基于农田管理分区的制种玉米产量估算与限制因子评价

为了提升规模化农田不同管理分区的玉米产量,实现精准管理,该研究使用相关成分回归法(Correlated Component Regression,CCR),考虑地形因素(高程)、土壤理化性质(砂粒、粉粒、黏粒、容重、土壤含水率、土壤有机碳、全氮、全磷、速效氮、电导率)11个因子,评估规模化农田和聚类分析得到的3个管理区(M1、M2和M3)内产量的限制因子,并在不同分区内建立产量估算模型。模型验证结果表明:未分区的情况下,产量限制因子为土壤粉粒、砂粒、土壤有机碳、土壤含水率、速效氮和全氮,经验证,产量估算模型的决定系数(R~2)为0.70,标准均方根误差(Normalized Root Mean Square Error,nRMSE)为0.21。分区后,M1的产量限制因子为土壤粉粒、砂粒、黏粒、速效氮、电导率、全氮和全磷,M2的产量限制因子为土壤粉粒、砂粒和土壤含水率,M3的产量限制因子为高程、土壤砂粒、黏粒和电导率,产量估算模型的精度高(经验证,0.71R20.83,0.16nRMSE0.18)。对农田进行分区管理,并根据各管理区内作物产量的限制因素制定分布式管理策略,可以更具针对性地提升作物产量。     

切段式甘蔗收割机排杂风机结构优化与试验

针对目前机械化收获甘蔗含杂率和损失率高的问题，该研究对广西农业机械研究院有限公司的 4GZQ-180切段式甘蔗收割机风机的内部流场进行了仿真分析并进行了结构优化。该研究表明，原风机叶片和出流室内壁的形状突变、液压马达安装部位凹陷以及主轴阻挡气流均会导致风机内部发生漩涡流动并引起能量损失。优化后的风机叶片前缘和尾缘平滑过渡，提升了叶片性能，优化后的出流室呈圆筒状，主轴轴线与气流主流方向一致，降低了能量损耗，叶轮安装位置远离蔗段，使蔗段不易与叶轮发生碰撞。流量和功率测定结果表明，仿真结果具有较高的准确性。含杂率测定结果表明，优化后的风机在高转速（1 650 r/min）、低行驶速度（1 km/h）时的含杂率与原风机相当，当行驶速度升高至3 km/h后，中（1 350 r/min）、低（1 050 r/min）转速时优化后风机的含杂率明显低于原风机，分别降低了13.91%和20.42%；损失率测定结果表明，优化后风机在低转速时的损失率与原风机最多相差6.48%，当喂入量为1 kg/s时，中、高转速下损失率分别降低了14.77%和28.08%。     

CeO2添加比例对Fe基催化剂催化纤维素气化制氢的影响

为研究CeO2添加对生物质催化气化制氢特性的影响，该研究采用分级气化系统分析了不同CeO2/Fe2O3比例（Ce∶Fe摩尔比为0∶1、3∶7、5∶5、7∶3、1∶0）双金属催化剂对纤维素水蒸气催化重整制氢气体产物产量、组成以及催化剂的结构演变特性的影响。结果表明，CeO2/Fe2O3催化剂在制氢反应中的催化性能明显优于纯CeO2或Fe2O3催化剂，当Ce∶Fe摩尔比为3∶7时，在800℃下氢气的最大产率为21.63 mmol/g（以纤维素计，下同）；当温度大于等于800℃时，催化剂氧化还原反应后可生成CeFeO3，且CeFeO3的存在对纤维素水蒸气气化过程有促进作用。CeO2的引入提高了催化剂的氧化性能和稳定性，提高了使用寿命。该研究对生物质气化机制的深入理解具有一定的指导意义。     

基于实地和遥感调查的离子型轻稀土尾砂土壤侵蚀对植被修复措施响应

稀土开采产生大量尾砂,导致严重土壤侵蚀,伴生水质和地质灾害,评价植被修复措施对稀土尾砂土壤侵蚀治理效果可为措施优选提供理论依据。以寻乌县离子型轻稀土尾砂区为研究区,基于1982—2015年GIMMS NDVI 3 g、DEM等遥感和尾砂理化性状现场调查数据,采用空间代时间方法,结合RUSLE模型及其全微分公式探究不同修复年限土壤侵蚀量对植被修复措施的响应机理。结果表明:1982—2015年研究区土壤侵蚀模数显著下降,倾向率为-60 t/(km~2·10a),突变年份为2008年;在植被修复措施实施年(2008年)前后,多年平均土壤侵蚀量减幅超过60%;土壤侵蚀模数呈现上升、平稳、上升、平稳、上升和下降的阶段性变化,与NDVI时程变化呈负相关;水土保持措施、植被覆盖、土壤可蚀性和降雨变化对土壤侵蚀量减小的贡献率分别为33.18%,32.19%,19.95%,13.19%。植被修复过程中,矿区土壤侵蚀量减少的主要影响因子为水土保持措施因子和植被覆盖因子。     

