陇东旱塬村域农田生态经济系统投入产出特征研究

以甘肃省镇原县北庄村为例,对比分析了不同类型农田的生态经济系统投入产出特征.结果表明:坡地与平地的农田系统产投比物质流为0.58、0.40;能量流为2.01、1.16;价值流为4.32、3.21.坡地为低投入、低产出、高利用效率的系统,而平地为高投入、高产出、低利用效率的系统,坡地农田系统种植效率高于平地.平地玉米纯收益最高,为4 132.5元/hm2,其次为苜蓿2 805.00元/hm2,小麦2 746.80元/hm2;坡地苜蓿的纯收益最高,为2 670.00元/hm2,其次为玉米2 524.95元/hm2,小麦1 695.00元/hm2.说明坡地种植小麦玉米等粮食作物收益低,而种植苜蓿等饲料作物收益高.     

山西省农田能量产投规律研究

研究了山西省农田能量的产投规律,分析了小麦、玉米两大作物水地与旱地条件下各类能源投入水平、投入结构、产出能及产投比。为今后发展持续农业,逐步改善农田投入结构,提高产出水平与能量产投比提供依据     

黑龙江省农田生态系统投能量及效率研究

把对农田系统的诸多投入，换算成能量来衡量投入水平和效率国内外通用的方式。与国内外相比，黑龙江省投能水平不高，产出能较高，能量转换效率高，投入产出比为１：３．５１，属于低投地区，投、产出潜力很大。     

乾县农田土壤养分含量与种植小麦、玉米的适宜性分析

通过对乾县农田土壤养分调查分类,结合不同区域自然条件提出小麦、玉米种植的技术改进措施：对于小麦、玉米种植高度适宜的农田,建立合理轮作制度和科学的施肥方法,施肥技术应以氮肥为主、磷肥为辅,防止土壤肥力退化;对于适宜和勉强适宜小麦、玉米种植的农田,应注重有机无机相配合,适当增施氮肥、控施磷肥、微补钾肥;对于不适宜的农田,应退耕还林还草,防止水土流失,保护生态环境为主。在施肥措施上要根据不同作物适当重施氮磷肥、补施钾肥。     

玉米甘薯间作套种栽培技术及效益分析

本文主要介绍了玉米甘薯间作套种种植模式的栽培技术和效益分析,栽培技术:品种选择、种植带宽、种植时间、施肥及田间管理;效益分析:分析了2B8型和1B8型的效益情况,2B8型玉米甘薯间作模式纯收入最高,为111274.2元/hm2,产投比为8.60;1B8型玉米甘薯间作模式纯收入最高,为113401.4元/hm2,产投比为8.80。     

小麦、菠菜、花菜、玉米、大豆高效立体种植

近几年，立体高效种植面积在我区迅速扩大，其中小麦、菠菜、花菜、玉米、大豆间作套种面积已发展到200公顷，年平均667m。产小麦326．6kg，价值293．94元；667m^2产菠菜301．8kg，价值301．8元；667m^2产花菜399kg，价值478．8元：667m^2产大豆192．75kg，价值424．05元；667m^2产玉米203．25kg，价值223．58元。全年合计667m。收入可达1722．17元，与一年两种两收小麦、玉米相比667m^2多收入830．82元。     

小麦套种玉米吨粮田施肥效果

吨粮田（每公顷年产粮１５吨以上）生产中，化肥的作用非常重要。在新疆和田地区，小麦套种玉米吨粮田栽培中，小麦施化肥纯氮２２５ｋｇ／ｈｍ２，纯磷１０５ｋｇ／ｈｍ２，玉米施化肥纯氮２２５ｋｇ／ｈｍ２，纯磷７５ｋｇ／ｈｍ２，产量最高，经济效益最好，产投比为２．６２－２．７８：１，且土壤主要养分含量呈上升趋势。     

小麦玉米价格倒挂

导读：正常年份，每公斤小麦市场价格应比玉米高到0．1-0．2元．而近年来它们的价格却时常倒挂。近期有媒体报道．因玉米收购价高于小麦，某地农民宁愿撂荒土地．也不愿种植成本高、挣钱少的小麦。     

