Contribution of green manure legumes to nitrogen dynamics in traditional winter wheat cropping system in the Loess Plateau of China

Excessive application of N fertilizer in pursuit of higher yields is common due to poor soil fertility and low crop productivity. However, this practice causes serious soil depletion and N loss in the traditional wheat cropping system in the Loess Plateau of China. Growing summer legumes as the green manure (GM) crop is a viable solution because of its unique ability to fix atmospheric N₂. Actually, little is known about the contribution of GM N to grain and N utilization in the subsequent crop. Therefore, we conducted a four-year field experiment with four winter wheat-based rotations (summer fallow-wheat, Huai bean–wheat, soybean–wheat, and mung bean–wheat) and four nitrogen fertilizer rates applied to wheat (0, 108, 135, and 162 kg N/ha) to investigate the fate of GM nitrogen via decomposition, utilization by wheat, and contribution to grain production and nitrogen economy through GM legumes. Here we showed that GM legumes accumulated 53–76 kg N/ha per year. After decomposing for approximately one year, more than 32 kg N/ha was released from GM legumes. The amount of nitrogen released via GM decomposition that was subsequently utilized by wheat was 7–27 kg N/ha. Incorporation of GM legumes effectively replaced 13–48% (average 31%) of the applied mineral nitrogen fertilizer. Additionally, the GM approach during the fallow period reduced the risk of nitrate-N leaching to depths of 0–100 cm and 100–200 cm by 4.8 and 19.6 kg N/ha, respectively. The soil nitrogen pool was effectively improved by incorporation of GM legumes at the times of wheat sowing. Cultivation of leguminous GM during summer is a better option than bare fallow to maintain the soil nitrogen pool, and decrease the rates required for N fertilization not only in the Loess Plateau of China but also in other similar dryland regions worldwide.     

不同类型肥料对甘薯产量和氮效率的影响

为了找到比较适合甘薯增产的肥料,采用田间小区试验的方法,在投入等量氮磷钾养分情况下,比较4种不同类型肥料(施可丰复合肥、土壤所包膜肥、金正大包膜肥、史丹利复合肥)的氮肥效率,以无氮处理、普通尿素、习惯施肥为对照。结果表明:施可丰复合肥对甘薯的增产效果明显,产量达到29940 kg/hm2,显著高于无氮处理、普通尿素处理(P0.05),与习惯施肥相比增产8.92%,另外,收获时氮肥利用率最高,pH值降低小,在甘薯吸氮量最高时,施可丰复合肥氮素释放最高,符合甘薯的氮肥吸收规律,在甘薯生产上是值得推荐的。     

In-field management of corn cob and residue mix: Effect on soil greenhouse gas emissions

In-field management practices of corn cob and residue mix (CRM) as a feedstock source for ethanol production can have potential effects on soil greenhouse gas (GHG) emissions. The objective of this study was to investigate the effects of CRM piles, storage in-field, and subsequent removal on soil CO₂ and N₂O emissions. The study was conducted in 2010–2012 at the Iowa State University, Agronomy Research Farm located near Ames, Iowa (42.0°′N; 93.8°′W). The soil type at the site is Canisteo silty clay loam (fine-loamy, mixed, superactive, calcareous, mesic Typic Endoaquolls). The treatments for CRM consisted of control (no CRM applied and no residue removed after harvest), early spring complete removal (CR) of CRM after application of 7.5 cm depth of CRM in the fall, 2.5 cm, and 7.5 cm depth of CRM over two tillage systems of no-till (NT) and conventional tillage (CT) and three N rates (0, 180, and 270 kg N ha⁻¹) of 32% liquid UAN (NH₄NO₃) in a randomized complete block design with split–split arrangements. The findings of the study suggest that soil CO₂ and N₂O emissions were affected by tillage, CRM treatments, and N rates. Most N₂O and CO₂ emissions peaks occurred as soil moisture or temperature increased with increase precipitation or air temperature. However, soil CO₂ emissions were increased as the CRM amount increased. On the other hand, soil N₂O emissions increased with high level of CRM as N rate increased. Also, it was observed that NT with 7.5 cm CRM produced higher CO₂ emissions in drought condition as compared to CT. Additionally, no differences in N₂O emissions were observed due to tillage system. In general, dry soil conditions caused a reduction in both CO₂ and N₂O emissions across all tillage, CRM treatments, and N rates.     

低碳节约型园林的探索

随着社会经济和城市建设的迅速发展，自然资源和生态环境等面临着巨大压力，矛盾日益突出，本文主要结合目前非常流行的低碳经济讨论了建设节约型的园林。     

中浙优8号在沙县作烟后稻种植表现及高产栽培技术

中浙优8号是中国水稻研究所和浙江勿忘农种业股份有限公司采用优质不育系中浙A与恢复系T-8配组而成的优质高产迟熟三系杂交稻新品种,经过3 a在沙县作烟后稻示范种植,表现群体整齐、分蘖力强、结实率高、米质较优、丰产稳产性好等特点。介绍其在沙县示范表现及高产栽培技术。     

