Study on Large Power Tractor Driver＇s Heart Rate and Fatigue in Sowing Work

In order to reduce the driving fatigue in sowing work, this paper based on heart rate （HR） as the main indicator to survey, tested and analyzed the fatigue condition of the drivers of three imported tractors and one domestic tractor in sowing work. The results showed that when driving the imported tractors in sowing work, the HR increasing rate was 10.4%-14.3%, labor intensity belonged to the light level; when driving domestic tractor in sowing work, the HR increasing rate was 23.4%-33.0%, it was remarkably bigger than that of driving imported tractors （P〈0.05）, labor intensity belonged to the middle level. The main effects on driving fatigue included the control methods, tractors＇ cab environment, processing time, operating content, and so on. Finally, we proposed the concrete measures and suggestions to reduce driving fatigue and improve drivers＇ work condition.     

Under-Winter Sowings of Red Beetroot in Uzbekistan

The results of the three-year researches which had the purpose to establish an optimum depth of seeding at sowing and rational norm of seeding of red beetroot seeds at under-winter sowing in conditions of mid-loamy typical grey soils of the central climatic zone of Uzbekistan are stated in article. The researches were spent at statement of field experiences in quadruple frequency with the area of a registration allotment 10 M^-1. Crops were carried out in the first decade of December against mulching surfaces of ridges by humus and without mulching. Crops were carried out on ridges in width of 70 sm tape-two-lined with distance between tapes of 50 sm, between lines-20 sm and distance between plants in a line of 12-13 sm, at density of standing of 228-230 thousand plants/hectares. Experiences were spent with zoned in Uzbekistan multi-seedling grade of a red beetroot ＂Bordo 237＂. Experiences were accompanied by phenological supervision, biometric accounts, the account of field germination of seeds, density of standing of plants and definition of size and quality of a crop. Results of researches were exposed to the statistical analysis by a dispersive method. It has been revealed that at under-winter sowing of a red beetroot the effective way providing acceleration of shoots occurrence, formations of high-grade density of standing and increase of productivity of root crops is mulching the surfaces of ridges by humus. It is defined that optimum depth of seeding at sowing both at application of mulching and without it is the depth of seeding 4 sm. It is established that the most rational norm of seeding of the seeds, providing high-grade density of standing, is at cultivation with application of mulching 8 kg/ha, and at cultivation without mulching 8-10 kg/ha. Application of mulching the surfaces of ridges by humus, depths of seeding of 4 sm and norms of seeding of seeds of 8-10 kg/ha in conditions of under-winter sowing in comparison with cultivation without mulching and depth of seeding 2 sm and norms of seeding of 6 kg/ha provides an acceleration of receipt of fresh production of a red beetroot for 12-14 days and considerably raises root crops productivity. Application of agro receptions improved by us is the important reserve of acceleration of receipt of red beetroot early production and increase of its manufacture.     

Contribution of Drought to Potential Crop Yield Reduction in a Wheat-Maize Rotation Region in the North China Plain

With consecutive occurrences of drought disasters in China in recent years, it is important to estimate their potential impacts on regional crop production. In this study, we detect the impacts of drought on wheat and maize yield and their changes at a 0.5＆#176;＆#215;0.5＆#176; grid scale in the wheat-maize rotation planting area in the North China Plain under the A1B climate change scenario using the Decision Support System for Agrotechnology Transfer （DSSAT） model and the outputs of the regional climate modeling system-Providing Regional Climates for Impacts Studies （PRECIS）. Self-calibrating palmer drought severity index was used as drought recognition indicator. Two time slices used for the study were the baseline （1961-1990） and 40 years of 2011-2050. The results indicate that the potential planting region for double crop system of wheat-maize would expend northward. The statistic conclusions of crop simulations varied considerably between wheat and maize. In disaster-affected seasons, wheat yield would increase in the future compared with baseline yields, whereas in opposite for maize yield. Potential crop yield reductions caused by drought would be lower for wheat and higher for maize, with a similar trend found for the ratio of potential crop yield reductions for both crops. It appears that the negative impact of drought on maize was larger than that on wheat under climate change A1B scenario.     

Impacts of Climate Change on Rice Yield in China From 1961 to 2010 Based on Provincial Data

The impacts of climate change on rice yield in China from 1961 to 2010 were studied in this paper, based on the provincial data, in order to develop scientiifc countermeasures. The results indicated that increase of average temperature improved single cropping rice production on national level by up to 11%relative to the average over the study period, however, it resulted in an overall loss of double cropping rice by up to 1.9%. The decrease of diurnal temperature range （DTR） in the major producing regions caused the decrease by up to 3.0%for single cropping rice production and 2.0%for double cropping rice production. Moreover, the contribution of precipitation change reached about 6.2%for single cropping rice production, but no signiifcant effect for double cropping rice production in recent 50 years.     

