By 2025, the global demand for maize (Zea mays L.) is expected to double, dictating the need to become the highest producing cereal crop (Ray, et al., 2013). Use of new technologies to increase food production has become essential so as to ensure food security and alleviate hunger. The Greenseeder® Hand Planter was developed by researchers at Oklahoma State University to assist in addressing this global challenge. The study’s purpose was to describe perceptions of early users of the Greenseeder® Hand Planter. An online questionnaire was sent to participants in 30 countries, including those in Africa, Asia, Central America, Europe, South America and the United States. A large majority (83.3%) of respondents indicated they would definitely or probably continue using the hand planter. Two-thirds of the respondents perceived the hand planter was somewhat better than other planting techniques. Participants reported that the hand planter presented relative advantages (Rogers, 2003) compared to other traditional planting tools, i.e., was more convenient; easier to use in some soils; reduced their workloads and it provided more time to do other farming activities. Two-thirds of the respondents indicated they would definitely recommend the tool to other farmers.
The influence of different irrigation water amounts was evaluated on tomato cultivation in the field experiment conducted in greenhouse, in Tokyo University of Agriculture, Japan, to determine the optimal water use amounts for dry season agriculture for vegetable cultivation in Uganda. The field was divided into three blocks (A, B and C) and soil samples were taken from each block for laboratory analysis. Hydraulic discharge measurement of low pressure drip irrigations system was carried out to assess the application efficiency of emitter discharge due to varying pressure distribution. Different irrigation water amounts (2 mm, 3 mm and 4 mm) were applied to blocks A, B and C respectively after 14 days of transplanting and tensiometers were installed to monitor the matrix potential at 10 cm soil depth. The results showed that the difference in emitter discharge was nearly constant due to small pressure distance of 5 m that corresponds to the field length. From statistical analysis, application of 4 mm and 3 mm irrigation water amounts had no significant difference on tomato growth, although 2 mm affects growth which could lead to wilting. Therefore, we can help smallholder farmers in Uganda, to optimize and save irrigation water use during dry and moisture deficit seasons, without affecting the crop growth and yield by application of 3 mm/day.
The Day forest, containing one of the only two relic forested areas of Djibouti is disappearing at an alarming rate mainly due to a combination of man-induced degradation and climatic condition. We investigate the forest cover dynamics changes in Day forest by using multi-spectral temporal satellite imagery series (from 1990 to 2016). The research was conducted by two approaches that employ different method to assess dynamics changes. First, we proceed with image differencing procedure of NDVI of different dates in order to quantify the overall vegetation change that occurred throughout time. Then, differences between the NDVI are classified as either forest gain or forest loss. Finally, we compared the resulted classified forest dynamics changes against the post classification comparison method. The results of both methods indicated a drastic decrease in the forested area Since 1990 to 2016. From 15 km2 (NDVI differencing) and 28 km2 (post classification) in 1990 to 204 km2. (NDVI differencing) and 216 km2 (post classification) in 2016. The recent climatic changes (period of drought since 1999) and the anthropogenic activities in the area are the main resean why such regression is observed.
Meteorological data of sufficient quality and quantity is not readily available in developing countries given the limitations in obtaining continuous, reliable and high time resolution data. However, it is possible to estimate rainfall using Precipitation Radar sensor and other satellite-mounted sensors. The observed result and processed data are available as free rainfall data namely: “Global Satellite Mapping of Precipitation (GSMaP)”. In order to verify GSMaP data, rainfall data observed in Eastern Uganda from the period 2015 to 2016 was used. Both the accuracy of detection of the rainfall event and the rainfall amount were verified based on the comparison of hourly GSMaP products and totalized hourly, 3 hourly, 6 hourly,12 hourly and 24 hourly observed rainfall data. Although Near Real-Time dataset of GSMaP showed the highest Possibility of Detection, it showed the lowest performance in False Alarm Ratio. The measured rainfall amount and trend become closer as the interval increases from 1 hour to 24 hours in general, despite GSMaP data being underestimated compared to the observed rainfall data. The trend of accumulated rainfall data during the observation period was established and it is observed that the onset of the rainy season can be identified from GSMaP data.
