With the aim of finding the geochemical differences and helping to build alleviating strategies against iron toxicity, two hematite dominant valley bottoms irrigating rice soils were investigated in the Tropical Savan...With the aim of finding the geochemical differences and helping to build alleviating strategies against iron toxicity, two hematite dominant valley bottoms irrigating rice soils were investigated in the Tropical Savannah region of Burkina Faso. The first site was Tiefora, a 15-ha modern double-season irrigated rice system and moderately affected by iron toxicity (10% of the area with a toxicity score of 4). The second site was Moussodougou, a 35-ha traditional singleseason irrigated rice valley-bottom, with 50% facing more severe iron toxicity (score 7). Nine soil extracts were taken from three depths—30, 50 and 100 cm—i.e. 27 at Tiefora and 27 at Moussodogou. Five techniques were used to measure the data: 1) the ferrous iron concentration was determined using a reflectometer, 2) a pH-meter yielded the pH, 3) clay-proportions were obtained by United States Department of Agriculture (USDA) grain size analysis and densitometry, 4) the organic matter was determined by oven drying (900℃) and v) the dry bulk density was determined by using undisturbed soil samples. Statistical hypothesis testing of One-way ANOVA and Welch t-test was applied to the data to isolate the similarities and the differences between the two sites. A geochemical analysis followed to find the causes of these differences. The results showed that while oxidation of pyrite leads to a simultaneous increase in Fe2+ concentrations and acidity in the soils of coastal floodplains and mangroves, the oxidation of hematite in Tropical savannah valley bottoms decreases Fe2+ but also increases acidity during the dry season. As a consequence, it was found that the single-season irrigation scheme Moussodougou is significantly (p-value 0.4%) more acidic (pH 5.7) than the double-season system of Tiefora (6.4) with also 750 - 1800 mg/l higher ferrous Fe2+. The ferrous iron reached 3000 mg/l in some layers in Moussodougou. This result is a justification to modernize a traditional single-season spate irrigation schemes into a double-season irrigated rice scheme.展开更多
Semarang urban coastal areas are experiencing tidal flood. In addition, land subsidence of 5 to 10 centimetres per year is taking place. The climate change phenomenon provokes land areas that are lower than sea water ...Semarang urban coastal areas are experiencing tidal flood. In addition, land subsidence of 5 to 10 centimetres per year is taking place. The climate change phenomenon provokes land areas that are lower than sea water level from time to time. This makes the situation with respect to flooding increasingly risky. Semarang Old City （heritage） as part of principal Semarang area is suffering also from regular flooding and pollution that hamper the revitalisation of the old city. These areas used to be productive lands, but flooding make the existing public infrastructure does no longer function, and residential areas have changed into unhealthy slams. To overcome these problems, the Government of Semarang chooses a polder drainage system to address the flooding in Semarang. In the framework of the cooperation between Indonesia and the Netherlands, these activities consist of research and workshops on Urban Heritage. The scope consists basically of five components： experiences with urban drainage and flood protection in Semarang with a focus on Semarang Old City, field visit to relevant places with respect to urban drainage and flood protection of Semarang Old City, lectures on the relevant aspects of urban drainage and flood protection, exercises to get an insight in the processes that can take place under normal and extreme conditions, formulation of a preliminary plan to improve the situation with respect to urban drainage and flood protection of Semarang Old City. In this paper, the various relevant points are described, such as scenarios analysis as well as the findings and recommendations for improvement of the urban drainage system and flood protection of Semarang Heritage City.展开更多
Rainfed agriculture has a high yield potential if rainfall and land resources are effectively used.In this study,conventional(NC)and six in-situ water conservation practices were used to cultivate Soybean in 2011 and ...Rainfed agriculture has a high yield potential if rainfall and land resources are effectively used.In this study,conventional(NC)and six in-situ water conservation practices were used to cultivate Soybean in 2011 and 2012 in Ile-lfe,Nigeria.The conservation practices are:Tied ridge(TR),Soil bund(BD),Mulch(ML),Mulch plus Soil bund(MLBD),Tied ridge plus Mulch(TRML),Tied ridge plus Soil bund(TRBD).The practices were arranged in Randomised Complete Block Design with four replicates.Seasonal rainfall was 539 and 761 mm in 2011 and 2012,respectively.Seasonal soil water storage(SWS)ranged from 485 mm for NC to 517 mm for TRML in the two seasons.ML increased the SWS in the upper 30 cm of the soil by 17% while TR increased the soil water content in the lower 30-60 cm by 22% compared with NC.ML reduced soil temperature in the upper 30 cm between 2.2 and 2.9℃ compared with NC,TR and TRML.Seasonal crop evapotranspiration ranged between 432 mm for NC and 481 mm for BD in the seasons.Grain yield increased by 41.7% and 44.3% for BD and MLBD,respectively compared with NC.Water conservation practices increased water productivity for grain yield by 14.0-41.8% compared with NC.Similarly,it increased average seasonal transpiration efficiency by 15.3-32.5% compared with NC.These findings demonstrate that when there are fluctuations in rainfall,in-situ water conservation practices improve SWS,land,and water productivity and transpiration efficiency of Soybeans.展开更多
