nitrogen fertilizer

In this research, the effects of combined application of biochar and nitrogen (N) fertilizer on some agronomical traits of rapeseed (Brassica napus L.), under water deficit stress conditions were studied in pot culture with a calcareous sandy loam soil.

Methods & Maerials: 

A factorial experiment was done in a completely randomized design with three replicates. The factors were organic matter at five levels (0, 0.75, and 1.5 g 100 g-1 from two sources  of biochar and wheat straw), N at two levels (150 and 300 mg kg-1 as urea), and moisture at two levels (without stress or optimum, 85–100 percent of field capacity, and stress, 50-60 percent of field capacity). Before the plants harvesting, leaf chlorophyll index, leaf water potential, stomatal conductance, and leaf area were measured. After the plant harvesting, water use efficiency, and some agronomical triats were determined.

Application of nitrogen and biochar significantly increased leaf chlorophyll index, leaf water potential, stomatal conductance, shoot dry matter weight, grain dry matter weight,  weight of one thousand seeds, water use efficiency and seed oil content. Wheat straw application decreased leaf chlorophyll index, number of leaves, relative water content, leaf water potential and leaf water use efficiency, but at the same time increased plant height, , stem diameter, stomatal conductance, shoot dry matter weight, , dry weight of seed, and thousand seed weight compared to the treatment without organic matter. Water defecit stress decreased the plant height, leaf number, stem diameter, stomatal conductance, relative water content, leaf water potential, pod number, fresh and dry weights of shoot, fresh and dry weights of root, fresh and dry weights of seed and weight of one thousand seed, except for water use efficiency and leaf chlorophyll index.

In this greenhouse study, B1.5 N150 FC0.5 treatment reduced nitrogen use compared to the same treatment with 300 mg N.kg-1 soil (B1.5 N300 FC0.5) without significant yield loss. The application of organic matter including wheat straw and biochar at both levels of 0.75% and 1.5% caused a significant increase in most of the agronomical traits of rapeseed plants, especially the seed oil content in a calcareous soil, and of course, future research in the field is recommended.

This study was performed to investigate the effect of nitrogen fertilizer levels and pre-planting of cover crops on some vegetative traits and yield of rice plants.

This was conducted over 2017-2018 and 2018-2019, at the research farm of Sari University of Agricultural Sciences and Natural Resources. The experimental design employed a three-replicated split-plot arrangement within a randomized complete block design. The main plots involved five nitrogen consumption levels (0, 120, 240, 320, and 400 kg ha-1). The sub-plots included four types of pre-planted cover crops (no cover crop, canola, bersim clover, and rye).

Based on the findings, employing berseem clover as a cover crop in pre-sowing resulted in a significantly more favorable rice yield than others. Nitrogen fertilizer at rates of 320- 400 kg ha-1 led to enhanced vegetative traits, yield, and various yield components, including leaf area index and tiller number, ultimately resulting in increased overall yield. Results revealed that planting bersim clover cover crop before planting rice, along with 320 kg ha-1 of urea fertilizer, leads to 41.5% higher yield compared to no fertilizer).).

Bersim clover stood out among the pre-planting cover crops, significantly enhancing many rice traits. Additionally, no significant difference was observed between urea fertilizer levels of 320 and 400 kg ha-1 in several measured traits. Thus, the integrated treatment of bersim clover cover crop and 320 kg ha-1 of urea fertilizer is recommended before planting rice.

This experiment was carried out in 2018 in the Lundville region of Astara for rice crop rotation, different amounts of nitrogen and potassium fertilizers, and varieties and dates of clover planting in the Gilan region. The experiment was evaluated in the form of s split-split plot with a completely randomized block design in three replications. The main factor includes nitrogen fertilizer with potassium at three levels (50, 100, and 150 kg per hectare) and the spreading of clovers in three different stages of rice growth, including after flowering, before harvest, and after harvest as split plot and secondary factors.

The results obtained from the variance analysis of the data showed that different levels of nitrogen and potassium fertilizers, distribution of clovers in different stages of rice growth, and clover cultivars on the height period, yield indices, and harvest index were significant in rice plants. Based on the results of comparing the average effects of treatments, it was observed that the highest yield of paddy per hectare was obtained under the conditions of application of 100 kg/hectare of fertilizer in the stage of spreading clovers after rice harvesting and from Iranian clover variety.

