不同作物还田秸秆的养分释放特征试验

为了探索秸秆还田与化肥的合理搭配施用,采用尼龙网袋法,研究了水稻秸秆、小麦秸秆、油菜秸秆在淹水培养下养分释放特征。结果表明,供试秸秆腐解速率均表现在培养前期腐解较快,不同秸秆之间表现为油菜秸秆大于水稻秸秆和小麦秸秆;后期腐解速率逐渐变慢,3种秸秆之间差异不明显。经过124 d的培养,水稻秸秆、小麦秸秆、油菜秸秆的累积腐解率分别为49.17%、52.17%和49.81%。秸秆中养分释放速率均表现为K＞P＞C＞N,释放量表现为C＞K＞N＞P。经过124 d的腐解,水稻秸秆、小麦秸秆、油菜秸秆的碳释放率分别为7.53%、66.58%、52.54%;氮分别为42.05%、49.26%、57.83%;磷分别为68.28%、59.93%、67.32%;钾在培养12 d后释放率均达到98%。根据秸秆腐解特征及养分含量,作物推荐施肥量中可以减少钾肥用量,并适当延后施用;在还田初期可以不调整氮磷肥的施用量。     

FARMERS' KNOWLEDGE AND PERCEPTION OF AGRICULTURAL WETLAND MANAGEMENT IN RWANDA

Most of Rwanda's wetlands are being reclaimed under government schemes with the aim of growing rice as the main crop. In the present study, information on farmers' knowledge and perceptions of agricultural wetland management was collected in Cyabayaga and Rugeramigozi wetlands. The two wetlands were selected as representatives for typical reclaimed wetland agriculture in Rwanda. They provide contrasts in both environmental and social terms. Three tools were used to investigate farmers' knowledge and perception of agricultural wetland management: (i) household survey; (ii) focus group discussions; and (iii) transect walk. The major constraints identified by farmers in the two wetlands were water shortage and lack of availability of improved seeds and high prices of fertilisers. The primary benefits from wetlands for farmers are income generation in Cyabayaga and food security in Rugeramigozi. The most commonly reported concern about the wetlands in the Cyabayaga and Rugerameragozi was that they are a source of malaria. Rice is an important crop in both wetlands, whereas farmers in Cyabahaga wish to continue cultivating rice, Rugeramigozi farmers prefer to grow rice only after it has been tested for its adaptability. Farmers have sufficient knowledge on the causes and the potential solutions to overcome most constraints. They know that soil suitability is closely related to relief. They classify soils by a number of criteria and choose crops accordingly. Any programme designed to address wetland management in the region will have to take account of farmers' knowledge and adopt a holistic view of wetland management. Copyright © 2011 John Wiley & Sons, Ltd.     

Diagnosis of zinc and boron availability in emerging vegetable‐based crop rotations in Nepal

Background : Nepal's traditional rice–wheat rotation systems are subject to continuing changes. Changing consumer demand currently drives a replacement of wheat by high‐value vegetables during the dry season, while emerging water shortages lead to a substitution of rice by maize in the wet season. Hence, associated changes in soil aeration status and shifting conditions of soil nutrient supply to match crop nutrient demand are expected to increase the requirements for the principle limiting micro‐nutrients such as boron (B) and zinc (Zn). Aim: Our aim was to investigate the changes in B and Zn availability as well as crop yields and nutrient uptake after system shifts from rice to maize and from wheat to vegetables. Method : We analyzed the B and Zn availability in rice‐ and maize‐based systems as well as crop yields and the nutrient uptake by wheat, cauliflower, and tomato during the dry season in Nepal. Plants were grown at two field sites (midhills vs. lowland) and under greenhouse conditions using soils from the field sites. Results : A change from irrigated rice to maize reduced soil C and N contents with resulting decreases in dry season crop yields. Low soil Zn after rice cultivation led to shortage in Zn uptake by vegetables in both greenhouse and field experiments. The shift from wheat to vegetables increased the demand for B and to a lesser extent for Zn, and consequently vegetables showed visual symptoms of B deficiency. Boron concentrations in dry biomass were below the critical limits with < 10 mg B kg^?1 in wheat, < 21 mg B kg^?1 in cauliflower, and < 23 mg B kg^?1 in tomato. Conclusions: Soils in larger parts of Nepal are low in available B and that the ongoing system shifts increase in the demand for B and Zn in the currently emerging and more diversified production systems.     

