Iranian Journal of Soil Research
Year:2020 | Volume:34 | Issue:1|Papers Count:12

In order to achieve an effective approach to improve nitrogen use efficiency in rice, a field experiment was conducted based on randomized complete block design with three replications and 13 treatments on a local rice variety, namely, Hashemi, in Rice Research Institute of Iran (Amol) during 2015 and 2016. The treatments included: N0: no N, N1: split application of 55. 2 kg ha-1 N from source of urea (recommended for Hashemi variety), (N2, N3), (N4, N5) and (N6, N7) application of 55. 2 and 27. 6 kg ha-1 N from SCU, USG and AS sources, respectively; N8: application of nitrogen nanofertilizer; N9, N10 and N11: application of Azospirillium, Azotobacter, and Azospirillium + Azotobacter. In addition to the mentioned sources, in N8 to N11 treatments, 27. 6 kg ha-1 N from urea was used. N12: Farmers’ fertilizer practice (Pre planting application of 55. 2 kg ha-1 N from urea). Results of the experiment showed that the effect of treatments on the measured traits, except nitrogen content of straw, caused a significant (p<0. 05) difference. The highest grain yield was obtained from N6 (4542 kg ha-1). The performance of N5 (deep placement of 27. 6 kg ha-1 N from source of USG) was not significantly different from the treatment with the highest grain yield (N6). The highest amount of PFP, AEN and REN was obtained from N5 treatment and the highest PEN and IEN was obtained from N10. N5 increased grain yield by 4. 6% and recovery efficiency by 59. 4% in compared to N12. The highest amount of N uptake (119. 5 kg ha-1) was obtained from N4 treatment. Based on the results, it could be concluded that the deep placement of USG fertilizer has relative advantage compared to other N supplying sources because of enhanced amount of N uptake and reduced N losses.

Grape is one of the most important agricultural products in East Azarbaijan Province (Iran), which has the third highest production in the country. The nutritional status of high-yield plants can be a real criterion for assessing the growth and favorable nutritional status of the plant. For this purpose, 62 vineyards in Malekan District were selected. In all vineyards, composite soil sampling was carried out at depths of 0-30 and 30-60 cm and over 1364 physical and chemical analyses were done. At flowering time, composite leaf samples were taken of leaves facing the bunch of grapes; then, 682 plant analyses were carried out using suitable laboratory methods. During the harvest, yield was measured and determined by visiting each vineyard. Finally, the Deviation from Optimal Percentage (DOP) and Compositional Nutrient Diagnosis Index (CND) were calculated for each nutrient element. Based on the yields, the studied vineyards were divided into two groups of high and low yield and quality. The results of CND and DOP indices showed that zinc and copper deficiencies were more prevalent among microelements and phosphorous and magnesium deficiencies were observed among macro elements. The results showed that the vineyards of this region faced the deficiency of phosphorus, magnesium, zinc, and copper. These results can be applied to the area's vineyards to enhance the yield and quality of the grapes.

The productivity of plants is adversely affected by soil salinity. However, it is predicted that plant growth-promoting rhizosphere bacterial (PGPRs) and the use of crop residues as biochar can improve plant growth and development in the presence of salinity and different stresses. A pot experiment was performed in a complete randomized design using two soils with different EC (S1 = 2, S2 = 15 dSm-1). Treatments included different types of enriched biochar (BC) as rock phosphate-biochar (BC-RP), BC-H3PO4-RP, BC-HCl-RP, BC-PSB and BC-RP-PSB to assess the effects of apple-grape pruning biochar, enriched biochar, and phosphate-solubilizing bacteria (PSB) isolated from saline soils around Lake Urmia on the phosphorus (P) availability. After harvesting, soil physicochemical properties (pH, EC), P-Olsen, acid, and alkaline phosphatase activities, and plant growth indices were investigated. The results showed that in both soils, the highest alkaline phosphatase activity was in BC-H3PO4-RP and BC-HCl-RP treatments. In both soils, the highest plant dry matter was obtained in BC-H3PO4-RP and the highest plant P in BC-H3PO4-RP, BC-HCl-RP, and BC-RP-PSB treatments. Experimental treatments did not affect the soil EC but significantly reduced the pH of soils. Indeed, BC-H3PO4-RP reduced the pH of S2 and S1 soils by 1. 1 and 0. 6 units, respectively, while BC-HCl-RP reduced the pH of S1and S2 soils by 0. 56 and 1. 16 units, respectively. The POlsen concentration of S1 soil under BC-H3PO4-RP and BC-HCl-RP treatments were 57. 7 and 41 mg kg-1and of S2 soil were 67. 4 and 38. 6 mg kg-1, respectively. Interestingly, in both soils, P-Olsen concentration in BC-RP-PSB treatment was more than TSP treatment, suggesting a remarkable ability of the studied bacteria. Since enriched biochar with various minerals and inoculation with PSBs showed an unexpectedly higher P-Olsen compared to TSP, more field studies are needed for supporting as well as clear understanding of Penriched biochar potential in different soils and climates.

