Straw return is an effective way to improve crop grain yield and potassium(K)use efficiency by increasing soil K content.However,the effects of straw return on soil K supplying capacity,replacement of K fertilizer,and...Straw return is an effective way to improve crop grain yield and potassium(K)use efficiency by increasing soil K content.However,the effects of straw return on soil K supplying capacity,replacement of K fertilizer,and K-use efficiency under maize(Zea mays L.)–rice(Oryza sativa L.)cropping systems are little studied.A two-year field experiment was conducted to determine the physiological determinants of K-use efficiency under straw return with four K fertilization rates.Sr33(straw returned plus 33%of K fertilizer applied)and Sr67(straw returned plus 67%of K fertilizer applied)increased annual crop yields by 1.5%and 3.2%and increased agronomic K-use efficiency by respectively 2.9 and 1.3-fold on average in the two years,compared with the conventional practice S0K100(no straw returned plus normal amounts of K fertilizer applied).The Sr33 and Sr67 treatments resulted in significantly greater equilibrium K concentration ratios(CR0 K)and specifically exchangeable K(KX)values according to quantity/intensity(Q/I)relationship analyses,indicating improvement of the potential soil K supply capacity.However,the Sr67 better maintained the soil exchangeable K level and K balance.The results suggested that K released from maize and rice straw can replace about half of chemical K fertilizer,depending on the available K content in maize–rice cropping system production.展开更多
Project management is vital for software project success. Project Management Body of Knowledge (PMBOK), CMMI for Development (CMMI-DEV), and other software project management models and practices established to assist...Project management is vital for software project success. Project Management Body of Knowledge (PMBOK), CMMI for Development (CMMI-DEV), and other software project management models and practices established to assist software organizations, each of these models offers diverse focal points. Combined effective software project management practices remain a challenge to software organizations. In striving to raise the likelihood of software project success, this paper introduces a framework for software project management effectiveness which integrated a set of software project management practices based on the PMBOK guide processes, CMMI-DEV processes, and management areas that influence a software project. The proposed framework called 4PTRB which includes people, process, product, project, technology, risk, and business management areas. The 4PTRB software project management framework provides a whole comprehensive view to help software project managers to improve their project management effectiveness. The framework is validated by conducting a web-based survey of software professional practitioners around the world. A statistical analysis of twenty software projects has been conducted as a case study thereafter, spanning small to large development projects. The consistency of the case study and survey results shows the power of the 4PTRB framework as an inclusive software project management framework.展开更多
基金supported by the Special Fund for Agroscientific Research in the Public Interest of China(201503122)the National Natural Science Foundation of China(31571622)。
文摘Straw return is an effective way to improve crop grain yield and potassium(K)use efficiency by increasing soil K content.However,the effects of straw return on soil K supplying capacity,replacement of K fertilizer,and K-use efficiency under maize(Zea mays L.)–rice(Oryza sativa L.)cropping systems are little studied.A two-year field experiment was conducted to determine the physiological determinants of K-use efficiency under straw return with four K fertilization rates.Sr33(straw returned plus 33%of K fertilizer applied)and Sr67(straw returned plus 67%of K fertilizer applied)increased annual crop yields by 1.5%and 3.2%and increased agronomic K-use efficiency by respectively 2.9 and 1.3-fold on average in the two years,compared with the conventional practice S0K100(no straw returned plus normal amounts of K fertilizer applied).The Sr33 and Sr67 treatments resulted in significantly greater equilibrium K concentration ratios(CR0 K)and specifically exchangeable K(KX)values according to quantity/intensity(Q/I)relationship analyses,indicating improvement of the potential soil K supply capacity.However,the Sr67 better maintained the soil exchangeable K level and K balance.The results suggested that K released from maize and rice straw can replace about half of chemical K fertilizer,depending on the available K content in maize–rice cropping system production.
文摘Project management is vital for software project success. Project Management Body of Knowledge (PMBOK), CMMI for Development (CMMI-DEV), and other software project management models and practices established to assist software organizations, each of these models offers diverse focal points. Combined effective software project management practices remain a challenge to software organizations. In striving to raise the likelihood of software project success, this paper introduces a framework for software project management effectiveness which integrated a set of software project management practices based on the PMBOK guide processes, CMMI-DEV processes, and management areas that influence a software project. The proposed framework called 4PTRB which includes people, process, product, project, technology, risk, and business management areas. The 4PTRB software project management framework provides a whole comprehensive view to help software project managers to improve their project management effectiveness. The framework is validated by conducting a web-based survey of software professional practitioners around the world. A statistical analysis of twenty software projects has been conducted as a case study thereafter, spanning small to large development projects. The consistency of the case study and survey results shows the power of the 4PTRB framework as an inclusive software project management framework.
