To accurately evaluate the carbon sequestration potential and better elucidate the relationship between the carbon cycle and regional climate change, using eddy covariance system, we conducted a long-term measurement ...To accurately evaluate the carbon sequestration potential and better elucidate the relationship between the carbon cycle and regional climate change, using eddy covariance system, we conducted a long-term measurement of CO 2 fluxes in the rain-fed winter wheat field of the Chinese Loess Plateau. The results showed that the annual net ecosystem CO 2 exchange （NEE） was （-71.6±5.7） and （-65.3±5.3） g C m-2 y-1 for 2008-2009 and 2009-2010 crop years, respectively, suggesting that the agro-ecosystem was a carbon sink （117.4-126.2 g C m-2 yr-1）. However, after considering the harvested grain, the agro- ecosystem turned into a moderate carbon source. The variations in NEE and ecosystem respiration （R eco ） were sensitive to changes in soil water content （SWC）. When SWC ranged form 0.15 to 0.21 m3 m-3, we found a highly significant relationship between NEE and photosynthetically active radiation （PAR）, and a highly significant relationship between R eco and soil temperature （T s ）. However, the highly significant relationships were not observed when SWC was outside the range of 0.15-0.21 m3 m-3. Further, in spring, the R eco instantly responded to a rapid increase in SWC after effective rainfall events, which could induce 2 to 4-fold increase in daily R eco , whereas the R eco was also inhibited by heavy summer rainfall when soils were saturated. Accumulated R eco in summer fallow period decreased carbon fixed in growing season by 16- 25%, indicating that the period imposed negative impacts on annual carbon sequestration.展开更多
A field experiment was conducted to assess the effects of combined application of farm yard manure (FYM) and inorganic NP fertilizers on soil physico-chemical properties and nutrient balance in a rain-fed lowland rice...A field experiment was conducted to assess the effects of combined application of farm yard manure (FYM) and inorganic NP fertilizers on soil physico-chemical properties and nutrient balance in a rain-fed lowland rice production system in Fogera plain, northwestern Ethiopia. The study was carried out during the main cropping seasons of 2010 and 2011. Twenty-seven treatments comprising a factorial combination of three rates of FYM (0, 7.5, and 15 t·ha-1), three rates of nitrogen (0, 60, 120 kg·N·ha-1) and three rates of phosphorus (0, 50 and 100 kg·P2O5·ha-1) were tested. The experiments were laid out as a randomized complete block design with three replications. Bulk density, organic matter content, and available water holding capacity, total N, and available P of the soil were measured just after harvesting the rice crop. Results showed that application of 15 t·FYM·ha-1 significantly increased soil organic matter and available water holding capacity but decreased the soil bulk density, creating a good soil condition for enhanced growth of the rice crop. Application of 15 tFYM·ha-1 increased the level of soil total nitrogen from 0.203% to 0.349%. Combined application of 15 t·ha-1·FYM and 100 kg·P2O5·ha-1 increased the available phosphorous from 11.9 ppm to 38.1 ppm. Positive balances of soil N and P resulted from combined application of FYM and inorganic N and P sources. Application of 15·t ha-1·FYM and 120 kg·N·ha-1resulted in 214.8 kg·ha-1·N positive balance while application of 15 t·ha-1·FYM and 100 kg·P2O5·ha-1 resulted in a positive balance of 69.3 kg·P2O5·ha-1 available P. From the results of this experiment, it could be concluded that combined application of FYM and inorganic N and P fertilizers improved the chemical and physical properties, which may lead to enhanced and sustainable production of rice in the study area.展开更多
