maryam sebti; F. Khormali; afshin soltani; kamran Eftekhari; abdolazim ghanghermeh; esmaeil dordipour
Abstract
Introduction Increasing concerns about global warming and climate change have led to special attention to soil and its capability in carbon sequestration in recent years. About 540,000 hectares of soils in Golestan province are under agronomic activities and so far no studies have been conducted on soil ...
Read More
Introduction Increasing concerns about global warming and climate change have led to special attention to soil and its capability in carbon sequestration in recent years. About 540,000 hectares of soils in Golestan province are under agronomic activities and so far no studies have been conducted on soil organic carbon changes and its interactions with climate change. The total organic carbon in soils is approximately twice the amount of carbon atmosphere, so changes in soil carbon have significant effects on climate change. On the other hand, factors such as climate change or changes in land use and management affect soil organic carbon changes. As soil temperature increases, the rate of organic carbon decomposition will increase, which potentially increases the average release of soil carbon dioxide emission into the atmosphere. Therefore, finding low-cost and rapid methods for estimating soil organic carbon in large ranges and predicting its changes in the future has became a necessity.Modeling is a tool that can be used to evaluate the feasibility of various land management techniques, and with the help of the results, the best methods can be selected and researched. In the field of soil organic carbon studies, the RothC model is one of the most widely used models, which is of great interest to researchers due to its simplicity and availability of inputs. Climatic changes are also investigated using the output of general circulation models (GCMs) under greenhouse gas emissions scenarios. These data are used after exponential microscale, in which Lars-WG statistical method has been used in this research.Materials and methods The purpose of this study is to investigate the status of soil organic carbon storage in agricultural lands of Golestan province and the effect of climate change on soil organic carbon storage in the coming decades. Therefore, in order to conduct this research along the northeast_southwest of the province were selected 3 points in 3 arid climates, semi-arid and Moist climate. In selected points, soil samples were collected by digging 3 profiles and several augers and soil organic carbon, soil texture and soil apparent specific weight were measured (year 2018). The Roth C model has been used to investigate changes in soil organic carbon storage in the future. Roth C model has been used to investigate future changes in soil organic carbon storage. In order to validate the Roth C model, the results of previous studies (1997 and 2004) were used. Also, the climatic data used in this project were extracted from the statistics of 1371 to 1398 weather stations of Chat, Kalaleh and Ramyan and using the output of general circulation models (GCMs), scaled by Lars WG6 model and precipitation and temperature data were predicted of future decades.Results and Discussion The study of temperature changes showed that by 2040, based on scenario 4.5, the temperature will increase between 0.6 and 0.8 and based on scenario 8.5 between 0.6 and 1.3 °C. Also, by 2080, based on scenario 4.5, the temperature increase was predicted between 1.5 and 2.3 and based on scenario 8.5 between 2.2 and 3.2 °C. Climate change in different regions can reduce, increase or no change in precipitation. According to the forecast of the third report of the InterGovernmental Panel on Climate Change, precipitation will increase in winter and decrease in the summer. Based on the findings of this study, the amount of precipitation in the studied stations will increase in the future (in 2040 and 2080) based on two scenarios of 4.5 and 8.5. The results of prediction of soil organic carbon storage show that in 2040 based on scenario 4.5 the amount of soil organic carbon storage in agricultural land use will decrease between 0.5 and 5.3 tons per hectare. Also, based on scenario 8.5, the reduction of soil organic carbon storage in these lands was predicted between 0.8 and 6 tons per hectare. Based on these results, the greatest reduction in soil organic carbon storage was predicted in the humid and rainy areas of the province in 2040. According to this research, in the three investigated stations, in 2080, based on scenario 4.5, the amount of soil organic carbon storage in agricultural land use will decrease between 1.5 and 13.1 tons per hectare. However, in this year, based on MIROC5 and MPI-ESM-MR climate models in Sufian station, we will see an increasement in soil organic carbon storage between 0.6 and 3.9 tons per hectare. Also, according the scenario 8.5, in 2080, the reduction of soil organic carbon in these lands is predicted between 0.5 and 10.5. According to these results, the greatest reduction in soil organic carbon storage in 2080 was calculated in wet and rainy areas (Ramian station).Conclusion According to the obtained results, the Rothamsted model has been able to simulate the dynamics of soil organic carbon storage in the study area with appropriate accuracy. The output of the four climate models showed that future temperature changes will increase in 2040 and 2080 based on scenarios 4.5 and 8.5. these findings are consistent with the results of most climate studies that have predicted temperature enhancement in the future decades. According to the findings of the current research, the amount of precipitation in the studied stations will increase in the future (in 2040 and 2080) based on two scenarios of 4.5 and 8.5. The results of Roth C model simulations for predicting soil organic carbon storage showed that soil organic carbon storage will decrease in 2040 and 2080 in both climatic scenarios. According to these results, with increasing of temperature, the rate of decomposition of soil organic carbon increases. Increasing the rate of decomposition in agricultural land use due to the lack of surface vegetation in periods of the year causes the waste of soil organic carbon in the form of CO2 in the upper layers of the soil. Some studies have shown that low vegetation cover (agricultural compared to rangeland) areas will be severely affected by climate change and will lead to soil organic carbon waste in these areas.
Soil Physics, Erosion and Conservation
Motahareh Noorzade Roshan; Reza Ghorbani Nasrabadi
Abstract
Introduction Soil quality has been defined as a “The potential of soil to play a positive relationship with the other parts of ecosystem”. Soil biological indicators provide insight into the living component of the soil. Similar to physical and chemical indicators, biological indicators have ...
