نشریه پژوهشهای خاک (علوم خاک و آب)
سال سی و پنجم شماره 3 (پاییز 1400)

The present study was conducted with the aim of studying the feasibility and determining the qualitative and quantitative suitability of irrigated wheat crop in some saline lands in the south of Khuzestan Province. Based on semi-detailed soil studies in the region, 13 series of soils were identified. The physiological needs of the wheat plant were determined and graded using available resources. Then, qualitative and quantitative assessment of land suitability was performed by parametric method (Square root) and, finally, the relevant maps were prepared in GIS environment. The results showed that climatic variables did not limit wheat production. Also, there were qualitative land suitability classes from relatively suitable class (S2) to unsuitable (N), and the most important limiting factors were salinity limits (4.7-115 dS), alkalinity (9.9-77%), calcium carbonate (40-60%), fertility characteristics (acidity) and soil wetness. The results of quantitative land evaluation also showed that 16260 hectares equivalent to 57% of the land available in the region for wheat cultivation was in class S2 (relatively suitable), 1380 hectares (4%) in class S3 (critical suitability), and 12680 hectares (37%) in class N (unsuitable lands). According to the results, in most units, the quantitative classes of land units for wheat cultivation corresponded to the qualitative class of land suitability, or had a higher suitability due to better management of this crop in the region. Therefore, due to the fact that most of the study area had salinity and alkalinity limitations, to increase production and create a sustainable agricultural system, land improvement operations are necessary.

Low availability of some nutrients is one of the major factors for the widespread occurrence of plant nutrient deficiency in calcareous soils. Therefore, any strategy for solution of this problem is important. For this purpose, an experiment was carried out in four sites (Chogha Narges, Mahidasht, Najaf Abad and Ghomsheh in Kermanshah Province), with different contents of available sulfate, using complete randomized blocks design with three replications, in 2018-19. The amounts of sulfur paired with Thiobacillius bacterium inoculants included no sulfur (S0), 250 kg sulfur/ha along with 5 kg/ha Thiobacillus bacterium inoculant (S1), 500 kg sulfur/ha with 10 kg Thiobacillus/ha (S2), and 1000 kg sulfur/ha with 20 kg Thiobacillus/ha (S3). The combined analysis results showed that the effect of sulfur, location, and their interaction on grain yield, 1000- grain weight, oil percent, and nutrients concentration in rapeseed grain in Chogha Narges, Mahidasht, Najaf Abad, and Ghomsheh were significant at 1% (p<1%). The highest grain yield, 1000- weight, oil percent and nutrients concentration was obtained in S3 treatment, which increased wheat yield by 647, 756, 474, and 406 kg.ha-1 in Chogha Narges, Mahidasht, Najaf Abad, and Ghomsheh, respectively, compared to the control treatment. Oil percent increment at the mentioned regions were 2.1%, 1.4%, 1.2%, and 0.5%, respectively.

Rice (Oryza sativa L.) is one of the strategic agricultural products of Iran. Recognizing the fertility status and quality of paddy soils is the effective factors on increasing rice yield. The aim of this study was to determine the quality of soil fertility and identify its limiting factors in paddy fields of Kuchesfahan District, Iran. For this purpose, before rice cultivation, a total of 130 composite soil samples with uniform geographical distribution were collected and prepared to measure some important physical and chemical properties affecting soil quality. Then, rice yield was measured in 70 locations. Principal component analysis and fuzzy logic were used to prepare the minimum effective data set and qualitative ranking of soil properties, respectively. After determining the soil quality index using the integrated algorithm, its relationship with rice yield was determined by statistical methods and spatial statistics using regression method. As the minimum effective data set, the total N, available P, K, Fe, percentages of clay and silt, and cation exchange capacity described 72% of the studied soil changes. Paddy fields in the western half of Kuchesfahan had more deficiency in total N and available P. These soils were also of lower fertility quality. Some of the lands located in the north and northeast of the study area had a soil quality index of more than 0.95 and were in the very fertile group. In these soils, the yield of rice was higher than other areas. The lowest yield of Hashemi cultivar was 3500 kg/ha in the southern half, and the highest yield was 5272 kg/ha in the eastern half of the study area. Due to deficiency of total N and available P in 36% and 50% of the studied lands, respectively, it is necessary that fertilizer application for these nutrients be site-specific and in proportion to their soil fertility status.