麦稻两熟地区不同埋深对还田秸秆腐解进程的影响

为探讨稻麦两熟地区还田秸秆的腐解进程,用尼龙网袋法研究了麦稻秸秆不同埋深(0、7、14.cm)对还田秸秆腐解及C/N比的影响。结果表明,在麦田,埋深14.cm的秸秆腐解速度最快,覆盖在表层较慢。稻田由于有水层的作用和高温高湿的环境,秸秆腐解比麦田快,覆盖在表层比埋入土中的略慢。麦季稻秸覆盖还田一季后秸秆残留率在60%左右,埋入土中的残留率在40%左右;稻季麦秸覆盖还田一季后秸秆残留率在25%左右,而埋在土中的残留率在20%左右。随着还田秸秆的腐解,秸秆含氮量逐渐增加,全碳含量下降,秸秆C/N比降低。麦季稻秸覆盖C/N比较高,而稻季麦秸覆盖的C/N比较低。一季后麦田稻秸的C/N比平均在30左右,稻田麦秸在15以上,比土壤腐殖质的C/N比高,说明种植一季作物后,还田的秸秆尚未完成腐殖化过程。     

基于HJ-1 CCD的县域农作物种植结构提取和时空分析(英文稿)

作物分类和时空变化监测信息可以为农业管理提供依据,多年作物种植结构图反映了作物种植方式的变化,对经济和社会分析起着重要作用。然而,用于绘制作物分布图的卫星影像不能同时具有高时间高空间分辨率,在提取作物种类复杂多样地区的种植结构图时,往往难以提供足够的作物生长周期内影像。该研究提出了一种既经济又高效的解决方案,即利用重复周期短的环境一号CCD（HuanJing-1 Charge-Coupled Device,HJ-1 CCD）图像和免费Landsat-8图像来提取中国监利县的作物种植区时空变化图。根据NDVI时间序列曲线定义了不同作物生育期物候指标例如归一化植被指数（Normalized Difference Vegetation Index,NDVI）的最大值、日期和天数等,用于作物分类。为了获取物候指标的阈值,首先从15m Landsat-8影像中提取典型种植区,然后利用典型种植区作物生长阶段NDVI时间序列曲线,得到物候指标中的NDVI阈值和时间阈值,再根据这些阈值制定了分类规则,并获得了2009-2016年作物分布图。根据多年主要作物分布图,分析不同作物的土地利用变化。最后利用高空间分辨率卫星图像和监利县统计年鉴中的作物面积数据对作物分类结果进行精度评估。与高空间分辨率图像相比,平均分类精度为84%,与统计作物面积数据相比,分类精度达到81.60%。结果表明,该研究为在像监利县这样复杂地区进行常规的作物分布制图提供了一种可行的分类方法。通过对夏收作物的时空动态变化分析可以发现,油菜农业机械化水平低、劳动力成本高,导致愿意种植油菜的农民较少。对于秋收作物,政府设定了中稻最低收购价标准,大大降低了农民种植中稻的风险,对农民种植秋收作物具有指导作用。     

Populations, Community Composition and Biomass of Aquatic Organisms in the Floodwater of Rice Fields and Effects of Field Management

As rice fields are managed for improved rice production, many studies on aquatic organisms in the floodwater have been restricted to agronomically important members such as blue-green algae (BGA) and Azolla , and ecological studies on common aquatic organisms were relatively limited to specific group members. In the present paper, studies on all the aquatic organisms in the floodwater, from protozoa to insects and fishes, were reviewed worldwide from the viewpoint of rice field ecology, paying attention to their populations, seasonal variations, antagonistic relations and biomass, and the effect of field management. Most studies conducted in India and in the Southeast Asian countries dealt with the BGA and green algal populations. In contrast, protozoa and aquatic animals were extensively studied in rice fields in Europe. Japanese studies in the past were intermediate between the previously cited studies. They generally described specific groups depending on the authors' interests, and surprisingly few studies dealt with the community level and prey-predator relationships. Field management such as fertilizer and pesticide application, water management and plowing was found to play a major role in determining the populations of aquatic organisms. Overview of research on aquatic organisms in the floodwater of rice fields suggests several directions for future studies.     

