【目的】酰胺态氮、铵态氮和硝态氮是蔬菜施肥的主要氮源,不同氮素形态配比既影响蔬菜的产量品质,又影响氮素损失,而氮素在不同土壤中转化进程不同。为确定辣椒主产区主要土壤类型上合适的氮素形态配比,本试验选用广东赤红壤(p H 5.97)...【目的】酰胺态氮、铵态氮和硝态氮是蔬菜施肥的主要氮源,不同氮素形态配比既影响蔬菜的产量品质,又影响氮素损失,而氮素在不同土壤中转化进程不同。为确定辣椒主产区主要土壤类型上合适的氮素形态配比,本试验选用广东赤红壤(p H 5.97)、安徽菜园土(p H 7.09)和山东潮土(p H 8.33)为供试土壤,研究辣椒产量和品质在三种不同类型土壤上对不同氮素形态配比的响应,确定适宜各土壤类型上辣椒生长的酰硝比,以期为辣椒主产区氮肥调控提供理论依据。【方法】采用土壤培养试验和盆栽试验,土壤培养试验每种土壤类型设两个处理:单施尿素(对照)、尿素添加硝化抑制剂处理。盆栽试验设:不施氮肥(CK)、NO_3-N 100%(T1);CO(NH_2)_2-N 25%+NO_3-N 75%(T2)、CO(NH_2)_2-N 50%+NO_3-N 50%(T3)、CO(NH_2)_2-N 75%+NO_3-N 25%(T4)、CO(NH_2)_2-N 100%(T5)6个处理。培养试验测定不同培养时期土壤铵态氮和硝态氮含量;盆栽试验在辣椒收获期测定辣椒的产量与品质、植株氮浓度,在施肥后不同时期测定土壤无机氮的含量。【结果】土壤培养试验结果表明三类土壤的硝化能力强弱顺序是潮土>菜园土>赤红壤,添加硝化抑制剂2-氯-6-(三氯甲基)吡啶(NServe)后能调控三类土壤的氮素转化速率,在培养第4天表观硝化率分别降低了30.3%、38.0%和8.3%。盆栽试验结果表明与不施氮肥处理相比,施氮处理能显著提高辣椒产量和品质,产量的提高源于单果重和果实数的增加,品质提升主要包括维生素C和可溶性固形物含量的提高;在添加N-Serve(酰胺态氮纯氮量的1%)的基础上,三类土壤上辣椒产量和品质对酰硝比的响应不同,赤红壤、菜园土和潮土最高产量对应的硝态氮占氮肥供应总量的75%,25%和50%,品质较优对应的硝态氮占比分别是75%,50%和25%;辣椒氮素吸收量也表现为菜园土>潮土>赤红壤,且与单施硝态氮相比,硝态氮与酰胺态氮配施在赤红壤、菜园土和潮土上氮肥利用率分别提高25.3%、9.0%和22.4%,淋洗液氮素损失量分别降低58.4%,53.6%和51.7%。【结论】统筹考虑辣椒优质高产以及环境代价等因素,在赤红壤、菜园土和潮土上适宜的硝态氮占比分别是50%~75%,25%~50%和25%~50%。展开更多
以长期农业气象田间观测和统计局产量资料为基础,研究得出:怀化市一季中稻生产农业气象灾害以干旱、洪涝、秧田低温、8月低温为主,对中稻产量的损失30 a来平均4%左右,最大22%。中稻产量损失率5%以上的年份约10 a 3遇,除2002年多种灾害...以长期农业气象田间观测和统计局产量资料为基础,研究得出:怀化市一季中稻生产农业气象灾害以干旱、洪涝、秧田低温、8月低温为主,对中稻产量的损失30 a来平均4%左右,最大22%。中稻产量损失率5%以上的年份约10 a 3遇,除2002年多种灾害影响和1996年特殊洪涝年外,其它均为持续30 d以上夏旱、夏秋连旱年份。展开更多
Sedimentation is a major problem for agricultural dams in Botswana, as it reduces the storage capacity and life span of the reservoirs. The process of sedimentation starts from day one of the impounding of water in an...Sedimentation is a major problem for agricultural dams in Botswana, as it reduces the storage capacity and life span of the reservoirs. The process of sedimentation starts from day one of the impounding of water in any given reservoir. Even though a provision is made for every reservoir during planning for a certain storage capacity, specifically for sediment deposition, called dead storage, a major portion of the sediment gets deposited for many years of the reservoir’s life in areas other than the dead storage, and this trend cannot be reversed at easy cost. This study is aimed at the analysis of prevailing sedimentation processes in the nearby dozens of dams found in the Lotsane catchment located within the Limpopo Basin of Botswana, and focuses on assessment of annual sedimentation rate. A spatial analysis and modelling study was conducted based on the Revised Universal Soil Loss Equation and GIS to determine sediment yield and degree of impact of each reservoir for a given landscape, rainfall and catchment heterogeneity. Field observations and soil sampling were carried out in order to determine the factors that lead to reservoir sedimentation. Spatial data on the dams in Lotsane catchment were also collected from Ministry of Agriculture, which were used for ground-truthing, GIS-based calculations and model validation. The average sediment rate and sediment delivery ratio were found to be 1.74 t/ha/year and 81%, respectively. These are useful parameters to estimate service life of the dams and plan remedial measures related to sedimentation problems.展开更多