The Tottori Sand Dunes, located along the Sanin Coast of Japan, are a UNESCO Global Geopark and popular tourist attraction with millions of visitors every year. Monitoring of environmental conditions is needed for protection and utilization of the dunes. We investigated three-dimensional (3D) modeling by UAV (Unmanned Aerial Vehicle: Drone) for cost- and time-efficient environmental monitoring of the dunes. The objectives of this paper were (i) aerial photogrammetry and 3D modeling of the dunes using UAV, and (ii) validation and evaluation of the 3D models. 1682 vertical photographs (side overlap: 60%, and top-bottom overlap: 80%) were taken at altitudes of approximately 100 m above ground level using an UAV (Phantom3 professional, DJI) for a 1500 m2 area of the dunes. The obtained images were processed using SfM software (PhotoScan Professional, Agisoft) for building 3D models. The position data of survey piles in the dunes were used as the GCP (ground control point) setting for image processing and model evaluation. We were able to build high-resolution 3D models with colorful texture that enable environmental monitoring of the dunes. Reasonably accurate models were built when a large number of survey piles were used as GCPs during processing. Accuracy of the models was further improved when only a small number of GCPs were used for modeling by (i) excluding inappropriate GCPs, (ii) setting GCPs for large areas, and (iii) adding a center point as a GCP.
Soil identification in arid areas, specifically at remote locations, is a difficult proposition. Current methodologies used in remote sensing techniques to identify Laterite soils have low reliability. In this paper, the new index “Normalized Difference Laterite Soil Index (NDLSI)” were developed for identification of Laterite soil by suppressing signature of vegetation using NDVI on RS data. The NDLSI were validated in Bidar taluk, which is a part of Deccan plateau, located in North-Eastern part of Karnataka, India. Spectral band combination of Landsat 8 OLI_TIRS (15th April, 2017) imagery were used to delineate the soil category. At first, conventional NDVI index is used to differentiate between vegetation and water body. Then SWIR (Band 6) along with Cirrus cloud (Band 9) were used to detect the Laterite soil. Ground verification showed the robustness of methodology with an accuracy of over 85%.
It is necessary for root of seedlings to firmly take root in the surrounding soil in afforestation in the desert in order to improve the revitalization rate of the seedlings. Previous studies have reported that root elongation is promoted by applying a constant electric field to the roots. In contrast, details of its elongation mechanism have not been clarified. In the present study, we focused on eucalyptus, used for afforestation in Australia, examined the mechanism of elongation of roots by application of electric field as follows. 1. Measurement of response time of plants against application of electric field, 2. Influence of addition of plant hormones upon application of electric field. When the electric field application time was changed from several hours to several minutes, growth response to the electric field was not confirmed at short electric field application time. In addition, growth promoting effect of the electric field application was not observed by adding plant hormones. However, long term electric application caused oblivious growth of roots and pH changing of the rhizosphere. Therefore, it was suggested that the eucalyptus growth due to the application of electric field requires a certain amount of application time, and physiological growth through plant hormones is occurring.
The progressing irrigation water shortage and land degradation has been challenging conventional agriculture in western Uzbekistan. With the aim to restore the degraded farm lands and to prevent further salinization and desertification, the Uzbekistan government has been promoting in recent years an alternative water-saving and value-added agriculture, such as domestication and farm production of native medicinal plants. We thus studied seed germination characteristics of Ephedra equisetina Bunge. to provide a basis for its cultivation. Based on the results we assessed different light emitting diode (LED) light factors that may promote E. equisetina seed germination. Experiments were made at the Advanced Plant Factory of Tokyo University of Agriculture and Technology for comparing pulp-coated and uncoated Ephedra seeds in their germination and establishment under different light colors. The seeds germinated in 24-hour LED illumination, with red light (660 nm) and blue light (460 nm) and dark (as a control), under 28/18°C day/night temperature and 40% relative humidity conditions. We used four replicates of 40 seeds in each treatment. Germination of pulp-coated E. equisetina seeds increased significantly under red light compared to control and decreased slightly under blue light. Meanwhile, germination of the uncoated seeds increased significantly under blue light compared to control and decreased relatively under red light. Red light had positive effect on seminal root growth of both pulp-coated and uncoated seeds, while shoot growth of pulp-coated seeds were higher in control. In germination of uncoated seeds, shoot length and seminal root growth significantly increased with red- and blue-light treatments compared to control.
