Arezoo Taghipour; S. Rezapour; B. Dovlati; Roghaie Hamzenejad
Abstract
Introduction: Intensified agriculture over a long-term is an important factor in soil change phenomena that can cause some unwanted effects on soil properties. To examine this hypothesis, chemical properties of the soils under sunflower cultivation over five decades and adjoining virgin lands were investigated ...
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Introduction: Intensified agriculture over a long-term is an important factor in soil change phenomena that can cause some unwanted effects on soil properties. To examine this hypothesis, chemical properties of the soils under sunflower cultivation over five decades and adjoining virgin lands were investigated in order to monitor changes caused by long-term cropping. The studied soils are influenced by continuous sunflower cultivation along with flooding irrigation and using chemical fertilizers for over five decades
Materials and Methods: This research was undertaken at Khoy area (38o 10′ to 38o 40′ N latitude and 44o 15′ to 45o 10′ E latitude) as the northern part of western-Azarbaijan province in the north-west Iran. The Khoy area is characterized by a semi-arid climate (mean annual rainfall of 300 mm) linked with soil moisture and temperature regimes of xeric and mesic, respectively. Agriculturally, the studied area is cropped continuously by sunflower-wheat or barley rotations for over five decades and has received irrigation water from rainfall, groundwater, or seasonal river water. Forty soil surface samples (0-30 cm) belonging to 10 soil series from the cultivated soils and the adjoining uncultivated soils were samplied and analyzed for the different chemical properties. In each soil serie, the samples (cultivated soil and adjacent virgin land) were selected in similar slope, aspect, drainage condition, and parent materials. Soil analyses were involved soil pH and electrical conductivity (EC), soil organic carbon (SOC), Calcium carbonate equivalent (CCE), cation exchange capacity (CEC), total N, soluble K, exchangeable K, and available K. Potassium absorption ration (PAR) was calculated by the concentration of solution K, Ca, Mg and exchangeable potassium percentage (EPP) was calculated by exchangeable Na and CEC values
Results and Discussion: This study illustrate that long-term continuous sunflower cropping had considerable effects on some soil chemical attributes. Over five decades of cultivation, a depletion face was observed in soil organic carbon, CCE, and some K forms (solution, exchangeable, available K) for most of the studied soils. In contrast, an enrichment aspect was occurred in the values of EC. The results showed that soil pH and calcium carbonate equivalent were increased by 0.09 – 0.39 units and 16 – 26 g.kg-1, respectively, in most of the examined soils after intensive agricultural practice. Increase in the CCE value may be caused by tillage operation because of the calcareous parent material is tilled periodically by farmers to cultivate a certain depth of soil in the studied soils. Compared to the uncultivated soils, the cultivated soils showed a relative enrichment in electrical conductivity (20 – 80%) which could be attributed to the chemistry of the irrigation water used and the interaction between the irrigation water and its receiving soils. A slight decline was observed in soil CEC values (1 – 9%) probably due to destruction of soil organic matter. There was a decreasing pattern in the content of soil organic carbon with cultivation ranging 17 to 39% which could be associated with the environmental conditions and management practices, i.e. (a) in the cultivated soils much of plant residues is removed or burned after harvest, (b) the present of livestock after harvest which can result in a substantial loss of SOC, (c) breaks up, decomposition, and mineralization of organic matter is accelerated by tillage practices, (d) the relatively high temperature in the cultivated soils compared to the uncultivated soils which might enhance oxidation of organic matter and destroying of organic C. A relative depletion was observed in the mean value of soluble K (10 – 330%), exchangeable K (25 -40%), available K (16 – 41%), potassium absorption ratio (16 – 61%), and exchangeable potassium percentage (26 – 40%) following continuous sunflower cropping mainly as removal of most sunflower residues after harvest and high uptake of K by sunflower as a high –K- requiring crop. In spite of the fact that exchangeable and available K declined by cropping for most of the studied soils, the soils were grouped as optimal to high category based on two the K forms. This means that intensive rotation cropping not be able to deplete soil exchangeable and available K below a certain level manly due to the presence of the high levels of K-bearing minerals.
Conclusion: Overall, the chemical properties of different soil series reflected different responses to (both increasing and decreasing pattern) long-term sunflower cultivation. Organic carbon, soluble and exchangeable K along with EC was known to be the most sensitive indicators following long-term continuous sunflower cropping and irrigation practices. In this cause, it seems hat monitoring the chemical characteristics of both the irrigation water and the soil must be considered in order to establish the water –soil-plant management strategies that will help to prevent environmental degradation and to maintain the overall heath of the studied soils.
zeinab khademolhosseini
Abstract
Introduction:Changes caused by grazing on range ecosystem are generally assessed based on the soil conditions and vegetation. Livestock as one of the major elements in range land ecosystems has different effects on different parts of this ecosystem. One of these impacts is excessive livestock grazing ...