Improvement of Forage Production Sustainability in the Leningrad Region under Climate Change

The increase of probability and depth of weather anomalies, which is important characteristic of climate change process, leads to higher risk of loss of perennial grasses forage yield, rise of price volatility on forage grain market. Increase of sustainability of dairy production supposes development of adapted to new weather conditions technologies of forage production, which are characterized by different investment and current costs. It generates a need of economic evaluation and comparative analysis of technologies taking into account climate change forecast and need of sustainable forage production guarantee. Purpose of the research project is the development of approaches to assessing adaptive technologies in forage production, increasing of dairy farming sustainability to changes in the external environment, including climate change. We assessed changes in forage production technologies in the Leningrad region of Russia, analyzed the implications of these changes for production and financial performance of dairy farming, proposed and tested methods for determination of the optimum harvesting time of perennial grasses. Special attention is paid to the long-term effects of changing the structure of cows＇ diet--shortening the productive use of animals, which reduces the efficiency of dairy herd use and limits the possibility of expanded reproduction. The primary method of the study is the analysis of milk production statistics in the Leningrad region and the Russian Federation. As a result of the study, the necessity to improve the production and investment planning quality, as well as the use of forecasts during planning of dairy production, is grounded.     

Drought Change Trend Using MODIS TVDI and Its Relationship with Climate Factors in China from 2001 to 2010

Changes in drought trends and its relationship with climate change in China were examined in this study. The temperature vegetation drought index （TVDI） datasets recorded during 2001 to 2010 in China were constructed by using the moderate-resolution imaging spectroradiometer （MODIS） data, and the temporal and spatial variations in drought were analyzed. In addition, the mean temperature, mean precipitation, mean relative humidity, and mean sunshine duration data collected from 557 local weather stations in China were analyzed. The relationships between drought and these climate factors were also analyzed by using correlation analysis and partial correlation analysis. Changes in drought tendency were shown to differ among four regions throughout the country. The lfuctuations in climate in the regions of northeastern China, Qinling-Huaihe, and central Qinghai were caused by the increase in soil moisture, and that in southern Tibet was caused by the intensiifcation of drought. Meteorological factors exhibited varied effects on drought among the regions. In southern China, the main inlfuential factor was temperature;other factors only showed minimal effects. That in the northern and northwestern regions was sunshine duration, and those in the Qinghai-Tibet Plateau were relative humidity and temperature.     

Interpretation of Climate Change and Agricultural Adaptations by Local Household Farmers：a Case Study at Bin County,Northeast China

Although climate change impacts and agricultural adaptations have been studied extensively, how smallholder farmers perceive climate change and adapt their agricultural activities is poorly understood. Survey-based data （presents farmers＇ personal perceptions and adaptations to climate change） associated with external biophysical-socioeconomic data （presents real-world climate change） were used to develop a farmer-centered framework to explore climate change impacts and agricultural adaptations at a local level. A case study at Bin County （1980s-2010s）, Northeast China, suggested that increased annual average temperature （0.6＆#176;C per decade） and decreased annual precipitation （46 mm per decade, both from meteorological datasets） were correctly perceived by 76 and 66.9%, respectively, of farmers from the survey, and that a longer growing season was conifrmed by 70%of them. These reasonably correct perceptions enabled local farmers to make appropriate adaptations to cope with climate change：Longer season alternative varieties were found for maize and rice, which led to a signiifcant yield increase for both crops. The longer season also affected crop choice：More farmers selected maize instead of soybean, as implicated from survey results by a large increase in the maize growing area. Comparing warming-related factors, we found that precipitation and agricultural disasters were the least likely causes for farmers＇ agricultural decisions. As a result, crop and variety selection, rather than disaster prevention and infrastructure improvement, was the most common ways for farmers to adapt to the notable warming trend in the study region.     