Juniperus sabina L. is an evergreen shrub with prostrate life form that can effectively fix sand and is autogenous species at Mu Us Sandy Land in China and expects important tree species for revegetation. We dug for the individual growing on the southeastward slope of the fixed sand dune, and measured underground tree form and checked for the existence of adventitious roots. Based on these date, 3D tree form diagram was set out to clarify the structure of subterranean tree form on the fixed sand dune. The downward parts can’t observe in the pit. The underground parts formed two-stage stratified structure. Due to this subterranean tree form, the individual dug from the fixed sand dune had been growing above ground. These results show that J. sabina can survive after the axes buried by sand. Adventitious roots were located on the buried axes and the axes grew a reverse triangular pyramid shape underground. This growth occurred next to basal side where the adventitious roots exist. Some species in an environment with moving sand have been reported that the amount of growth increase with an increase biomass of adventitious roots from the buried main shoot. J. sabina is also suggested that the amount of growth increases by using adventitious roots on the buried axes. Characteristics of J. sabina for the sand burial would be associated with the fixation of the semi-fixed sand dunes.
In the Inner Asian Gobi desert, vegetation distribution mainly has annual herbs and perennial shrubs. Annual plants strongly depend on rainfall, and perennial plants can survive even in years of extreme drought. In this study, we used remote sensing method and field experiment method, to extract the area where regime shift had occurred in semi-arid region and to estimate the critical wind speed of dust emission from dry lake beds and desert steppe. Hovmoller diagrams are efficient for displaying large amounts of data in a meaningful manner. Hovmoller (time-longitude) diagrams were generated to summarize and examine the space-time features of seasonal evolution and the anomaly patterns for the entire monthly time series during 1985-2013. Because of analyzing the Hovmoller diagrams generated using vegetation index and precipitation data, NDVI values tended to increase with increasing precipitation during the vegetation growth period (VGP) between May and September. Vegetation showed high response to precipitation during the VGP. Moreover, the results of this study showed that the areas with less precipitation were more sensitive to the dynamics of precipitation than the areas with more precipitation. The most degraded area was the southwest region of Gobi with the least precipitation. The NDVI values responded to precipitation over vast areas including Inner Mongolia, China. In some areas, we estimated that the ecosystem has been destroyed and regime shift of ecosystem had occurred.
To automatically meet crop water requirement and regulate drought stress to enhance sugar content, a capillary-driven automatic irrigation system (new sand ponics, NSP) was invented. This system keeps water level below the root zone which is packed with a non-woven fabric and water is automatically supplied by capillary force responding to root water uptake. However, this upward capillary movement irreversibly accumulates salts unless leaching is carried out. To examine whether NSP can still be profitable in spite of additionally required water for leaching, we carried out an experiment under green houses. Tomato was cultivated using 1000 ppm NaCl solution containing fertilizer at constant daily application rate. Leaching was carried out when estimated root zone salinity reached prescribed limit. Income was calculated assuming that 30 USD/kg of sugar while water price was assumed to be 1 USD/t. Results showed that NSP can still be more profitable than SP even when frequent leaching is required.
Coal fly ash (FA) was tested as soil water retention agent aiming for FA recycle in arid areas. Effects of raw and apatite-synthesized FA amendment on water retention capacity (WRC) of soils and sands were analyzed. Apatite-synthesized FA with certain phosphorous/calcium ratio was effective to increase WRC, in particular at high temperature. This study found that specific surface area and water repellency were insufficient to explain positive effect of apatite-synthesized FA amendment on WRC.
