低温环境下消化污泥和玉米秸秆强制通风堆肥过程中物理化学和生物学指标的研究

在低温环境下采用强制通风堆肥技术对消化污泥和玉米秸秆进行了堆肥化处理。在环境温度为9～15℃和初始C/N比为19.61情况下,第4天堆体温度达到最高温度60℃,堆体温度保持55℃以上时间为9d。污泥堆肥过程中总有机碳和C/N比下降明显,而NO3--N和重金属含量升高。pH值、电导率、NH4+-N、纤维素酶和脲酶的活性呈先增加后降低的趋势。种子发芽指数在第35天达到84.14%。研究结果表明,消化污泥和玉米秸秆强制通风堆肥在35d达到了腐熟要求。     

松嫩平原玉米带土壤有机质和全氮的时空变异特征

采用地统计学和GIS相结合的方法,研究了松嫩平原玉米带1980～2005年间土壤有机质和全氮的时空变异特征.结果表明:去除异常值后,土壤有机质和全氮均符合对数正态分布,两个时期土壤有机质的平均含量分别为2.14%和2.54%,土壤全氮的平均含量均为0.12%.通过变异函数分析,两个时期土壤有机质和全氮均符合高斯模型,1...     

鲁西北平原夏玉米产量与土壤硝态氮淋失

供水量和氮肥施用量是影响农田硝态氮淋失的主要因素。本文通过田间小区试验,研究了水分和氮肥用量对夏玉米产量和土壤硝态氮的影响。试验表明,高水处理（0～50cm平均含水量控制在85%FC,FC为田间持水量032）和低水处理（0～50cm平均含水量控制在70%FC）间产量差异不显著,施肥量（0、100、200、和300kgNha^-1）则具有显著影响,并且在200kgNha^-1左右时达到最高产量;高水条件下土壤水分硝态氮下渗强,运移深度大,所有施肥处理在200cm处的土壤水硝态氮浓度都要高于国家饮用地下水标准10mgNL-1;低水条件下水分下渗弱,运移深度小于高水处理,但是在200cm处,200、300kgNha^-1处理的土壤溶液硝态氮浓度依然高于10mgNL^-1。     

云南南亚热带地区气候资源与水稻、冬播玉米的适应性

云南南亚热带地区光能资源丰富 ,不仅表现在太阳辐射量高于我国华南和华东地区 ,而且辐射强度大 ,是籼型杂交水稻、冬播玉米等作物的高产区。全年热量资源充足 ,≥ 1 0℃积温在 6 0 0 0～ 75 0 0℃·d之间。但温度年较差小 ,日较差大 ,冬暖夏凉 ,一年四季都能种植玉米 ,是云南南亚热带地区玉米气候生态的一大特点。夏季高温强度不够 ,日照时数偏少是限制杂交水稻提高结实率和产量的主要因子。全年降水适中 ,但分布不均 ,地域差异大 ,干季降水量仅占全年总降水量的 1 0 %～ 1 5 % ,冬春干旱严重制约着冬播玉米以及水稻拔节前的生长发育。发展农田水利和灌溉是云南南亚热带地区夺取水稻、冬播玉米高产、稳产最重要的措施。     

The influence of climate change on maize production in the semi-humid–semi-arid areas of Kenya

The effect of climate change on maize production in the semi-humid and semi-arid, agro-climatic zones III-IV of Kenya was evaluated using two General Circulation Models (GCMs): the Canadian Climate Center Model (CCCM) and the Geophysical Fluid Dynamics Laboratory (GFDL), as well as the CERES-Maize model. Long-term climate data was obtained from three meteorological stations situated in eastern, central and western regions of Kenya, while maize data was obtained from six sites within the regions. The climate scenarios were projected to the year 2030. Temperature increases of 2·29 and 2·89°C are predicted by the CCCM and GFDL, respectively. Rainfall levels are predicted to remain unchanged, but there are thought to be shifts in distribution. It is predicted that the short-rains season (October–January) will experience some increased rainfall, while the long-rains season (April–July) will show a decrease. Maize yields are predicted to decrease in zone III areas, while an increase is predicted in zone IV areas. However, the predicted changes in yields are low since they all fall below 500 kg ha⁻¹, except the Homa Bay site. Thus, to counter the adverse effects of climate change on maize production, it may be necessary to use early maturing cultivars, practice early planting, and in eastern Kenya, shift to growing maize during the short-rains season.     

基于吉林省观测土壤水分的WOFOST模型模拟研究

利用吉林省白城站试验数据进行模型参数调整,通过独立的观测资料对生育期、叶面积指数、地上部分各器官生物量进行模拟验证与评价。以白城站和榆树站代表吉林省西部玉米种植区和中部黄金玉米带参数,利用农业气象观测站发育期资料、气象资料和经过质量控制后的逐日土壤水分自动站观测数据进行模拟。为了提高WOFOST模型模拟精度,将由模型通过降水量计算的土壤体积含水量替换为实测土壤水分计算的体积含水量,采用替换后的土壤体积含水量参与模型下一步运算,以此来模拟2001—2016年春玉米穗生物量变化状况,构建玉米土壤体积含水量改善率(PD)指标,来表征降水驱动和土壤水分驱动对作物模型模拟结果的影响。结果表明:(1)模型对白城站春玉米生育期、叶面积、地上部分总生物量和叶生物量较准确,而穗生物量模拟效果一般。(2)从代表站白城来看,穗生物量模拟值与降水量存在明显正相关,降水偏少的年份土壤模拟效果明显优于降水驱动。(3)从区域来看,以盐碱土为主的地区或降水量偏少的年型下土壤水分驱动效果优于降水驱动;在以黑土为主的区域或降水偏多的年型下,两者模拟效果基本接近。(4)总体来说,利用观测土壤水分替换降水量参与模型能够显著提高模型模拟精度。     