Asymmetric Price Transmission and Structural Breaks in the Relationship between Costa Rican Markets of Livestock Cattle,Beef and Milk

The vertical price transmission is generally considered as the relationship between two markets of the same production chain However, we can expand this concept to another relation which has not been deeply investigated： the joint products. They are the products which are produced in a single production process, but not correspond to the same chain. An especial case is the beef and milk markets in Costa Rica. Even if these products usually correspond to disconnect chains, in Costa Rica farms make use of cattle to produce both meat and milk. The cointegration framework is applied in order to indentify the price transmission among these markets. In addition, the asymmetric behavior and structural breaks are taken into account. Price transmission between each market pair was found. First, the cattle prices adjust in the milk-cattle relationship, second, beef meat prices adjust in the cattle-beef meat and in the milk - beef meat relationship. Finally, the equations allowing for structural breaks affect the estimates in the following three ways： after the break the elasticities became higher than 1, there is more evidence of cointegration, and the adjustment coefficients are significant only when a change in the long run is allowed.     

Observed Climatic Variations in the Growing Season of Field Crops in Northeast China from 1992 to 2012

To determine the potential effects of climate change on crop phenological development and productivity, an integrated analysis was conducted based on the observed climatic and phenological records of Northeast China from 1992 to 2012. A set of quality assurance procedures, including repeated record checks, agro-meteorological station selection, internal consistency checks, temporal outlier checks, spatial outlier checks, and interpolation of missing data, were designed and applied to the phenology datasets of spring maize and paddy rice. Our results indicated that almost all phenological dates of spring maize and paddy rice became increasingly delayed from 1992 to 2012, The duration of the growing season was prolonged, particularly for the grain-filling stage （GS3）. The prolonged growing season was beneficial to productivity. For spring maize, the average precipitation during GS3 decreased at a rate of 27.46 mm/decade, and the annual accumulated temperature over 10℃ increased at a rate of 31.07℃/ decade. Farmers initiatively adjusted crop cultivars and selected drought-resistant crops to cope with the challenges of drought.     

Spatio-Temporal Changes in the Rice Planting Area and Their Relationship to Climate Change in Northeast China：A Model-Based Analysis

Rice is one of the most important grain crops in Northeast China （NEC） and its cultivation is sensitive to climate change. This study aimed to explore the spatio-temporal changes in the NEC rice planting area over the period of 1980-2010 and to analyze their relationship to climate change. To do so, the CLUE-S （conversion of land use and its effects at small region extent） model was ifrst updated and used to simulate dynamic changes in the rice planting area in NEC to understand spatio-temporal change trends during three periods： 1980-1990, 1990-2000 and 2000-2010. The changing results in individual periods were then linked to climatic variables to investigate the climatic drivers of these changes. Results showed that the NEC rice planting area expanded quickly and increased by nearly 4.5 times during 1980-2010. The concentration of newly planted rice areas in NEC constantly moved northward and the changes were strongly dependent on latitude. This conifrmed that climate change, increases in temperature in particular, greatly inlfuenced the shift in the rice planting area. The shift in the north limit of the NEC rice planting area generally followed a 1＆#176;C isoline migration pattern, but with an obvious time-lag effect. These ifndings can help policy makers and crop producers take proper adaptation measures even when exposed to the global warming situation in NEC.     

Geographic Variation of Rice Yield Response to Past Climate Change in China

Previous studies demonstrated climate change had reduced rice yield in China, but the magnitude of the reduction and the spatial variations of the impact have remained in controversy to date. Based on a gridded daily weather dataset, we found there were obvious changes in temperatures, diurnal temperature range, and radiation during the rice-growing season from 1961 to 2010 in China. These changes resulted in a signiifcant decline of simulated national rice yield （simulated with CERES-Rice）, with a magnitude of 11.5%. However, changes in growing-season radiation and diurnal temperature range, not growing-season temperatures, contributed most to the simulated yield reduction, which conifrmed previous estimates by empirical studies. Yield responses to changes of the climatic variables varied across different rice production areas. In rice production areas with the mean growing-season temperature at 12-14＆#176;C and above 20＆#176;C, a 1＆#176;C growing-season warming decreased rice yield by roughly 4%. This decrease was partly attributed to increased heat stresses and shorter growth period under the warmer climate. In some rice areas of the southern China and the Yangtze River Basin where the rice growing-season temperature was greater than 20＆#176;C, decrease in the growing-season radiation partly interpreted the widespread yield decline of the simulation, suggesting the signiifcant negative contribution of recent global dimming on rice production in China＇s main rice areas. Whereas in the northern rice production areas with relatively low growing-season temperature, decrease of the diurnal temperature range was identiifed as the main climatic contributor for the decline of simulated rice yield, with larger decreasing magnitude under cooler areas.     