北京地区旱稻作物需水与降水的耦合分析

基于4a的田间试验资料,采用农田水分平衡法确定了旱稻出苗后各生育阶段的需水量;利用1971年-2000年北京地区逐日降水资料,计算了旱稻各生育阶段在不同降水保证率下的降水量,并选取25％、50％、75％和95％保证率作为典型的湿润年、平水年、干旱年和极枯水年,进行旱稻各生育阶段降水与作物需水的耦合度分析和补灌量估算。结果表明：旱稻出苗后总需水量平均为596.1 mm,需水强度平均为4.3 mm/d,需水强度峰值出现在孕穗-抽穗阶段。4种降水年型下旱稻出苗后降水和旱稻需水的耦合度分别为0.82、0.71、0.50和0.39,所需的补灌量分别为106.6、171.1、296.0和363.9 mm。     

虾稻共作灌溉定额确定方法研究

近年来,中国长江中下游流域大面积发展了虾稻共作适水农业,该种养模式改变了田块结构及用水模式,其灌溉定额计算有别于普通农作物且具有一定复杂性,目前还未见相关研究报道。该文在实地调研的基础上,根据虾稻共作田块结构与用水特点,将1个周年划分为水稻非生育期阶段、水稻生育期虾稻分养阶段、水稻生育期虾稻共养阶段3个阶段,基于水量平衡原理,提出虾稻共作灌溉定额确定方法。以湖北省潜江市为例,通过资料搜集和计算参数确定,采用该文提出的计算方法对虾稻共作灌溉定额进行了计算,虾稻共作灌溉定额多年平均12 945 m3/hm2。该研究成果为虾稻共作灌溉定额提供了理论依据,对指导虾稻共作灌溉用水及水资源管理具有重要意义。     

Copper and zinc balance in soils,rice plants and aquatic systems in an area along the fuchu precipice line,Tokyo, Japan

The abundance and distribution of Cu and Zn in spring water, irrigation water and sediment from the Fuchu Irrigation Canals, ground water for irrigation, rice plants and paddy soil at Tokyo University of Agriculture and Technology's Hommachi Farm were studied. The balance of Cu and Zn in the paddy field at the Hommachi Farm was investigated. The discharge of Cu and Zn influenced by human activities was observed in sediment of the Fuchu Irrigation Canal, and rice plants and paddy soil at the Hommachi Farm where irrigation water from the Fuchu Irrigation Canal was used until 1970. From Cu and Zn balance calculated, several hundred years are needed to decrease by half the present level of these metals at the Hommachi Farm.     

秸秆覆盖旱作对稻田甲烷排放和水稻产量的影响

为较全面评价秸秆覆盖旱作水稻栽培模式的生态意义,采用田间试验研究了常规淹水（F）、秸秆覆盖旱作（NF-M）和无覆盖旱作（NF-ZM）3种栽培模式稻田甲烷排放、水稻产量及土壤养分的变化规律。结果表明：3种水稻栽培模式的甲烷排放均集中在水稻生育期的前20d;在水稻生育期内,秸秆覆盖旱作稻田甲烷的排放总量为11.12g·m^-2,显著高于常规淹水稻田的7.78g·m^-2和无覆盖旱作稻田的4.23g·m^-2。秸秆覆盖旱作稻田的水稻产量为8.60t·hm^-2,与常规淹水处理没有显著差异,但二者均显著高于无秸秆覆盖旱作处理的6.78t·hm^-2;与常规淹水处理相比,秸秆覆盖旱作还可以提高水稻单株生物量10g以上。秸秆覆盖旱作还可以显著提高稻田表层土壤有机质含量,维持和改善表层土壤养分状况,对实现农业可持续性有重要意义。因此,在水资源缺乏地区,秸秆覆盖旱作是一种值得考虑的替代传统淹水栽培的水稻栽培模式,同时秸秆覆盖旱作还田也是一种值得推广的稻田秸秆管理技术。     

