影响花生氮素利用的因素研究及高效施氮技术规程

研究了影响花生氮素利用的因素,结果表明：（1）不同基因型花生对氮素利用存在较大差异。土壤供氮率为51．9％～73．7％,其中晋安花生等较高,潍花8号较低;根瘤供氮率为10．5％～37．4％,其中3--XC135、潍花8号等较高,晋安花生较低;肥料供氮率10．8％～15．2％,其中蓬莱小粒皮红较高,3-XC128较低。（...     

广东省杂交水稻育种利用的现状与展望

“九五”期间，广东省杂交水稻育种利用研究取得了显著进展，共计育成通过省品种审定新组合24个，国家品种审定新组合10个，育成通过省级技术鉴定优质新不育系4个，与“八五”比较，“九五”期间育成的新组合在综合品质性状上取得了明显改善，其中998系列和培杂系列杂交稻组合正发展成为广东省当家组合。     

基于文献计量分析的国内农业生态补偿研究态势

基于CNKI文献,检索以农业、农田、农户、耕地、水域、林业、森林、草原、湿地、退耕和生态补偿、生态效益补偿为主题,从年代、期刊、作者、作者机构、研究对象、地域和方法等方面对1988～2016年间国内农业生态补偿相关研究成果进行了文献计量分析。分析显示：中国农业生态补偿研究论文数量逐年增长,但并未形成稳定的核心作者群;研究对象以农户受偿意愿、补偿方式、补偿额度、补偿的法律问题等为主,研究领域涉及森林、草原、耕地、湿地等;研究手段方面,目前仍以实证研究为主,定量研究方法的运用逐步增加,但仍有待加强。从多角度对中国农业生态补偿有关文献成果进行分析,有助于更全面、客观地了解该领域的研究现状及发展趋势。     

Calculation of theoretical nitrogen rate for simple nitrogen recommendations in intensive cropping systems: A case study on the North China Plain

Nitrogen (N) is a crucial nutrient that requires careful management in intensive cropping systems because of its diverse beneficial and detrimental effects. Here we propose the concept of theoretical N rate (TNR) to answer the important question of how much fertilizer N should be applied to intensive systems based on the N fluxes due to transformation processes in the soil-crop-environment continuum. We define TNR as the theoretically calculated fertilizer N rate with the quantitative relationships of the core N fluxes among fertilizer N, soil N and crop uptake N in the crop root zone to obtain high target yield, maintain soil N balance and minimize environmental risk. We deduced one basic mathematical expression (N_fert = N_uptake − N_straw + N_fert3) and two simplified expressions [N_fert = (N_uptake − N_straw)/(1 − Coeff); N_fert ≅ N_uptake] for calculating the TNR. These expressions do not need much field experimentation or elaborate soil and plant testing to obtain information on crop N demand and soil N supply, and are simple to implement in farming practice to provide a very cost-effective approach. We consider this scheme to be a useful contribution to rational fertilizer practice, especially in developing countries where other N recommendation systems are usually not available and agricultural extension services are poorly developed or absent.     

Optimising harvest date in sugar production: A case study for the Mossman mill region in Australia: I. Development of operations research model and solution

Cane and sugar yields within a sugar mill region can vary with geographical location, harvest date, harvest age, variety and crop class. It is not possible, due to limited mill capacity, to harvest all cane when maximum yields are attained. Given a prolonged harvest season, an important question is how the harvest of individual paddocks of cane should be scheduled so as to maximise net revenue for the entire mill region. This paper presents the application of an optimisation model to the Mossman mill region with the objectives of maximising sugar yield and net revenue in relation to harvest date and crop age. Six years of block productivity data classified according to district, crop class, variety, harvest date, harvest age, cane yield and sugar yield, were used to generate the input parameters for the model. Other inputs were sugar price, growing and milling costs, and transport and crushing capacity. With current crushing capacity and harvest season lengths, an application of the model to maximise sugar yield showed a 4% increase in sugar yield compared to current practice, but a 23% decrease in net revenue due to a shorter crop cycle with less ratoons before replanting. Optimising with respect to net revenue, gave a 3% gain in sugar yield with an 8% gain in net revenue. When crushing capacity was allowed to increase for current season lengths, the model showed a 14% gain in net revenue given fixed milling costs. It is concluded that there is scope for optimising harvest date to improve profitability in this mill region given current harvest season lengths and land area.