In arid and semiarid regions of China, the decrease in agricultural production due to excessive salts is a very serious problem. In addition, the accelerating urbanization has generated a huge amount of construction and demolition wastes. Therefore, we have investigated the effectiveness as salt-affected soil amendment of cement fine powder (CFP) and waste concrete particle (WCP) and compared with the effect of soil amelioration using a gypsum from wet flue gas desulfurization process (W-FGDG). In this study, sodic soil in Yinchuan of China (pH=10.4, EC=2.4 dSm-1 and ESP=56.4%) was used in amelioration test. Waste CFP (≦200 µm) and three WCPs (0.6-1.0 mm, ≦2.36 mm and ≦4.75 mm) were examined as a soil amendment. The CFP and three WCPs based on both 0.5 wt% application rate of W-FGDG were examined in soil amelioration test. Soil chemical properties (pH, EC, exchangeable Na and soluble ions (Na and Ca)) before and after mixing with soil amendments were examined. The pH and EC value in CFP and WCPs took the higher value than W-FGDG as soil amendments, but the Ca concentration that is effective for salt-affected soil amelioration in WCP could be confirmed an adequate quantity for amelioration compared to W-FGDG. In addition, the application rate and the soil amelioration time were determined from the result in Ca elution of WCP. And the order of Ca concentration in soil amendments was W-FGDG>WCP>CFP. Consequently, salt-affected soil decreased drastically in EC and ESP using CFP and WCPs. Thus we could propose a new salt-affected soil amelioration method using CFP and WCP in China.
In Uzbekistan, secondary salinization of irrigated lands is caused by rising groundwater level due to excessive irrigation and drainage system malfunction. Countermeasures such as drainage system maintenance, drainage facility construction, and leaching have been adopted to control salinity. However, there are still fields where salinity levels remain high because of incomplete dredging operations, reduced deep subsurface drainage system discharge capacity, or ineffective approaches to vertical drainage operations. To achieve stable production and crop diversification, prompt salt removal is necessary. Thus, we proposed a shallow subsurface drainage technology to ensure effective salt removal from the surface soil layer. The technology was investigated in combination with a new drain drilling technique (cut-drain) developed in Japan. It was experimentally introduced in farmers’ fields in the Syrdarya Province. A leaching test performed in the study field revealed that highly saline water was observed at the outlet of the drainage pipe. The results of our study showed an approximately 20% increase in cotton yield, along with a decreasing salinity trend in the surface soil layer. Our study demonstrated that this technology can be employed as an effective measure for controlling salinity in a field.
During the trial of the afforestation of a dry area in Western Australia for carbon fixation, it was found that Eucalyptus camaldulensis, a species of broadleaf tree, is superior as a plantation tree. Gasification of the trees is a promising energy conversion method which can ongoingly reduce carbon dioxide emissions from the fossil fuel. In the present study, the gasification rate of the char produced by pyrolysis of E. camaldulensis was measured and was found to be reduced at the pyrolysis temperature higher than 1100°C, while it was partly recovered at high conversion. The present phenomena were explained by ash deposit on char surface, which was once released at high conversion.
Agriculture, particularly livestock production, is central to the livelihoods of families in Afghanistan, with over 80% of Afghans directly involved in agricultural production. However, in the country’s arid and semi-arid environments, livestock producers often face substantial losses in years of drought, primarily caused by inadequate access to nutrition for animals. Compounding the biological constraints of forage and fodder production are the challenges faced by the Ministry of Agriculture, Irrigation, and Livestock (MAIL) to develop, evaluate, and disseminate innovations and agronomic packages for farmers and herders to mitigate these constraints. This paper presents preliminary results from applied trials and field demonstrations of a variety of forage and fodder crops. Based on this work we conclude that there are forage varieties showing tolerance to limited water and fertility resources that are readily adaptable to the varied Afghan climatic and production conditions. As a result of two years of applied research, extension capacity building, and key stakeholder engagements, this paper also presents recommendations for building the capacity of Afghanistan to equip farmers with the knowledge and technologies necessary to respond to constraints to forage and fodder production.
Grassland occupies about 50% of the Tibetan Plateau and acts as a carbon sink nowadays. Climate warming may increase the productivity of the grassland and may also accelerate carbon releasing at the same time, especially when grassland degradation occurs. We have been measured the CO2 flux at a wide-distributed alpine meadow since 2001 and at a wide-distributed alpine wetland since 2009 by eddy covariance (EC) method on the Tibetan Plateau. Recent climatic change and change of livestock production in relation with in situ observation of grassland net ecosystem CO2 exchange (NEE) are analyzed. We find that livestock production increased more greatly in recent years although the climate warming is not so clear as before and in situ NEE observation does not show any increase trend. It is suggested that the expansion of artificial grassland plays a critical role in promoting livestock production in recent years due to there is very good linear relationship between the increased amount of meat production and annual production of fodder after 2001 in Xizang.