The use of nitrogen and potassium fertilizers along with crop rotation of rice and clover due to nitrogen stabilization and improvement of the soil substrate increased the height of the plant, increased the number of claws, spike length, the weight of 1000 seeds, and finally increased the yield of the rice plant.

This study was performed to investigate some quantitative characteristics and quality of hyssop under heat stress and nitrogen fertilizer.

The experiment was conducted as a split-plot in a completely randomized block design with six planting dates and three replications in 2017-2018. The main factor was different levels of nitrogen fertilizer: 0, 50, 100 and 150 kg.ha-1 and sub-factor was planting dates between 30-day periods from October 17 to March 25.

Increasing nitrogen fertilizer at the level of 150 kg/ha resulted in the increase of 18.1%, 39.5%, 20.1%, 43.3% and 47.2% in flowering top-branch length, flowering top-branch weight, plant height, biomass yield and total essential oil yield, respectively, compared to not consumption. The highest yield of total essential oil (36051 g.ha-1) was obtained in T1N4, which was 89.7% higher than T4N1. Increasing ambient temperature in the range of 25–40 °C linearly led to decline of top-branch length, top-branch weight and biomass decreased but decreased essential oil yield in the above temperature range was fitted as a quadratic function (R2 = 0.86). Heat stress on delayed sowing dates T3, T4, T5 and T6 reduced the essential oil yield compared to the sowing date T1 by 30.5%, 70.3%, 66.4% and 39.3%, respectively.

The application of nitrogen fertilizer increased the studied traits. To reduce the effect of heat stress and achieve optimal yield, are recommended the hyssop planted from 25 October to 25 November and are used 150 kg.ha-1 of nitrogen fertilizer in the subtropical region of Jiroft.

CO2 is considered the most important greenhouse gas, due to the dependence of world economies on fossil fuels. CO2 concentration are enhancing in the last decades, mainly due to the increase of anthropogenic emissions. Carbon dioxide capture is a technology aimed at mitigating greenhouse gas emissions from burning fossil fuels during industrial processes. Conservation tillage, crop rotation, and crop residue management are agronomic practices that potentially decrease CO2 and other greenhouse gas emissions from agriculture. Crop residues also improve organic matter decomposition due to declined soil-residue contact. Soil is one of the significant “friends” in combating climate change and global warming, and a zero-soil consumption approach is the best way to stop adverse effects, although it is not the only one that should be applied. The soil has been considered as a possible carbon sink for sequestering atmospheric CO2.
Our purposes were to determine a set of coefficients for calculating conversion coefficients, dry weight, organic carbon, and carbon sequestration of above-ground and below-ground tissues and assess global warming potential (GWP) for wheat as an essential crop in Khorasan-e Razavi province.

A systematic random sampling method was employed to select five samples from 25 fields situated in Khorasan-Razavi Province, Iran, during 2016 and 2017. The experimental design was a completely randomized design with three replications. Below-ground tissues by using a cylinder were manually sampled and then separated from the soil. After sampling, the above-ground tissues (such as flower and leaf) were isolated from below-ground tissues (including tunic and corm) to measure the above-ground and below-ground biomasses, respectively. Above-ground and below-ground biomasses were separately dried to constant weight and expressed on a dry matter basis. Conversion coefficients of above- ground and below- ground tissues were determined with the combustion method separately. Then, sequestration carbon potential for above- ground and below- ground tissues of saffron and soil were computed. The ash method was used to determine the conversion coefficients in spikes, stems, leaves, and roots. Finally, greenhouse gases (such as CO2, N2O, and CH4) emission were also calculated using emission coefficients. Cronbach's alpha was used for assessing the reliability of the questionnaire.
For statistical analysis, analysis of variance and Duncan’s test were performed using SAS version 9.3.