基于遥感与多变量概率抽样调查的作物种植面积测量

针对传统抽样调查工作中调查基础资料时效性不高和野外调查工作量较大等问题,该文提出了一种遥感与MPPS(multivariate probability proportional to size)抽样调查相结合的农作物种植面积测量方法。利用第2次农业普查数据进行抽样框的编制;利用时序中分辨率遥感数据进行农作物种植面积的分类;在中分辨率遥感分类图的基础上进行MPPS抽样;采用高空间分辨率遥感数据对抽选样本进行面向对象的分类;根据MPPS抽样方法进行总体农作物种植面积的推断;计算CV值,评价抽样精度,以国家统计局公布数据为标准进行总体面积精度评价。以辽宁省北镇市为研究区对该方法进行了测试。结果显示,该方法能够有效的提取县级农作物种植面积,农作物种植面积提取精度优于92%。     

Study on the improvement of fertilizer dressing and soil management in the rice field

Major part of nitrogen and phosphorus in the harvested rice plants was proved to be derived from soil nutrients by our field tracer experiments using 15-N and 32-P, even under heavy dressing of ammonium sulfate and superphosphate of over 75 kg per hectare in terms of N and P₂O₅ respectively. It fits quite nicely to Japanese farmer's common understanding, that the upland crops grow on the basis of fertilizer, and paddy rice on soil fertility. The Japanese rice soils, particularly under waterlogged conditions in summer, liberate rich nutrients from the organic matter, and the fertility of soils presents continuous supply of nitrogen and phosphorus throughout the rice Plant life.     

气候变化对我国主要粮食作物产量的影响及适应措施

过去几十年气候变化对我国主要粮食作物产量产生了重要影响,为了研究作物产量对气候变化的响应和适应,保障粮食安全,基于国内相关研究文献,分析归纳了研究方法,综述了国内小麦、玉米和水稻等主要粮食作物产量对气候变化的响应和适应,得出如下结论:（1）作物产量对气候变化响应的研究方法主要包括田间试验观测、统计分析和作物模型模拟等方法,其中田间观测法最直观,统计分析法可操作性强、应用最为普遍,作物模型模拟机理性强,可以定量描述气候因子对作物产量的影响,外推效果好;（2）近几十年来,小麦生育期内气温升高和辐射变化使我国北方小麦增产0.9%~12.9%,南方小麦减产1.2%~10.2%;气候变暖对玉米产量贡献率为-41.4%~0.4%;水稻生育期内气温升高和辐射增强有利于东北地区水稻产量增加,增产贡献率为1.01%~3.29%,而辐射减弱对长江流域等南方主要水稻种植区的水稻产量（长江流域晚熟稻除外）产生不利影响;（3）未来气候变化情境下小麦应从延长生殖生长期、增加籽粒数量和提高收获指数等方面培育新品种应对气候变暖对作物产量的不利影响;耐高温和长生殖生长期的玉米品种可以用来应对气温、降水等气候因子的变化;水稻则应选育耐高温品种应对气温和辐射等因子的变化所带来的作物生产上的风险。     

Integration of rice crop residue into sustainable rice production system

Rice is the staple food for nearly 40% of the world's population. In Malawi, rice is ranked second only to maize as a cereal food crop. In rainfed areas of Malawi, grain yields typically average 1.0–1:5 t ha^‐1 while potential yield is 4–5 t ha¹. To bridge the gap between current and potential yields, several novel nutrient management systems were studied. Many research reports indicate that rice responds to silicon (Si) application as well as to nitrogen (N), phosphorus (P), and potassium (K) which are commonly applied. Rice crop residues (straws and hulls) are rich in Si and K, but are not utilized currently in rice production. The effect of rice‐hull ash, rice straw, and method of N application (prilled or briquetted urea) on a transplanted rice crop was studied through field experiments in Malawi during 1995 and 1996. Application of urea in briquette form increased rice grain yield by 1056 and 122 kg ha^‐1 compared to prilled urea in the 1995 winter and 1996 summer experiments, respectively. However in the 1996 winter experiment, prilled urea was superior to urea briquette and increased the rice grain yield by 307 kg ha¹. Incorporation of rice straw significantly increased rice grain yields over the control in three consecutive experiments. Rice‐hull ash alone increased the rice grain yields in all three experiments up to 12%; however, the increase was not statistically significant. The combination of rice straw and rice‐hull ash along with optimum N rates (60 kg ha^‐1) increased the rice grain yields significantly in 1996 winter season but the increase was not significant in the other two experiments.     