This work describes about the performance analysis of a passive type single basin solar still with two types of top covers such as Double Slope and Pyramid Top Covers. The performance parameters such as hourly yield, daily productivity and efficiency were calculated. The internal and external heat transfer modes and also the thermo physical properties such as dynamic viscosity, saturation pressure, thermal conductivity and latent heat of vaporization of basin water were calculated and compared for the two modes of the still. It has been observed that the effect of the cover tilt angle and the distance between the basin water surface and condensation surfaces influence the still productivity to an appropriate levels. The thermal conductivity of basin water, saturation pressure and the release or absorption of latent heat play vital role to improve still efficiency as well as overall productivity was analyzed. The above mentioned properties on comparison revealed that the still with double slope cover had more value than the still with this particular pyramid top cover. The average efficiency of the stills were calculated as 31% for pyramidal top cover is and 36% for double slope top cover. The total amount of distillate yield was obtained as 1200 ml/m2 for the pyramidal still and 1350 ml/m2 for the double slope still. The both efficiency and yield rate from this study also showed that the double slope still performed better than this particular Pyramid shaped still.
Solar stills made of stainless steel still are most durable and low cost. This is especially important for villages, where pos-sibility of mishandling exists. Present work evaluates stainless steel basin still of area (0.7 m x 0.7 m) with insulation at the bottom of height as 15 cm and side gaps of 10 cm between outer cover and stainless steel basin using locally available sawdust. A spherical copper absorber of water storage capacity of 4 1/2 liter is used. The aperture area of the compound conical concentrator (CCC) of 92 cm is integrated with the system. The still and absorber of the CCC is linked under thermosyphon mode to transfer heat to the basin water. The thermal performance of the system is studied by measuring the different parameters such as water temperature, air temperature, top cover temperature, inlet and outlet temperature, ambient temperature, solar radiation and distillate yield. The daily yield collection is 1.522 liter/day in low solar radiation condition.
The Aral Sea is a large closed lake located in the arid area of Central Asia. The water level of the Aral Sea was heavily depending on the amount of water contributed by two major tributaries, Amu-Darya and Syr-Darya. In the past 60 years, it was the world’s fourth largest lake in area. However, its area has decreased rapidly, and its water salinity have become high. They decrease in Aral Sea area was caused by the large scale irrigated agriculture which started in 1950’s, especially in the Aral Sea basin. The study investigates the changes in the chemical characteristics of Aral Sea water in Central Asia in 2015 compared with in 1965 and 1994. Results indicated that the current major ion concentrations were higher than in 1965 and 1994. However, Ca2+ concentration showed different trends.
In Central Asia which belong to the arid land, secondary salinization caused by incorrect irrigation has become a serious problem. Water-saving techniques, drainage improvements, and leaching have been adopted as general measures to mitigate salinization. However, the construction of water-saving and drainage facilities requires plenty of funds. A relatively easy and inexpensive water-saving method is skip furrow irrigation (SFI), by which every alternate furrow is irrigated. In regular SFI, furrows are irrigated alternately (ASFI) during each irrigation event. However, if the irrigation furrows are fixed (FSFI), the salts in the soil might be pushed towards the other side of the ridge. To analyze this salt distribution, a field study comparing every furrow irrigation (EFI), ASFI and FSFI was conducted at a farmland in Uzbekistan. In EFI, the salt content in the center of the ridge increased. Also in ASFI, the salt content decreased at the wet side of the ridge but after second irrigation, increasing at the center of the ridge. Whereas in FSFI, the salt content on the left (dry) side of the ridge increased, indicating a salt pushing effect. The findings of this study suggest a possibility of more efficient removal of the salt in the surface soil by combining FSFI and the dehydration method.
