This experiment has been conducted at Mazandaran Agricultural Research center based in Gharakheil in Ghaemshahr in the crop year 1389 as complete blocks located in 4 replications. Sowing dates at 4 levels 24 July, 2, 12, 23 th August were the major factor and 3 corn hybrids pre maturing S.C540, mide maturing S.C647 & Late maturing S.C704 were the sub- factors. Maximum forage yield was obtained for sowing dates 24 July & 2 August to scales 43.3 & 41.82 ton/hec respectively and by delaying the plantation due to stem wet weight to scales 52.8%, corn until 39.1% leaves wet weight until 52.0% & corn diameter until 27.9% the yield of wet forage decreased to 47.2%. The corn length increased 12.7% due to delay cropping. Maximum wet forage yield was obtained for pre maturing hybrid 38.24 ton / h and the minimum was obtained for mid maturing hybrid with 31.41 ton/ h. The maximum Protein% of forage was obtained for sowing date of 2 th August with 6.762% and the minimum % for sowing date of 24 th July to scales 4.037%. The intraction effects of hybrid and sowing date just had significant effect on the corn Length & diameter. For summery sowing of Silo corn in gharakheil in ghaemshahr region, pre maturing hybrid S.C540 by sowing on 24 July is suggestioned.

While providing conditions for crop diversification and improving productivity of northern Iran’s paddy fields, subsurface drainage can be a threat to downstream water resources. This research was done to quantify the effects of two types of conventional water management in rice cultivation systems including midseason drainage and alternate irrigation and drainage as well as free drainage in canola growing season on salinity of subsurface drainage effluents. Required experiments were conducted on subsurface drained paddy fields during 4 rice growing seasons and two canola growing seasons (2011- 2015). Each type of management strategy was repeated twice during the study period. Measurements of water table depth and drain discharge were done during drainage periods of different growing seasons. Moreover, drainage water salinity was measured in due times. Alternate drainage and increase in water table depth raised drainage water salinity in rice and canola seasons, respectively.Compared with midseason drainage, alternate irrigation and drainage resulted in 121- 420 kg ha-1 increase in salt loss in different drainage systems. Salt discharge was considerably higher in canola season than rice season due to free drainage condition in canola seasons. Total salt load under midseason drainage, alternate irrigation and drainage and canola cropping through different drainage systems ranged, respectively, 78.4-365, 240- 695 and 3056- 5656 kg ha-1. Based on the results, water table management through installation of shallow- suitable spaced drains can be effective to decrease salt load from subsurface drained paddy fields.

Rotation can be used as an approach for weed management, because density and combination of weed seed bank may be affected by rotation. In this study effect of rotation in diversity and density of weed seed was studied in three rotation systems (fallow-barely, maize-barely and canola barely). Results showed that fallow-barely rotation system have high population density in seed bank and highest amount of Shannon diversity index (H=0.84).In canola- barely rotation system because of different herbicide uses and special traits of canola, population of weed seeds in seed bank was significantly lower that other rotation systems. Results showed that canola-barely rotation system because of combination special herbicide and agronomical and biological characteristic of canola, in comparison with other rotation systems is more successful in decreasing of weed seed bank.

IntroductionSoil protection against water and wind erosion is of great importance. Since most soils of arid and semi-arid regions of Iran are poor in organic matter and continuous use of conventional tillage (moldboard plow) has increased the severity of soil organic matter depletion and degradation of soil structure. Therefore replacing conventional tillage with conservation tillage (reduced tillage and no tillage) is needed to improve soil structure and increase soil organic matter. Due to the increasing population growth and the limitation of arable land, it is necessary to remove the fallow year in dryland. Legumes are crops that can be in rotation with wheat. Materials and MethodsThis study was conducted to evaluate the effect of crop rotation and different tillage systems on rain-fed wheat farming in Kaboudarahang Township during 2012-2014. The experiment was conducted as split-plot in a randomized complete block design with three replications. In this study, different crop rotations including fallow-wheat rotation, and chickpea-wheat rotation as main plots and different tillage systems including conventional tillage (moldboard plow + power harrow), conservation tillage (chisel plow equipped with roller), conservation tillage (sweep plow equipped with roller) and direct drilling were investigated as subplots.In the economic evaluation of this project, the economic impacts of the treatments were analyzed using the partial budgeting method and the cost-benefit ratio. For this purpose, the difference between treatments income and cost compared with control treatment has been calculated and compared. The differences in the benefits of the treatments are due to the different yields of wheat. Results and DiscussionResults showed:1- The highest wheat yield in the first and second years of the study was 605.3 and 2135.1 kg ha-1, respectively in rotation of fallow wheat.2- In the first year, the highest wheat yield (690.7 kg ha-1) was related to direct planting (no tillage), but in the second year, the highest yield (2268.6 kg ha-1) was related to conservation tillage (sweep blades + roller).3- In the first and second year, the highest value of treatment was related to direct planting and conservation tillage (sweep tiller + roller), respectively.4- In the chickpea-wheat rotation, the highest net income in the first and second year was related to direct planting and conservation tillage (sweep + roller), respectively. Thebenefit-cost ratio in the conservation tillage (sweep + roller) (second year) and direct drilling (first year) methods shows that for each rial of expenses, 5.7 and 2.8 rials can be earned respectively. Therefore, economically, these tillage treatments are superior to the control treatment (conventional cultivation).5- In the wheat rotation, the highest net income in the first and second year was related to direct planting and conservation tillage (sweep + roller), respectively. The benefit-cost ratio in the conservation tillage (sweep + roller) (second year) and direct drilling (first year) methods shows that for   each rial of expenses, 4.2 and 1.3 rials can be earned respectively. Therefore, it is economically justified and these tillage treatments are superior to the control treatment (conventional tillage).ConclusionThe results of this study showed that in the first and second years, economically the direct method and the conservation tillage treatment (sweep blades + roller) were superior to the conventional method, respectively. Therefore, conservation tillage methods can be replaced by the conventional method (plowing with moldboard plow) in dryland farming. Also, in dry years, direct cultivation (no tillage) is a good and economical method.