Enhancing water use efficiencies of rain-fed maize is a requirement for sustainable maize production, particularly in areas prone to low/drought and erratic rainfall patterns. This study was conducted to assess the re...Enhancing water use efficiencies of rain-fed maize is a requirement for sustainable maize production, particularly in areas prone to low/drought and erratic rainfall patterns. This study was conducted to assess the relationship between total biomass/grain yield and water use efficiencies of three maize cultivars (Golden Crystal, Mamaba and Obatanpa) grown under rain-fed conditions in a coastal savannah agro-ecological environment of Ghana. Results of the study showed that a unified linear model, WUETDM = 0.03TDM with R2 = 0.765 and P ≤ 0.001, described adequately the relation between wa-ter use efficiency and total biomass (dry matter), which is applicable for the three maize cultivars for both the major and minor cropping seasons. A linear model could only, however, describe adequately well the relation between WUEGY and GY for the major (WUEGY = 0.001GY – 0.67;R2 = 0.996;P ≤ 0.001) and minor (WUEGY = 0.002GY + 0.289;R2 = 0.992;P ≤ 0.001) cropping seasons for all the maize cultivars. The linear models developed for the maize cultivars, re-lating WUEGY to GY, are specific to each of the crop growing seasons, indicating that seasonal rainfall impacts significantly on harvest index of the maize cultivars but differently in each of the crop growing seasons as a results of dif-ferences in seasonal rainfall. However, the models could be used to estimate water use efficiencies of each of the three maize cultivars given the appropriate TDM and GY as inputs for the environment under which the study was conducted.展开更多
This paper is aimed at examining the applicability of methods for resilience, reliability and risk analyses of rain-fed agricultural systems from modeled continuous soil moisture availability in rain-fed crop lands. T...This paper is aimed at examining the applicability of methods for resilience, reliability and risk analyses of rain-fed agricultural systems from modeled continuous soil moisture availability in rain-fed crop lands. The methodology involves integration of soil and climatic data in a simple soil moisture accounting model to assess soil moisture availability, and a risk used as indicator of sustainability of rain-fed agricultural systems. It is also attempted to demonstrate the role of soil moisture modeling in risk analysis and agricultural water management in a semi-arid region in Limpopo Basin where rain-fed agriculture is practiced. For this purpose, a daily-time step soil moisture accounting model is employed to simulate daily soil moisture, evaporation, surface runoff, and deep percolation using 40 years (1961-2000) of agroclimatic data, and cropping cycle data of maize, sorghum and sunflower. Using a sustainability criterion on crop water requirement and soil moisture availability, we determined resilience, risk and reliability as a quantitative measure of sustainability of rain-fed agriculture of these three crops. These soil moisture simulations and the sustainability criteria revealed further confirmation of the relative sensitivity to drought of these crops. Generally it is found that the risk of failure is relatively low for sorghum and relatively high for maize and sunflower in the two sites with some differences of severity of failure owing to the slightly different agroclimatic settings.展开更多
Based on the eddy-covariance observation data over rain-fed maize agricultural ecosystem during 2005-2011, the dynamics of net ecosystem CO2 exchange (NEE) and its control mechanism were analyzed in the present study....Based on the eddy-covariance observation data over rain-fed maize agricultural ecosystem during 2005-2011, the dynamics of net ecosystem CO2 exchange (NEE) and its control mechanism were analyzed in the present study. We found that the average carbon budget of non-growing season, growing season and annual were 153.16 - 202.03 g C/m2, −689.36 - −488.17 g C/m2, and −316.96 - −487.33 g C/m2, respectively. Maize carbon content of grain yield was −226.6 - −339.94 g C/m2, accounting for 55.4% of carbon budget in the growing season. From sowing to seven-leaf stage, the carbon budget of this ecosystem was characterized by carbon release, with the