The results showed that dry weight, organic carbon content, conversion coefficients, and carbon sequestration for above- ground and below- ground tissues of wheat were significantly different. The biomass of above-ground tissues was higher than below-ground tissues of wheat. The results revealed that the maximum (52.0%) and minimum (31.99%) conversion coefficients of wheat were related to spikes (seeds included) and roots, respectively. Besides, the total carbon sequestration of below-ground and above-ground of wheat was calculated 8.25 t.ha-1 so that the maximum (4.28 t.ha-1) and minimum (0.35 t.ha-1) values were found in stems and roots, respectively. GWP was recorded as 8884.86 kg CO2-equiv. per one ton of seed.

This study shows that while there is significant potential for sequestering carbon in wheat agroecosystems through root and straw incorporations. It is recommended that returning wheat crop residues to the soil affected the soil's physical, chemical, and biological properties. Furthermore, as nitrogenous fertilizer application plays a crucial role in increasing GWP, thus it is suggested that organic fertilizers and legumes might be suitable alternatives for chemical fertilizers. It is therefore concluded that the application of crop residues in agroecosystems seems to be a rational ecological approach for sustainable management of wheat agroecosystems with a consequence of the reduction in greenhouse gases and mitigation of climate change. This could make a significant contribution to improving agricultural sustainability and stability in arid and semiarid regions.

The competitive ability of weed is one of the key elements in describing the interactions of crops with weeds and predicting crop yield loss in sustainable agricultural systems. The aim of this study was to quantify the interactve effects of nitrogen fertilizer and reduced dose of bromoxynil+2,4-D on the competition of wheat–mallow.

An experiment was conducted in the research field of Agricultural Sciences and Natural Resources University of Khuzestan during 2016-2017 growing season. Experimental design was split block based on completely randomized block design with three replications. Experimental factors consisted of nitrogen level (0, 75, 150, 225 and 300 kg.ha -1  of urea fertilizer) as main plot and reduced dose of bromoxynil+2,4-D (0, 0.25, 0.5, 0.75 and 1 time of recommended dose (1.5 L.ha -)) as sub plots.

Results showed that wheat biomass was the most in case of applying more doses of herbicide plus nitrogen fertilizer. However, it was the least without herbicide and fertilizer application. Nitrogen fertilizer (130 Kg.ha -1 )+recommended dose of herbicide (1.5 L.ha -1 ) or 220 Kg.ha -1 nitrogen fertilizer+50% recommended dose of herbicide and/or 300 Kg.ha -1 nitrogen fertilizer+55% recommended dose of herbicide can be used to achieve wheat biomass about 600 (g m -2 ). Mallow biomass was greatest without herbicide application and use of 300 kg ha -1 of urea fertilizer. Competitive ability of mallow (μ) increased with increasing nitrogen fertilizer use and reached maximum with applying of 150 (kg h -1 of urea), but the use of more than this, reduced the competitive ability of mallow.

In this study, wheat biomass was significantly reduced in competition with mallow, which was significantly higher in non-herbicide treatment than other treatments. Therefore, increasing urea consumption without mallow control will significantly reduce wheat biomass.

This study was conducted to investigate the effect of water (irrigation with ordinary water and magnetic water) and fertilizer treatments on cumin growth and yield by split plot experiment based on randomized complete block design in three replications at the Research Farm of Tabriz Branch Islamic Azad University, Tabriz, Iran, in 2018. Treatments included control without fertilizer, application of nitrogen fertilizer, application of Penergetic fertilizer P, K and application of nitrogen fertilizer with 50% dose with use of Penergetic P, K. Results showed that, the highest grain yield (164 g.m-2) was obtained in nitrogen fertilizer application and application of chemical fertilizer and Penergetic P, K under magnetic irrigation conditions. This treatments increased grain yield in comparison with control (42.6%). Biological yield also showed a similar response to the application of magnetic irrigation and fertilizer treatments. Based on the results of two treatments, application of nitrogen fertilizer alone and nitrogen fertilizer with Penergetic P, K produced a significant increase in essential oil percentage, but the highest essential oil yield was obtained from application of chemical fertilizer (3.13 g.m-2) however, application of Penergetic fertilizer caused a significant increase in the percentage and essential oil yield, although less than the increase caused by nitrogen fertilizer. In general, with respect to economic performance, using Penergetic, the level of nitrogen fertilizer can be reduced without any significant reduction in grain yield. On the other hand, magnetic irrigation has an important role in increasing the effect of application of fertilizers on grain yield.