In recent years, application of municipal solid waste compost (MSW) on the farm land has received considerable attention. This research was conducted to evaluate the influences of municipal solid waste compost (MSW) and chemical fertilizers on some nutrients concentration in soil and sugar beet yield. This field research was conducted with MSW at four levels (0, 10, 20 and 30 t ha-1) and chemical fertilizers at four levels (0, farmers’ conventional practice, based on soil test, and 25% lower than the soil test), using a factorial experiment based on a randomized complete blocks design with three replications, in Kermanshah region during 2014-15. Before cultivation, soil samples were taken and their characteristics were determined. At post-harvest stage, root yield and nutrients concentration (N, P, K, Fe, Zn, Mn and Cu) and soil O. C, N, P, K, Fe, Zn, Mn, Cu, Pb and Cd were measured. The results showed that between effects of different amounts of MSW and chemical fertilizers on root yield and qualitative characteristics of sugar beet (sugar content, extractable sugar, sodium, potassium, nitrogen content) and their interaction effect on root yield and sugar content was significant at 1% (P<0. 01). The highest root yield (52. 8 t ha-1) was obtained with the application of 10 t ha-1 MSW and chemical fertilizer application based on soil test, which increased 17. 2 t ha-1 compared to the control treatment. Also, differences between effects of various amounts of MSW and chemical fertilizers on most of the nutrients concentrations in soil were significant (P<0. 01) and their interaction effects on the organic carbon content, concentration of Zn, Fe and Cu were significant at P< 5%. The highest concentration of Zn, Fe, and Cu were observed with the application of 30 t MSW ha-1 and chemical fertilizer application based on farmers’ conventional practice, and their differences compared to the control treatment were 0. 29%, 1. 67, 2. 7 and 0. 7 mg kg-1, respectively. According to the results of this study in terms of yield, sugar content, and impurities, the combined application of 10 t ha-1 MSW and chemical fertilizer based on soil test is recommended.

In this study, the interactive effects of soil moisture and S levels were investigated on alfalfa (Medicago sativa c. v Garehyounjeh) shoot and root fresh weights, water use efficiency (WUE), and concentrations of some elements in a loam soil under greenhouse conditions. A factorial experiment based on a randomized complete blocks design with three replications was conducted with two factors: soil moisture at three levels (0. 81 FC– FC, 0. 56– 0. 75 FC, and 0. 35– 0. 50FC) and SS at four levels (0, 15, 30, and 60 g/kg soil). When 10% of the alfalfa plants flowered, the shoot and root fresh weights, concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) and WUE of alfalfa plant were measured. The results showed that the main and interactive effects of SS and soil moisture on alfalfa shoot and root fresh weights, WUE, and concentrations of elements were significant (p≤ 0. 01). The decrease in soil moisture content, decreased alfalfa shoot and root fresh weights, WUE, concentrations of Fe in the shoot and concentrations of P, Fe, and Na in the root (p≤ 0. 05); while it increased concentrations of Cu in the root, and Cu and Zn in the shoot (p≤ 0. 05). Effect of soil water content on concentrations of N, K, Ca, Mg, Zn, and Mn of the root depended on the level of SS. Concentrations of Mg, Fe, Zn, Cu, and Mn in the root and shoot and concentrations of P, K, and Ca in the root were increased (p≤ 0. 05) with the use of SS and increase in its level. By increasing the SS level, shoot and root fresh weights were initially increased and then decreased (p≤ 0. 05). Effect of SS on WUE depended on soil water content. With sufficient water supply (0. 81FC– FC), WUE was increased with increment of SS level, while under water-deficit stress (0. 35FC– 0. 50FC), application of SS up to 30 g/kg increased WUE but at the level of 60 g/kg, increase in the soil salinity reduced WUE (p≤ 0. 05). To increase WUE and improve the nutrition and growth of alfalfa at similar conditions, 30 grams of SS per kilogram of soil may be recommended under both well-watered and water-deficit conditions. Although the use of sewage sludge had some beneficial effects in this experiment, the potential risks of heavy metals in longterm application of this organic waste should be considered and avoided.

