, and T2 had the highest water productivity with 0.61 kg/m3, which had no significant difference with T1. The lowest water productivity belonged to T4 with 0.45 kg/m3. The highest and lowest irrigation water productivity belonged to T2 and T1 with 0.67 and 0.52 kg/m3, respectively Based on the results, conventional planting with drip irrigation did not have a significant reduction in yield compared to conventional planting with flood irrigation and increased water productivity by saving water consumption Therefore, the conventional planting method with drip irrigation was recognized as the best treatment in this study.

This quantitative research was carried out with the aim of identifying the driving and deterrent factors in the formation, activity, and development of Khuzestan Province's water users’ associations of irrigation networks. The research method was survey and descriptive-correlational. The statistical population of this study consisted of all experts of the exploitation companies of Khuzestan Province Water and Electricity Organization (N = 200), 130 of them (n = 130) were selected by stratified random sampling. The research instrument was a researcher-made questionnaire whose validity and reliability were confirmed by agricultural extension and training specialists of Agricultural Sciences and Natural Resources University of Khuzestan and the use of Cronbach Alpha test. Data were analyzed using SPSS16 software. The results of factor analysis indicated that the driving factors of water organizations were in 5 groups of production, social capital, legal, economic and executive, which in general explain 68.6% of the total variance. The results of factor analysis indicate that the driving factors of water users’ associations included 5 groups of production, social capital, legal, economic, and executive factors, which, in general, explain 68.64% of the total variance. In the factor analysis, the deterrents of water users' associations were identified as 5 groups including supportive, legal, managerial, extra-organizational and extension factors, which explain 47.29% of the total variance. According to the findings, the share of the promoters and driving factors in the activities and development of water users’ associations in Khuzestan Province is more than the deterrent factors.

Wheat is considered a strategic crop in the country and even in the world. It covers a large area under cultivation (approximately 50% of the country's irrigated lands).The main objective of this study was to review and analyze wheat WP in Iran and compare it with data of some other world countries. For this purpose, national and international scientific references were collected and reviewed, and the reported values for wheat WP (at the national, basin, and provincial scales) were arranged, calculated, and summarized, and necessary analyses and some conclusions were derived. According to the results, the range of wheat WP values in Iran and the world is very wide (0.25-2.2 and 0.3-3.9 kg/m3, respectively), depending on the geographical areas, water and soil conditions, different irrigation systems, climate, etc. The country's wheat WP (on a national scale) is estimated at 0.87 kg/m3, which is in the middle range compared to world. However, based on the reported wheat WP at the provincial level, the average wheat WP in the country is equal to 0.75 kg/m3, which is again in the (lower) middle range in comparison with the global values. Comparison of  WP mean value at provincial level (0.75 kg/m3) with the average WP of 10 major wheat producing countries (0.93 kg/m3), indicated that the country's wheat WP is about 25% lower than the average of these countries. Moreover, the Iranian national wheat WP and the global scale average of this index is about 0.93 and 1.1 kg/m3, respectively. Therefore, the value of the country's wheat WP is not very low compared to the global average, and there is a relatively small gap (just 22%) with the global average. However, it is far from the values of the leading wheat producing countries (1.4 kg/m3), such as most Western European countries, South Africa, and Egypt in the Middle East, with a relatively large distance (50% lower). In conclusion, the range of wheat’s WP are very wide in different provinces and regions of the country, therefore there are many opportunities to increase it event up to twofold. This target could be achieved in the country in the medium term with the necessary investments and planning.