农业劳动力结构、粮食生产与化肥利用效率提升——基于随机前沿生产函数与Tobit模型的实证研究

以我国2000—2014年31个省份的面板数据为基础,运用随机前沿生产函数测算了粮食生产技术效率和化肥利用效率,随之用面板Tobit模型主要考察农业劳动力结构变化对化肥利用效率的影响。研究发现,农业劳动力老龄化、女性化与化肥利用效率呈显著的正相关关系,而教育水平与化肥利用效率呈显著的负相关关系,但影响较弱。总体上农业劳动力结构变化有利于化肥利用效率的提高。因此,应加大现代农业生产技术培训力度;开发适合女性劳动者使用的低成本农用机械;加大农村教育投入,同时加强高效施肥等相关培训。     

井水增温灌溉对寒地水稻生物学特征及水肥利用效率的影响

为解决井水灌溉温度低导致北方寒地水稻水肥利用效率差和产量低的问题,以"垦稻24"(主茎叶片数11叶)为材料,于2015—2016年在黑龙江省八五二农场进行井水增温灌溉大田试验。结果表明,提高井水灌溉温度对寒地水稻植株形态特征、光合特性、产量及水肥利用效率均产生了显著的影响。与井水常温灌溉模式相比,井水增温灌溉模式明显促进了水稻植株的生长与根系的下扎,分别使水稻叶面积指数、单株不定根数、根系总根长、总表面积及总体积提高了14.7%、14.5%、11.6%、33.1%、17.0%;井水增温灌溉模式显著增强了齐穗期的光合作用,分别使水稻光合速率和净光合速率提高19.5%和22.2%;提高了水稻的产量和纯收入,使穗粒数和理论产量增加11.1%、25.6%,实收产量增加4.8%,平均年纯收入达6 749.6元/hm~2,增收13.98%;同时井水增温灌溉模式显著提高了水稻的水肥利用效率,使水分利用率、氮肥农学利用率、籽粒吸收氮量、产谷利用效率及氮收获指数分别提高了8.5%、5.4%、9.2%、4.9%、3.8%。而井水直灌模式造成水稻秧苗发生冷水害问题,导致水稻发育迟缓,显著抑制了水稻形态特征、光合特性、产量及水肥利用效率。井水增温灌溉为本研究的最佳增温灌溉模式,也是适合在我国北方推广的水稻节水节肥丰产技术措施。     

基于三生视角的内蒙古自治区不同类型土地整治效益评价

为研究不同区域类型的土地整治工程在生产、生态、生活功能方面所体现的效益,选取内蒙古3个不同类型区域的土地整治的案例,采用层次分析法(AHP)、专家打分法和模糊综合评价方法构建三生指标体系,对土地整治后效益进行评价。结果发现土地整治获得的各项效益具有一定的协同提升作用,但体现在各项指标层次上仍具有一些差异:在自然本底条件好的地区获得的生产效益的提升大于自然条件较差的地区;人口密集区域的生产、生活服务性设施的改善明显强于人口稀疏地区;具有较多限制性自然条件地区获得的生态效益的提升大于自然本底条件的区域。因此,在土地整治应该充分做到土地整治工作的开展与当地自然条件相契合,挖掘发展潜力,以现有的生产能力和生态环境为基础,提高整治效益。     

包膜尿素与普通尿素配施减氮对夏玉米产量及氮肥效率的影响

为探求减氮增效技术、实现夏玉米科学施肥,通过田间试验,研究了包膜尿素与普通尿素配施及氮肥减施对夏玉米产量、养分吸收利用和土壤氮素的影响。结果表明：夏玉米施氮显著增产7.53%~16.28%,氮素积累量增加15.66%~29.16%,氮肥利用率为19.66%~42.28%;包膜尿素与普通尿素配施一次施肥,提高了夏玉米灌浆期叶绿素含量（SPAD值）,可获得较高产量,且包膜尿素比例越大,氮肥农学效率和利用率越高。本试验条件下,施氮145.6 kg/hm2 （75%包膜尿素+25%普通尿素）基本实现了高产、高效、简化施肥,可在豫北地区推广应用。     

Design of a spatial sampling scheme considering the spatial autocorrelation of crop acreage included in the sampling units

Information on crop acreage is important for formulating national food polices and economic planning.Spatial sampling,a combination of traditional sampling methods and remote sensing and geographic information system(GIS)technology,provides an efficient way to estimate crop acreage at the regional scale.Traditional sampling methods require that the sampling units should be independent of each other,but in practice there is often spatial autocorrelation among crop acreage contained in the sampling units.In this study,using Dehui County in Jilin Province,China,as the study area,we used a thematic crop map derived from Systeme Probatoire d’Observation de la Terre(SPOT-5)imagery,cultivated land plots and digital elevation model data to explore the spatial autocorrelation characteristics among maize and rice acreage included in sampling units of different sizes,and analyzed the effects of different stratification criteria on the level of spatial autocorrelation of the two crop acreages within the sampling units.Moran’s I,a global spatial autocorrelation index,was used to evaluate the spatial autocorrelation among the two crop acreages in this study.The results showed that although the spatial autocorrelation level among maize and rice acreages within the sampling units generally decreased with increasing sampling unit size,there was still a significant spatial autocorrelation among the two crop acreages included in the sampling units(Moran’s I varied from 0.49 to 0.89),irrespective of the sampling unit size.When the sampling unit size was less than3 000 m,the stratification design that used crop planting intensity(CPI)as the stratification criterion,with a stratum number of 5 and a stratum interval of 20%decreased the spatial autocorrelation level to almost zero for the maize and rice area included in sampling units within each stratum.Therefore,the traditional sampling methods can be used to estimate the two crop acreages.Compared with CPI,there was still a strong spatial correlation among the two crop acreages included in the sampling units belonging to each stratum when cultivated land fragmentation and ground slope were used as stratification criterion.As far as the selection of stratification criteria and sampling unit size is concerned,this study provides a basis for formulating a reasonable spatial sampling scheme to estimate crop acreage.     

