Asieh Naroie; Javad Zamani; Shapour Kohestani; Farideh Abbaszadeh Afshar
Abstract
Introduction: The application of biochar in soil as a method for disposal of organic wastes from environment has been considered by environmental scientists in recent years, due to the unique properties of these components. Biochar is a carbon-rich compound that is produced by burning different types ...
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Introduction: The application of biochar in soil as a method for disposal of organic wastes from environment has been considered by environmental scientists in recent years, due to the unique properties of these components. Biochar is a carbon-rich compound that is produced by burning different types of organic wastes under anaerobic or limited supply of oxygen, which called pyrolysis. Biochar due to its physicochemical properties such as porous structure, expanded specific surface area, high organic carbon content, active functional groups, and also high cation-exchange capacity could able to stabilize organic and mineral compounds. Many studies showed that the biochars enhance soil fertility and improve plant growth but if we want to recommend or apply a specific biochar as an amendment of soil, it's necessary to know about the effects of this biochar on the soil properties and growth of plant. So, the aim of this study was to find out the effect of two biochar (biochar of Date Palm's Leaves (DPL biochar) and biochar of Pistchio Harvesting wastes (PW biochar)) on the growth and heavy metals concentrations of Maize (Zea mays L.) under two different soil textures (Sandy and Sandy Loam).Materials and Methods: This study was conducted in a greenhouse condition on the growth of maize in two types of soil (Sandy and Sandy Loam) with application of 5 levels (0, 1, 2, 3 and 5% w/w) of two different types of biocahr (DPL biochar and PW biochar). Maize were cultivated in treatments for 38 days and at harvesting the shoot and root dry weight and shoot height were measured. Also, the concentration of heavy metals (including Fe, Zn, Cu, Mn, Ni, Pb, and Cd) in plant shoots were evaluated.Results and Discussion: The result showed that the growth of maize severely decreased due to the application of the biochar and the negative effect of PW biochar was more than DPL biochar. Meanwhile, the negative effect of PW biochar on plant growth in sandy soil was more than other one (i.e. Sandy Loam soil), which medium (2 and 3% w/w) and high (5% w/w) levels of this biochar caused the plant to stop growing. Also application of 5% of DPL biochar in Sandy Loam soil caused in a decrease of about 19, 69 and 72% in plant height, shoot dry weight and root dry weight of maize in compared with control (without biochar application in this soil), respectively and these ratios were about 15, 44 and 31% with application of 3% DPL biochar; while with application of 3% of PW biochar in sandy loam soil has decreased plant height, shoot dry weight and root dry weight of maize about 17, 53 and 37%, in compared to control respectively. These results approved the greater negative effect of PW biochar on plant growth. Assessment of soil salinity as the application of different levels of biochars showed that these materials increased salinity and thus had a negative effect on plant growth. In overall, the results of this study showed that the use of different biochars have different effects on plant growth, since most of biochars have high salinity, coarse-textured soils could more affected by salinity, because of the lower water holding capacity of this soils. Since, biochar is a stable substance, the results of the concentration of elements in the shoot of plants showed that the concentration of most elements not significantly affected by the application of biochar, however the increase in Fe concentration in sandy soil due to application of PW biochar, also Mn uptake in the effect of applying 1% of DPL biochar was observed. On the other hand, the results of this part of the research showed that DPL biochar at higher levels has even reduced the concentration of Mn in the plant. The results of this section also showed that the application of biochar in sandy loam soil, although it was significant on the concentration of heavy metals Pb and Cd in the plant and had slightly increased them, but their concentration was less than critical levels (dangerous) for human health.Conclusion: The effect of biochar on improving plant growth can be greatly influenced by the combined effect of biochar properties and soil conditions. The results showed that despite the many benefits of the soil application of biochar in the different scientific literatures, it is necessary to study the effect of biochar on soil properties and plant growth before applying any type of biochar in the soil.