Modelling of the effects of water and different levels of nitrogen on evapotranspiration and water productivity of rainfed soybeans is very important in optimising resource use in the production of the crop.The object...Modelling of the effects of water and different levels of nitrogen on evapotranspiration and water productivity of rainfed soybeans is very important in optimising resource use in the production of the crop.The objective of the study was to model evapotranspiration,soil water storage and water productivity of rainfed soybeans under different levels of nitrogen fertilizer by using the FAO AquaCrop model.Field experiments were conducted at the Teaching and Research Farms of Obafemi Awolowo University,Nigeria in the rainy seasons of 2015 and 2016.There were five levels of nitrogen,which are 00,25,50,75 and 100%of the recommended nitrogen applications and two varieties of soybeans,which produced a 2 by 5 factorial experimental design.The data of the wetter year 2015,were used for calibration of the AquaCrop model because AquaCrop is water driven.The 2016 data were used for the validation.The AquaCrop model simulated canopy cover with R2 and EF>0.90,d-in-dex>0.99.The model captured the trend of the soil water storage well,R2 and EF>0.70.The AquaCrop model simulated soil water storage below wilting point for seasonal rainfall less than 600 mm,and it did not overestimate it.The model predicted evapotranspirationwith R and EF>0.89,d-index=1.00.Above ground biomass was overestimated even though R2>0.98.Although,nitrogen stress reduced seed yield and water productivity,there was no under or over estimation of the seed yields.They were predicted with low error under the different levels of nitrogen fertilizer,R>0.99,EF and d-index>0.99.The AquaCrop model is suitable for simulating canopy cover,soil water storage,evapotranspiration,and seed yieldof rainfed soybeans with different levels of nitrogen fertilizer under temporal distribution of seasonal rainfall.Therefore,it can serve as a useful tool for smallholder farmers in predicting productivity of soybeans and optimising resource allocation,land and water use in the tropical farming systems.We recommend simulation of the effects of pest on biomass,seed yield and water produc-tivity by subsequent versions of the AquaCrop model.In addition,incorporating an eco-nomic sub-unit in the model will enable users to make financial decisions.展开更多
文摘With the aim of finding the geochemical differences and helping to build alleviating strategies against iron toxicity, two hematite dominant valley bottoms irrigating rice soils were investigated in the Tropical Savannah region of Burkina Faso. The first site was Tiefora, a 15-ha modern double-season irrigated rice system and moderately affected by iron toxicity (10% of the area with a toxicity score of 4). The second site was Moussodougou, a 35-ha traditional singleseason irrigated rice valley-bottom, with 50% facing more severe iron toxicity (score 7). Nine soil extracts were taken from three depths—30, 50 and 100 cm—i.e. 27 at Tiefora and 27 at Moussodogou. Five techniques were used to measure the data: 1) the ferrous iron concentration was determined using a reflectometer, 2) a pH-meter yielded the pH, 3) clay-proportions were obtained by United States Department of Agriculture (USDA) grain size analysis and densitometry, 4) the organic matter was determined by oven drying (900℃) and v) the dry bulk density was determined by using undisturbed soil samples. Statistical hypothesis testing of One-way ANOVA and Welch t-test was applied to the data to isolate the similarities and the differences between the two sites. A geochemical analysis followed to find the causes of these differences. The results showed that while oxidation of pyrite leads to a simultaneous increase in Fe2+ concentrations and acidity in the soils of coastal floodplains and mangroves, the oxidation of hematite in Tropical savannah valley bottoms decreases Fe2+ but also increases acidity during the dry season. As a consequence, it was found that the single-season irrigation scheme Moussodougou is significantly (p-value 0.4%) more acidic (pH 5.7) than the double-season system of Tiefora (6.4) with also 750 - 1800 mg/l higher ferrous Fe2+. The ferrous iron reached 3000 mg/l in some layers in Moussodougou. This result is a justification to modernize a traditional single-season spate irrigation schemes into a double-season irrigated rice scheme.