Introduction: Transient and persistence of weed seed banks impact on weed population dynamics. Therefore, any management tools with having a reducing role can affect weed population size. Reduction of weed seed rain using effective control tools can reduce weed density. The seed bank density is the main factor corresponding to seedling density. Decline of seed bank is critical to success in crop production, so that, poor performance in weed control only for a season cause to rain weed seeds and to improve soil seed bank. Most of the commonly used herbicides recommended for controlling weeds in wheat fields are not efficiently able to control the wild barley (Hordeum spontaneum C. Koch). Hence, utilizing appropriate agronomic strategies to control this weed is critical. Evaluation the effect of wild barley spike cut-off in the previous wheat field, and the effects of chickpea planting date and chemical weed control in chickpea cultivation in rotation on wild barley weed population in chickpea cultivation are among the aims of this study. Materials and Methods: The effect of wild barley spike cut-off in the previous wheat field, and sowing date and management strategies in chickpea on its population in chickpea for the following years was evaluated in Khorramabad, Lorestan, Iran during 2009-10 and 2010-11 growing seasons. The experiment was arranged in a factorial split plot in a completely randomized block design with three replications. The wild barley spike cut-off in wheat (at two levels: No cut-off and with cut-off) and chickpea planting date in the next season (at two levels: early planting and late planting) were assigned into the main plots. Chickpea weed management treatments (at five levels: pre emergence application of metribuzin at 0. 7 kg per hectare, pre emergence application of imazethapyr 0. 7 litter per hectare, post emergence application of Clethodim 1 liter per hectare, weed free treatment, and weedy infest)was assigned into the sub plots. Results and Discussion: Wild barley spike cut-off in previous wheat reduced 71% of the density and biomass of this weed in chickpea cultivation in the following years. This suggests the importance of recent year's wild barley seeding rain in the completion of the soil seed bank for the next season. Early planting of chickpea compared to late planting decreased the wild barley density by 75%. It was mainly related to the ineffectiveness of planting operations in full control of the large wild barley plants in the late planting treatment. Early planting of chickpea under wild barley weed spike cut-off in previous wheat crop condition, was completely free of wild barley. Accordingly, the prevention of wild barley seed rain and the completion of the soil seed bank in the previous year, along with the timely planting of chickpea led to full control of this weed. Triple interaction effects of experiment factors on wild barley biomass in chickpea was statistically significant. This suggests the difference of wild barley biomass response to weed management treatments in different planting date of chickpea in spike cut-off and without spike cut-off of wild barley in the previous wheat crop. In addition to manual weeding treatments in different conditions, all weed management practices, even uncontrolled weedy check, in early chickpea planting under spike cut-off of wild barley conditions in wheat cultivation in the previous year, did not emerged any wild barley seedling. This indicates the high efficiency of spike cut-off of wild barley in the previous year and the prevention of seeding and the timely planting of chickpeas in the management of this weed. Conclusion: Thus, it seems that the major part of the growing population of this weed is dependent on previous year seed rain. In the other words, the wild barley population dynamics is largely dependent on the temporary transient seed bank instead of a persistent seed bank. This suggests the possibility of managing problematic wild barley and reducing its population below the economic damage threshold through prevention of seed rain and soil seed bank management.

