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Metadata only record ; Despite government subsidies and the potential benefits to yield and income, fertilizer use in most of Africa remains low. Determining the barriers to its use and the factors influencing its profitability is critical in increasing its popularity. This study uses longitudinal farm data in a generalized asymmetrical production model in order to approximate maize yields in response to household features, traditional production inputs, and government programs in Zambia. The analysis determined that both input and non-input factors, such as market conditions, application rate, fertilizer availability, animal use, and even death of a family member, played roles in determining yield response and overall profitability of fertilizer use on maize. This research illustrates the importance of considering household heterogeneity in regards to fertilizer use and yield response in both productions models and, perhaps more importantly, in government programming and planning.

AbstractSolute transport characteristics and groundwater connection structures are mainly studied in this paper by adopting the numerical simulation and field tracer test. Firstly, the simulation method of solute transport is proposed. Then two kinds of representative geological models of tracer test are built, and the process of solute transport is simulated. The variation characteristics of solute transport under the conditions of straight pipeline and branch pipeline are summarized by analysis of the simulation results. The effects of the pipeline width, flow velocity and path difference of branch pipelines on the tracer curve are discussed. General laws of groundwater connection tracer curve are obtained. Finally, based on the field test results, and combined with engineering geological conditions, characteristics of karst groundwater systems, the groundwater connection structures are analysed and speculated in detail by the flow velocity and local monitoring curve. The results show that: (i) As the flow velocity increases, the peak of the tracer curve decreases gradually, as well as the time to peak; (ii) The peak of the tracer curve gradually decreases with the increasing pipeline width; (iii) Under the different path difference of branch pipeline, the tracer curves all present obvious 'trailing' phenomenon; (iv) The analysis process of groundwater connection structures can provide references for the same type of hydrological geological problems.

202202 bchy ; Version of Record ; Others ; This study was supported in part by the National Key Research and Development Project (No.2018YFB2101200), the National Natural Science Foundation of China (Nos.62002034, 62002306), the Fundamental Research Funds for the Central Universities (Nos.2020CDCGRJ072, 2020CDJQY-A021, and JUSRP121073), China Postdoctoral Science Foundation (No.2020M673137), the Special Funds for the Central Government to Guide Local Scientific and Technological Development (No.YDZX20195000004725), the Natural Science Foundation of Chongqing in China (No.cstc2020jcyj-bshX0114), the Key Project of Technology Innovation and Application Development of Chongqing (No.cstc2019jscx-mbdxX0020), HKPolyU Start-up Fund (No.ZVU7), CCF-Tencent Open Research Fund (No.ZDCK), and the European Commission grant (No.825,040) RADON. ; Early release