rate of 0.028 ±0.0056 mg CO2 m−2⋅s−1. From seven-leaf to mature stage, the carbon budget was characterized by carbon absorption, with the rate of −0.256 ±0.0693 mg CO2 m−2⋅s−1. The key meteorological factors affecting annual carbon budget included daily average temperature (R = −0.81, P = 0.03) and saturated vapor pressure deficit (R = −0.64, P = 0.12). At the same photosynthetically active radiation (PAR) level, CO2 assimilation rate was linearly correlated with leaf area index (P 【0.05), and the slopes increased with PAR, indicating the increase in net ecosystem CO2 exchange in growing season was unlikely to be resulted from the extension of growing season. On the contrary, the carbon sink of rain-fed maize ecosystem in growing season might be decreased by extending the growing season ahead of the sowing date.展开更多
During the period spanning the 1970s and1980s, countries in the West African Sahel experienced severe drought. Its impact on agriculture and ecosystems has highlighted the importance of monitoring the Sahelian rainy s...During the period spanning the 1970s and1980s, countries in the West African Sahel experienced severe drought. Its impact on agriculture and ecosystems has highlighted the importance of monitoring the Sahelian rainy season. In Sahelian countries such as Mali, rainfall is the major determinant of crop production. Unfortunately, rainfall is highly variable in time and space. Therefore, this study is conducted to analyze and forecast the impact of climatic parameters on the rain-fed rice yield cultivation in the Office Riz Mopti region. The data were collected from satellite imagery, archived meteorology data, yield and rice characteristics. The study employed Hanning filter to highlight interannual fluctuation, a test of Pettitt and the standardized precipitation index (SPI) to analyze the rainfall variability. Climate change scenarios under the RCP 8.5 scenario (HadGEM-2 ES) and agroclimatic (Cropwat) model are carried out to simulate the future climate and its impact on rice yields. The results of satellite image classifications of 1986 and 2016 show an increase of rice fields with a noticeable decrease of bare soil. The analysis of the SPI reveals that over the 30 years considered, 56.67% of the rainy seasons were dry (1986-2006) and 43.33% were wet (2007-2015). The modelling approach is applied over 1986-2006 and 2007-2015 periods—considered as typical dry and rainy years—and applied over the future, with forecasts of climate change scenarios in 2034. The results show a decrease in potential yield during dry and slightly wet years. The yields of rain-fed rice will be generally low between 2016 and 2027. Deficits are observed over the entire study area, in comparison with the potential yield. Thus, this situation could expose the population to food insecurity.展开更多
This study examines social vulnerability by exploring the socio-economic factors, infrastructures, and social networks that can determine how prone and how prepared the rain-fed farming communities are to the adverse ...This study examines social vulnerability by exploring the socio-economic factors, infrastructures, and social networks that can determine how prone and how prepared the rain-fed farming communities are to the adverse impacts of climate change. Increased variability in climatic conditions due to climate change seriously affects the productivity of rain-fed farms. The rain-fed farming communities in the Philippines are located in poor and environmentally fragile rural areas. Their vulnerability is greatly affected by restricted entitlement and access to social and economic capitals. This study is framed on qualitative approach to provide a rich and in-depth understanding on the elements of vulnerability based on the capacities and the practical affairs of life in rain-fed communities. The three subject communities from two agricultural provinces are examined to understand how the context and interactions of people can explicate sociological themes on the social dimension of climate change. The usefulness of multi-site study in probing the unique ways of how people understand and respond to certain environmental issue is part of reflections about the methodology.展开更多
