农业废弃物资源化利用新途径——覆膜槽干法发酵沼气工程技术

本文简述了沼气干法发酵的原理及工艺条件,回顾了沼气干法发酵技术向工程化发展的历程,重点描述了覆膜槽干法发酵沼气工程的设施及装备、工艺流程、技术优势,最后对覆膜槽干法发酵沼气工程在我国农业废弃物资源化利用中的前景进行了展望。     

活塞式挤奶机节拍比与真空时相比测试研究

挤奶机的节拍比、最大和最小真空时相比是影响挤奶机正常工作、挤奶速度、乳牛健康等的因素，该文利用电测技术，分别在空载和带载两种状态下，测试和分析研究了活塞式挤奶机的节拍比、最大真空时相比和最小真空时相比，通过测试分析表明，所研究活塞式挤奶机的节拍比、最小真空时相比、最大真空时相比均不完全满足标准规定值。     

低温胁迫下增施锌肥对水稻氮代谢与干物质积累的影响

[目的]施锌是缓解低温胁迫对水稻伤害的有效途径之一,低温胁迫下研究增加施锌量对水稻氮代谢与物质积累的影响,为低温年提高水稻抗低温能力提供理论依据.[方法]采用三叶一心期水稻幼苗进行水培试验,设置低(Zn?0.08?μmol/L)、常规(Zn?0.15?μmol/L)、高(Zn?0.30?μmol/L)?3个ZnSO4·...     

南果梨周年干物质与氮磷钾积累动态

【目的】明确南果梨干物质积累特征和氮磷钾养分周年动态积累规律,为南果梨优化施肥量和施肥时期提供依据。【方法】以12年生南果梨树为试材,采用田间采样和树体分解方法,分别于萌芽后10 d(萌芽期)、 30 d(花期)、 65 d(幼果膨大期)、 100 d(果实膨大或新稍停止生长期)、 130 d(果实着色前)、 155 d(果实采收期)、 185 d(采收后)、 210 d(落叶前)8个生育期,选干周和树高一致的3株树,将树体连根从土壤中挖出,分出果实、 叶片、 枝条、 主干、 主根、 侧根、 须根,各器官单独称重,并取200 g左右的鲜样按清水、 洗涤剂、 清水、 1%盐酸、 3次去离子水冲洗、 杀青、 烘干后,电磨粉碎过0.15 mm筛,测定样品中氮、 磷、 钾含量。【结果】1)南果梨周年生育期内,树体干物质当年净积累量为18.4 kg/plant,干物质累积速率出现两次累积高峰,分别是幼果膨大期(0.15 kg/d)和采收期(0.11 kg/d)。2)南果梨树体总氮周年积累量为154.0~301.0 g,新生器官为0~116.2 g,果实膨大期达到最高;多年生器官氮积累量为154.0~194.8 g,落叶前达到最高。3)南果梨树体总磷周年积累量为17.1~37.2 g,果实着色前最高。其中新生器官为13.7 g,果实采收期最高;多年生器官为17.1~24.9 g,果实转色期最高。4)南果梨树体总钾周年积累量为27.9~174 g。新生器官钾为97.3 g,采收期最高;多年生器官钾为27.6~76.6 g,落叶前最高。5)产量大约为17 t/hm2的12年生南果梨从萌芽到落叶前树体当年氮磷钾的单株净累积量分别为146.2、 20.1、 146.1 g,折合1000 kg果实经济产量需吸收氮(N)、 磷(P)、 钾(K)5.4、 0.7、 5.4 kg。【结论】南果梨周年干物质单株积累总量为41.4 kg,当年净积累量为19.7 kg。南果梨干物质积累主要集中在花期到果实膨大期和果实转色到落叶前,分别占47.3% 和47.5%。南果梨从萌芽到落叶前氮、 磷、 钾的单株净累积量分别为146.2、 20.1、 146.1 g,每1000 kg果实经济产量需吸收氮(N)、 磷(P)、 钾(K)5.4、 0.7、 5.4 kg。从开花到果实膨大期和从果实着色到采收后30天对氮吸收分别占总氮累积量的39.0%和49.0%,而磷、 钾的累积从萌芽到开花较快,到果实膨大期磷的累积达67.4%,钾的累积达65.1%,果实膨大期是干物质和氮磷钾积累的关键时期。     

High speed, high precision digital phase sensitive detector design for electrical impedance tomography

Electrical impedance tomography (EIT) system must have the properties of high precision and speed, thus the digital phase sensitive detector (DPSD) based on the field programmable gate array(FPGA) is developed for data collection of EIT. Based on the principle of DPSD, the relationship between signal to noise ratio (SNR) and sample resolution as well as total number of samples is deduced. An implementation scheme of this system and a method of designing analog to digital converter (ADC) clock based on direct digital synthesis (DDS) technology are provided. The system adopts high speed multi channel ADC and low jitter clock conditioner for ADC. Real time DPSD is implemented with FPGA. The experiments show that the measurement accuracy reaches 0.03% and the SNR reaches 85 dB. The agar phantom experiments prove that the performance of the DPSD meet the designing requirement for EIT.     