In the last decade, severity of climatic condition in arid and desert areas, has increased phenomenally. Disaster control mechanism in arid and desert area needs to be supplemented by fleet of driverless vehicles, which could be remotely controlled. It would be prudent not to create permanent infrastructure for disaster control services in order to reduce cost component and quick services. This paper presents simulator result for the Cooperative Adaptive Cruise Control (CACC) system based on a Model Predictive Control. CACC is one of promising technologies to achieve the group-level safety and energy aware control in driverless vehicle platoon. The system allows information exchange through Vehicle to Vehicle (V2V) or Individual to Vehicle (I2V) communication. Since the proposed method enables the application of CACC to mixed vehicle fleet consists of manual-driven vehicles and driver-less vehicles. This technology also realizes driver-less accompany vehicle to improve vehicle level redundancy in severe driving environment. Proposed system is implemented and its performance is tested in a simulator experiment.
Autonomous driving is one of the technologies that will become the next milestone in mobility advancement. Before reaching public roads, autonomous driving is expected in areas where driving is considered to be hard and unsafe, like arid and desert terrains. We are trying to achieve fully automated driverless vehicle in transportation sector. Demand of high performance computation using limited space and minimum energy is a pressing need for the mass application of autonomous driving systems. This paper presents a control system for autonomous driving based on model predictive control (MPC) in which a graphics processing unit (GPU) was used to enhance the computation speed for a better real-time performance. The motion controls for the lateral direction is formulated as a model predictive control problem. The lateral MPC was partly executed using GPU for speed enhancement. The implemented MPC package and its adaptation to GPU will make autonomous driving feasible on relatively smaller and cheaper on-board computers, it will also be beneficial to the developers and researchers in various fields other than control engineering field.
Dilapidated land with sandy soils in coastal areas caused by the tsunami from the Great East Japan Earthquake could be extensively used when recovery of the agricultural system is temporally difficult. Biomass production using fast-growing willow (Salix spp.) can be an alternative. The present study aimed to determine the feasibility of adding arbuscular mycorrhizal fungi (AM fungi) and biochar to retain phosphate fertilizer and water for willow production. Two willow clones were tested in the sandy soil of a tsunami-damaged area in Watari Town in Miyagi Prefecture. We found that the fungi significantly promoted willow growth at the start of the cultivation season whereas biochar negatively affected willow growth despite providing a significantly higher soil water content compared with its absence. Biochar might have diluted soil components (phosphate and nitrogen) while increasing the pH. Further study is needed to determine how to apply AM fungi and biochar for optimal long-term growth outcomes.
Land is becoming a challenge and maximization on use is very important. Improvement of runoff for effective and efficient water harvesting is very important. To improve on water harvesting, application of water repellency has been analyzed to see how it can reduce or maximize a catchment in supply of runoff for water harvesting which is consequently expected to help improve use of land especially in arid lands. A series of experiment using heated Eucalyptus leaves under various temperature ranging from 170°C to 300°C was done using a furnace. The optimum temperature of 250°C with heating time of 50 minutes and 300°C with heating time of 30 minutes gave better results on positive effect in the runoff as analyzed in laboratory. Comparing these two optimum experimental settings, the infiltration rate for 250°C case was lower than that for 300°C. The results showed soil water repellency can be used in the improvement of water harvested by limiting infiltration in areas where water is less needed.
Electric power generation from natural resources is a promising method to reduce carbon dioxide emission by combustion of fossil fuel. Arid land has wide area and plenty of natural resources for energy production. However output power of natural energy resource is not stable in general. For example, electric power of photovoltaic cell alters with the daily cycle of solar radiation. So, large-scale energy storage is essential facility for practical use of natural energy as primary resource. Redox flow battery (RFB) is one of the most expected battery systems for such storage. In RFB, redox chemical pair is solved in electrolyte and emits or accepts electron from electrodes to generate electric current. The solutions of active material are circulated between the battery cell and reservoir, and battery capacity is proportional to the liquid amount in reservoir tanks. RFB utilizing vanadium ions for redox pair has been studied extensively and some of experimental plants are in practical operation. However, organic materials can also be explored for more safety and cost efficiency. As candidates of such redox pair, different kinds of organic molecules, produced by plants or other biological body, are under investigation. In this study, molecular species related to energy metabolism and their derivatives were tested as active materials for organic RFB.