Rain-fed(dryland)farming is an ancient agricultural production system in China.It occurs widely across almost the whole country,especially in the Northwest and North China.The semi-arid Loess Plateau is the most impor...Rain-fed(dryland)farming is an ancient agricultural production system in China.It occurs widely across almost the whole country,especially in the Northwest and North China.The semi-arid Loess Plateau is the most important region of rain-fed farming in China,but unfortunately,soil erosion on the Loess Plateau area is the highest in China,and indeed amongst the highest in the world.This highlights the necessity for developing practices that can reduce soil and water erosion,improve soil water use efficiency,improve crop productivity,and reduce rural poverty in the region.Many techniques of soil and water conservation are being used in rain-fed areas of China,including such systems as mulch,ridge and furrow systems.The Appendix describes a unique system of soil and water conservation,called Shatian.Modern research on conservation tillage(No Till),although essential for reducing erosion,increasing crop productivity,and ameliorating poverty,is just beginning in China.Modern conservation tillage research started in the1990s’with support from Australia and other countries.The procedures,however,were modified to be in accord with local conditions and prevailing farmer experiences.With 10 years of experimentation,results show that the most successful conservation practice on the Western Loess Plateau is no till with stubble retention.This technique helps to conserve soil water,increases soil organic carbon,improves soil structure and water infiltration,reduces soil and water erosion,and improves crop productivity and sustainability of rain-fed farming systems.However,its adoption rate remains low due to barriers such as traditional attitude,insufficient rural extension,and so forth.展开更多
Agriculture,significantly impacted by climate change and climate variability,serves as the primary livelihood for smallholder farmers in South Asia.This study aims to examine and evaluate the factors influencing small...Agriculture,significantly impacted by climate change and climate variability,serves as the primary livelihood for smallholder farmers in South Asia.This study aims to examine and evaluate the factors influencing smallholder farmers'adaptive capacity(AC)in addressing these risks through surveys from 633 households across Nepal,India,and Bangladesh.The findings reveal that AC is influenced by various indicators categorized under eight principal factors.The first three factors,which explain about one-third of the variance in each country,include distinct significant indicators for each nation:in Nepal,these indicators are landholding size,skill-development training,knowledge of improved seed varieties,number of income sources,access to markets,and access to financial institutions;in India,they encompass ac-cess to agricultural-input information,knowledge of seed varieties,access to markets,access to crop insurance,changing the sowing/harvesting times of crops,and access to financial ser-vices;in Bangladesh,the key factors are access to financial institutions,community coopera-tion,changing the sowing/harvesting times of crops,knowledge of improved seed varieties,and access to agricultural-input information.Notably,indicators such as trust in weather in-formation,changing sowing/harvesting times of crops,and crop insurance were identified as important determinants of AC,which have been overlooked in previous studies.展开更多