文摘【目的】酰胺态氮、铵态氮和硝态氮是蔬菜施肥的主要氮源,不同氮素形态配比既影响蔬菜的产量品质,又影响氮素损失,而氮素在不同土壤中转化进程不同。为确定辣椒主产区主要土壤类型上合适的氮素形态配比,本试验选用广东赤红壤(p H 5.97)、安徽菜园土(p H 7.09)和山东潮土(p H 8.33)为供试土壤,研究辣椒产量和品质在三种不同类型土壤上对不同氮素形态配比的响应,确定适宜各土壤类型上辣椒生长的酰硝比,以期为辣椒主产区氮肥调控提供理论依据。【方法】采用土壤培养试验和盆栽试验,土壤培养试验每种土壤类型设两个处理:单施尿素(对照)、尿素添加硝化抑制剂处理。盆栽试验设:不施氮肥(CK)、NO_3-N 100%(T1);CO(NH_2)_2-N 25%+NO_3-N 75%(T2)、CO(NH_2)_2-N 50%+NO_3-N 50%(T3)、CO(NH_2)_2-N 75%+NO_3-N 25%(T4)、CO(NH_2)_2-N 100%(T5)6个处理。培养试验测定不同培养时期土壤铵态氮和硝态氮含量;盆栽试验在辣椒收获期测定辣椒的产量与品质、植株氮浓度,在施肥后不同时期测定土壤无机氮的含量。【结果】土壤培养试验结果表明三类土壤的硝化能力强弱顺序是潮土>菜园土>赤红壤,添加硝化抑制剂2-氯-6-(三氯甲基)吡啶(NServe)后能调控三类土壤的氮素转化速率,在培养第4天表观硝化率分别降低了30.3%、38.0%和8.3%。盆栽试验结果表明与不施氮肥处理相比,施氮处理能显著提高辣椒产量和品质,产量的提高源于单果重和果实数的增加,品质提升主要包括维生素C和可溶性固形物含量的提高;在添加N-Serve(酰胺态氮纯氮量的1%)的基础上,三类土壤上辣椒产量和品质对酰硝比的响应不同,赤红壤、菜园土和潮土最高产量对应的硝态氮占氮肥供应总量的75%,25%和50%,品质较优对应的硝态氮占比分别是75%,50%和25%;辣椒氮素吸收量也表现为菜园土>潮土>赤红壤,且与单施硝态氮相比,硝态氮与酰胺态氮配施在赤红壤、菜园土和潮土上氮肥利用率分别提高25.3%、9.0%和22.4%,淋洗液氮素损失量分别降低58.4%,53.6%和51.7%。【结论】统筹考虑辣椒优质高产以及环境代价等因素,在赤红壤、菜园土和潮土上适宜的硝态氮占比分别是50%~75%,25%~50%和25%~50%。
文摘以长期农业气象田间观测和统计局产量资料为基础,研究得出:怀化市一季中稻生产农业气象灾害以干旱、洪涝、秧田低温、8月低温为主,对中稻产量的损失30 a来平均4%左右,最大22%。中稻产量损失率5%以上的年份约10 a 3遇,除2002年多种灾害影响和1996年特殊洪涝年外,其它均为持续30 d以上夏旱、夏秋连旱年份。
文摘Sedimentation is a major problem for agricultural dams in Botswana, as it reduces the storage capacity and life span of the reservoirs. The process of sedimentation starts from day one of the impounding of water in any given reservoir. Even though a provision is made for every reservoir during planning for a certain storage capacity, specifically for sediment deposition, called dead storage, a major portion of the sediment gets deposited for many years of the reservoir’s life in areas other than the dead storage, and this trend cannot be reversed at easy cost. This study is aimed at the analysis of prevailing sedimentation processes in the nearby dozens of dams found in the Lotsane catchment located within the Limpopo Basin of Botswana, and focuses on assessment of annual sedimentation rate. A spatial analysis and modelling study was conducted based on the Revised Universal Soil Loss Equation and GIS to determine sediment yield and degree of impact of each reservoir for a given landscape, rainfall and catchment heterogeneity. Field observations and soil sampling were carried out in order to determine the factors that lead to reservoir sedimentation. Spatial data on the dams in Lotsane catchment were also collected from Ministry of Agriculture, which were used for ground-truthing, GIS-based calculations and model validation. The average sediment rate and sediment delivery ratio were found to be 1.74 t/ha/year and 81%, respectively. These are useful parameters to estimate service life of the dams and plan remedial measures related to sedimentation problems.