农村环境问题的法制思考

我国是一个农业大国,农村占地面积大,区域性分布广泛,人口众多,随着经济的发展, 农村的环境出现了诸多问题,受到越来越多的关注,如何在经济发展的同时维护农村良好的生 态环境,确保农村可持续发展,是我国三农问题面临的重要挑战。本文就上述问题,从法律视角 出发,探讨如何建立农村环境防治的长效机制。     

乡村振兴战略下乡村文化重构路径研究

党的十九大提出实施乡村振兴战略,为乡村文化振兴指明了方向,规划了蓝图,提供了 动力。乡村文化重构要从精神文化、行为文化、物态文化、环境文化几方面进行综合考虑,在乡 村现代农业重构、增强村民文化自觉意识、先进文化引领、城乡融合发展、凸显乡村特色具体路 径上予以实现。     

Postponed and reduced basal nitrogen application improves nitrogen use efficiency and plant growth of winter wheat

Excessive nitrogen(N) fertilization with a high basal N ratio in wheat can result in lower N use efficiency(NUE) and has led to environmental problems in the Yangtze River Basin, China. However, wheat requires less N fertilizer at seedling growth stage, and its basal N fertilizer utilization efficiency is relatively low; therefore, reducing the N application rate at the seedling stage and postponing the N fertilization period may be effective for reducing N application and increasing wheat yield and NUE. A 4-year field experiment was conducted with two cultivars under four N rates(240 kg N ha–1(N240), 180 kg N ha–1(N180), 150 kg N ha–1(N150), and 0 kg N ha–1(N0)) and three basal N application stages(seeding(L0), fourleaf stage(L4), and six-leaf stage(L6)) to investigate the effects of reducing the basal N application rate and postponing the basal N fertilization period on grain yield, NUE, and N balance in a soil-wheat system. There was no significant difference in grain yield between the N180 L4 and N240 L0(control) treatments, and the maximum N recovery efficiency and N agronomy efficiency were observed in the N180 L4 treatment. Grain yield and NUE were the highest in the L4 treatment. The leaf area index, flag leaf photosynthesis rate, flag leaf nitrate reductase and glutamine synthase activities, dry matter accumulation, and N uptake post-jointing under N180 L4 did not differ significantly from those under N240 L0. Reduced N application decreased the inorganic N content in the 0–60-cm soil layer, and the inorganic N content of the L6 treatment was higher than those of the L0 and L4 treatments at the same N level. Surplus N was low under the reduced N rates and delayed basal N application treatments. Therefore, postponing and reducing basal N fertilization could maintain a high yield and improve NUE by improving the photosynthetic production capacity, promoting N uptake and assimilation, and reducing surplus N in soil-wheat systems.     

控失尿素与普通尿素配施对水稻产量及氮肥利用效率的影响

为探讨控失尿素与普通尿素配施在海南省水稻上的应用效果,通过 2016 年和 2017 年两季田间试验,采用随 机区组设计,以不施氮肥处理作为对照（CK）,设置常规尿素（CU）与控失尿素（CLU）不同配施比例,在等氮量条 件下,设 100% CU、70% CU+30% CLU、50% CU+50% CLU、30% CU+70% CLU 和 100% CLU 5 个处理,分析水稻叶 绿素含量、稻谷产量及其构成因子、氮吸收累积量、氮肥利用效率以及经济效益等指标。结果显示,施氮显著增加稻 谷产量,与 CK 相比,增幅为 67.2%~82.0%（2016 年）和 36.7%~46.7%（2017 年）。30% CU+70% CLU 的稻谷产量和 有效穗均显著高于 100% CU 处理,产量增幅为 8.8%（2016 年）和 7.3%（2017 年）,有效穗数增幅为 14.2%（2016 年） 和 12.0%（2017 年）。随着 CLU 所占比例的提高,水稻地上部氮吸收累积量、氮肥回收利用率和农学利用率均呈增加 趋势。与 100% CU 处理相比,其余控失尿素处理的氮肥回收利用率增幅为 12.3%~18.4%（2016 年）和 12.7%~17.7%（2017 年）,氮肥农学利用率增幅为 20.8%~21.9%（2016 年）和 16.8%~23.5%（2017 年）。随着 CLU 所占比例的提高,水稻 总产值和相对净收益呈先增加后降低的趋势,30% CU+70% CLU 处理达到最大。综上所述,在本试验条件下,30% CU+70% CLU 能够获得较高的稻谷产量、氮肥利用效率及经济效益,其可作为该地区氮肥施用的推荐比例。     

耕地资源与城市化发展的计量和协调性分析

以延安市为例,对1978~2004年耕地资源面积与城市化水平进行计量和协调性分析,利用SPSS软件构建耕地资源面积与城市化水平的相关回归模型,并借鉴经济与环境协调度模型,计算耕地资源面积与城市化水平的协调度。结果表明,耕地面积与城市化水平存在很强的负相关关系,随着城市化水平提高,耕地面积减少;大部分年份延安的耕地资源与城市化水平协调度呈调和型,耕地资源保持在承载力阈值内,短期内可接受。