为探究雨养和灌溉条件下氮肥后移对冬小麦面粉加工品质的影响及其谷蛋白形成机制,本研究选用强筋小麦品种中麦886(ZM886)和中筋小麦品种中麦30(ZM30)为试验材料,在雨养处理(W)和灌溉处理(D)条件下,总施氮量为210 kg hm^(-2)的基础上设置...为探究雨养和灌溉条件下氮肥后移对冬小麦面粉加工品质的影响及其谷蛋白形成机制,本研究选用强筋小麦品种中麦886(ZM886)和中筋小麦品种中麦30(ZM30)为试验材料,在雨养处理(W)和灌溉处理(D)条件下,总施氮量为210 kg hm^(-2)的基础上设置2个追氮处理:常规氮肥处理(N1:底肥50%+拔节肥50%)和氮肥后移处理(N2:底肥50%+拔节肥30%+孕穗肥20%),研究其对冬小麦籽粒谷蛋白大聚合体(GMP)形成和面粉加工品质的影响。试验结果表明,2小麦品种产量最大值均出现在WN2处理,其中ZM30在WN2处理下产量较其他处理平均提高12.36%(2021—2022年)和13.97%(2022—2023年),ZM886同期分别提高9.85%和18.31%。在花后10 d检测到籽粒中高分子量谷蛋白亚基(HMW-GS)和低分子量谷蛋白亚基(LMW-GS),ZM886在DN2处理下HMW-GS、LMW-GS、free-SH、-S-S-含量最高,ZM30则在WN2处理达到峰值。花后30 d检测到2小麦品种籽粒GMP的存在,ZM886在DN2下较其他处理增高5.40%~33.90%,ZM30在WN2下增高2.50%~14.70%,同时分别在2处理下增加了GMP大颗粒体积和表面积百分比,从而不同程度地提高面粉加工品质。小麦籽粒GMP含量与HMW-GS含量和LMW-GS含量呈正相关,ZM886籽粒GMP含量与面团形成时间和稳定时间呈正相关,但与产量呈负相关;ZM30籽粒GMP含量与产量呈极显著正相关,但与吸水率呈负相关。综上,本试验条件下,氮肥后移通过调控谷蛋白亚基合成,提升GMP含量,优化GMP粒径分布。因小麦产量而言,适宜的水氮配置为:灌溉处理下,氮肥施用底肥50%+拔节肥30%+孕穗肥20%;因小麦品质而言,适宜的水氮配置因品种类型而异:强筋小麦中麦886为在雨养处理下,氮肥施用底肥50%+拔节肥30%+孕穗肥20%,中筋小麦中麦30为在灌溉处理下,氮肥施用底肥50%+拔节肥30%+孕穗肥20%。展开更多
基金supported by the National Natural Science Foundation of China (31171506 and 31071375)
文摘To accurately evaluate the carbon sequestration potential and better elucidate the relationship between the carbon cycle and regional climate change, using eddy covariance system, we conducted a long-term measurement of CO 2 fluxes in the rain-fed winter wheat field of the Chinese Loess Plateau. The results showed that the annual net ecosystem CO 2 exchange （NEE） was （-71.6±5.7） and （-65.3±5.3） g C m-2 y-1 for 2008-2009 and 2009-2010 crop years, respectively, suggesting that the agro-ecosystem was a carbon sink （117.4-126.2 g C m-2 yr-1）. However, after considering the harvested grain, the agro- ecosystem turned into a moderate carbon source. The variations in NEE and ecosystem respiration （R eco ） were sensitive to changes in soil water content （SWC）. When SWC ranged form 0.15 to 0.21 m3 m-3, we found a highly significant relationship between NEE and photosynthetically active radiation （PAR）, and a highly significant relationship between R eco and soil temperature （T s ）. However, the highly significant relationships were not observed when SWC was outside the range of 0.15-0.21 m3 m-3. Further, in spring, the R eco instantly responded to a rapid increase in SWC after effective rainfall events, which could induce 2 to 4-fold increase in daily R eco , whereas the R eco was also inhibited by heavy summer rainfall when soils were saturated. Accumulated R eco in summer fallow period decreased carbon fixed in growing season by 16- 25%, indicating that the period imposed negative impacts on annual carbon sequestration.
文摘A field experiment was conducted to assess the effects of combined application of farm yard manure (FYM) and inorganic NP fertilizers on soil physico-chemical properties and nutrient balance in a rain-fed lowland rice production system in Fogera plain, northwestern Ethiopia. The study was carried out during the main cropping seasons of 2010 and 2011. Twenty-seven treatments comprising a factorial combination of three rates of FYM (0, 7.5, and 15 t·ha-1), three rates of nitrogen (0, 60, 120 kg·N·ha-1) and three rates of phosphorus (0, 50 and 100 kg·P2O5·ha-1) were tested. The experiments were laid out as a randomized complete block design with three replications. Bulk density, organic matter content, and available water holding capacity, total N, and available P of the soil were measured just after harvesting the rice crop. Results showed that application of 15 t·FYM·ha-1 significantly increased soil organic matter and available water holding capacity but decreased the soil bulk density, creating a good soil condition for enhanced growth of the rice crop. Application of 15 tFYM·ha-1 increased the level of soil total nitrogen from 0.203% to 0.349%. Combined application of 15 t·ha-1·FYM and 100 kg·P2O5·ha-1 increased the available phosphorous from 11.9 ppm to 38.1 ppm. Positive balances of soil N and P resulted from combined application of FYM and inorganic N and P sources. Application of 15·t ha-1·FYM and 120 kg·N·ha-1resulted in 214.8 kg·ha-1·N positive balance while application of 15 t·ha-1·FYM and 100 kg·P2O5·ha-1 resulted in a positive balance of 69.3 kg·P2O5·ha-1 available P. From the results of this experiment, it could be concluded that combined application of FYM and inorganic N and P fertilizers improved the chemical and physical properties, which may lead to enhanced and sustainable production of rice in the study area.