黄淮海地区玉米生育期农业气候资源分析

为指导气候变化背景下黄淮海地区夏玉米种植科学布局,提高气候资源利用率,本研究基于黄淮海地区179个气象站1971—2013年逐日地面气象观测资料,采用气候倾向率及空间分析等方法,从光、温、水等角度研究了夏玉米生育期农业气候资源的时空分布及变化特征。结果显示:黄淮海地区日照时数及太阳辐射空间分布为南低北高,呈逐渐减少的趋势,递减率分别为3.9157 h·a~(-1)和2.6754 MJ·m-2·a~(-1),且中部地区递减率高于边缘地区的;≥10℃积温为1630—2699℃·d,南高北低,呈逐年增加趋势,递增率为2.0764℃·d·a~(-1),沿海地区递增速率大于内陆的;可生长日数空间分布为南多北少,逐年增加,增加量更多来自于≥15℃终日的后推,递增率为0.1302d·a~(-1),东南部递增率大于西北部的;累积降水量为320—950 mm,空间分布为东南多西北少,南部及北部呈减少趋势,中部呈增多趋势,全区域变化趋势不明显,但年际波动幅度较大。     

我国东北地区玉米冷害风险评估

根据年平均寒积温水平,将东北地区的玉米冷害分成4个区域。在分析各冷害区域年寒积温距平与年减产率关系的基础上,确定东北地区各地无冷害影响年、一般冷害年、严重冷害年的年寒积温距平指标。将危险度、脆弱度和暴露度作为冷害风险的评估因子,建立了冷害风险评估指标体系,并应用层次分析法对各指标赋予权重。建立了冷害危险度与年平均寒积温的回归方程,利用地理因子构建了年平均寒积温空间格点化模型,应用地理信息系统推算东北地区玉米冷害危险度,由危险度、脆弱度和暴露度得到我国东北地区玉米冷害风险指数,并开展风险评估。结果表明:东北地区的玉米冷害风险空间分布呈北侧和南部低、东部中等、西部高,松嫩平原东北部和西北部以及吉林省中北部主要为较高或高风险区,三江平原主要为中等风险区,黑龙江省北部、吉林省东南部和辽宁省主要为较低或低风险区。     

东北春玉米积温模型的改进与比较

积温是农业气象科研和业务工作中最常使用的指标之一,但由于受其他环境条件的影响,农作物生育期间的积温在年际间和地区间均表现出不稳定性。因此,如何对已有积温模型进行修正,使农作物生育期间积温计算值趋于稳定并反映实际情况,对农业生产和气象服务均有重要意义。该文以东北春玉米四单19为例,应用沈国权提出的非线性积温模型（简称NLM）进行拟合,分析了参数选择对积温稳定性的影响,提出使用平均温度的二次函数对线性积温模型（简称LM）进行修正（修正后模型称TRM）并进行效果分析,与NLM进行比较。结果表明:NLM拟合时参数P越小,模拟有效积温越稳定;NLM积温在年际间、地区间均存在差异,造成积温不稳定的主要因子是温度强度,与其他因子相关性较差;有效积温与生育期平均温度呈二次曲线关系,对LM的温度二次方修正结果与NLM结果比较发现,二次方修正方法具有可行性。     

Drip irrigation enhances shallow groundwater contribution to crop water consumption in an arid area

Shallow groundwater plays a key role in agro‐hydrological processes of arid areas. Groundwater often supplies a necessary part of the water requirement of crops and surrounding native vegetation, such as groundwater‐dependent ecosystems. However, the impact of water‐saving irrigation on cropland water balance, such as the contribution of shallow groundwater to field evapotranspiration, requires further investigation. Increased understanding of quantitative evaluation of field‐scale water productivity under different irrigation methods aids policy and decision‐making. In this study, high‐resolution water table depth and soil water content in field maize were monitored under conditions of flood irrigation (FI) and drip irrigation (DI), respectively. Groundwater evapotranspiration (ET_g) was estimated by the combination of the water table fluctuation method and an empirical groundwater–soil–atmosphere continuum model. The results indicate that daily ET_g at different growth stages varies under the two irrigation methods. Between two consecutive irrigation events of the FI site, daily ET_g rate increases from zero to greater than that of the DI site. Maize under DI steadily consumes more groundwater than FI, accounting for 16.4% and 14.5% of ET_a, respectively. Overall, FI recharges groundwater, whereas DI extracts water from shallow groundwater. The yield under DI increases compared with that under FI, with less ET_a (526 mm) compared with FI (578 mm), and irrigation water productivity improves from 3.51 kg m^?3 (FI) to 4.58 kg m^?3 (DI) through reducing deep drainage and soil evaporation by DI. These results highlight the critical role of irrigation method and groundwater on crop water consumption and productivity. This study provides important information to aid the development of agricultural irrigation schemes in arid areas with shallow groundwater.