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Introduction:Changes caused by grazing on range ecosystem are generally assessed based on the soil conditions and vegetation. Livestock as one of the major elements in range land ecosystems has different effects on different parts of this ecosystem. One of these impacts is excessive livestock grazing capacity which can have different effects on soils and plants in various intensities.
Materials and Methods:Gardaneh ZanbooriRangelandis located in Arsanjan in Fars province. This isanareaof mountains, hillsandplains with the maximum height of 2280 meters and minimum height of 1640 meters above sea level. Related areas were separated under three different management methods of enclosure, moderate grazing and heavy grazing. These three areas are considered as symbolic areas of grazing intensity including the reference area where no grazing intensity was observed, the key area where medium to heavy grazing was applied and critical area where heavy grazing was used. These areas were similar in all characteristics such as topography, soil type and rainfall and differed only in their grazing intensity factor. Then, soil samples were collected. Random systematic soil sampling was conducted at two horizons of 0 -15 and 15 -30 cm. Therefore, five profiles in each area (enclosure, moderate grazing and heavy grazing), a total of 15 soil profiles, were excavated and two samples were taken in each profile (one sample from each horizon). Finally, the thirty soil samples were transported to the laboratory. Samples were dried in the air laboratory and passed a two millimeter sieve after smashing. Factors such as N, P, K, OM, EC and PH were measured in each sample In the laboratory, the percentage of P was determined by the Olsen method while the percentage of K was determined using the flamephotometry method. Moreover, N was measured using the Kjeldhal method. C was measured by the Walkley and Black method. The percentage of OM was found by carbon multiplying percentage at 1.72 numbers. PH was determined with measuring the PH of saturated soil by PH meter machine. Measurement of soil EC was performed by the electrical conductivity meter. Data analysis was conducted by SPSS software. Comparing of mean values for each factor and between areas with different grazing intensity was done by the Tukey test.
Results and Discussion: Two-way analysis of variance and Tukey test showed no significant differences in term of N, OM and PH between critical and reference areas. But the amount of N and OM in the key area is lower than that of the reference and critical areas. While value of PH is higher than the other regions. Also values of P and K decreased within creasing grazing intensity but the EC factor increased.
Conclusion: Since vegetation removal and its exclusion from the ecosystem followed by considerable effect on the cycle of nutrient elements and their absorbability, it seems that in the studied ranges, the P and K elements decrease through the use and leaving of vegetation in the area. The results of N and OM showed that moderate grazing causes further decomposition of plant residues and organic nitrogen mineralization but there was no difference between the two treatments of heavy grazing and enclosure areas. In heavy grazing intensity, the amount of OM and N increases by several mechanisms. First, with soil bulk density and increased soil compaction, the oxygen supply and degradation rate decreases. In the second mechanism, intensive grazing changes the vegetation composition and root to shoot ratio. In the third mechanism, animal urine and feces can speed up the nitrogen cycle in grassland ecosystems. It seems that the simultaneous effect of the above factors studied in the related range causes no significant difference between heavy grazing and enclosure areas in the percentage of total nitrogen. EC is the lowest in the enclosure area. This is due to the absence of livestock and therefore no stepping on the soil and also more vegetation. The PH level of enclosure area is less than that of the moderate grazing area. This may be caused by more presence of organic matter in the soil of enclosure. When organic matter decomposes, organic acid and mineral acids are produced. Permanent production of acids in the soil in places where the root density is high causes dissolution of limestone and the soil is washed and so it reduces the PH.
payam najafi; S.H. Tabatabaei; H. Taheri-Sodejani
Abstract
Introduction: Reuse of wastewater for agricultural irrigation is increasing due to an increased demand for water resources in different parts of the world. Almost 70% of deviated water from rivers and pumped groundwater is used for agriculture. If wastewater is used for irrigation in agriculture, then ...
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Introduction: Reuse of wastewater for agricultural irrigation is increasing due to an increased demand for water resources in different parts of the world. Almost 70% of deviated water from rivers and pumped groundwater is used for agriculture. If wastewater is used for irrigation in agriculture, then the amount of discharged water from natural sources will be decreased and the flow of wastewater to the environment and its ensuing pollution will be prevented. Using wastewater in applications such as irrigation of agricultural lands has caused an increase of some exchangeable ions, salts and suspended solids (organic and mineral) in the soil and has significantly affected physical, chemical and biological features. Therefore, paying attention to the soil health is important during use of wastewater when it is the source of irrigation water. In such cases, there will be some worries about pollution of harvested products, contact of farm workers with pathogenes and environmental issues in the farm. In these conditions, attention to irrigation methods along with consideration of environmental protection standards is important.