文摘Enhancing water use efficiencies of rain-fed maize is a requirement for sustainable maize production, particularly in areas prone to low/drought and erratic rainfall patterns. This study was conducted to assess the relationship between total biomass/grain yield and water use efficiencies of three maize cultivars (Golden Crystal, Mamaba and Obatanpa) grown under rain-fed conditions in a coastal savannah agro-ecological environment of Ghana. Results of the study showed that a unified linear model, WUETDM = 0.03TDM with R2 = 0.765 and P ≤ 0.001, described adequately the relation between wa-ter use efficiency and total biomass (dry matter), which is applicable for the three maize cultivars for both the major and minor cropping seasons. A linear model could only, however, describe adequately well the relation between WUEGY and GY for the major (WUEGY = 0.001GY – 0.67;R2 = 0.996;P ≤ 0.001) and minor (WUEGY = 0.002GY + 0.289;R2 = 0.992;P ≤ 0.001) cropping seasons for all the maize cultivars. The linear models developed for the maize cultivars, re-lating WUEGY to GY, are specific to each of the crop growing seasons, indicating that seasonal rainfall impacts significantly on harvest index of the maize cultivars but differently in each of the crop growing seasons as a results of dif-ferences in seasonal rainfall. However, the models could be used to estimate water use efficiencies of each of the three maize cultivars given the appropriate TDM and GY as inputs for the environment under which the study was conducted.
文摘This paper is aimed at examining the applicability of methods for resilience, reliability and risk analyses of rain-fed agricultural systems from modeled continuous soil moisture availability in rain-fed crop lands. The methodology involves integration of soil and climatic data in a simple soil moisture accounting model to assess soil moisture availability, and a risk used as indicator of sustainability of rain-fed agricultural systems. It is also attempted to demonstrate the role of soil moisture modeling in risk analysis and agricultural water management in a semi-arid region in Limpopo Basin where rain-fed agriculture is practiced. For this purpose, a daily-time step soil moisture accounting model is employed to simulate daily soil moisture, evaporation, surface runoff, and deep percolation using 40 years (1961-2000) of agroclimatic data, and cropping cycle data of maize, sorghum and sunflower. Using a sustainability criterion on crop water requirement and soil moisture availability, we determined resilience, risk and reliability as a quantitative measure of sustainability of rain-fed agriculture of these three crops. These soil moisture simulations and the sustainability criteria revealed further confirmation of the relative sensitivity to drought of these crops. Generally it is found that the risk of failure is relatively low for sorghum and relatively high for maize and sunflower in the two sites with some differences of severity of failure owing to the slightly different agroclimatic settings.
文摘Based on the eddy-covariance observation data over rain-fed maize agricultural ecosystem during 2005-2011, the dynamics of net ecosystem CO2 exchange (NEE) and its control mechanism were analyzed in the present study. We found that the average carbon budget of non-growing season, growing season and annual were 153.16 - 202.03 g C/m2, −689.36 - −488.17 g C/m2, and −316.96 - −487.33 g C/m2, respectively. Maize carbon content of grain yield was −226.6 - −339.94 g C/m2, accounting for 55.4% of carbon budget in the growing season. From sowing to seven-leaf stage, the carbon budget of this ecosystem was characterized by carbon release, with the rate of 0.028 ±0.0056 mg CO2 m−2⋅s−1. From seven-leaf to mature stage, the carbon budget was characterized by carbon absorption, with the rate of −0.256 ±0.0693 mg CO2 m−2⋅s−1. The key meteorological factors affecting annual carbon budget included daily average temperature (R = −0.81, P = 0.03) and saturated vapor pressure deficit (R = −0.64, P = 0.12). At the same photosynthetically active radiation (PAR) level, CO2 assimilation rate was linearly correlated with leaf area index (P 【0.05), and the slopes increased with PAR, indicating the increase in net ecosystem CO2 exchange in growing season was unlikely to be resulted from the extension of growing season. On the contrary, the carbon sink of rain-fed maize ecosystem in growing season might be decreased by extending the growing season ahead of the sowing date.