文摘Semarang urban coastal areas are experiencing tidal flood. In addition, land subsidence of 5 to 10 centimetres per year is taking place. The climate change phenomenon provokes land areas that are lower than sea water level from time to time. This makes the situation with respect to flooding increasingly risky. Semarang Old City （heritage） as part of principal Semarang area is suffering also from regular flooding and pollution that hamper the revitalisation of the old city. These areas used to be productive lands, but flooding make the existing public infrastructure does no longer function, and residential areas have changed into unhealthy slams. To overcome these problems, the Government of Semarang chooses a polder drainage system to address the flooding in Semarang. In the framework of the cooperation between Indonesia and the Netherlands, these activities consist of research and workshops on Urban Heritage. The scope consists basically of five components： experiences with urban drainage and flood protection in Semarang with a focus on Semarang Old City, field visit to relevant places with respect to urban drainage and flood protection of Semarang Old City, lectures on the relevant aspects of urban drainage and flood protection, exercises to get an insight in the processes that can take place under normal and extreme conditions, formulation of a preliminary plan to improve the situation with respect to urban drainage and flood protection of Semarang Old City. In this paper, the various relevant points are described, such as scenarios analysis as well as the findings and recommendations for improvement of the urban drainage system and flood protection of Semarang Heritage City.
文摘Rainfed agriculture has a high yield potential if rainfall and land resources are effectively used.In this study,conventional(NC)and six in-situ water conservation practices were used to cultivate Soybean in 2011 and 2012 in Ile-lfe,Nigeria.The conservation practices are:Tied ridge(TR),Soil bund(BD),Mulch(ML),Mulch plus Soil bund(MLBD),Tied ridge plus Mulch(TRML),Tied ridge plus Soil bund(TRBD).The practices were arranged in Randomised Complete Block Design with four replicates.Seasonal rainfall was 539 and 761 mm in 2011 and 2012,respectively.Seasonal soil water storage(SWS)ranged from 485 mm for NC to 517 mm for TRML in the two seasons.ML increased the SWS in the upper 30 cm of the soil by 17% while TR increased the soil water content in the lower 30-60 cm by 22% compared with NC.ML reduced soil temperature in the upper 30 cm between 2.2 and 2.9℃ compared with NC,TR and TRML.Seasonal crop evapotranspiration ranged between 432 mm for NC and 481 mm for BD in the seasons.Grain yield increased by 41.7% and 44.3% for BD and MLBD,respectively compared with NC.Water conservation practices increased water productivity for grain yield by 14.0-41.8% compared with NC.Similarly,it increased average seasonal transpiration efficiency by 15.3-32.5% compared with NC.These findings demonstrate that when there are fluctuations in rainfall,in-situ water conservation practices improve SWS,land,and water productivity and transpiration efficiency of Soybeans.
文摘Modelling of the effects of water and different levels of nitrogen on evapotranspiration and water productivity of rainfed soybeans is very important in optimising resource use in the production of the crop.The objective of the study was to model evapotranspiration,soil water storage and water productivity of rainfed soybeans under different levels of nitrogen fertilizer by using the FAO AquaCrop model.Field experiments were conducted at the Teaching and Research Farms of Obafemi Awolowo University,Nigeria in the rainy seasons of 2015 and 2016.There were five levels of nitrogen,which are 00,25,50,75 and 100%of the recommended nitrogen applications and two varieties of soybeans,which produced a 2 by 5 factorial experimental design.The data of the wetter year 2015,were used for calibration of the AquaCrop model because AquaCrop is water driven.The 2016 data were used for the validation.The AquaCrop model simulated canopy cover with R2 and EF>0.90,d-in-dex>0.99.The model captured the trend of the soil water storage well,R2 and EF>0.70.The AquaCrop model simulated soil water storage below wilting point for seasonal rainfall less than 600 mm,and it did not overestimate it.The model predicted evapotranspirationwith R and EF>0.89,d-index=1.00.Above ground biomass was overestimated even though R2>0.98.Although,nitrogen stress reduced seed yield and water productivity,there was no under or over estimation of the seed yields.They were predicted with low error under the different levels of nitrogen fertilizer,R>0.99,EF and d-index>0.99.The AquaCrop model is suitable for simulating canopy cover,soil water storage,evapotranspiration,and seed yieldof rainfed soybeans with different levels of nitrogen fertilizer under temporal distribution of seasonal rainfall.Therefore,it can serve as a useful tool for smallholder farmers in predicting productivity of soybeans and optimising resource allocation,land and water use in the tropical farming systems.We recommend simulation of the effects of pest on biomass,seed yield and water produc-tivity by subsequent versions of the AquaCrop model.In addition,incorporating an eco-nomic sub-unit in the model will enable users to make financial decisions.