Fatemeh Miri; Javad Zamani babgohari
Abstract
Introduction: Biochar which is used as a soil amendment, is defined as a stable-carbon-rich product, and can endure in soil for thousands of years. Biochar is produced from biomass such as wood, manure, leaves, and other agricultural waste via pyrolysis, by heating at temperatures 300-1000°C in a ...
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Introduction: Biochar which is used as a soil amendment, is defined as a stable-carbon-rich product, and can endure in soil for thousands of years. Biochar is produced from biomass such as wood, manure, leaves, and other agricultural waste via pyrolysis, by heating at temperatures 300-1000°C in a closed container with little or no available air. Biochar, because of its potential to improve the physical and chemical properties of soil, is known as an effective soil amendment. Different types of organic waste particularly the residual of plants can be used as feedstock to produce biochar, but it's important to assess the Biochar properties to apply it as a soil amendment.Materials and Methods: In this study, we investigated some physicochemical properties of biochar of pistachio ́s waste, produced in different pyrolysis temperatures. The pistachio harvesting waste was collect from pistachio orchards in Zarand city, which mainly consisted of the green husk, pistachio cluster, leaves and small amounts of nut and woody shell and thin wood waste. A series of biochar were produced from pistachio waste by slow pyrolysis at different temperatures (300, 450, 600 and 750◦C, for 2 h) to find out the best temperature for the preparation of biochar from this matter. After preparation of biochars, their physicochemical properties including pH, electrical conductivity (EC), bulk density, particle density, biochar yield (mass of the biochar to dry mass of feedstock), ash content, water holding capacity (WHC) and stable-OC, were measured.Results and Discussion: In general, optimal biochar is the one that its yield, water holding capacity and stable organic carbon (OC) are higher and its electrical conductivity is lower. The results showed that as temperature increased from 300 to 750◦C, biochar yield and bulk density of the biochar decreased. In contrast, with increasing the temperature, pH, EC, particle density, ash content and stability of OC were increased. The electrical conductivity (EC) in the feedstock material was about 5.8 dS/m and their conversion to biochar and the increasing of pyrolysis temperature, increased the salinity of this material. The highest of EC was observed at 750◦C which was more than 2.5 and 6 times than in at temperature 300◦C and in the feedstock, respectively. The biochars produced at all temperatures have a high pH which it may be considered as an amendment for the reclamation of acidic soils, however the high salinity of the biochars could be a negative factor for plant growth. Also, as the pyrolysis temperature increased, the amount of ash in the biochar increased. The highest of ash content was observed at the highest temperature (58.3%) which was about 460% more than in the feedstock. Stable organic carbon in biochars produced at temperatures of 300, 450, 600 and 750◦C was about 49, 206, 227 and 227% higher than that of raw pistachio residue, respectively; and the percentage of yield of biochar at 300◦C was more than 65% higher than that of 750◦C. Although the WHC of biochars in different temperatures had no clear trend; it was slightly lower at a temperature of 450◦C in compared to the other temperatures. Also, in a trend, the biochars prepared at the higher temperatures showed higher stable-OC but lower yield.Conclusion: The temperature of the pyrolysis process is a key factor in the yield, quality, and physicochemical properties of the pistachio’s waste biochar. In the context of carbon sequestration as an environmental aspect and more yield of biochar as an economic aspect in the production of biochar and application of this matter in the soil, our results recommend the preparation of biochar from pistachio ́s waste, at temperature 450◦C or 600◦C, or a temperature in between. In the previous studies it has also been shown, the biochars produced at temperatures of 450◦C or higher was most likely to improve soil drainage and make more water available to plants but it needs more energy in the production procedure, while ones produced at lower temperatures could induce soil water repellency.Temperature of pyrolysis process is a key factor on yield, quality, and physicochemical properties of the pistachio’s waste biochar. In context of carbon sequestration as an environmental aspect and more yield of biochar as an economic aspect in production of biochar and application of this matter in soil, our results recommend the preparation of biochar from pistachio ́s waste, at temperature 450◦C or 600◦C, or a temperature in between. In the previous studies it has also been shown, the Biochars produced at temperatures of 450◦C or higher was most likely to improve soil drainage and make more water available to plants but it needs more energy in production procedure, while ones produced at lower temperatures could may induce soil water repellency.