Evaluation of Spatial Variability of Soil Properties in a Long-Term Experimental Tobacco Station in Southwest China

Analysis of the spatial variability of soil properties is important to arrange the experimental treatments in the experimental station. This paper aims to study the spatial structure of soil variables and their distribution in the Pengshui tobacco experiment station in Chongqing, China. Soil samples were taken from 289 soil points on 20 m grid in March 2012. Twenty-two soil chemical and physical properties were analyzed by classical statistical and geo-statistical methods. Soil pH, cation exchange capacity （CEC）, total phosphorus （TP）, available phosphorus （AP）, zinc （Zn）, magnesium （Mg） and sulphur （S） have the strong spatial dependence, with nugget/sill ratios of less than 25%. The others have the moderate dependence with nugget/sill ratios of 26.17% to 71.04%. Ranges of the spatial correlation varied from 51.30 m for chlorine （C1） to 594.90 m for TP. The clearly patchy maps of the nutrients showed the spatial distributions of the soil variables, which can be used for better management of experimental treatments, achieving reliable exoerimental results in the tobacco exnerimental station.Highlight： Scientific experimentation assumes the existence of random variability for soil attributes. This research was to evaluate the spatial variability of soil chemical and physical attributes and to interpolate the spatial distribution of soil properties in the tobacco experimental station in Chongqing. The result of this work can be used for the agricultural management of tobacco cultivation.     

The Effects of Climate Change on the Planting Boundary and Potential Yield for Different Rice Cropping Systems in Southern China

Based on climate data from 254 meteorological stations, this study estimated the effects of climate change on rice planting boundaries and potential yields in the southern China during 1951-2010. The results indicated a signiifcant northward shift and westward expansion of northern boundaries for rice planting in the southern China. Compared with the period of 1951-1980, the average temperature during rice growing season in the period of 1981-2010 increased by 0.4＆#176;C, and the northern planting boundaries for single rice cropping system （SRCS）, early triple cropping rice system （ETCRS）, medium triple cropping rice system （MTCRS）, and late triple cropping rice system （LTCRS） moved northward by 10, 30, 52 and 66 km, respectively. In addition, compared with the period of 1951-1980, the suitable planting area for SRCS was reduced by 11%during the period of 1981-2010. However, the suitable planting areas for other rice cropping systems increased, with the increasing amplitude of 3, 8, and 10%for ETCRS, MTCRS and LTCRS, respectively. In general, the light and temperature potential productivity of rice decreased by 2.5%. Without considering the change of rice cultivars, the northern planting boundaries for different rice cropping systems showed a northward shift tendency. Climate change resulted in decrease of per unit area yield for SRCS and the annual average yields of ETCRS and LTCRS. Nevertheless, the overall rice production in the entire research area showed a decreasing trend even with the increasing trend of annual average yield for MTCRS.     

Impacts of Nighttime Warming on the Soil Nematode Community in a Winter Wheat Field of Yangtze Delta Plain,China

Changes in the soil nematode community induced by global warming may have a considerable influence on agro-ecosystem functioning. However, the impacts of predicted warming on nematode community in farmland （e.g., winter wheat field） have not been well documented. Therefore, a field experiment with free air temperature increase （FATI） was conducted to investigate the responses of the soil nematode community to nighttime warming in a winter wheat field of Yangtze Delta Plain, China, during 2007 to 2009. Nighttime warming （NW） by 1.8~C at 5-cm soil depth had no significant impact on the total nematode abundance compared to un-warmed control （CK）. However, NW significantly affected the nematode community structure. Warming favored the bacterivores and fungivores, such as Acrobeles, Monhystera, Rhabditis, and Rhabdontolaimus in bacterivores, and Filenchus in fungivores, while the plant-parasites were hindered, such as Helicotylenchus and Psilenchus. Interestingly, the carnivores/ omnivores remained almost unchanged. Hence, the abundances ofbacterivores and fungivores were significantly higher under NW than those under CK. Similarly, the abundances of plant-parasites were significantly lower under NW than under CK. Furthermore, Wasilewska index of the nematode community was significantly higher under NW than those under CK, indicating beneficial effect to the plant in the soil. Our results suggest that nighttime warming may improve soil fertility and decrease soil- borne diseases in winter wheat field through affecting the soil nematode community. It is also indicated that nighttime warming may promote the sustainability of the nematode community by altering genera-specific habitat suitability for soil biota.     