Read More
Introduction Soil quality has been defined as a “The potential of soil to play a positive relationship with the other parts of ecosystem”. Soil biological indicators provide insight into the living component of the soil. Similar to physical and chemical indicators, biological indicators have a relationship to soil functions and can evaluate soil functions to assess soil quality. Between biological indicators, an index that can be measured quickly and easily is more useful to show the changes. In many studies an indicator of microbial respiration, microbial population, nitrogen mineralization and enzymes activity can be used. Special ability is required to measure quickly and show the quality of soil microorganisms and reaction to environmental changes. Soil health is defined by chemical and physical parameters such as soil texture, soil pH, electrical conductivity, etc., that are not quantifiable completely. Therefore, conservation practices planting and forestry may directly or indirectly affect a organism’s activities. The results of land-use systems without consideration of the consequences on soil quality have been environmental degradation. Agricultural management systems have been generally adopted without attending to soil conservation and soil quality, and this therefore causes significant decline in agricultural soil health worldwide. Different methods of soil conservation have been proposed to prevent erosion and improve soil quality destructive phenomena. In Golestan province due to topographical and climatic conditions and less soil sensitivity to erosion, more attention should be given to this issue. But it remains unclear how far this conservation practice can take to prevent damage. This study aimed to investigate the role of conservative practices to improve the soil quality indicators.Materials and Methods The watershed of Chehelchai is located between North latitudes 36° 59´ and 37° 13´ and Earth longitudes 55° 23´ and 55° 38´. The history of land use in the region shows that more than about 40 years ago, all the study area was covered by forest. Agricultural land use changes occurred on a large scale. With emphasis on conservation operation, parts of the agricultural land were changed to productive gardens, partly forested, partly pasture with native species. Different land uses were selected in loess formations, and slope of 41 %, with life operations was about 6 to 7 years. Protective Operations Garden species, terraces and forestry were selected and quality of soil was compared with agricultural land, pasture and natural forest. In this regard, 10 soil samples were taken. After preparation of the samples, physical, chemical and biological analysis were measured. Additionally, soil properties (pH, Electrical Conductivity, Calcium carbonate, organic matter, texture, bulk density, aggregate stability, microbial respiration, microbial biomass population count of micro- arthropods, biological soil quality) were analyzed. The data were analyzed using software SAS. Ver 9. and the results were compared in a randomized complete block design. Analysis of variance in the form of randomized complete block design was done using the LSD multiple comparison. Results and Discussion Our results showed that the dominant soil texture class in land uses was silty loam. It seems that soil texture is less affected by the land use changes. The results showed that the changes of forest and pasture to agricultural lands have destroyed the soil quality. Soil quality indicators such as organic matter and aggregate stability have declined by 60 and 70 percent respectively. Like wise, biological indicators such as microbial respiration, microbial biomass carbon and QBS (biological soil quality indicators based on the population of micro- arthropods) and EMI (index dependence of soil to soil organisms) showed a similar trend. In contrast, the Conservation practices improved the indices. Biological indicators in the forestry and gardening showed an increase of 40 percent in EMI Microbial biomass carbon and 80 percent in microbial respiration. Terracing had less improvement than other operations in about 11 to 20 percent in EMI and microbial biomass carbon. Conclusion Conservation operations had fewer effects on indicators such as aggregate stability and organic matter. Under estimation of effects in certain indicators maybe due to short time of conservation practices. It seems that these operations will show better results in the future Received: 19 July, 2016Accepted: 10 April, 2018
Plant Nutrition, Soil Fertility and Fertilizers
G. Roshani; A. Gharanjiki
Volume 37, Issue 2 , March 2015, , Pages 87-99
Abstract
The fertility maps are useful tools to know about the land resources. These maps are essential to do a correct fertilizer recommendation, monitoring the changes of soil fertility level and also to do prediction of toxicity or deficiency of necessary plants nutritional elements in the soil. The present ...
Read More
The fertility maps are useful tools to know about the land resources. These maps are essential to do a correct fertilizer recommendation, monitoring the changes of soil fertility level and also to do prediction of toxicity or deficiency of necessary plants nutritional elements in the soil. The present research was carried out to digital mapping of macro and micro elements as well as some important physical and chemical properties of the soil for agricultural service centers of Golestan province to optimize the use of chemical fertilizers in operating plan pattern. The studied areas were under irrigated and rain-fed wheat cultivation and the total surface area was about 520000 hectares. Using based maps with the scale of 1: 50,000, the area was divided into 5200 grids each having one kilometer square area. Using Global Positioning System (GPS) instrument a composite soil sample was taken from the center of any grid and analyzed for major macro- and micronutrients as well as physical and chemical properties of the soil namely; pH, EC,TNV, sand, silt and clay contents. At the time of sampling, some additional information like latitude, longitude, elevation, owner's name, date of sampling, kind of water resources, possibility of water logging, crop history (present and previous) was collected and recorded. After getting the laboratory results, for the above stated data sets, an electronic layer was created for any particular parameter and after doing interpolation, the layers were polygonized. Anisotropy of the data sets in different directions was evaluated by the help of variogram surface operation. Then spatial correlation of each data set was calculated. After variogram analysis, spatial variation of the data sets was studied and a suitable model was selected. Finally, through point interpolation using kriging technique, the digital map of each parameter was established.