Soil, Water and Plant Relationships
Javad Zamani; Mohammad Ali Hajabbasi
Abstract
Introduction Due to the difficulties in observing root growth in soil, our knowledge regarding soil-root system is limited. The roots are the hidden half of the plants but our knowledge of root’s growing is limited. Now, there are some methods and devices that have been used to analyze and monitoring ...
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Introduction Due to the difficulties in observing root growth in soil, our knowledge regarding soil-root system is limited. The roots are the hidden half of the plants but our knowledge of root’s growing is limited. Now, there are some methods and devices that have been used to analyze and monitoring roots architecture and growth and their relation with soil. The assessment of the root growth of plants is possible with some photographic techniques such as neutron radiography and tomography, as well X-Ray imaging, but the use of these methods for root studies is very costly especially in Iran. The use of the rhizotron can also be one of the most practical and cost effective methods. The rhizotron is a box with a transparent side and uses to study the roots growing by photography or drawing roots on transparent acetate sheets. Here we aimed to introduce the rhizotron as a technique for studying plant roots, and conducted this study to investigate the effects of heterogeneous petroleum pollution in soil and endophytic fungus on growth and distribution of maize root. Materials and Methods In order to bring rhizotron forward as a method for in situ assessment of growth, establishment and distribution of plant roots a greenhouse experiment was performed. The effect of Piriformospora indica and soil petroleum polluted layers on the growth and distribution of maize (Zea mays L.) roots was studied. The rhizotrons had a wooden frame and back plate, and a removable front cover made of a 4 mm thick glass plate. The inner space was 30 cm high, 20.5 cm wide, and 1.5 cm thick (Figure 1a). The rhizotrons were placed on a rack with a 45˚ inclination to induce roots growing along the front glass to enable visual growth monitoring. The front glass plate was covered with an opaque black plastic to prevent light entering except for the times of observation. Two different patterns of soil-petroleum contamination layering were generated in the packings of the rhizotrons. 1) a shallow layer of 2.5 cm thick petroleum-contaminated soil, underlying of a 2.5 cm and above a 22.5 cm layer of uncontaminated soil (NSC), and 2) 27.5 cm of uncontaminated soil (‘control’). The packing procedure was layer by layer using uniform filling in all three cases. The contaminated soil layers were covered with a 2.5 cm layer of uncontaminated soil in order to facilitate plant establishment. The experiment with three replications was included as the packing methods each for growing maize plants inoculated with and without P. indica, and plant-free controls. The root development was recorded 12, 16, 22, 26, 33, and 45 days after transplanting by tracing all roots that were visible through the front glass on acetate transparencies, then were scanned at 300 dpi and analyzed for parameters such as root length, number of root tips and depth of rooting using the SmartRoot plugin of the software package ImageJ. After the last recording, the experiment was terminated. Roots and shoots were separated after harvesting, weighed and oven-dried. Rhizosphere soil samples were taken from the layer 2.5–5.0 cm below the soil surface for total petroleum hydrocarbons analysis. Results and Discussion The results well showed that root length, root depth and number of root tips could be monitored by this method. The presence of petroleum pollution in the soil significantly decreased the growth and distribution of roots but inoculated plants had more root length and root depth than uninoculated plants. The number of root tips which representing lateral distribution of roots had similar trend with root the length and they were significantly increased in the inoculated plants as compared with uninoculated ones. Results showed that inoculation of maize by P. indica increases root biomass more than the aboveground biomass. Conclusion Despite the limitation in the study of the effect of soil treatments on the growth and distribution of plant roots, the use of rhizotron could be a technique to solve this limitation. Our study proved that by using of rhizotron we can show the growth and 2-dimension distribution of plant roots, while the effects of treatment and root-soil interaction could also be assessing by this device.
