Journal of Soil Management and Sustainable Production
Year:2015 | Volume:4 | Issue:4|Papers Count:18

Converting point data to continuous one is the first step in order to use them in scorpan flowchart. For this purpose, different geostatistic methods are available which at present research regression kriging with local variogram, kriging and co-kriging was applied. For mapping apparent electrical conductivity at the area covering 72000ha located in Ardakan region, 700 readings in horizontal and vertical modes were carried out by electromagnetic induction. Auxiliary data used in this study to represent predictive soil forming factors were terrain attributes, Landsat 7 ETM+ data and a geomorphologic surfaces map. At first, the relationship between independent variables (i.e. auxiliary data) and dependent variable (i.e. apparent electrical conductivity) was calculated by regression tree. Then, the residuals, derived from regression tree, were mapped by using kriging with local variogram. Finally, the residual and ECa maps were aggregated in order to produce the final maps. Results showed some auxiliary variables had more influence on predictive apparent electrical conductivity model which included: wetness index, geomorphology map and the first principal component analysis. Also, results showed that model predicted ECah with determination of coefficient, root mean square error and mean error were 0.48, 29.64 and -2.23, respectively. This founding confirmed that regression kriging with local variogram had high performance; however, RK decreases the error of prediction in comparison with OK and CK up to 21% and 28%. Thus, using of regression kriging with local variogram for digital mapping of soil properties in future studies is suggested.

Earthworms are an important part of food chain in soil ecosystem. In polluted soils, heavy metals are consumed by earthworms and transferred to other organisms through food chain, resulting in many adverse health impacts. Due to the benefits of earthworms for soil fertility, it is important to assess the effects of soil pollution on population, biomass and functions of earthworms. To determine the effects of organic matter on earthworms´ growth, in a soil with different levels of chromium, a factorial experiment with completely randomized design and three replications was performed. The levels of soil chromium were 0, 5, 10, 20, 40, 80, 160 and 320 mg kg-1 and the rates of organic matter (cow manure) added were 0, 5 and 10% w/w. The earthworms were exposed to soil pollution for different time periods (0, 15, 30, 45 and 60 days) and after that the number of living earthworms, their weights, the number of produced cocoons and the chromium concentrations of earthworm tissues were determined. The results of analysis of variance of data showed that the number of living earthworms, their weights and the number of produced cocoons decreased as the exposure time and the level of soil pollution by chromium increased. The chromium concentrations of earthworm tissues increased as the exposure time and the levels of soil chromium increased. The number of living earthworms, their weights and the number of produced cocoons increased as the level of soil organic matter increased.

To evaluate the impact of the application of Tehran municipal solid waste compost (MSWC) on zinc and copper concentrations in the soil under maize (Zea Mays. L.) cultivation, a factorial experiment in base randomized complete block design (RCBD) with two different amounts of municipal solid waste compost (zero, 30.15 and 60 t ha-1) and time (compost applied once or twice) was performed with three replications. The results showed that MSWC has a significant effect on reducing pH and increasing cation exchange capacity and organic carbon (P≤0.01). MSWC significantly increased soil total and DTPA extractable Zn and Cu. (P≤0.01). The highest amount of DTPA extractable zinc and copper respectively observed were 10.82 and 9.29 mg kg-1, respectively in the 60 T ha-1 second year of treatment. As compared with control 97.94% and 110.02% increase were observed for Zn and Cu, respectively. Results showed that MSWC has a significant effect on increasing Zn and Cu concentration in roots and shoots (P≤0.01). The highest amount of zinc and copper uptake was observed in the 60 T ha-1 in second year of treatment, As compared with control respectively 92.36 and 70.26 percent for zinc and 73.87 and 118.62 percent for copper in root and shoot were observed. MSWC for both zinc and copper caused an increase in bioavailable factor, although this was more pronounced for copper. There were significant positive correlation between total and DTPA-extractable Zn and Cu and concentrations of these elements in root and shoot.