文摘During the period spanning the 1970s and1980s, countries in the West African Sahel experienced severe drought. Its impact on agriculture and ecosystems has highlighted the importance of monitoring the Sahelian rainy season. In Sahelian countries such as Mali, rainfall is the major determinant of crop production. Unfortunately, rainfall is highly variable in time and space. Therefore, this study is conducted to analyze and forecast the impact of climatic parameters on the rain-fed rice yield cultivation in the Office Riz Mopti region. The data were collected from satellite imagery, archived meteorology data, yield and rice characteristics. The study employed Hanning filter to highlight interannual fluctuation, a test of Pettitt and the standardized precipitation index (SPI) to analyze the rainfall variability. Climate change scenarios under the RCP 8.5 scenario (HadGEM-2 ES) and agroclimatic (Cropwat) model are carried out to simulate the future climate and its impact on rice yields. The results of satellite image classifications of 1986 and 2016 show an increase of rice fields with a noticeable decrease of bare soil. The analysis of the SPI reveals that over the 30 years considered, 56.67% of the rainy seasons were dry (1986-2006) and 43.33% were wet (2007-2015). The modelling approach is applied over 1986-2006 and 2007-2015 periods—considered as typical dry and rainy years—and applied over the future, with forecasts of climate change scenarios in 2034. The results show a decrease in potential yield during dry and slightly wet years. The yields of rain-fed rice will be generally low between 2016 and 2027. Deficits are observed over the entire study area, in comparison with the potential yield. Thus, this situation could expose the population to food insecurity.
文摘This study examines social vulnerability by exploring the socio-economic factors, infrastructures, and social networks that can determine how prone and how prepared the rain-fed farming communities are to the adverse impacts of climate change. Increased variability in climatic conditions due to climate change seriously affects the productivity of rain-fed farms. The rain-fed farming communities in the Philippines are located in poor and environmentally fragile rural areas. Their vulnerability is greatly affected by restricted entitlement and access to social and economic capitals. This study is framed on qualitative approach to provide a rich and in-depth understanding on the elements of vulnerability based on the capacities and the practical affairs of life in rain-fed communities. The three subject communities from two agricultural provinces are examined to understand how the context and interactions of people can explicate sociological themes on the social dimension of climate change. The usefulness of multi-site study in probing the unique ways of how people understand and respond to certain environmental issue is part of reflections about the methodology.
文摘Rain-fed(dryland)farming is an ancient agricultural production system in China.It occurs widely across almost the whole country,especially in the Northwest and North China.The semi-arid Loess Plateau is the most important region of rain-fed farming in China,but unfortunately,soil erosion on the Loess Plateau area is the highest in China,and indeed amongst the highest in the world.This highlights the necessity for developing practices that can reduce soil and water erosion,improve soil water use efficiency,improve crop productivity,and reduce rural poverty in the region.Many techniques of soil and water conservation are being used in rain-fed areas of China,including such systems as mulch,ridge and furrow systems.The Appendix describes a unique system of soil and water conservation,called Shatian.Modern research on conservation tillage(No Till),although essential for reducing erosion,increasing crop productivity,and ameliorating poverty,is just beginning in China.Modern conservation tillage research started in the1990s’with support from Australia and other countries.The procedures,however,were modified to be in accord with local conditions and prevailing farmer experiences.With 10 years of experimentation,results show that the most successful conservation practice on the Western Loess Plateau is no till with stubble retention.This technique helps to conserve soil water,increases soil organic carbon,improves soil structure and water infiltration,reduces soil and water erosion,and improves crop productivity and sustainability of rain-fed farming systems.However,its adoption rate remains low due to barriers such as traditional attitude,insufficient rural extension,and so forth.