河套灌区典型灌排单元农田耗水机制研究

由于耕荒地交错分布、作物插花种植、地下水埋深浅等特点,河套灌区灌溉水利用情况极为复杂。该研究以灌区典型灌排单元(农渠尺度)为研究对象,基于2 a野外试验观测数据,对整个观测区及其内部的不同作物田块分别建立水平衡方程,推求研究区平均给水度和不同作物田块腾发量,继而对研究区灌溉水利用状况及盐分归趋进行了评价分析。结果表明,研究区给水度为0.062,而仅考虑地下水位变动带的给水度为0.037;该研究提出的经验方法"上升下降法"可以较好地估算不同作物田块的腾发量;2 a中农毛渠系统输水损失水量(包括渗漏和蒸发)约占引水量的18%,灌到田间的水量占76%,直接退走的水量占6%;通过不同土地类型间地下水的横向交换,农田不但全部利用了田间灌溉水量,还通过地下水侧向流入的方式利用了约12%的渠道渗漏量,荒地利用了约65%的渠道渗漏量,排沟排走了23%;最终研究区农田腾发消耗了总引水量的78%,积累了总引入盐分的39%,荒地腾发消耗了总引水量的11%,承纳了总引入盐分的40%。研究结果可为灌区水盐管理提供依据。     

基于无人机遥感影像的玉米冠层温度提取及作物水分胁迫监测

针对当前无人机热红外遥感提取冠层温度不准确、监测作物水分胁迫状况精度不高的问题,该研究以不同水分处理的拔节期夏玉米为研究对象,利用无人机获取试验区域热红外和可见光图像资料,分别采用Otsu算法、EXG-Kmeans算法和Otsu-EXG-Kmeans算法获取冠层区域图像,并对提取结果进行精度评价,而后采用最优算法求得对应作物水分胁迫指数（Crop Water Stress Index,CWSI）,通过分析CWSI同土壤含水率相关关系以及CWSI日平均变化趋势来监测玉米水分亏缺状况。结果表明：1）相比于其他方法,Otsu-EXG-Kmeans算法对冠层温度提取精度更高（用户精度为95.9%）,提取的冠层温度更接近实测温度（r=0.788）,可以准确获取图像冠层温度。2）相比于冠层温度,CWSI与土壤含水率的相关性更高（r= -0.738）,CWSI日平均变化趋势更符合实际情况,可更加精确地监测玉米缺水状况。该研究为无人机遥感精准监测作物水分胁迫状况提供参考。     

施肥对中日水稻品系土壤养分及食味品质的影响

采用田间试验方法,研究不同施肥方法对5种水稻品系土壤养分与稻米食味品质的影响。结果表明:日本优质水稻栽培的施肥方法(日本施肥)比常规施肥产量低,5个品系以ZR13产量最低,ZR63最高。与日本施肥相比,常规施肥显著提高了5个水稻品系土壤NH4+-N含量,降低了土壤速效磷含量;从食味品质指标的变化看,日本施肥比常规施肥蛋白质和淀粉含量低,具有较高的食味值。从不同品系看,ZR63的产量和蛋白质、直链淀粉含量均最高,但食味值最低。日本施肥下,ZR13的食味值比ZR63高17.2%;常规施肥下,ZR51的食味值比ZR63高56.1%。综合产量和食味品质,ZR32、ZR51是比较理想的品系,ZR6、ZR13食味值高,但产量低,ZR63产量高,食味品质差。     