Background and objectives: Land suitability analysis is a valuable application of GIS for spatial design and management. Crop rotation as a critical agricultural management is a site-specific approach that farmers implement traditionally. However, suitability of lands for cultivation of two or more crops at different time must be determined scientifically. Kamkar et al., (2014) investigated the land suitability and possibility of canola-soybean rotation for four basins of Golestan province. Results showed that only 11. 82 percent of studied lands were suitable for implementation of canolasoybean rotation. Bidadi et al., (2015) studied the land suitability of Qaresoo basin in Golestan province for wheat cultivation. Results showed that wheat cultivation in studied area was categorized in four zone including very suitable, moderately suitable, poor and unsuitable. This research was conducted for agroecological zoning of Golestan province based on cultivation of wheat and soybean and for determining of suitable lands for implementation of wheat-soybean rotation. Materials and methods: Foraccomplishment of this research, ecological requirements of wheat and soybean were determined using scientific resources. Minimum, maximum and average temperatures, precipitation, electrical conductivity, pH, soil texture, slope, aspect and elevation were ecological factors for determination of wheat and soybean land suitability. IRS images for 2008 and Landsat five images for 2011 were used to prepare the land use map for wheat and soybean. Possibility of wheat-soybean rotation was evaluated by combination of the suitability maps of wheat and soybean crops. Results: Suitable arable lands of Golestan province for wheat were classified in four categories (suitable, moderately suitable, poor and unsuitable). Suitable class is 489538. 6 ha (67. 82% of total province arable lands) which is the highest proportion. For soybean cultivation, arable lands were also classified in four categories (suitable, moderately suitable poor and unsuitable). Suitable class for soybean cultivation is 362192. 3 ha (50. 17% of total province arable lands). Results showed that arable lands of Golestan province can be classified in 12 categories for performance of wheat-soybean rotation. Suitable-suitable wheat-soybean class with 358514. 1 ha (49. 74% of the lands) had the highest proportion. In the other hand, the unsuitable-moderately suitable and unsuitable-suitable classes of wheat-soybean rotation with 3. 52 and 11. 84 ha, respectively comprises less than 1% of the total land. Discussion: In general, wheat-soybean rotation is conducted extensively in Golestan province despite climatic and management limitations. It is clear that breeding of early maturing cultivars of wheat and soybean is one of the most crucial steps to improve the performance of this rotation. Results revealed that using GIS can be very useful and efficient an important tool for determination of ecological potentials of a crop.

Effect of wheat based crop rotations including wheat and corn, wheat and sunshade, wheat and onion and wheat and sorghum rotations on weed seed bank of wheat farms was investigated in around of research field of Islamic Azad university, Miyaneh branch. Soil samples were collected at 0-10 and 10-20 centimeter soil depth using Uger in September 2005. Experiment was carried out with five treatments as factorial in a completely randomized design with 25 replications and continuous cultivation of wheat was considered as control. Leaching with cloth bags method was used to study of seed weed bank in different treatments. In this research, 14314 weed seeds belonging to 35 species were collected and identified. The results of variance analysis revealed that Cyperus fuscus L. seeds in control and wheat and corn treatments, and Amaranthus retroflexus in wheat and sunshade, wheat and onion and wheat and sorghum rotations were more frequent. Seeds of A. blitoides, A. retroflexus, Avena fatua L., Fumaria spp. and Cuscuta spp. were also seen in all treatments. However A. retroflexus, C. fuscus, A.blitoides and Fumaria spp. were the most frequent of 21 common weeds of wheat farms, respectively. Seed production of Fumaria spp., Setaria verticillata, Schoenoplectus mucronatus L., C. fuscus, Hibiscus trionum L. and Portulaca oleracea L., in all rotation treatments was much less than control. However the mentioned treatments had not significant effect on seed numbers of some weeds such as A. blitoides, C. fuscus, Sorghum halopens and P. oleracea. In continuous cultivation of wheat (control), seeds of two mentioned Amaranthus species, S. halopens, Polygonum hyracanicum, P. paulum, S. verticillata, Hyosyamus spp. and Marribium vulgare L. were significantly less than those of wheat and sunshade treatment. Also seeds of Euphorbia spp., Cuscuta spp. and P. paulum, in comparison to wheat and onion, Sisymbrium loesselii L., in comparison to wheat and corn and Aleopecurus myosuroides Hudson, in comparison to wheat and sorghum treatments were significantly more than control. In the other word, some weeds were better controlled by continuous cultivation of wheat. Rotations of wheat and sorghum, wheat and onion and wheat and corn caused significant reduction in seed bank of 35 collected weed species. However, total numbers of collected weed seeds at two studied soil depths had no significant differences.