Phosphorus is one of the nutritional elements that has an important effect on the quantity and quality of corn plant. Knowledge about the P critical level and plant response to application of P can effectively help with the proper use of this element. Therfore, in this study, P critical level for corn plant (Zea mays L.) was determined using PBC in 25 combined soilsamples from different fields of East Azerbaijan province. To calculate the PBC, current soil P test methods such Olsen, Colwel, Soltanpur and Schowab, Kelna2 and iron impregnated strips as a quantity factor (Q) and the methods of soluble P measurements such as distilled water, calcium chloride and Paauw method as an intensity factor (I) was used. According to the results, the method of PBC (Olsen-P/ Paauw-P) compared to other methods for calculating PBC, was the best method to predict of P uptake by corn plant. The high correlation of PBC (Olsen-P/ Paauw-P) data with the shoot content of phosphorus was confirmed. PBC linear correlation with shoot P content was separated in two positive and negative parts and the positive value of the correlation was 0.91** and negative value was -0.89**. Critical level of soil P for corn with PBC method based on 90% relative dry matter was determined as 2.2, 2.44 and 1.19 by using graphical Cate-Nelson, Cate-Nelson analysis of variance and Mitscherlich-Bray methods, respectively. Mitscherlich-Bray equation coefficient C1 and C, for PBC, were 0.08411 and 0.0122 respectively.

Rice is one of the most important foods for more than half of the world's population. Paddy soils are among the widest wet lands being affected by human activities. Long term rice cultivation and especially flooding conditions have great influence on soil characteristics. This study was conducted in Noorabad County, Fars Province. The aim of this study was to evaluate the effects of long-term rice cultivation on physico-chemical properties and clay mineralogy of the soils of two regions and comparison with the adjacent virgin lands. According to the results, paddy soils showed significant increase in soil organic carbon and oxalate extractable Fe and Mn (Feo, Mno) and significant decrease in soil pH and dithionite extractable Fe and Mn (Fed, Mnd). No significant change was observed between total amounts of these two elements in both land uses. Clay mineralogy investigation showed that rice cultivation has drastically resulted in decrease of palygorskite and increase of smectite contents. Transmission electron microscope (TEM) images showed longer palygorskite fibers (2-3 mm in length) in virgin soils compared to the paddy soils with shorter fibers (0.5 mm), suggested the effect of the physical destruction or transformation of palygorskite to smectite in paddy soils.

Over the past decades, the fallout radionuclides 137Cs, 210Pbex and 7Be are increasingly being used to quantify soil erosion and sedimentation rates. Although studies using 137Cs and to some extent 210Pbex are now well-documented, there is a need for further work aimed at exploring the use of 7Be, particularly in arid and semi-arid areas. Investigating soil erosion processes occurring over shorter timescales, particularly individual storm events or short periods of heavy rainfall is the major advantages of 7Be method over the two other radionuclides. A hillslope 200 meter length, average slope of 8 percent and mean annual rainfall of about 480 mm, located in south west of Kermanshah was selected. Soil sampling was performed in April 2011, after occurring 150 mm rainfall in 40 days, along three transects. The 7Be activity in soil samples was measured by gamma spectrometry. The net erosion rate was estimated to be 6.8t ha-1 yr-1 by using Profile Distribution model. According to the short period, the high net soil erosion rate is most likely the result of the mismanagement of the dry farm, cultivation operation along the main slope direction, the heavy rainfall occurring during the late winter and early spring seasons without major vegetative cover and the steep topography. The sediment delivery ratio was about 80 percent indicating that significant part of the mobilized soil was removed from field by erosion. The results confirm the potential for use of the 7Be technique to determine the soil redistribution associated with short periods in semi-arid area.

Nitrogen is one of the most important nutrients in crop production, but it's losses to the environment is harmful. The SUNDIAL model (simulation model of N dynamics in the soil) was used to quantify the cycle of N and it's losses in different production systems of sugar beet (Beta Vulgaris L.) in former Khorasan province, east of Iran. The data were collected from traditional, semi-mechanized and mechanized production systems in 26 regions of 10 geographic areas of Khorasan (Northern, Razavi and Southern Khorasan provinces) to be used in the model as inputs. Results showed that the total N loss from the soil profile in traditional, semi-mechanized and mechanized systems did not differ significantly and were 50, 41 and 45 kg N ha-1, respectively. In average, 59% of total N loss occurs as gaseous losses and 41% as leaching. The most part of the gaseous losses in traditional system occurs via denitrification (63%), but in semi-mechanized (75%) and mechanized (82%) systems volatilization was dominant. The key finding is that while various systems of sugar beet production are similar with respect to N loss per hectare, they are different with respect to N loss per ton of crop yield. The average of N loss in traditional system was significantly higher than other systems in terms of kg N ton-1. This implies the possibility of reducing N losses and its environmental effects through improving crop management.