Salinity problem caused by shallow underground water level widely occurs in some semi-arid area within the wheat belt of Western Australia. As a countermeasure to this type of salinity problem, agro-forestry was proposed and carried out. By planting salinity tolerant trees in the saline area, underground water is used by planted trees, and then underground water level will gradually go down and expansion of salinization area is prevented. This approach will not only improve the salinity problem by agro-forestry, but also fix carbon as tree biomass by planted trees reducing carbon dioxide in the atmosphere. Then, this approach is considered as an effective countermeasure to climate change due to carbon dioxide increment. Up to now we have reported that Eucalyptus camaldulensis grows very rapidly in arid lands in Western Australia, while that its growth is slow due to salt damage in the semi-arid areas in Western Australia. Therefore, in this study, in order to clarify the influence of various factors on the growth of E. camaldulensis, the effect of planting density, soil salt concentration and precipitation amount and pattern was examined. As a result, the growth of E. camaldulensis was found to be markedly suppressed by the salt in the soil.
Rising atmospheric CO2 concentrations may lead to various problems, such as abnormal weather, rising sea level, decreasing food production and so on. In order to address these problems, carbon sequestration programs, including afforestation and reforestation are gaining attention globally and research activities have been conducted all over the world. There are some requirements in carbon sequestration by large-scale afforestation, and only arid land meets this requirement. However, afforestation of arid land is difficult due to a little amount of precipitation. To establish efficient afforestation plan, it is necessary not only to understand movement of water for tree growth but also to assess the impact of the afforestation on the water movement and periphery vegetation. In the present study, we applied the numerical runoff model so far developed to simulate water movement in arid land to the model site area (annual rainfall 215 mm) near Leonora in Western Australia, where we have planted trees for demonstration of afforestation. Some simulations were carried out under several rainfall patterns and water movement was visualized for better understanding of afforestation impact and efficiency.
A quantitative evaluation of the root system is necessary to discuss an interaction between plant growth and the soil environment. Although there are a number of root system evaluation methods, little studies to investigate a relationship among each method have been undertaken, particularly, between length and special distribution of the root. The current study analyzed a relationship between the Root Frequency Index (RFI), which is one of indices to indicate the spatial distribution of the plant root, and the Root Length Density (RLD) which is another index to evaluate the root length of plants. Gramineae species (i. e. Gamba grass and Maize) and Leguminous species (i. e. Stylo and Soybean) were used. While the root systems of Stylo and Soybean are characterized by the tap root system, the Gamba and Maize roots are characterized by the fibrous root system. Gamba and Stylo were established in an experimental field of semi-arid country (Thailand) having a compacted subsoil, while Maize and Soybean were subject to both a field and pot cultivation experiments. As a result, both the RFI and RLD indicated characteristics of contrasting root systems. Further, a logarithmic relationship between RFI and RLD was found independent of differences in species and soil condition. The result suggests that the root length increase exponentially as the root system develops spatially.
Environmental contamination by heavy metals is increasing worldwide, particularly in semi-arid developing countries due to rapid industrialization. In this study, we focused on phytoextraction of heavy metals by fast growing willow. The objectives of the study are to clarify the growth properties under heavy metal conditions and to evaluate the potential of willow for phytoextraction. Cultivation tests were carried out hydroponically and on an actual polluted field. Four clones of the willow were used. Although there was a slightly negative relationship between Cd content in the solution of culture media and dry weight on hydroponic tests, Cd seldom significantly prevented growth of the plants. Cd concentration (mg･kg-1) and Cd content in the plant (mg･plant-1) increased with Cd content in the culture medium. The KKD clone of willow (Salix petsusu) showed the best growth, even when compared with previous studies. On the actual polluted fields, Cd uptake derived from Cd content multiplied by plant weight was the greatest in the FXM clone, S. pseudolinearis, which showed almost the same performance as in a previous study. Cd was concentrated in litter before defoliation, thus litter collection will show better performance for Cd phytoextraction by fast growing willow.