Materials and Methods: In this study, the effects of treated wastewater (TW) irrigation were tested on some chemical properties of soil for three years under five different irrigation treatments. The treatments were as follows: surface furrow irrigation (FI), surface drip irrigation (SDI), subsurface drip irrigation in 30 cm depth (SDI30), subsurface drip irrigation in 60 cm depth (SDI60) and bubbler irrigation (BI). At the end of the experiment, soil samples were collected from a depth of 0-30, 30-60 and 60-90 cm in order to measure the electrical conductivity (EC), pH, sodium adsorption ratio (SAR), organic matter (OM) and calcium carbonate equivalent (CaCO3).
Results and Discussion: According to the results of soil analysis, the soil became more saline than the beginning by applying the treatments. Generally, in two plots of urban and industrial wastewater, the least salinity was observed in SDI (19.0% increase in salinity) and the maximum value of these parameters was observed in BI (99.7% increase in salinity). The results showed that average SAR in soil saturation extract of three layers were 5.5 and 6.6 dS m-1, respectively for urban and industrial plots. Considering these values along with EC, the soil will be categoraized as normal soil in terms of salinity and alkalinity. An increase of 14.3 % in BI and 8.2% in SID30 were observed in comparison with the initial values of the period. These were the extremums for SAR. The results also showed that the application of TW caused a 38.75 % reduction in SAR for the 30-60 cm. Soil pH of the plots under study was decreased significantly and reached its acceptable limit in the soil during the experiment. On the average, the pH of soil layer has been 7.4 and 7.3 for urban and industrial plots, respectively. The results showed that soil organic matter was influenced by the irrigation method and this was more pronounced in the location of wastewater injection. In the soil surface, the highest amount of organic matter was observed in treatment FI and SDI. However, in a depth of 30-60 and 60-90, SDI30 and SDI60 revealed the highest amount of organic matter content. The average concentration of chloride (Cl-) ions in industrial wastewater (12.3 meq L-1) was more than that of urban wastewater (7.3 meq L-1). Therefore, the effect of industrial wastewater on increasing soil Cl- has been more pronounced than that of urban wastewater. Soil Cl- was increased at the location of wastewater injection and the highest amount of Cl- in the irrigation treatments was observed in BI. The results also showed that the application of TW caused a 23.4% reduction in soil CaCO3 content at a depth of 60-90 cm. The lowest amount of CaCO3 was recorded in treatment SDI60. There was no significant difference between the average of irrigation treatments in the urban plots. But in the last layer, it showed that SDI30 had a significant difference with both SDI and SDI60, in the industrial plots.
Conclusion: Generally, SDI irrigation in the root zone depth (in this study was up to 60 cm) is recommended for protecting safe environmental conditions, supplying water demand in the root zone and improving soil quality.
Keywords: Industrial wastewater, Irrigation methods, Soil chemical properties, Urban wastewater
A. Atefi; ali asghar ghaemi
Abstract
The aim of the present research is to study the effect of both different irrigation water quality (treated wastewater and urban water) and N. P. K fertilizer via Tape subsurface micro irrigation on the soil chemical properties in the test area was investigated in Fras Bajgah Region in 2010. In this study, ...
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The aim of the present research is to study the effect of both different irrigation water quality (treated wastewater and urban water) and N. P. K fertilizer via Tape subsurface micro irrigation on the soil chemical properties in the test area was investigated in Fras Bajgah Region in 2010. In this study, the impact of treated Shiraz urban wastewater under micro irrigation in broccoli cultivation on the soil chemical properties was evaluated. According to the results of this research, Electrical Conductivity to a depth of 30 cm of soil was increased significantly due to irrigation with wastewater and irrigation fertilizer comparing to urban water. Also, using wastewater increased pH in surface layer of soil. Although, considering the buffer wastewater and soil environment and its resistance to ph variations, there was little increase. Moreover, the treatment containing the wastewater was led to increase Sodium Absorption Ratio (SAR) in the surface layer of soil. However, this effect was more in treatments which that have benefited the fertilizer and wastewater. Also, variations of Bicarbonate , Sulfate and accumulation B , sodium;Na, ferro;Fe, zinc;Zn, copper;Cu, potassium;K and magnesium;Mg, to a depth of 30 cm of soil and also the accumulation of nitrogen, calcium, phosphorus in the depth of soil in an area under studying was increased significantly due to irrigation with wastewater and irrigation fertilizer comparing to urban water. As expected, using the wastewater increases the concentration of heavy metals of nickel, lead and cadmium in under studying soil area.
