Yield and water productivity of rice–wheat on raised beds at New Delhi, India     

B.U. Choudhury  B.A.M. Bouman  A.K. Singh 《Field Crops Research》2007,100(2-3):229-239

Permanent raised beds are being proposed for the rice–wheat system in the Indo-Gangetic Plain to increase its productivity and to save water. It is not clear whether reported water savings in rice arise from the geometry of the beds per se or from the particular water management that keeps the soil in aerobic conditions and that can also be applied on flat land. Moreover, little research has been reported on direct seeding of rice on raised beds and on the effect of raised beds on the subsequent wheat crop. In this paper we compare the yield, input water (rainfall and irrigation) use and water productivity of dry-seeded rice on raised beds and flat land with that of flooded transplanted and wet-seeded rice, and analyze the effects of beds on the subsequent wheat crop. The experiment was conducted in 2001–2003 at New Delhi, India.

Rice yields on raised beds that were kept around field capacity were 32–42% lower than under flooded transplanted conditions and 21% lower than under flooded wet-seeded conditions. Water inputs were reduced by 32–42% compared with flooded rice, but could also be accomplished with dry seeding on flat land with the same water management. Reduced water inputs and yield reductions balanced each other so that water productivity was comparable among most treatments. Wheat yield was 12–17% lower on raised beds than on flat land with conventional (20 cm) row spacing. Neither wheat nor rice on raised beds compensated for the loss in rows by extra tillering or leaf growth at the edges of the rows. There was no carry-over effect of type of land preparation in rice on the growth and yield of the subsequent wheat crop. Further research on raised beds should focus on the selection of suitable rice and wheat varieties, soil health issues such as nematodes and micro-nutrient deficiencies, weed control, bed stability and long-term carry-over effects from one crop to the other.  相似文献   

Effects of Soil pH on Wheat Grain Yield and Quality     

《Communications in Soil Science and Plant Analysis》2012,43(5):581-591

The effects of planting wheat in permanent beds with fertilization on grain yield and quality need to be better understood. An experiment was conducted at five sites during 2008 and 2009. The objective was to estimate the effects on wheat (Triticum aestivum L.) grain yield and quality of two granular forms of nitrogen (N) (urea and ammonium sulfate, AS) split applied at planting and tillering, and three sprays (urea, AS, and a fungicide) at anthesis. The granular N source affected yield, spike number, and rheological parameters depending upon the soil reaction. Dough resistance/extensibility ratio (P/L) was associated with the normalized difference vegetative index (NDVI) readings collected during tillering before the granular N application. Fungicide spray at anthesis improved yield and grain physical quality evaluated as thousand-grain weight (TGW), test weight, and hardness. Grain protein concentration (GPC) appeared to be mainly affected by environmental factors rather than fertilization practices.  相似文献   

固定床-固化细胞流化床耦合工艺处理乡镇园区综合废水研究     

余海晨  郑先强  王松  张维 《安徽农业科学》2011,39(16):9819-9821

应用固定床-固化细胞流化床耦合工艺处理某乡镇园区综合废水,考察了其对CODCr、BOD5、NH3-N和SS的去除效果及影响因素。结果表明,该耦合工艺对乡镇园区综合废水具有良好的处理效果,稳定运行后,CODCr、BOD5、NH3-N和SS的平均去除率能达到92.2%、88.9%、91%和92.1%。出水水质可以稳定达到《天津市污水排放综合标准》（DB12/356—2008）中二级标准。试验系统结构简单,运行可靠,为乡镇园区综合废水的深度达标处理提供了一种稳定、简便和经济的解决方案。  相似文献   

Crop performance in permanent raised bed rice–wheat cropping system in Punjab,India     

Yadvinder Singh  E. Humphreys  S.S. Kukal  B. Singh  Amanpreet Kaur  S. Thaman  A. Prashar  S. Yadav  J. Timsina  S.S. Dhillon  N. Kaur  D.J. Smith  P.R. Gajri 《Field Crops Research》2009

Raised beds are widely used in agriculture in developed countries and have proven to be an excellent option for wheat. Permanent raised beds may also offer benefits for rice–wheat (RW) systems in South Asia, in terms of both production and the possibility that furrow-irrigation may be more efficient than flood irrigation. The performance of a RW system on permanent raised beds (37 cm wide, 15 cm high, furrow width 30 cm) was compared with conventional cultivation on the flat on sandy loam and loam soils in replicated experiments in central Punjab, India. The experiments commenced with wheat sown in November 2002, and were continued for 8 crops.  相似文献   

喷动循环流化床生物质快速热解设备的特性分析与发展研究综述   总被引：2，自引：0，他引：2  

任学勇  常建民  王鹏起  苟进胜  张立塔  佟立成 《林产化学与工业》2009,29(5):122-126

简要综述了生物质快速热解设备研究的国内外现状,继而详述了喷动床和循环流化床,重点对喷动循环流化床作了较深入的探析,探讨了喷动循环流化床快速热解设备研究的发展方向。  相似文献   

High N fertilizer application to irrigated wheat in Northern Mexico for conventionally tilled and permanent raised beds: Effects on N balance and short term N dynamics          下载免费PDF全文

Kathrin Grahmann  Nele Verhulst  Klaus Dittert  Bram Govaerts  Andreas Buerkert 《植物养料与土壤学杂志》2018,181(4):606-620