The present study was conducted to investigate changes in soil physical and chemical properties and organic carbon storage at different stages of sugarcane growth (Plant, Ratoon 1, Ratoon 2, Ratoon 3, and Ratoon 4) in some sugarcane plantations in southern parts of Khuzestan Province, Iran. For this purpose, a number of soil profiles were dug in the sugarcane fields and 30 sites were selected and studied in a completely randomized design with five treatments (i.e. sugarcane growth stages) and six replications. The results of this study showed that long-term cultivation of sugarcane and different stages of growth in soils of Sugarcane Cultivation and Industry Company caused changes in physicochemical properties and soil carbon storage. Indeed, abundant irrigation and leaching and cultivation management of sugarcane reduced the salinity and sodium in soil solution. Also, different growth stages changed the physical and chemical properties of the soil. Different stages of sugarcane growth reduced electrical conductivity (EC), dissolved sodium in the soil, the available potassium (K), and increased the amount of bulk density (Bd) in the soil. There was no significant difference in the amount of organic matter (OM) and soil acidity (pH) of sugarcane fields at different stages of growth. Finally, in order to prevent possible negative consequences and depletion of soil nutrients, especially potassium, it is necessary to periodically study the complete properties of the soils and evaluate these changes, appropriate management methods can be performed to maintain soil quality. The results showed that difference in soil carbon sequestration was significant (p<5%) in the treatments, such that the highest carbon sequestration was in Raton 3 (28.84 tons/ha) and the lowest in Raton 4 (15.50 tons/ha). The reason for the higher amount of carbon storage can be attributed to more vegetation and, therefore, more plant debris, which reduce evaporation from the soil surface, a positive effect on vegetation, especially in arid and semi-arid regions. In general, optimal management of sugarcane fields plays an important role in improving atmospheric carbon sequestration capacity.

The goal of any greenhouse owner is to adopt strategies that can maintain the plant's yield under temperature stress conditions. The aim of this study was to investigate the effect of different levels of potassium salicylate C7H5KO3 (0, 0.5, and 1 mM) and potassium silicate (0 and 4 parts per thousand (ppt)) on the yield and nutritional status of greenhouse cucumber (Cucumis sativus) under cold stress conditions (in the temperature range of 15-17 ͦC). This experiment was conducted as factorial arrangement based on a completely randomized design with 3 replications under greenhouse condition in Karaj, Iran. The results showed that the treatments significantly affected the concentration of nitrate and nutrients in the plant tissue, quality, and yield of cucumber. Also, simultaneous foliar application of potassium salicylate and silicate significantly affected the total yield and marketable yield of cucumber. The highest increase in total yield and marketable yield compared to the control (94.91% and 96.01%, respectively) were measured in 0.5 mM potassium salicylate treatment. Also, concentrations of N, B, and Mn in leaf significantly increased compared to the control (P<0.05). Furthermore, compared to the control treatment, the spray treatments significantly reduced nitrate content of leaf dry matter: 11% in 1 mM potassium salicylate+4 ppt potassium silicate and 78% in 0.5 mM potassium salicylate+4 ppt potassium silicate. Generally, the findings of this study showed that application of potassium salicylate and potassium silicate can increase the yield and promote the marketable yield of greenhouse cucumber under cold stress conditions.

Tensile strength is one of the most important indicators for soil physical quality, which is equivalent to the maximum stress applied to an aggregate without any disruption. The purpose of this study was to investigate the performance of different modeling methods for estimating soil tensile strength of some Rafsanjan pistachio orchards. For this purpose, soil samples (80 samples from 0- 30 cm depth mostly sandy loam) were taken and some soil physical and chemical properties were determined. Aggregate tensile strength was also measured in different sizes. The average EC, pH, and SAR indicated that soils of the study area were saline and sodic. Multiple regression between tensile strength and other soil properties were investigated. Tensile strength modeling was also performed using multilayer perceptron neural network and decision tree. The mean squares of error and coefficient of determination were used to evaluate different modeling models. The results of model evaluation showed that the use of regression decision tree for predicting tensile strength was better than the other modeling methods because of the lowest error (R2=0.88 and RRMSE = 14%) compared to the two methods of multiple regression and the multilayer perceptron neural network. Also, the results of different tensile strength modeling showed that the percentage of clay, percentage of dispersible clay, adsorption ratio of sodium, percentage of calcium carbonate equivalent, and the percentage of organic matter are the most influential variables on tensile strength. According to the results, it seems that the most effective way to increase soil tensile strength and reduce soil bulk density in pistachio orchards is to increase the percentage of soil organic matter.

Production and soil application of biochars derived from crop residue is known as an environmental friendly strategy for increasing soil health and quality. Therefore, the present study aimed to elucidate the effect of 4 pyrolysis temperatures (350, 400, 450, and 500 °C) on the physicochemical properties of biochar derived from pistachio pruning. The results showed that increasing pyrolysis temperature up to 500 °C increased electrical conductivity, pH, K, Na and P by 32%, 27%, 27%, 25%, and 29% compared to the pyrolysis temperature of 350 °C, respectively. While the increasing trend in Ca, Mg and Zn content was significant up to 450 °C, there were no significant difference in   Ca, Mg and Zn content at pyrolysis temperatures of 450 and 500 °C. The results also, confirmed the positive effect of pyrolysis temperature on specific surface area as well as porosity. Overall, it was concluded that the biochar derived from pistachio pruning woods is rich in plant nutrients and can be used as a source of nutrient supply for plants. It can also act as a soil amendment and improve plant performance.