Climate Change Impact and Its Contribution Share to Paddy Rice Production in Jiangxi,China

In the study, an improved approach was proposed to identify the contribution shares of three group factors that are climate, technology and input, social economic factors by which the grain production is shaped. In order to calibrate the method, Jiangxi Province, one of the main paddy rice producers in China was taken as an example. Based on 50 years （1961-2010） meteorological and statistic data, using GIS and statistical analysis tools, the three group factors that in certain extent impact China＇s paddy rice production have been analyzed quantitatively. The individual and interactive contribution shares of each factor group have been identiifed via eta square （η2）. In the paper, two group ordinary leasr square （OLS） models, paddy models and climate models, have been constructed for further analysis. Each model group consists of seven models, one full model and six partial models. The results of paddy models show that climate factors individually and interactively contribute 11.42-15.25%explanatory power to the variation of paddy rice production in the studied province. Technology and input factors contribute 16.17%individually and another 8.46%interactively together with climate factors, totally contributing about 25%. Social economic factors contribute about 7%of which 4.65%is individual contribution and 2.49%is interactive contribution together with climate factors. The three factor groups individually contribute about 23%and interactively contribute additional 41%to paddy rice production. In addition every two of the three factor groups also function interactively and contribute about 22%. Among the three factor groups, technology and input are the most important factors to paddy rice production. The results of climate models support the results of paddy models, and display that solar radiation （indicated by sunshine hour variable） is the dominate climate factor for paddy rice production.     

Challenges and Opportunities of On-farm Tree Planting as an Alternative Wood Source on Mt. Marsabit,Northern Kenya： Towards Mitigating Climate Change

Constraints and probable pathway towards increasing tree density and diversity within farmlands as a means of reducing human dependency on Mt. Marsabit forest for wood are addressed. The forest provides a carbon sink to counteract the risks and hazards associated with climate change. A structured questionnaire was administered to a sample of 205 respondents that were selected from a population of 3075 farming households using a systematic random sampling procedure. While majority of the farms （53%） had low tree density （1-10 trees）, only 8% of the farms had high density （≥ 20 trees）. About 50% and 15% farms had Grevelia robusta and Eucalyptus cammudelensis, which were grown for timber production, respectively. Broad leafed trees, like Croton megalocarpus and Moringa stenoptella had been established in 17% of the farmlands, respectively. With only 20% of the households having a fence around the crop fields, coupled by widely inter-household sharing of crop residues for grazing, tree browsing by livestock was a constraint to tree establishment. The challenges present an opportunity to establish governance structures and processes for communal responsibility and management of tree resources in the farms. A plausible approach entails the Adaptive Collaborative Management （ACM） as a process that facilitates to experiential learning and negotiation for probable actions and policies in management of natural resources.     

Impact of Climate and Grazing on Biomass Components of Eastern Russia Typical Steppe

Spatial and structural characteristics of plant communities in the steppe ecosystems of the Baikal region, Russian Federation have been researched in connection with climate change and grazing. The present study, based on a total of 15 typical steppe sampling plots, investigated above-ground biomass （AGB）, below-ground biomass （BGB）, total biomass （TB） and root：shoot ratios （R：S） and their relationships with climatic factors and grazing. All biomass components varied widely depending on the climatic parameters and the degree of grazing affected transformation. A strong negative correlation between mean annual temperature （MAT） and total plant biomass was revealed for all study area. Mean annual precipitation （MAP） signiifcantly affected communities productivity increasing only in the south of the region. Due to the large and mountainous territory, the inlfuence of latitude and elevation （mountain） factors on the components of the biomass were studied. Although all studied plant steppe communities were transformed by uncontrolled grazing, their productivity is signiifcantly reduced only at plots with maximum digression. Vegetation shift is an indicator of climate change, as well as providing a diagnostic tool to build predictive models. Based on the complex index of effective precipitation, it was revealed that at the end of last century in the steppes of the Baikal region the structural and production processes will be affected by an arid climate trend.     

