APPLIED SOIL RESEARCH
Year:2018 | Volume:6 | Issue:3 |Papers Count:11

This study was carried out to investigate the effect of different plantations on the activity of soil organisms, biodiversity indices and their relationships with the measured soil physical and chemical characteristics. Sampling of soil, soil organisms and microbial indicates were done in plantation of Populus deltoides, Pinus taeda and natural forest stand by random systematic method. In each mentioned tree stands, 40 places were selected and soil samples were taken from a depth of 0-20 cm. The results showed that the highest microbial respiration, microbial biomass carbon, microbial biomass nitrogen and bacteria were observed in Populus deltoides and natural forests. Two indicators of metabolic and microbial also showed significant differences among the stands. The result of Pearson correlation between microbial indicators and different soil properties showed that there is a positive and significant correlation between these indicators and organic carbon and total nitrogen. On the base of this study, it is declared that the variations of soil qualities properties and the diversity indices are proportional to the properties and the forest site productivity. Population of macrofauna, as an indicator of the site productivity, will be suitable indicators for evaluation of the forest management roles related to ecosystem conservation and permanency. Based on the results, Populus deltoides compared to the other forest stands showed favorable conditions to produce more organic matter and microbial respiration.

Information about chemical forms of copper (Cu) is important for the evaluation of its status in soil and also understanding of soil fertility, plant nutrition and soil chemistry. To obtain such information, in this research available Cu was determined in 21 calcareous surface soil samples (0-30 cm) by six methods including DTPA, AB-DTPA, AC-EDTA, hydroxylamine, reference ammonium oxalate and rapid ammonium oxalate. Cu fractions were also determined by the modified sequential extraction procedures introduced by Singh et al. According to the results, rapid ammonium oxalate and DTPA-TEA methods extracted the maximum (25. 69 mg kg-1) and minimum (1. 57 mg kg-1) amounts of Cu, respectively. Also, Cu-residual and Cu-CFeox forms the greatest amount of Cu in studied soils respectively. AC-EDTA extraction method, in addition to Cu-Residual, extracted other fractions of copper such as Cu-Exchangeable, and Cu-CFeoxide. Hydroxylamine method extracted Cu mostly from the manganese oxides source compared to other methods. Regression analysis indicates that Cu-CFeox forms the maximum copper extracted by extractants AB-DTPA, AC-EDTA and DTPA in soils was studied. According to the statistical relationships presumably Cu-CFeox, does seem a potential source of available Cu in studied soils. Among chemical properties of soil, CCE content of the soils appear the most influential properties that predict available Cu in the studied soils.

Salinity is the most important challenge in arid and semi arid regions. Recently, biological methods are considered as a way for decreasing harmful effects of salinity on plant. In this study halotolerant bacteria were isolated from saline soils. The characteristics of plant growth promotion (PGP) such as production of exopolymer, siderophore, HCN, auxin, ability of potassium and phousphate solubilization and tolerance to drought stress were investigated. Among the 20 isolates selected, two isolates (5, 17) selected as super isolates based on PGP test. Results shown that mean produced exopolymer was in range of 0. 8 to 4. 2 g l-1 and maximum value was observed by the isolate17. All of the isolates can produce halo in CAS-Agar and bacteria isolate No. 5 produced maximum siderophore with the halo to colony ratio two. Maximum auxin production (8. 14 mg l-1) was observed by the isolate17. Also, this isolate had highest ability of potassium solubilization in presence (12. 20) and absence (18. 62) of salt. Most of the isolates showed drought tolerance at 2 and 5 bar levels. At 15 bar, Isolates 17 and 5 has the highest tolerance to drought stress in comparison to control with 55. 6 and 53. 2 percentage reuction in growth rate, respectively. With 16S rRNA sequencing, the more closley studied of halotolerant superior isolates were identified as Bacillus. Isolate No. 17 had 99. 4% similarity to Bacillus licheniformis DSM13, while isolate No. 5 showed 99. 57% sequence homology to Bacillus megaterium NBRC 15308.