湖南省粮食产量波动的影响因素分析及预测

旨在维护国家稳定,为预判粮食生产前景、提高粮食生产效率、保障粮食安全提供理论依据。利用湖南省统计数据,运用灰色关联分析法筛选关联性较强的影响因素,并建立GM(1,N)预测模型预测粮食产量。2008—2017年与湖南省粮食产量关联度最大的影响因素是粮食作物播种面积和农业机械总动力;科技因素是影响2008—2017年湖南省粮食产量的主要因素,其次是自然因素,社会因素;2018—2027年湖南省粮食产量有较小波动,且农业机械总动力和财政农业支出影响较大;农业机械总动力在前后十年对粮食产量都有较重要的影响,越来越占据主导地位。粮食产量受国家政策的影响,受农业机械总动力影响最大,维持产量水平需高度重视农业机械化水平,稳步提高粮食作物播种面积。     

瓠瓜新品种浙蒲8号的选育

浙蒲8号是以自交系G7-4-3-1-2-1为母本、自交系J63-1-6-3-2-1为父本配制而成的耐热瓠瓜一代杂种。植株生长势较强,早中熟,以侧蔓结瓜为主,坐瓜性较好。商品瓜中棒形,上下粗细较均匀,平均瓜长约30cm,横径约5cm,瓜皮绿色,具光泽,单瓜质量0.4~0.5kg。耐高温性较强,高温期商品瓜率较对照杭州长瓜高6个百分点;品质佳,游离氨基酸总量1304.193μg·g-1,其中谷氨酸含量85.663μg·g-1;田间对枯萎病和白粉病的抗性强于对照杭州长瓜。适宜作露地栽培和夏秋季设施避雨栽培,夏秋季栽培每667m2产量2600kg以上。     

基于改进GM(1,N)模型的我国大豆价格影响因素分析及预测研究

大豆是我国重要的粮食作物和油料作物,其价格对于国民经济尤其是农业经济的影响意义深远。大豆价格的稳定对于我国大豆市场的健康发展有着重要的现实意义。在灰色理论的基础上,提出了一种改进GM(1,N)大豆价格预测模型,首先运用灰色关联分析法对我国大豆价格的影响因素进行分析,选择主要的影响因素;再将这些影响因素作为模型的相关因素变量,构建GM(1,N)大豆价格预测模型。采用2010-2015年的大豆数据进行实证研究,模型选取国内大豆自给量、世界大豆产量、国民消费价格指数、消费者信心指数4个变量作为相关因素变量;模型预测误差为2.10%,预测精度较高,能够较好地掌握大豆价格的变化规律,可以为大豆价格市场预测及国家宏观政策的制定提供理论指导。     

有机肥、碱性物质对龙舌兰麻H.11648幼苗营养生长影响

以玄武岩发育而成酸性粘土、龙舌兰麻H.11648幼苗为试材,以施用充足化肥为对照,施用有机肥、碱性物质(碳酸钙、白云石粉)作为其他处理,测量各处理对龙舌兰麻H.11648幼苗株高、叶宽、叶片数影响,为龙舌兰麻H.11648合理施用有机肥和碱性物质提供依据。结果如下： 1、用碱性物质碳酸钙或白云石粉调节的土壤pH值6.0、6.5处理的龙舌兰麻H.11648幼苗株高、叶宽、叶片数增长率与对照(pH5.5)没有显著差异,龙舌兰麻H.11648幼苗在玄武岩发育土壤上生长酸害阈值为pH值5.5；2、有机肥处理对龙舌兰麻H.11648幼苗株高、叶片数增长率没有显著影响,但4%、8%有机肥显著增加了叶宽(增长率分别比对照提高62.7%、76.7%),有机肥显著促进了龙舌兰麻H.11648幼苗生长。     

第24届冬奥会举办地空气质量特征及环境因子响应机制

空气质量问题是近些年来广受关注的问题，尤其对国际性盛会冬奥会而言，举办地的空气质量也是其能否举办成功的重要评估标准。为评估冬奥会举办地近6 a空气质量状况及动态变化环境相应机理，该研究收集了2014年以来3个冬奥会场馆所在地（北京延庆、奥体中心和河北张家口）的空气质量数据，分别分析了3个监测点的6个空气质量指标（CO、NO₂、O₃、SO₂、PM_2.5、PM₁₀）的浓度动态，并结合2016年奥体中心的气象数据分析了6个指标环境因子的响应机制，结果表明:1)张家口空气质量相对最佳，PM_2.5达标率均在80%以上，但春季大颗粒物污染仍需治理；2)2014-2019年3个监测点的空气质量有明显改善，尤其张家口SO₂从37.50 μg/m³（2014）降至11.06 μg/m³（2019），但截至2019年奥体中心NO₂仍高于国际标准，气体污染物仍是其治理的重点；3)CO和NO²日变化呈“U型”，O³和SO²为“单峰型”，CO、O₃、SO₂季节变化明显。各空气质量指标的主要影响因子分别为CO-太阳净辐射（R_n）、NO₂-太阳净辐射（R_n）、O₃-空气温度（T_a）、SO₂-空气温度（T_a），其中风速（Ws）与各空气质量指标呈负相关关系；6个指标年最大值（7.6 mg/m³、155.5、186.9、68.4、373.2 μg/m³和465.5 μg/m³）均出现在Ws<1 m/s时；然而，由于各空气质量指标的来源及彼此转换，各空气质量指标之间的相关性强于与环境因子的相关性。