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.