Soil fertility describes the ability of soil to create the conditions for sustainable growth, optimum plant. The elements in the soil productive effects on soil structure, soil texture, water retention in the soil, water infiltration in the soil. On the other hand, with respect to the elements in the soil, the manure is used for different plants. One of the major goals of modern agriculture, efficient use of fertilizers. The use of chemical fertilizers, regardless of the elements in the soil, causing the balance of nutrients, loss of energy and environmental problems. Consequently, to determine the fertility of the soil due to fertilizer and plant species to determine the next Managing agricultural land is important. Due to its importance in the study of soil fertility in the southern province of Fars, Iran was investigated. The parameters such as potassium, phosphorus, organic matter, copper, manganese, zinc and iron were studied. For this purpose, the data of 38 soil samples were used. Average Inverse Distance method (IDW) for mapping each element was used in GIS. In order to homogenize the data to produce a map of soil fertility phase method was used. Fuzzy membership functions were prepared using standard soil fertility. Finally, in order to ensure a different level of soil fertility maps sorted by weighted average (OWA) was used. The results of soil fertility study area using OWA showed that risk appetite (no trade-off) is most problematic area in terms of soil fertility. So that the results showed that the class 4 and 5 areas with fertile soil and good average in the study area show a greater area than the rest of their class. However, with increasing levels of reliability and reduce the risk areas was more difficult in terms of soil fertility. So that more area in the classroom is one that has a poor soil fertility.

Knowledge of soil phosphorus (P) mineral forms is important in soil fertility and plant nutrition. This study was conducted to evaluate of mineral P fractions with addition of triple superphosphate fertilizer and wheat cultivation in incubation and greenhouse conditions. Incubation test was performed in three soil types: Dizan, Qaznin1 and Qaznin2 with various amounts of available P which in each soil 50 mg kg-1 P used from triple super phosphate. Soil's P fractions including: Ca2P, Ca8P, AlP, FeP, OP and Ca10P were measured at 0, 45 and 90 days of incubation based on a complete randomized block design with three replications. Results showed that soil type effect on fixation of mineral P under incubation conditions and Dizan soil ranked in the first place. In this soil, Ca2P: 67. 5 and 73. 8%, Ca8P: 74. 5 and 59. 7%, AlP: 31. 9 and 50. 3 %, FeP: 47. 9 and 63. 7%, OP: 50. 7 and 60% and Ca10P: 62. 8 and 69% were more than Qaznin1 and Qaznin2, respectively. By addition of 50 mg kg-1 P from TSP, concentrations of Ca2P and Ca8P increased in all soils and more in Dizan. The highest concentrations of Ca2P, Ca8P, AlP, FeP and OP achieved by T45 and Ca10P by T90 times. Greenhouse trial was conducted on three soils mentioned with 50 mg kg-1 P used from triple super phosphate and cultivated with wheat based on a complete randomized block design with three replications. The concentration of mineral P was higher than other soils under wheat cultivation in Dizan. Comparison of mineral P fractions under incubation and greenhouse conditions proved a reduction in P concentrations for Ca2P: 30. 63, Ca8P: 12. 1, AlP: 7. 17 and FeP: 3. 33 mg kg-1. The amount of P fixation forms (Ca2P) had an obvious decrease in association with wheat planting in the greenhouse.