Effects of different tillage systems on dispersion ratio, status of aggregation, degree of aggregation, mean weight diameter, geometric diameter, the rain-fed wheat yield and the yield components were investigated by a field trial using a completely randomized block design with five treatments in four replicates during 2009-2010 growing season at Gorgan University of Agricultural Science and Natural Resources Research Farm located at seyedMiran, Gorgan. Tillage treatments used were moldboard plough (20-25 cm) with disc, roto-tiller (12-17 cm), double disc (8-10 cm), Chisel plough (25-30 cm) and No-tillage. Results showed that the maximum and minimum dispersion ratios occured with chisel and moldboard plough respectively which indicate various tillage methods hardly influence aggregate stability in soils with high specific surface. With no concerns for loss in aggregate stability, tillage intensities may be intensified for greater yield goals. Maximum status and degree of aggregation occurred with moldboard ploughing with the consequent increases of potassium root uptake and the yield of wheat at both before heading and harvest stages.

In order to study the changes in chemical forms of zinc in the rhizosphere of two tuber plants and their relationship to plant uptake in a polluted soil, sequential (Tessier et al., 1979) and single step extraction methods were used. In this research, three radish cultivars (Raphanus sativus) and two turnip (Brassica rapa) cultivars were planted in a complete randomized design pot experiment with four replications (20 pots) and 4 pots with no cultivation as blank. Results indicated that the largest forms of zinc include Fe and Al oxide bounded carbonates and the residual forms respectively. The exchangeable and soluble forms comprise only less than one percent of total zinc in the rhizospheric soils of all plants. The zinc concentration of shoots for different cultivars of each plant did not show significant difference and in all plants zinc accumulation factor and the translocation factor were less than unit. Sequential and single step extractions showed significant increase of Zn in the rhizosphere of both plants compared to bulk soil. Different cultivars of both plants could significantly increase the rhizosphere DOC up to 9 mg.L-1, which consequently increased soluble and exchangeable Zn in this zone for both plants compared to bulk soil. Zinc extracted by calcium nitrate and ammonium nitrate had a significant and positive correlation with plant concentration (0.45* and 0.42* respectively) and uptake (0.55* and 0.44* respectively) of Zn. For all cultivars, the rhizosphere soil pH increased compared to bulk soil which was statistically significant for some cultivars.

Cation exchange capacity (CEC) is one of the main factors in monitoring and management of soil quality in order to achieve sustainable production. Although CEC can be measured directly, these measurements are difficult, time-consuming and costly, especially for Aridisols due to their high amounts of calcium and gypsum. One alternative method to direct measurements is the use of pedotransfer functions (PTF), in which CEC of soils is estimated through available soil information. A dataset including 1141 data points was used as the calibration set for development and accuracy test of functions and another independent data set with 232 data points was used for validation of the PTFs. The results showed that, grouping the soils based on clay and organic carbon contents are generally reduced the coefficient of variation of clay, organic carbon and CEC. In general, the grouping of soils declined the correlation of clay and organic carbon with CEC. In soils with organic carbon contents of less than 0.5%, CEC was predicted with reasonable accuracy using only the clay as input. Generally, grouping the soils enhanced the accuracy of the PTFs, while in most cases decreased their reliability. However grouping the soils based on their clay content, except for soils with clay content ≥35%, was more effective in improving the accuracy and reliability of the functions. Results also showed that clay (except for soil with clay content of ≥35%) was the most influential factor in predicting the CEC of the soils, so that including the other variables did not significantly improve the accuracy and reliability of the functions.

The plant growth promoting bacteria as biological fertilizers play an important role in increasing productivity and improving plant growth in stress condition. In order to evaluate the ability of plant promoting rhizobacteria on germination and growth of corn (Zea mays L.) under salinity conditions, a pot experiment was conducted in factorial based on randomized complete block design with three replications at the college of Agriculture, Shahrood University of Technology in 2011. The treatments were consisted of salinity stress at five levels [zero (control), 2, 4, 6 and 8 dSm-1 of sodium chloride] and four levels of bacterial [non-inoculation (control), Azotobacter chroococum, Pseudomonas fluorescens and Pseudomonas putida]. The results showed a significant effect (P<0.01) on maximum germination (Gmax), germination uniformity (GU), time to 10% (D10) and 90% (D90) germination due to salinity stress, while inoculation with PGPR significantly increased Gmax and D10. Also results revealed that Gmax and GU values were decreased and D10 and D90 increased with increasing salinity stress. The interaction effects of salinity stress and bacterial inoculation significantly affected the Gmax values. Bacterial inoculation has significantly increased Gmax values compared to non-inoculation plants in all of salinity levels. Also salinity stress effect was significant (P<0.01) for biomass, root weight, leaf number and height of corn. The highest biomass and plant height were obtained from the inoculation with Azotobacter chrococum. Results indicated that biomass yield and plant height decreased with increasing salinity stress in noninoculated treatments. Based on our results, PGPRs can alleviate the negative effects of salinity stress in corn through increasing plant growth.