In order to study of the effects of nitrogen and zinc sulfate fertilizer on yield and yield components of  forage sorghum (var. Pegah), a factorial experiment was conducted based on randomized complete block design with three replications on farm of agricultural jihad Qasr Shirin, Kermanshah Province. The treatments were included four levels of nitrogen fertilizer (0, 125, 250 and 375 kg.ha-1) by urea and three levels of zinc sulfate (0, 40 and 80 kg.ha-1). The results showed that the effect of nitrogen fertilizer and zinc sulfate was significant on the content of photosynthetic pigments, Cu concentration, plant height and dry forage yield. The effect of nitrogen fertilizer was significant on the concentration of Fe and Mg, nitrogen content of plant, the number of tiller and fresh forage yield. According to the results this study, it be suggested that  nitrogen and zinc sulfate fertilizer be appliedas 375 and 80 kg.ha-1, respectively.

In order to study of some flax characteristics under nitrogen and organic fertilizer, a field experiment was conducted in experimental farm of Agricultural Faculty of Shahid Chamran University of Ahvaz at 2015-2016 growing season. Experimental design was randomized complete block as factorial arrangement with three replications. The first factor was different nitrogen fertilizer sources, control (no nitrogen fertilizer), 150kg.ha-1 urea, 75 kg.ha-1 urea+Nitrocara biological fertilizer and 100 kg.ha-1 Slow Released Urea). The second factor was different organic fertilizer sources as control (no organic fertilizer application), 5 tones.ha-1 vermicompost, 2.5 tones vermicompost+ humic acid and humic acid). The results showed the highest crop growth rate (CGR)(2.28 g.m-2.day-1) and leaf area index(LAI) (4.35) in nitrogen treatments were related to 150 kg.ha-1 urea fertilizer and in organic fertilizer treatment, the highest CGR(22.8 g.m-2.day-1) and LAI (4.15) were conducted at 2.5 tones/ha vermicompst+humic acid treatments on GDD=737 at capsuling phonological stage. The highest relative growth rate (RGR) were obtained at urea fertilizer (0.09) and humic acid (0.02) at GDD=527 (flowering stage). The highest grain yield (2706.67 kg) was obtained at vermicompost(2.5 tons.ha-1)+ humic acid +urea fertilizer. The results of this study indicated that application of organic and biological fertilizers alone or in combination with chemical fertilizers have a positive effect on improving the quality and quantity of flaxen. In this experiment, application of organic fertilizers showed good effect than nitrogen fertilizer and it was significantly more than control treatment.

Removing the yield gap (the difference between farmed yield and potential yield) is known as the most important way to increase crop production (Egli and Hatfield, 2014). Therefore, the amount of yield gap and the reasons for it are important. Soybeans [Glycine max (L.) Merrill] are one of the most important oilseed crops in the world (FAOSTAT, 2016). In Iran, the area of soybean cultivation is up to 66,000 hectares and annual production is 151,000 tons (Ministry of Agriculture Jihad, 2013). This does not meet domestic requirements, however, so soybean production should be increased. For this purpose, a field study was conducted in 138 farms using an application of regression modeling in 2013-15 in cities of Gorgan and Aliabad Katul.
Farms were selected with the help of agricultural service centers. Based on information provided by the service centers, farms were selected based on their diversity in terms of area under cultivation, management and yield. Management factors included a history of production, planting methods, inoculated or non-inoculated seed with bacteria, seed rate, nitrogen fertilizer (N) rate, phosphorus fertilizer (P2O5) rate, potash fertilizer rate, the number of plowings, planting date, cultivar type, previous crop, use or non-use of N fertilizer top-dressing, number of N fertilizer top-dressing, use or non-use of herbicides, use or non-use of pesticides, animal manure type, irrigation type and amount, harvest methods, and others (a total of 67 management factors). All information about management operations were recorded and measured. Then, the relationship between actual yield and the 67 management variables were assessed using stepwise regression.
The average yield for farms was 2,908 kg per hectare and the maximum yield was 5,100 kg per hectare. Model Root Mean Square Error (RMSE) was 274 kg per hectare and coefficient of variation (CV) was 9 percent. These statistics showed that the accuracy of the model was acceptable. Therefore, the model could be used to determine the yield gap and the share of yield constraints. Model yield, on average, was estimated at 2,918 kg per hectare and maximum yield was 4,820 kg per hectare. In this model, total yield gap has been estimated at 1,902 kg per hectare. Accordingly, the most important factors in yield gap for the region included: number of irrigations with 29% (equivalent to 535 kg per hectare), net nitrogen with 22% (equivalent to 419 kg per hectare), P2O5 with 20% (equivalent to 365 kg per hectare), planting date with 16% (equivalent to 302 kg per hectare) and disk number with 13% (equivalent to 250 kg per hectare).
With optimized items listed, soybean yield could be increased approximately 1,871 kg per hectare in Gorgan and Aliabad Katul. Use of this method isn’t suitable for determining optimum values. In order to determine optimum values for each listed item, other methods can be used for yield gap analysis, such as a boundary line analysis.