Optimal rate and schedule of nitrogen fertilizer application for enhanced yield and nitrogen use efficiency in dry-seeded rice in north-western India

Dry direct-seeded aerobic rice (DSR) is an emerging attractive alternative to traditional puddled transplanted rice (PTR) production system for reducing labour and irrigation water requirements in the Indo-Gangetic plains (IGP) of India. The fertilizer N requirement of DSR grown with alternate wetting and drying water management may differ from that of PTR grown under continuous flooding due to differences in N dynamics in the soil/water system and crop growth patterns. Limited studies have been conducted on optimizing N management and application schedule for enhanced N use efficiency in DSR. Therefore, field experiments were conducted over 3 years in NW India to evaluate the effects of N rate and timing of its application on crop performance and N use efficiency. Interaction effects of four N rates (0, 120, 150, and 180 kg ha^?1) as urea and four schedules of N application on yield and N use efficiency were evaluated in DSR. The N schedules included N application in three equal split doses (0, 35 and 63, and 14, 35 and 63 days after sowing, DAS) and four equal split doses (0, 28, 49 and 70; 14, 28, 49 and 70 DAS). There was no significant interaction between N rate and schedules on grain yield. Significant response to fertilizer N was observed at 120 kg N ha^?1 and economic optimum dose for three equal split doses and skipping N at sowing was 130 kg N ha^?1. Highest mean grain yield of 6.60 t ha^?1 was obtained when N was applied in three equal split doses at 14, 35 and 63 DAS which was about 8.5% higher compared with N applied in four equal split doses at 14, 28, 49 and 70 DAS. Under the best N application schedule, agronomic N use efficiency (26 kg grain kg^?1), recovery efficiency (49%) and physiological efficiency (53 kg kg^?1) were comparable to the values reported in Asia for PTR. Results from our study will help to achieve high yields and N use efficiency in DSR to replace resource intensive PTR.     

水氮调控对苜蓿与无芒雀麦混播草地生长和辐射利用的影响

针对我国内陆干旱区人工草地生产管理粗放及气候资源利用不充分等问题,探究合理的牧草种植与水氮供应模式,以充分挖掘区域牧草的生产潜力。采用3 a生(2018年播种)紫花苜蓿(简称‘苜蓿’)和无芒雀麦,分析种植模式(苜蓿与无芒雀麦混播,D1;无芒雀麦单播,D2)、施氮量(低氮量N1:60 kg·hm^-2;高氮量N2:120 kg·hm^-2)和灌水量(以灌水下限占田间持水量θ_f的百分比计,分枝期均充分灌水(75%～85%θ_f),现蕾和初花期轻度亏水W1:65%～75%θ_f、中度亏水W2:55%～65%θ_f、重度亏水W3:45%～55%θ_f,灌水上限均为85%θ_f)对牧草叶面积指数(LAI)、干物质累积量、累积截获光合有效辐射量(CIPAR)、辐射利用效率(RUE)、产量(Y)、耗水量(ET_a)、水分利用效率(WUE)和氮肥偏生产力(PFP_N)的影响。结果表明：(1)牧草LAI和...     

A STUDY ON HEAT AND MOISTURE STATE OF HULL LAYER FOR THERMAL INSTULATION OF A COLD STORAGE

This paper analyses the thermal moist characteristics of the hull layer beside an air layer at lower temperature in an envelope for a cold storage and presents a new method of waterproof by air layer. With test data from engineering practice, the theory on the barrier of self moisture proof at the surface sublayer of the hull layer in an attic on a cold storage is proven. The dried zone about three phase point is confirmed. It is a new knowledge for thermophysics on thermal design of a cold storage with an optimum thermal performance.     

7个鲜食葡萄品种在黔东南地区的引种表现

为筛选适宜黔东南及其相近气候地区栽培的优质鲜食葡萄品种,2015—2016年对引进的7个鲜食葡萄品种成龄树的物候期、果实性状、生长和结果习性等进行观察比较,并对果实性状与品质进行比较分析。结果表明:7个鲜食葡萄品种在简易避雨棚栽培条件下,萌芽期为3月中下旬,成熟期主要集中在8月;夏黑生长势最旺,巨玫瑰和黑巴拉多生长势较弱,其余品种生长势中等;夏黑产量最高,达1 632.6kg/667m~2,巨玫瑰、紫珍香、紫脆无核和甬优1号产量约1 500kg/667m~2,黑巴拉多产量最低。综合而言,以夏黑、巨玫瑰、紫珍香和紫脆无核综合表现最优,可在黔东南及相近气候地区推广种植;醉金香和甬优1号可作为特色品种适度发展;由于转色不良和产量较低的问题,黑巴拉多不宜在黔东南地区推广种植。     

水稻根系生长及根构型对氮素供应的适应性变化

采用全根、分根培养系统,研究根构型参数对氮素供应方式和水平的适应性变化。结果表明:水稻根构型参数对供氮量和供氮方式具有适应性反应。分根供氮时,无论供氮量高低,供氮均能诱导根系生长发育,表现为供氮侧侧根长、根表面积、根系体积、根重等根构型参数明显高于无氮一侧,但是根系平均直径明显变细。分根处理,供氮侧中量和高量供氮使侧根长分别增加9%和91%,而在无氮侧,侧根长分别减少54%和42%;供氮侧根表面积分别增加20.1%和87.9%,无氮侧分别减少45.2%和33.3%;供氮侧根系体积分别增加32.4%和88.0%,无氮侧根体积分别减少33.9%和22.4%。供氮量适当时(N40),侧根长、根表面积、根体积的增加归因于生物量的增加;而在供氮量多时(N80),侧根长、根表面积、根体积的增加既有生物量增加的作用,又有比根长、比表面积的直接贡献。研究结果表明,根构型参数变化是水稻适应不同氮素供应的可能机理之一。