Iron is an essential nutrient for rice. Accurate assessment of this element in paddy soils is very important. This study was done in order to investigate available iron, determine the impressive soil factors and choose the best interpolation method for determining spatial variability of plant available iron in 162 soil samples of the paddy fields of Guilan province, around Rasht city. Estimating and interpolating of variables were investigated with kriging (KG) and inverse distance weighting (IDW) methods with power one to four and the best interpolation method was selected using evaluating statistics such as ME and NRMSE. Organic carbon, clay and soil pH by controlling soil reduction conditions had the highest effect on available Iron. Linear, exponential, exponential and spherical semivariogaram models were fitted to soil available iron, organic carbon, clay and pH and the range of OC, clay and pH were 1910, 4940 and 4946 m respectively. IDW method was better than kriging for interpolating available iron. Spatial variability of available iron in the study area showed that high concentration of available iron was in soils with acidic pH (west and southwest regions of study area). Results showed that there was not any shortage in amount of available iron in the studied soils, but in order to retain the amount of available iron in the studied paddy fields, usage of iron fertilizers based on site specific management is necessary.

This research was performed to investigate the combined effect of soil salinity and soil compaction on some physiological characteristics of corn. For this purpose a factorial pot experiment on the basis of completely randomized design with three replications was performed. The experimental factors were three levels of soil salinity (saturated paste extract electrical conductivity of 1.5, 2.5 and 4.5 dS/m) and three levels of soil compaction (bulk density of 1.3, 1.55 and 1.75 g/cm3). For creating salinity, different amounts of NaCl was dissolved in the required volume of distilled water to increase the gravity soil water content to 16% and then added to soil. For creating soil compaction a cylinder with 4.5 kg weight was allowed to fall freely to the soil surface in the pots from 45 cm elevation. Soil salinity led to significant increase in stomatal resistance, proline concentration and Na concentration of corn shoots and caused significant decrease in shoot dry matter. Soil compaction significantly decreased leaf water potential and aerial dry matter and increased stomatal resistance. At the applied range of soil salinity and compaction, soil salinity caused more adverse effects than the soil compaction on physiological characteristics of corn. Despite the fact that the combined effect of soil salinity and compaction became statistically significant only on stomatal resistance and shoot dry matter, combination of soil salinity and compaction led to increase in proline and Na concentration and to decline leaf water potential, relative water content, K concentration and K/Na in corn shoots. Combined effect of salinity and compaction led to more drastic effects than their individual effect on the stomatal resistance and shoot dry matter. Therefore, one of the approaches of soil salinity alleviation could be to avoid or reduce soil compaction.

Soil erosion is a major environmental threat to sustainability and agricultural productivity leading to reduction of soil fertility, loss of nutrients and declines of crop yields in arable lands. In this study, the suitability of SWAT model for simulating the daily runoff and sediment in the Bazoft watershed (one of the main sub-basins of the Karun river basin in central Iran) was investigated. For this purpose, three different climate data sets including climate data obtained from the Bazoft watershed (Bazoft watershed data), the climate research unit data (CRU data) and a combination of the CRU and Bazoft watershed data (Bazoft-CRU data) were first investigated. Then, the potential use of PSO algorithm for calibrating and validating of the model was evaluated. The constructed SWAT model using a combination of the CRU data and the Bazoft climate data had a better runoff simulation performance in the study area. The obtained Nash-Sutcliff (NS) coefficient for the constructed SWAT model using the Bazoft-CRU data was 0.38 while it was 0.31 and 0.21 for the proposed SWAT model using the Bazoft watershed data and the CRU data, respectively. The obtained r-factor and p-factor values in the model calibration period using the PSO algorithm were 1.25 and 0.81, respectively. The R2 and NS coefficients for the validation period were also 0.64 and 0.60, respectively. Furthermore, in the sediment simulation step, the r-factor and p-factor values for the calibration period were 0.69 and 0.85, respectively and they were 0.63 and 0.80 for the validation period, respectively.

