نشریه پژوهشهای خاک (علوم خاک و آب)
سال سی و ششم شماره 2 (تابستان 1401)

In order to investigate the effect of seed inoculation with Azotobacter and, urea and manure on yield and protein content of rainfed wheat, an experiment was carried out with two levels of manure including M0 (without manure) and M15 (15 ton per hectare) and ten fertilizer treatments with different application methods of urea and seed inoculation with Azotobacter. Experimental treatments on Azar2 variety included T1=Check (without application of urea), T2=Total of urea in autumn, T3=Total of urea in spring, T4=Half of urea in autumn + Half of urea in spring, T5=Half of urea in autumn + spraying of urea in spring, T6=Inoculation of seed with Azotobacter, T7=(T2+T6), T8=(T3+T6), T9=(T4 +T6), T10= (T5+T6) as subplots. The experiment was carried out with three replications in fallow-wheat rotation as split-plot in a randomized complete block design at Ghamloo Research Station. Results showed that the effect of manure on biological yield, grain yield, and thousand kernel weight (TKW) was significant at 1%, 1%, and 5% probability levels, respectively. The effects of urea treatments on biological yield, grain yield, and TKW were all significant at 1% probability levels. Interaction effects of manure and fertilizer treatments on biological yield, grain yield, and TKW were not significant. Mean comparison of different traits on Duncan multiple range tests, indicated that grain yield of T4, T8, T3, T2, T5, T9, T7, and T10 compared with check increased significantly (p<0.05) as 845, 833, 759, 755, 678, 657, 670 and 622 kg. ha-1, respectively, and all were in one statistical group. T6 did not differ relative to the check. Interaction effects of manure and fertilizer treatments on grain protein content were significant (p<0.05). Mean comparison of the main effect of different fertilizer treatments were indicated that except for treatment 6, other treatments compare with check were increased grain protein content but this increase was significant (p<0.05) only for T8. Generally, result indicated that for rainfed wheat, the best application time of total urea was in autumn; and in the conditions of using half of urea in autumn, foliar application of urea (5%) in spring (tillering stage) as a plant nitrogen supplement can be recommended.

Land suitability studies of Iran have been scattered and few of them have investigated specifically land suitability for agriculture. Indeed, most of the studies have been conducted locally and, so far, comprehensive studies have not been done at the country level. Determining the suitability of Iran’s agricultural lands for production of crops is one of the most important tools for the optimal use of soil resources. For this purpose, by consolidating, preparing and digitizing soil survey and classification studies in the country and according to satellite images and land use maps and considering agro-climatic zones, soil units were identified to determine the potential of land for irrigated wheat in the irrigated plains of the country. Then, by entering the climate, soil and topographic data in the prepared software based on the FAO approach and parametric square root method, the suitability of all soil units was assessed for irrigated wheat. The results show that, in the irrigated plains, 1.4 Mha of land is in S1 class, 2.08 M ha are in S2 class, 1.4 Mha in S3 class, and 524 thousand ha have currently unsuitable class (N1), with 503 thousand ha being permanently unsuitable (N2). Statistical analysis of the data showed that the separation of land suitability classes has acceptable accuracy. The main limiting characteristics of lands are the soil physical properties including texture, salinity and alkalinity, slope, drainage, and in some areas, climatic characteristics. Due to the comprehensive map of land suitability and differentiation of suitable lands from the unsuitable ones, application of the results obtained with ideal management and usage of irrigated lands in the country will lead to the conservation of land resources, especially soil and sustainable production. Notably, the above results are the basic information layer that along with other aspects including economic issues are needed for developing  a suitable cropping pattern.

In order to determine the efficiency of different safflower (Carthamus tinctorius L.) cultivars in terms of their uptake and response to phosphorus fertilizer application, a 2-year (2016-2018) experiment was conducted in a randomized complete block design as 2 x 5 factorial with three replications at the Arak Agricultural Research Center Station. Treatments included two cultivars of Sina and Padideh and five levels of phosphorus (0, 25, 50, 75 and 100 kg.ha-1) as triple superphosphate. The results of analysis of variance showed that grain yield, number of bolls, 1000-seed weight, phosphorus, nitrogen, and potassium uptake, and total phosphorus yield were affected by the effect of cultivar and phosphorus levels. Apart from the total dry matter weight and phosphorus concentration, other studied characteristics were affected by the year. Plant height and nitrogen concentration were affected only by cultivar, while total dry matter weight and phosphorus concentration were affected by phosphorus levels. Comparison of the mean effect of phosphorus levels on grain yield showed that the maximum grain yield in both cultivars was obtained in treatment of 25 kg P/ha. In terms of total phosphorus efficiency, the level of 50 and in terms of phosphorus grain uptake efficiency and phosphorus-stress factor the level of 25 kg P/ha were optimal. Phosphorus efficiency indices did not differ significantly between the two cultivars, but Sina cultivar showed higher phosphorus uptake than Padideh.