The estimation of the amount of water flow through intact soils, sedimentary deposits or compacted soils is one of the most important issues in field operations. Because, the consolidation and dissolution of substances in soil, infiltration rate and surface runoff vary through the time. The aim of this study was to investigate the changes of runoff and sediment production in gypsiferous soils using rainfall simulator in the Arayez plain, Khuzestan province. The treatments consisted of natural soil (Control), polyacrylamide at two levels 3 and 6 grams per square meter (P3 and P6, respectively) and Parsian mulch (Pc) that were conducted in sandy loam soil with three replications. The rainfall intensities were set up with 32 and 50 mm per hour in slopes 7. 5 and 12. 5 percent. For statistical comparisons, split split plot design was used. Results highlighted that sediment produced only in control treatment. The investigation of runoff changes in different treatments indicated that the use of mulch P3, P6 and Pc, in most cases, increased runoff volume compared to control treatment. Statistical comparison of the total amount of runoff indicated that control, mulch P3, P6 and Pc treatments had significant differences with each other. Moreover, results revealed that amount of sediment in Control, P3, P6 and Pc treatments had a significant differences and P3, P6 and Pc treatments had not produced any sediment and belonged to one group.

Phosphorus (P) is an essential nutrient that its bioavailability controlled by sorption and desorption process. To study the behavior of phosphorus (P) sorption in agricultural soils of Khoy region, bath experiments were carried out with 60 cultivated soil samples and 9 initial P concentrations from 0 to 30 mg L-1 in 0. 01M CaCl2 as a background solution. After equilibrium, remaining amount of P in solution was measured and the experimental sorption data were fitted to Langmuir, Freundlich and Temkin models. Based on coefficient of determination (R2) and standard error of estimate (SE), Langmuir isotherm models, is relatively better fitted to experimental data compared with Freundlich and Temkin models. The maximum mono layer sorption of Langmuir (qmax) varied from 135 to 486 mg kg-1 and energy parameter of Langmuir (KL) varied from 0. 09 to 0. 52 L mg-1. Also, Freundlich sorption capacity (KF) and intensity (n) parameters was varied from 16. 0 to 123. 4 mg kg-1 and 1. 1 to 2. 4 respectively, and Temkin equation constants, A and KT varied from 10. 3 to 196. 3 mg kg-1 and 17. 3 to 88. 7 L mg-1, respectively. The soils with high clay and CaCO3 showed maximum qmax, KF and A, and mentioned sorption parameters significantly correlated with clay and CaCO3. The result showed that the amount of equilibrium P concentration (EPC) values varied from 0. 01 to 0. 89 mg l-1, 0. 35 mg l-1 on average for the cultivated soils. Also, there was a highest significant correlated between EPC and extractable phosphorus with sodium bicarbonate (r = 0. 90**). The Potential buffering capacity (PBC) values was from 3. 2 to 122. 4 and 33. 5 mg kg-1 on average. PBC significantly correlated with soil clay content (r= 0. 80**) and amount of calcium carbonate (r=0. 43**).

Iron (Fe) deficiency in soil is a limiting factor for the growth of most plants. Fe availability in soil depends on distribution of Fe chemical forms among soil components which it is affected by physicochemical characteristics of soil. The aim of the present study was to investigate the distribution of Fe chemical fractions in some calcareous soils of orange orchards in Drab region (Fars province) and their relationships with some soil physicochemical properties and Fe concentration in leaves of orange trees. A sequential extraction procedure was used to fractionate Fe chemical forms in the studied soils. The results showed that the distribution of Fe chemical fractions in the studied soils were in the order: CFeOx > Fe-Res > AFeOx > Fe-WsEx > Fe-OM > Fe-Car > Fe-MnOx. There was about 98. 2 percent of total soil-Fe in both CFeOx and Fe-Res fractions which it indicates the presence of Fe in unavailable forms for plant in the studied soils. Among the Fe chemical forms, AFeOx fraction only showed a significant and positive correlation with DTPA extractable Fe in soil and Fe concentration in leaves of orange trees. Also, among the soil properties, organic matter, calcium carbonate equivalent and cation exchange capacity were the effective characteristics of soil in determining the bioavailability of Fe and content of AFeOx form in soil. There were significant and positive correlations among some Fe chemical forms in soil that it represents a dynamic relationship between Fe chemical forms in soil. According to the results, it seems that the amount of soil organic matter can have an effective role on the availability of Fe in calcareous soils of orange orchards.