基金The Alliance of International Science Organizations(ANSO),No.ANSO-CR-PP-2021-06The Second Tibetan Plateau Scientific Expedition and Research,No.2019QZKK0603。
文摘Agriculture,significantly impacted by climate change and climate variability,serves as the primary livelihood for smallholder farmers in South Asia.This study aims to examine and evaluate the factors influencing smallholder farmers'adaptive capacity(AC)in addressing these risks through surveys from 633 households across Nepal,India,and Bangladesh.The findings reveal that AC is influenced by various indicators categorized under eight principal factors.The first three factors,which explain about one-third of the variance in each country,include distinct significant indicators for each nation:in Nepal,these indicators are landholding size,skill-development training,knowledge of improved seed varieties,number of income sources,access to markets,and access to financial institutions;in India,they encompass ac-cess to agricultural-input information,knowledge of seed varieties,access to markets,access to crop insurance,changing the sowing/harvesting times of crops,and access to financial ser-vices;in Bangladesh,the key factors are access to financial institutions,community coopera-tion,changing the sowing/harvesting times of crops,knowledge of improved seed varieties,and access to agricultural-input information.Notably,indicators such as trust in weather in-formation,changing sowing/harvesting times of crops,and crop insurance were identified as important determinants of AC,which have been overlooked in previous studies.
文摘为探究雨养和灌溉条件下氮肥后移对冬小麦面粉加工品质的影响及其谷蛋白形成机制,本研究选用强筋小麦品种中麦886(ZM886)和中筋小麦品种中麦30(ZM30)为试验材料,在雨养处理(W)和灌溉处理(D)条件下,总施氮量为210 kg hm^(-2)的基础上设置2个追氮处理:常规氮肥处理(N1:底肥50%+拔节肥50%)和氮肥后移处理(N2:底肥50%+拔节肥30%+孕穗肥20%),研究其对冬小麦籽粒谷蛋白大聚合体(GMP)形成和面粉加工品质的影响。试验结果表明,2小麦品种产量最大值均出现在WN2处理,其中ZM30在WN2处理下产量较其他处理平均提高12.36%(2021—2022年)和13.97%(2022—2023年),ZM886同期分别提高9.85%和18.31%。在花后10 d检测到籽粒中高分子量谷蛋白亚基(HMW-GS)和低分子量谷蛋白亚基(LMW-GS),ZM886在DN2处理下HMW-GS、LMW-GS、free-SH、-S-S-含量最高,ZM30则在WN2处理达到峰值。花后30 d检测到2小麦品种籽粒GMP的存在,ZM886在DN2下较其他处理增高5.40%~33.90%,ZM30在WN2下增高2.50%~14.70%,同时分别在2处理下增加了GMP大颗粒体积和表面积百分比,从而不同程度地提高面粉加工品质。小麦籽粒GMP含量与HMW-GS含量和LMW-GS含量呈正相关,ZM886籽粒GMP含量与面团形成时间和稳定时间呈正相关,但与产量呈负相关;ZM30籽粒GMP含量与产量呈极显著正相关,但与吸水率呈负相关。综上,本试验条件下,氮肥后移通过调控谷蛋白亚基合成,提升GMP含量,优化GMP粒径分布。因小麦产量而言,适宜的水氮配置为:灌溉处理下,氮肥施用底肥50%+拔节肥30%+孕穗肥20%;因小麦品质而言,适宜的水氮配置因品种类型而异:强筋小麦中麦886为在雨养处理下,氮肥施用底肥50%+拔节肥30%+孕穗肥20%,中筋小麦中麦30为在灌溉处理下,氮肥施用底肥50%+拔节肥30%+孕穗肥20%。