The purpose of this study was to use some plant growth biostimulants to improve canola yield in calcareous saline conditions. Therefore, a two-year experiment was conducted in Qomroud section of Qom Province during two cropping years of 2018-20 in a soil with salinity of about 13 and 10 dS.m-1, respectively, and irrigation water of 7.5-8 dS.m-1. The study was carried out in field conditions with uniform and flat soil using a randomized complete blocks design, in three replications. Seeds of Hayola-50 cultivar were planted by hand. Experimental treatments were: 1) Control (application of chemical fertilizer based on soil test), 2) Soil application of humic acid (treatment 1+ soil application of 5 kg of humic acid.ha-1), 3) Amino acid spraying (treatment 1+ spraying of amino acid with a concentration of 5 g per thousand), 4) Foliar spraying of humic acid (treatment 1+ spraying of humic acid with a concentration of 5 g per thousand), 5) Foliar spraying of folic acid (treatment 1+ foliar acid spraying with a concentration of 5 g per thousand), 6) Spraying of seaweed extract (treatment 1+ spraying of seaweed extract with a concentration of 5 g per thousand), and 7) Combined treatment (including treatment 1+ treatments 2, 3, 4, 5 and 6). Foliar application was done at two stages of 57 (after rosette) and 59 (before flowering). The biennial results showed that the combined treatment of growth biostimulants had a significant effect on grain and oil yield as well as some agronomic characteristics of rapeseed. The highest grain and straw yield was obtained from treatment 7 with an average of 4565 and 1066 kg.ha-1, respectively. Also, the highest mean values ​​of K, Na, Ca, Mg, Fe, Zn, Mn, and Cu were obtained in, respectively, treatments 7, 1, 7, 7, 3, 4, 1, and 6. In addition, the highest uptake of K, Ca, Mg, and Fe was observed in treatment 7, followed by Zn and Cu in treatment 6, and in the case of Cu, in treatment 1. Based on the results, the combined use of growth biostimulants, compared to the control treatment, had a significant effect on yield and some agronomic characteristics of rapeseed in saline conditions, indicating the effect of these substances on increasing rapeseed tolerance to saline conditions.

One of the most important factors limiting the growth and yield of plants is moisture stress. The purpose of this experiment was to investigate the effect of different levels of vermicompost and moisture stress on some plant and soil characteristics after harvesting basil. The experiment was performed as a factorial experiment in a completely randomized design with two factors and three replications in the greenhouse of the Faculty of Agriculture, Lorestan University. Treatments consisted of four vermicompost levels (0, 10, 20, and 30 g kg-1soil) and three moisture levels (no stress), 75%, and 55% of field capacity (FC). The results showed that the highest fresh weight (58.96 g.pot-1), dry weight (5.9 g.pot-1) and shoot phosphorus concentration (0.42%) were observed in the treatment without moisture stress and with application of 30 g of vermicompost, and the lowest amounts of fresh and dry weight and shoot phosphorus were observed in the highest level of moisture stress and non-application of vermicompost. The results also showed that the highest concentrations of nitrogen (4.74%) and potassium (3.90%) of shoots were observed at the highest level of moisture stress and application of 30 g of vermicompost. In the soil after harvest, the highest concentrations of nitrogen (0.2%) and available phosphorus (26.25 mg kg-1) were observed in 30 g.kg-1 treatment of vermicompost with moisture stress (55% FC), and the lowest was observed in the control treatment. Considering these results, it can be stated that vermicompost has positive effects on increasing the growth of basil under water stress.

Lack of awareness of changes in soil content of nutrient elements in different farms and applying the same fertilizer recommendations cause some soils to receive more, and some less, than the required fertilizer. The aim of this study was to investigate the spatial changes and status of macro elements including N, P and K and some important soil properties such as OC, EC, and pH in some paddy fields of Gilan Province. To this end, in 2018, before preparing the land for cultivation, composite soil sampling was performed from 0 to 30 cm depth of paddy fields in Masal, Rudbar, Meqdad (Khoshkbijar, Lashtnashah, Khomam) and Siahkal areas, with spacings of at least 500 m. Using the results of soil analysis, status of the desired characteristics was evaluated based on descriptive statistics. Then, excess and deficiency of nutrients in paddy lands were determined. Data analysis showed that  available phosphorus was one of the major limitations in the study areas, such that more than 80% of the sampled soils in Siahkal, 72% in Rudbar, 65% in Masal, and 54% in Meqdad were deficient in P. Potassium had better conditions than P, such that 51.3% of the soils in Siahkal area, 31% in Rudbar, 66% in Masal, and 26%in Migdad had available K lower than the critical level. Also, 19.4% of soils in Meqdad region,  36.6% in Siahkal, 48.4% in Masal, and 100% in Rudbar had total N lower than the critical level (0.2 %). Examination of the condition of paddy soils at the sampling points showed that the spatial distribution of nutrients was not the same. The findings of this study showed that using the same fertilizer recommendation is not suitable for different paddy lands; and distribution of fertilizer in different areas of the province should be done according to the soil analysis of each region.

The aim of this study was to investigate the effect of application of 0, 1.5, 3, and 4.5% of crude oil, kerosene, and gasoline on spontaneously and mechanically dispersible clay in three texturally different soils of clay loam, loamy sand, and sandy loam. In general, the results showed that the percentage of spontaneously dispersible clay in soils treated with kerosene and gasoline was significantly higher than that treated with crude oil by, respectively, 34% and 44%. Mechanically dispersible clay in soils treated with kerosene and gasoline were significantly higher than that of the crude oil treaded soils by nearly two folds. The percentage of spontaneously dispersible clay in the loamy sand soils was significantly higher than that of the clay loam and the sandy loam soils by nearly 21% and 57%, respectively. While mechanically dispersible clay in loamy sand soil was significantly less by about 31% than that in clay loam soil and about 32% more than that in sandy loam soil. In general, increasing the application rates of petroleum products increased the percentage of spontaneously and mechanically dispersible clay at low levels, but decreased the mentioned attributes at higher levels. The results showed that different levels of petroleum products had significant effects on dispersible clay. Therefore, the results of this study can provide the necessary information about the effect of petroleum materials on the amount of dispersible clay, as one of the soil strength and cohesion criteria and other related characteristics. This information can be used in making the necessary decisions for management and reclamation of different types of oil-contaminated soils, and for using petroleum compounds to protect the soil against erosion.