Knowledge of the phosphorus (P) forms is essential for understanding the behavior of phosphorus. The aim of this study was to investigate the effect of wheat cultivation on different soil inorganic P forms. A greenhouse factorial experiment in a completely randomized design was carried out with three replications in 20 soil types and plantation at two levels (with and without plantation). The aerial parts were harvested after two months and different forms of phosphorus were determined by Jiang and Gus' inorganic-P fractionation method. The results showed that wheat cultivation had a significant effect on all forms of phosphorus in soil except occluded P in Fe oxides. Duncan's means comparisons test at P. value ≤0.05 also showed that the amount of phosphate dicalcium (Ca2-P) in all of calcareous loess derived soils after wheat cultivation was less than uncultivated soils and it was significant in 30% of soils at P. value ≤5%. Similarly, wheat planting also reduced the amount of octacalcium phosphate (Ca8-P) and aluminum phosphates (Al-P), but the reduction was significant only in three soil samples. Decrease of iron phosphates (Fe-P) and apatite (Ca10-P) after the wheat harvest was significant only in one of the soils studied.

Crop residues are important internal inputs which have been considered for decades to sustain agroecosystems. This experiment was conduceted to evaluate the effect of some fungi on decomposition of crop residues. Crop residues from rice, wheat, cotton, canola and soybean were inoculated with Pleurotus ostreatus, Phanerochaete chrysoporium, Aspergillus niger and Trichoderma viride in vitro. After 30 days, hemicellulose, cellulose, lignin, nitrogen and inorganic carbon were measured in both treated and control samples. The greatest growth rate and establishment occurred for P. ostreatus and these parameters declined for T. viride, A. niger and P. chrysoporium in the written sequence. The rate of fungi establishment after 5 days on different substrata was greatest for soybean and it decreased on cotton, canola, wheat and rice residues. In all residues, hemicellulose was decomposed more than cellulose and lignin. Fungi were also different with respect to their decomposition potentials; maximum hemicellulose decomposition was observed in P. ostreatus with a continuous decline in T. viride, A. niger and P. chrysoporium. Maximum cellulose decomposition occurred by P. ostreatus and T. viride on all substrata except rice. P. ostreatus and P. chrysoporium (Basidiomycota) had the maximum effect on the residue lignin content, while T. viride and A. niger (Ascomycota) had less effect under the same environmental conditions. Results revealed maximum nitrogen mobilization on soybean and rice by A. niger while the minimum one observed on soybean by T. viride, P. ostreatus and P. chrysoporium. Finally it could be concluded that both fungal species and substrate composition are determining for plant residue decomposition rate.

The effect of fire was investigated on some soil chemical properties of forest area of BagheShadi Herat-Yazd Province. To perform the experiment, 18 profiles of soil in control area and 7 profiles from each of burned areas were dug and samples of two depth (0-15 and 15-30) a total of 64 samples were collected. Results showed the area was significantly affected with regard to organic matter and carbon percentage, P and N. The average amount of carbon, organic matter and N in burned areas were significantly more than control. The average amount of carbon, organic matter and N in control were equal to 0.76, 1.31 and 0.82 and in burned area were equal to 1.35, 2.4 and 1.03 respectively. There are significant differences in organic matter and carbon percentage, P and N between two depths of 0-15 and 15-30 and the measured characters were high in 0-15 compared to 15-30. It is concluded that fire can positively be effective in increasing some element such as the average amount of carbon, organic matter and N and therefore other studies such as fauna and flora of soil, erosion possibility and ecological and forestry changes would also be useful studies to be done at the same time.

The challenge for researchers of agricultural sciences is to increase productivity while maintaining or improving environmental quality (including water, soil and air). Rapid population growth and increasing demand for food are the reasons why researchers are continuing to focus their efforts on the management of high yielding varieties that are suitable for rain-fed farming conditions and provide appropriate solutions and technical manuals for planting and harvest to enhance crop production. The purpose of soil conservation tillage is reducing soil tillage operations and crop residue management on soil surface. This study was conducted to investigate the role of different tillage on soil's NPK in some agricultural lands of Kalale. Soil tillage treatments including: conventional, reduced and no tillage that is accomplished with three replications in a completely randomized design. The results of the study have shown that conventional tillage caused the highest N and K contents in comparison to other tillage treatments; while the highest P value was observed when no-till and reduced tillage systems were applied, respectively.