In order to investigate the effect of sodium chloride application, organic matter sources and growth promoting bacteria on fresh and dry matter yield and concentration of micro nutrients in shoot of spinach, a factorial experiment was conducted in a completely randomized design with three replications. The treatments were sodium chloride (control (S0), 2 (S2) and 4 (S4) g Na Cl kg-1 soil), organic matter (control (OM0), 0. 5% and 1. 0 % rice husk and 0. 5% and 1. 0 % rice husk biochar, w/w) and PGPR bacteria (without and with bacteria). Results showed that application of 2 and 4 g salt kg-1 of soil slightly increased iron concentration of aerial part, while Cu concentration increased by 48. 10% and 48. 32%, respectively. However, Zn and Mn concentrations decreased. Plant yield was not affected by salinity, probably due to the osmotic adjustment resulting from gradual increase in salt addition. Application of organic matter sources increased spinach fresh and dry weight, and Fe, Zn, Cu and Mn concentrations. Inoculation with Pseudomonas fluorescence significantly increased fresh and dry weight as well as Fe, Zn, Cu, and Mn concentrations in aerial part, compared with the related control (without bacteria). In conclusion, spinach (cv Virofly) very well tolerated gradual addition of salinity; and application of organic matter with growth promoting bacteria increased micronutrients concentration and growth of spinach in a calcareous soil affected by salinity.

Integral Water Capacity (IWC), as one of the recently defined criteria for soil water availability, uses weighting functions to takes into account various soil physical limitations for calculating plant available water. Also, the weighting functions can be calculated from plant responses. In this study, in a pistachio orchard, surface (DI) and subsurface (SDI) drip irrigation systems were established, afterwards soil physical properties and water and salinity distribution in root zone were measured. IWC were calculated using soil physical properties and sap flow (SF) as one of the plant responses features. The result of plant measurements indicated that SF decreased progressively during the time between successive irrigation periods, but the decrease in DI was greater than SDI. By considering equal depth of irrigation water applied to DI and SDI, the more favorable moisture and salinity distribution in the root zone of SDI compared to DI treatment was the reason for more water availability in SDI. The calculated IWC by Groenevelt weighting function (􀜫 􀜹 􀜥 􀭋 􀭰 ) in DI and SDI showed the lowest amount (0. 0557 and 0. 0545 􀜿 􀝉 􀬷 􀜿 􀝉 􀬿 􀬷 , respectively) but IWC􀭗 􀭊 values were calculated as 0. 176 and 0. 191, respectively, and were close to IWC calculated without any salinity effect (0188 􀜿 􀝉 􀬷 􀜿 􀝉 􀬿 􀬷 ). Van Genuchten equation led to more realistic estimates of salinity limitations on water availability (IWC􀭚 􀭋 were obtained as 0. 146 and 0. 151 􀜿 􀝉 􀬷 􀜿 􀝉 􀬿 􀬷 ) and the integral energy based on IWC􀭚 􀭋 was very close to integral energy calculated by SF. These findings indicate that the salinity weighting functions used in IWC􀭚 􀭋 had the best estimates of soil physical conditions to consider water uptake energy and plant water availability. It is found that based on all soil water availability criteria, SDI provided more available water and less integral energy than DI.