Interactive Effects of Elevated CO2 and Temperature on Rice Planthopper,Nilaparvata lugens

It is predicted that the current atmospheric CO2 concentration will be doubled and global mean temperature will increase by 1.5-6＆#176;C by the end of this century. Although a number of studies have addressed the separate effects of CO2 and temperature on plant-insect interactions, few have concerned with their combined impacts. In the current study, a factorial experiment was carried out to examine the effect of a doubling CO2 concentration and a 3℃ temperature increase on a complete generation of the brown planthopper （Nilaparvata lugens） on rice （Oryza sativa）. Both elevated CO2 and temperature increased rice stem height and biomass of stem parts. Leaf chlorophyll content increased under elevated CO2, but only in ambient temperature treatment. Water content of stem parts was reduced under elevated temperature, but only when coupled with elevated CO2. Elevated CO2 alone increased biomass of root and elevated temperature alone enhanced leaf area and reduced ratio of root to stem parts. Brown planthopper （BPH） nymphal development was accelerated, and weight of and honeydew excretion by the F1 adults was reduced under elevated temperature only. Longevity of brachypterous females was affected by a signiifcant interaction between CO2 and temperature. At elevated temperature, CO2 had no effect on female longevity, but at ambient temperature, the females lived shorter under elevated CO2. Female fecundity was higher at elevated than at ambient temperature and higher at elevated CO2 than at ambient CO2. These results indicate that the combined effects of elevated temperature and CO2 may enhance the brown planthopper population size.     

The Characteristics of Plant Communities Along East Eurasian Steppe Transect

The East Eurasian Steppe Transect （EEST） is the ifrst international transect across regions of middle and high latitudes in the eastern Eurasian steppe. The EEST is an ideal platform for researching the response of Eurasian temperate steppe to global change, because of its integrated gradients of temperature and human activities on a large-scale. In this study, basic characteristics of plant communities along the EEST across a latitudinal gradient was analyzed. According to the survey of 58 sampling sites, there are 140 species belonging to 34 families and 94 genera. Of particular note was the ifnding of Astragalus dalaiensis which has disappeared in the grasslands of China. On the whole, Gramineae plants are dominant with Liliaceae plants in the communities signiifcantly decreasing along the latitudinal gradient from south to north. The Shannon-Wiener index and biomass of communities all decreased along the latitudinal gradient with signiifcant negative linear regressions. The SDR2 （summed dominance ratio based on two factors） of dominant plants in the upper layers of communities, such as Stipa and Leymus chinensis, decreased along the latitudinal gradient from south to north. Especially, the SDR2 of L. chinensis decreased signiifcantly. The SDR2 of Cleistogenes squarrosa, Agropyron cristatum in the lower layers of communities and the indicator species for degradation were not affected. Potentilla acaulis was found mainly in the southern and northern areas. Stellera chamaejasme was found just in a few sites in the southern area of the EEST. In communities of Stipa grandis and Stipa krylovii, annual and biennial species are dominant. The ratio of annual and biennial species in the community is signiifcantly related to the latitudinal gradient. Perennial herbaceous plants and shrubs were not affected. According to the principal component analysis （PCA）, with the data from 58＆#215;140 dimensions, the ifrst and second components had the lowest proportion, thus indicating that the species compositions and community structures are homogeneous along the EEST. There is a certain degree of spatial differentiation along the EEST due to degradation’s differences resulting from the different land uses.     

Influence of Climate and Socio-Economic Factors on the Spatio-Temporal Variability of Soil Organic Matter： A Case Study of Central Heilongjiang Province,China

For the scientific management of farmland, it is significant to understand the spatio-temporal variability of soil organic matter and to study the influences of related factors. Using geostatistical theory, GIS spatial analysis, trend analysis and a Geographically Weighted Regression （GWR） model, this study analyzed the response of soil organic matter to climate and socio-economic factors in central Heilongjiang Province during the past 25 years. Second soil survey data of China for 1979-1985, 2005 field sampling data, climate observations and socio-economic data for 1980-2005 were analyzed. First, soil organic matter in 2005 was spatially interpolated using the Co-Kriging method along with auxiliary data sets of soil type and pH. The spatio-temporal variability was then studied by comparison with the 1980s second soil census data. Next, the temporal trends in climate and socio-economic factors over the past 25 years were investigated. Finally, we examined the variation of the response of soil organic matter to climate and socio-economic factors using the GWR model spatially and temporally. The model showed that 53.82% area of the organic matter content remained constant and 29.39% has decreased during the past 25 years. The impact of precipitation on organic matter content is mainly negative, with increasing absolute values of the regression coefficient. The absolute value of regression coefficient of annual average temperature has decreased, and more areas are now under its negative effects. In addition, the areas of positive regression coefficient of annual sunshine hours have northward shifted, with the increasing absolute value of positive coefficient and decreasing absolute value of negative coefficient. The areas of positive regression coefficient of mechanized farming as a socio-economic factor have westward shifted, with the increasing absolute value of negative coefficient and decreasing absolute value of positive coefficient. The area of regions with the positive regression coefficient of irrigatio