豫东村级农业生态系统能流和养分循环特征

以河南省虞城县范庙村农业生态系统为研究对象。分析了农田种植和养殖亚系统的能量输入输出、能量转化效率等能流特征和农田系统养分循环特征。结果表明：①在农田种植的能量输入中，有机能与无机能之比为1：1．29；在农田种植系统中，总光能利用率为0．74％，光和有效辐射能利用率为1．35％，人工辅助能与总输出能量之比为1：3．15，能量转化效率居于全国中上等水平。该村种植业已达到较高水平，其技术管理、机械化程度已接近现代农业的水平。②畜牧养殖系统的投产比为0．4：1，饲草料转化率为13．7％。畜牧业发展缓慢。③在农田生态系统内养分循环中，NPK三元素的输入比例为2．84：1：0．78，输出比例为2．4：1：1．85，N素处于盈余状态，P素基本平衡，K素处于严重亏缺状态。根据研究结果，提出了农业可持续发展的建议。     

陕西省典型农区农田生态系统养分平衡研究

研究了陕西省及典型农区农田生态系统中养分平衡的结果表明，1977年氮磷处于亏缺状态，80年代末达到平衡且略有盈余，到1997年盈余较多，钾则一直赤字，1997年N：P2O5：K2O为1：0．26：0．08，低于发达国家水平（1：0．42：0．42），预计到2007－2012年全省农田年化肥需求量为：氮肥（N）870000t，磷肥（P2O5） 365000t，钾肥（K2O）174000t，适宜的N，P2O5，K2O养分比为1：0．40－0．42：0．15－0．20。     

Hotspots, basalts, and the evolution of the mantle

The trace element concentration patterns of continental and ocean island basalts and of mid-ocean ridge basalts are complementary. The relative sizes of the source regions for these fundamentally different basalt types can be estimated from the trace element enrichment-depletion patterns. Their combined volume occupies most of the mantle above the 670 kilometer discontinuity. The source regions separated as a result of early mantle differentiation and crystal fractionation from the resulting melt. The mid-ocean ridge basalts source evolved from an eclogite cumulate that lost its late-stage enriched fluids at various times to the shallower mantle and continental crust. The mid-ocean ridge basalts source is rich in garnet and clinopyroxene, whereas the continental and ocean island basalt source is a garnet peridotite that has experienced secondary enrichment. These relationships are consistent with the evolution of a terrestrial magma ocean.     

Climate change, deforestation, and the fate of the Amazon

The forest biome of Amazonia is one of Earth's greatest biological treasures and a major component of the Earth system. This century, it faces the dual threats of deforestation and stress from climate change. Here, we summarize some of the latest findings and thinking on these threats, explore the consequences for the forest ecosystem and its human residents, and outline options for the future of Amazonia. We also discuss the implications of new proposals to finance preservation of Amazonian forests.     

Diamonds, Eclogites, and the Oxidation State of the Earth's Mantle

The reaction dolomite + 2 coesite --><-- diopside + 2 diamond + 2O(2) defines the coexistence of diamond and carbonate in mantle eclogites. The oxygen fugacity of this reaction is approximately 1 log unit higher at a given temperature and pressure than the oxygen fugacities of the analogous reactions that govern the stability of diamond in peridotite. This difference allows diamond-bearing eclogite to coexist with peridotite containing carbonate or carbonate + diamond. This potential coexistence of diamond-bearing eclogite and carbonate-bearing peridotite can explain the presence of carbon-free peridotite interlayered with garnet pyroxenites that contain graphitized diamond in the Moroccan Beni Bousera massif at the Earth's surface and the preferential preservation of diamond-bearing eclogitic relative to peridotitic xenoliths in the Roberts Victor kimberlite.     

Pre-Columbian urbanism, anthropogenic landscapes, and the future of the Amazon

The archaeology of pre-Columbian polities in the Amazon River basin forces a reconsideration of early urbanism and long-term change in tropical forest landscapes. We describe settlement and land-use patterns of complex societies on the eve of European contact (after 1492) in the Upper Xingu region of the Brazilian Amazon. These societies were organized in articulated clusters, representing small independent polities, within a regional peer polity. These patterns constitute a "galactic" form of prehistoric urbanism, sharing features with small-scale urban polities in other areas. Understanding long-term change in coupled human-environment systems relating to these societies has implications for conservation and sustainable development, notably to control ecological degradation and maintain regional biodiversity.     

Oxytocin, vasopressin, and the neurogenetics of sociality

There is growing evidence that the neuropeptides oxytocin and vasopressin modulate complex social behavior and social cognition. These ancient neuropeptides display a marked conservation in gene structure and expression, yet diversity in the genetic regulation of their receptors seems to underlie natural variation in social behavior, both between and within species. Human studies are beginning to explore the roles of these neuropeptides in social cognition and behavior and suggest that variation in the genes encoding their receptors may contribute to variation in human social behavior by altering brain function. Understanding the neurobiology and neurogenetics of social cognition and behavior has important implications, both clinically and for society.