Identification of soil quality changes, including soil organic matter (SOM), is one of the most important usages of remote sensing and geographical information system. Available phosphorus is also an important nutrient for optimal growth of plants. The purposes of this study were to investigate the capability of satellite images data and to compare the accuracy of SOM and available phosphorus maps by using Landsat 8 and Sentinel 2A satellite images. The location of sampling points was determined by using conditional Latin hypercube sampling for 84 soil samples in agricultural lands of Semnan plain. The SOM content, the particle size fractions including sand, clay, and silt were measured using wet oxidation and hydrometer methods, respectively, and available phosphorus was measured by the Olsen method. The auxiliary variables included the bands and combination of bands. The results showed that soil available phosphorus had the highest correlation with SOM content. Results of Random Forest algorithm indicated that axillary variables derived from multi-spectral instruments (Sentinel 2A satellite) evaluated the amount of SOM and available phosphorus more accurately than the axillary variables extracted by Landsat 8 satellite images. The random forest nonlinear method estimated the amounts of SOM and available phosphorus with low error values and a relatively high coefficient of determination. The root means square error (RMSE) and coefficient of determination (R2) for prediction of SOM were 0. 413 and 0. 758 for the multi-spectral instrument, and 0. 432 and 0. 736 for the operational land imager, respectively. Also, the RMSE and R2 for prediction of available phosphorus were 5. 96 and 0. 74, for the multi-spectral instrument, and 7. 24 and 0. 56 for the operational land imager, respectively.

Rill erosion is one of the most important types of water erosion in semiarid dry land areas. The importance of this study is more in the soils of semi-arid regions, similar to many parts of Iran, which have unstable soil aggregates. The aim of this study was to investigate the role of raindrop impact on the size distribution and homogeneity of sediment particles in rill erosion of soils with different textures. Therefore, the effect of raindrops on changes in the size distribution of sediment particles was determined in rills of 4 meters in length and 0. 10 meters in width under rainfall simulated with a constant intensity of 90 mm h-1 in different slope gradients (5%, 10%, 15%, and 20%) in 12 soil texture classes. Experiments were carried out in two soil surface cover conditions including with raindrop impact (bare soil) and without raindrop impact (use plastic net), and the effect of raindrop impact on the variables was determined. The experiment was conducted in four replicates with a total of 352 experimental units. The study of this subject using the particle size distribution curve showed that there was a clear difference between the curves in the two soil surface cover conditions. The sediment particles size distribution curves were below the original soil particles size distribution curve, suggesting an increase in the mean diameter of the particles in sediments and an increase in the transport of coarse particles such as sand at the end of the experiment. The increase in geometric standard deviation in the sediment was strongly dependent on soil texture and slope and, contrary to the expected, homogeneity of sediment particles was not significantly affected by the removal of raindrop impact, and by increasing the slope in all soil texture classes, sediment particles heterogeneity increased, likely due to increase in flow velocity and flow power. The highest non-homogeneity of sediment particles was observed after precipitation in silty soil.

Soil saturated hydraulic conductivity is one of the most important physical characteristics of soils that affects water movement in soil. . The aim of this study was to determine the most important parameters in prediction and modeling of saturated hydraulic conductivity from conveniently available parameters, using the decision tree and error estimator cross validation and resubstitution. In this study, 72 soil samples with six different textures were collected from the village of Morgmalek and Shahrekord District. Conveniently available soil properties were introduced into software in 4 scenarios (the first scenario: pH, EC, % sand, % clay, OM%, CaCO3, mean weight diameter of dry aggregate (MWD dry), mean weight diameter of wet aggregate (MWD wet), BD; the second scenario: CaCO3, OM%, % sand, % clay, BD, % gravel, electrical resistivity, dielectric constant, root penetration resistivity; the third scenario: pH, EC, Geometric mean diameter (dg), Geometric standard deviation (σ g), OM%, CaCO3, mean weight diameter of dry aggregate (MWD dry), mean weight diameter of wet aggregate (MWD wet), BD; and the fourth scenario: CaCO3, OM%, dg, σ g BD, % gravel, electrical resistivity, dielectric constant, root penetration resistivity). Saturated hydraulic conductivity was measured with single ring. The results showed that moisture followed by structural features such as (σ g) in the first scenario, and OM and BD in the second scenario, BD and MWD in the third scenario, and OM and BD in the fourth scenario were the most important parameter affecting saturated hydraulic conductivity. Correlation between predicted data by decision tree and measured data in the second and fourth scenarios were 0. 83 and 0. 82, respectively, and 0. 79 in the first and third scenarios. All four scenarios were successful in modeling with respect to error rate and %RMSE. However, the %RMSE in the second and fourth scenarios was lower and the correlation coefficient was higher than the other two scenarios. The RMSE values in the four scenarios were 0. 79, 0. 83, 0. 79, and 0. 82, respectively.