Nitrogen (N) surpluses from fertilizer application can cause major environmental harm including pollution of surface water, groundwater, and air. To assess such negative externalities, N balances are a complex but useful tool to predict surpluses and to measure effects of nutrient optimization strategies in agriculture. The Yaqui Valley in north‐western Mexico is representative for thousands of square kilometres of intensive, irrigated wheat production under arid conditions worldwide and has been targeted for conservation agriculture in recent years. For these cropping systems, detailed N balances are scarce and often incomplete. To help fill this knowledge gap, data from a long‐term experiment were collected in 2013/14 on a Vertisol to examine the impact of three tillage‐straw management practices (CTB: conventionally tilled beds; PB‐straw: permanent raised beds with residue retention; PB‐burn: permanent raised beds with residue burning) on N dynamics. Tillage had significant effects on soil NO₃‐N, NH₄‐N, and total N contents across the cropping period. Soil total N content was at all sampling depths lowest in CTB. Soil NO₃‐N in the 0–90 cm profile was highest in PB‐burn over the cropping period and ranged from 77 kg ha^?1 in the bed before pre‐planting fertilizer application up to 269 kg ha^?1 in the furrow after the second fertilizer application. Annual simple N balances were +59 kg N ha^?1 in CTB, +39 kg N ha^–1 in PB‐straw, and +46 kg N ha^?1 in PB‐burn. Residual mineral soil N was significantly affected by tillage‐straw management and lowest for PB‐straw (+205 kg N ha^?1) and highest for CTB, and for PB‐burn (+283 kg N ha^?1 each) in the 0–90 cm soil profile. Soil NO₃‐N moved out of the effective wheat root zone, as indicated by the high residual NO₃‐N content at 30–90 cm depth, which is an important pathway of N leaching. Quantifiable N losses through leaching and volatilization averaged 100 kg N ha^?1. Our findings suggest that there is potential for substantial reductions in N inputs in all tillage‐straw systems to decrease N losses and to reduce mineral residual soil N, but care should be taken to avoid reducing grain protein content, which in PB straw was already below the quality standard. A knowledge transfer of the European “N_min” concept is advisable in this region to regulate N fertilizer over‐application.  相似文献   

Factors affecting irrigation water savings in raised beds in rice and wheat     

S.S. Kukal  Sudhir-Yadav  E. Humphreys  Amanpreet-Kaur  Yadvinder-Singh  S. Thaman  B. Singh  J. Timsina 《Field Crops Research》2010

Raised beds have been proposed for rice–wheat (RW) cropping systems in the Indo-Gangetic Plains as a means of increasing irrigation water productivity, among many other potential benefits. Field experiments were carried out in Punjab, India, during 2002–2006 to compare irrigation water use and productivity of transplanted rice and drill-sown wheat on fresh and permanent beds and conventionally tilled flats.  相似文献   

油菜籽流化床气体分布板结构参数优化   总被引：2，自引：0，他引：2  

张健平  卢玉斌  王晓宏  李星萍 《农业机械学报》2016,47(2):237-244

为优化油菜籽流化床气体分布板的结构参数,根据欧拉(Euler)方法的双流体模型和标准k-ε湍流模型,采用计算流体力学(CFD)分析软件Fluent,对气体分布板的开孔率和布孔方式进行优化设计。结果表明:开孔率为15.84%圆形不均匀布孔的气体分布板是油菜籽流化床干燥的最佳气体分布板,增强了热空气的流通性,减少了局部区域的热空气聚集,实现了气粒两相流动的正常流态化,达到了流化床内油菜籽颗粒均匀分布,无沟流和死区的目的。通过实验,对模拟结果进行了实验验证,结果发现数值模拟与实验结果相吻合,证明了所优化的最佳气体分布板是合理可行的,为工程实践缩短油菜籽干燥时间提供了一种较理想的气体分布板。  相似文献   

多馈源热风微波流态化干燥试验台   总被引：1，自引：0，他引：1  

韩清华  谢时军  李树君  马季威  尹青  王也 《农业机械学报》2014,45(2):210-214

阐述了多馈源热风微波流态化干燥试验台的总体结构和工作原理,分析了微波干燥室、微波管开口位置和振动流态化装置的设计,确定了具体结构和相关参数。微波干燥室的总模式数为106,品质因素达到1 398,6管单面开口磁控管配置方式的微波场更为均匀,调节振动电动机频率可使物料处于流态化状态,保证物料更均匀地吸收热能和微波能。利用试验台对鲜胡萝卜的分段组合干燥工艺进行了试验,脱水胡萝卜颗粒之间的含水率差异在1.22%之内,保持胡萝卜原有色泽、气味和滋味的干制品合格率达到88.63%。  相似文献   

玉米秸秆在等离子体加热流化床上的快速热解液化研究   总被引：15，自引：5，他引：15  

柏雪源  易维明  王丽红  李永军  蔡红珍 《农业工程学报》2005,21(12):127-130

为了进一步研究生物质热解液化技术,寻找较为理想的生物油产率所对应的试验条件,设计制作了以等离子体为主热源的流化床热解液化装置,反应器的内径为52 mm,高1150 mm。以玉米秸秆粉为原料在不同温度、不同喂料速率下进行一系列的热解液化试验。试验结果表明：喂料速率在0.6～0.7 kg/h时,生物油产率较高;反应温度升高,生物油产率增高,但是当反应温度超过750 K时,产率反而随温度的上升而下降。使用色质联用仪(GC-MS)对生物油进行了成分分析,4种试验条件下制取生物油的主要成分均为乙酸、羟基丙酮、水、乙醛、呋喃等,试验条件不同各主要成分的相对含量有所不同。高含水量和含氧量降低了生物油的热值和稳定性,容易发生聚合反应,必须经过改性后才能应用。所采用的试验装置及试验方法亦可用于以其它原料获取生物油的研究。  相似文献