江苏省里下河地区“沤改旱”种绿肥的经验

“沤改旱”变一熟为二熟是耕作制度的重大改革,生产上如果安排不当,就会带来很大损失.例如,1958年兴化县林湖公社姚家大队改旱800亩,使三麦面积一下由1164亩扩大到1936亩,由于劳畜力和肥料跟不上,三麦单产平均只有50斤.1959年以后,该队逐年在沤改旱地区扩种绿肥,使绿肥面积由200亩扩大到800亩,粮盒单位面积产量由1959年的260斤上升为1963年的428斤,说明沤改旱后种植绿肥是沤田改良利用的一项有力措施.但一熟沤田地区群众尚缺乏种植绿肥的经验.为此,1963年秋我们在兴化县林湖公社姚家大队和严家公社严家大队沤改旱田上进行种植绿肥和施用磷肥的试验.1964年除继续在上述二点进行试验外,又协助宝应县芦村公社芦南生产队在沤改早的田上进行种绿肥的试验.本文除对沤改旱田上种好绿肥的几项重要措施分别叙述以外,还讨论几个问题.     

兼顾农业生产与环境保护的农田控制排水研究进展

农田控制排水(又称地下水位管理)是一种通过调控农田排水量以达到减少污染物输出并保证农业生产的环境友好型水管理措施。该措施的发展经历了不同的阶段,从最早的保墒增产到后来的污染物削减以及节约灌溉用水等功能,对其研究和应用的不断深入,对于变化环境下农田排水的设计和管理都具有重要意义。该文回顾了农田控制排水发展的历史,阐述了该措施的各项功能及其研究方法和应用特点。结果认为,农田控制排水是新形势下农田排水的必要手段,通过对排水出口水位的调控可以达到调节农田水分,减少营养物流失,节约灌溉用水,增加雨水资源利用等多重目的,是存在排水问题地区农业生产可持续发展的最佳水管理措施。目前各地对于控制排水研究的热点问题是寻求一种适合当地农业生产形式的排水水位调控方案,使其具有可操作性、易于推广。     

Effect of water management on cadmium and arsenic accumulation by rice (Oryza sativa L.) with different metal accumulation capacities

Purpose

Water management affects the bioavailability of cadmium (Cd) and arsenic (As) in the soil and hence their accumulation in rice grains and grain yields. However, Cd and As show opposite responses to soil water content, but information, particularly on irrigation, is missing on a field scale. The purpose of the present study was therefore to find a water management regime that can lower accumulation of both Cd and As in grain without yield loss.

Materials and methods

Two rice (Oryza sativa L.) cultivars, A16 and A159, with different grain Cd accumulation capacities were employed in field plot experiments with four water management regimes comprising aerobic, intermittent, conventional practice and flooded. The dynamics of Cd and As bioavailability in the soil and Cd and As concentrations in roots, straw and grains were determined at the early tillering, full tillering, panicle initiation, filling and maturity stages of crop growth.

Results and discussion

The lower water content regimes (aerobic and intermittent) mostly led to higher soil HCl-extractable Cd than the higher soil water content regimes (conventional and flooded). HCl-extractable As in contrast was favoured by the higher soil water content treatments. Conventional and flooded irrigation accordingly gave higher plant As concentrations but lower Cd compared to aerobic and intermittent irrigation. Cd concentrations in roots and straw of both varieties increased with growth stage, especially in aerobic and intermittent regimes, while As concentrations in plants showed little change or a slight decrease. As the water irrigation volume increased from aerobic to flooded, brown rice Cd decreased from 1.15 to 0.02 mg?kg^?1 in cultivar A16 and from 1.60 to 0.05 mg?kg^?1 in cultivar A159, whereas brown rice As increased. Aerobic and flooded treatments produced approximately 10–20 % lower grain yields than intermittent and conventional treatments. Cultivars with low Cd accumulation capacity show higher brown rice grain As than those with high Cd uptake capacity.

Conclusions

Of the four water management regimes, the conventional irrigation method (flooding maintained until full tillering followed by intermittent irrigation) ensured high yield with low Cd and As in the brown rice and so remains the recommended irrigation regime.