In sustainable agriculture، using green manure as an alternative for chemical fertilizers has a high importance. To investigate the response of some corn (Zea mays L.) growth indices to green manure and nitrogen fertilizer an experiment was carried out at the Research Farm of Agricultural and Natural Resources Faculty، Razi University during the 90-91 growing season. The experiment was split plot based on a randomized complete block design with three replications. The main factor was green manure and its incorporation time including rye incorporated in March، rye incorporated in April، common vetch incorporated in March، common vetch incorporated in April، mixed (rye + commom vetch) incorporated in March، mixed incorporated in April and control (no green manure). The sub factor was nitrogen fertilizer as urea with three levels including 0 (no fertilizer)، 200 kg. ha-1 (the 50% of the recommended amount) and 400 kg. ha-1 (the 100% of the recommended amount). Results indicated that the highest corn leaf area index، crop growth rate and grain yield were obtained in common vetch treatment incorporated in April and the lowest ones were recorded in control treatment (without green manure). Moreover، common vetch in both incorporation times led to the highest specific leaf area. However، corn relative growth rate، net assimilation rate and leaf area ratio were not significantly influenced by green manure treatments. Among the nitrogen treatments، the 100% of the recommended dose showed the highest values of the traits under study and unfertilized treatment showed the lowest ones.

In order to study of effects of nitrogen fertilizer and seed inoculation with plant growth promoting rhizobacteria (PGPR) on yield، fertilizer use efficiency، rate and effective grain filling period of soybean (Glycine max L.)، a factorial experiment was conducted based on randomized complete block design with three replications in 25 km Gorgan at Golestan province in 2011. Factors were different rates of nitrogen fertilizer in four levels (without nitrogen and application 25، 50 and 75 kg urea/ha) and seed inoculation with plant growth promoting rhizobacteria in five levels (without inoculation، seed inoculation with Pseudomonas putida strain 41، Pseudomonas putida strain 186، Azotobacter chroococoum strain 5 and Bradyrhizobium japonicum). The results showed that nitrogen fertilizer rates and seed inoculation with PGPR had significantly effects on grain yield، grain 100 weight، number of seeds per plant، plant height and all of grain filling parameters. Maximum of grain yield and grain filling period were obtained in application of 75 kg urea/ha × seed inoculation with Bradyrhizobium japonicum. Seed inoculation with plant growth promoting rhizobacteria and Bradyrhizobium japonicum increased nitrogen use efficiency compared to no seed inoculation. Of course، the highest nitrogen use efficiency belonged to seed inoculation with Brady rhizobium japonicum. Means comparison showed that maximum of nitrogen use efficiency was obtained in application of 25 kg urea/ha×seed inoculation with Bradyrhizobium japonicum and minimum of it was obtained in application of 75 kg urea /ha × no seed inoculation. It seems that in order to increasing of grain yield and the other traits (except nitrogen use efficiency) can be suggested that be applied seed inoculation with Bradyrhizobium japonicum × application of 75 kg urea /ha in second cropping of soybean.