Increasing demand for agricultural products and lack of appropriate soil and water resources with problems of field research reveals the application of efficient models to predict crop yield. This research aimed to examines the efficiency of artificial neural networks, comparative fuzzy neural network, adaptive nerofuzzy inference system and particle swarm optimization algorithm models for estimating the wheat yield through soil and land properties. For this purpose, 80 soil profiles were drilled in wheat fields’ area in East Azarbaijan province with temperature and moisture regimes of mesic and aridic border to xeric, respectively. Soil samples were collected from each genetic horizon. The results of sensitivity analysis showed that total nitrogen, absorbable phosphorus, slope, gravel, soil reaction and organic matter are effective soil properties in wheat yields. The hybrid model of ANFIS-PSO was the best model from the viewpoint of statistical indices including R2 (0. 89) and RMSE (213. 5). Also, neuro-fuzzy method has a R2 (0. 84) and RMSE (243. 2) and artificial neural networks have a R2 (0. 81) and RMSD (274. 5), respectively. The GMER index also indicated overestimation of artificial neural network (0. 24) and nerofuzzy (0. 53) and underestimation of ANFIS-PSO model (1. 13). The results indicated that the hybrid neuro-fuzzy-swarm particles model performed better than other models that can be used a powerful tool for estimating wheat yield.

Nitrogen management (N) is one of the important factors in improving root yield and quality of sugar beet (Beta Vulgaris, L). Suitable source and rate of N fertilizer application are crucial to produce a high– yielding, high-quality sugar beet crop. The aim of this study was to evaluate the response of sugar beet to three levels of nitrogen fertilizer including N application based on soil test (125 kg ha-1), 25% less and 25% more than that one and four N sources including Urea (U), ammonium-nitrate (AN) and two delayed-release N sources e. g. Urea soaked with sulfur (domestic production) and sulfur coated urea (SCU). A field experiment was carried out during 2006/2007 and 2007/2008 growing seasons at the agricultural experimental station of Miandoab in West Azerbaijan, Iran. Plots were arranged in a factorial randomized complete block design with three replications. The results revealed that, N rates influenced significantly root and sugar yields and the superiority was to adding 125 kg ha-1 pertinent to soil-based-test rate treatment. N rates did not influence sugar beet response to N sources. The value of mentioned parameters was not affected by N sources. N sources had consistent effects on mineral N (N-NO3 and N-NH4) concentration in the soil. Mineral N content increased with increasing N rates. The highest amount of mineral N contents were measured in N rate applied based on soil test in the form of AN source. The obtained results are recommended by application of N entirely in pre-plant in the form of delayed-release sources or split application in the form of, Urea or AN.

Organic matter is one of the most important factors in soil fertility. Different sources are involved in the supply of organic matter, including municipal solid waste compost, poultry and cow manures. These fertilizers often contain toxic substances and heavy metals which are extremely harmful for human and animal health. Toxicity and hazard of heavy metals in the soil is dependent on the form and amount of heavy metal. This research was conducted in a based on design completely randomized with three replications in Hamedan province. In this study, three types of soil texture (sandy loam, clay and loam) along with three types of organic fertilizers such as municipal solid waste compost, poultry and cow manure have been used in five levels (0, 20, 40, 80 and 120 ton/ha). Availability and total concentrations of Zn, Cu, Ni, Pb and Mn were measured in each treatment. The results showed that soil cation exchange capacity (CEC) as well as availability and total amount of heavy metals were increased by enhancing the amount of organic fertilizers. The availability of heavy metals was much less than the total amount of elements. Overall, it was observed that increment of heavy metals caused by organic fertilizers was more in the clay soil compared to other soils because of the fact that clay texture showed high capacity for the uptake of heavy metals. Solid waste compost revealed the greatest effect on increasing the concentrations of heavy metals in the soil among other fertilizers while poultry manure was in the second place.