Intensive organic vegetable production increases soil organic carbon but with a lower carbon conversion efficiency than integrated management

Intensive vegetable production in greenhouses has rapidly expanded in China since the 1990s and increased to 1.3 million ha of farmland by 2016, which is the highest in the world. We conducted an 11‐year greenhouse vegetable production experiment from 2002 to 2013 to observe soil organic carbon (SOC) dynamics under three management systems, i.e., conventional (CON), integrated (ING), and intensive organic (ORG) farming. Soil samples (0–20 and 20–40 cm depth) were collected in 2002 and 2013 and separated into four particle‐size fractions, i.e., coarse sand (> 250 µm), fine sand (250–53 µm), silt (53–2 µm), and clay (< 2 µm). The SOC contents and δ¹³C values of the whole soil and the four particle‐size fractions were analyzed. After 11 years of vegetable farming, ORG and ING significantly increased SOC stocks (0–20 cm) by 4008 ± 36.6 and 2880 ± 365 kg C ha^?1 y^?1, respectively, 8.1‐ and 5.8‐times that of CON (494 ± 42.6 kg C ha^?1 y^?1). The SOC stock increase in ORG at 20–40 cm depth was 245 ± 66.4 kg C ha^?1 y^?1, significantly higher than in ING (66 ± 13.4 kg C ha^?1 y^?1) and CON (109 ± 44.8 kg C ha^?1 y^?1). Analyses of ¹³C revealed a significant increase in newly produced SOC in both soil layers in ORG. However, the carbon conversion efficiency (CE: increased organic carbon in soil divided by organic carbon input) was lower in ORG (14.4%–21.7%) than in ING (18.2%–27.4%). Among the four particle‐sizes in the 0–20 cm layer, the silt fraction exhibited the largest proportion of increase in SOC content (57.8% and 55.4% of the SOC increase in ORG and ING, respectively). A similar trend was detected in the 20–40 cm soil layer. Over all, intensive organic (ORG) vegetable production increases soil organic carbon but with a lower carbon conversion efficiency than integrated (ING) management.     

Impact of vegetation restoration on soil organic carbon stocks and aggregates in a karst rocky desertification area in Southwest China

Journal of Soils and Sediments - The objectives of the study were as follows: (a) to determine the response of soil organic carbon (SOC) fractions to vegetation restoration; (b) to examine the...     

Minor topography governing erosional distribution of SOC and temperature sensitivity of CO2 emissions: comparisons between concave and convex toposequence

Journal of Soils and Sediments - Erosion processes spatially redistribute soil particles and the associated carbon across landscapes. Their spatial redistribution pattern is governed by the...     

施肥对灌漠土作物产量、土壤肥力与重金属含量的影响

有机物还田是提升土壤肥力的主要措施,但也存在造成土壤金属污染的潜在风险。为查明不同有机物还田对土壤质量及作物产量的影响,本文通过长期定位试验,研究了无肥对照、常规施化肥(氮磷配施)以及70%常规化肥与牛粪、沼渣、污泥、鸡粪、菌渣和猪粪配施对土壤理化性状、有机碳和氮的固存率、氮磷钾活化系数、作物产量及重金属含量的影响。结果表明:牛粪、沼渣、污泥、菌渣、鸡粪和猪粪与70%化肥配施虽作物产量与常规施化肥相似,但6种有机物处理土壤有机质、全氮和碱解氮含量都较常规施化肥处理显著增加,污泥、鸡粪和猪粪处理土壤全磷与速效磷含量较常规施化肥处理显著增加,而且牛粪、沼渣、鸡粪和猪粪处理的速效钾、土壤磷活化系数和土壤钾活化系数较常规施化肥处理也显著提升。牛粪、沼渣、污泥、菌渣、鸡粪和猪粪处理土壤有机碳固存率为36.42%～71.61%,较常规施化肥处理都显著提高;而其氮固存率为6.47%～49.44%,仅有菌渣处理与常规施化肥处理差异不显著,而其他处理较常规施化肥处理显著增加。长期施鸡粪和菌渣处理的土壤铜含量较常规施化肥处理显著增加,增加量分别为4.17mg·kg~(-1)和14.2mg·kg~(-1);而污泥、鸡粪和菌渣处理的土壤锌含量较常规施化肥处理显著增加,增加量分别为13.53 mg·kg~(-1)、22.60 mg·kg~(-1)和49.73mg·kg~(-1)。综上,等有机质(4 500kg×hm~(-2))的牛粪、沼渣、污泥、菌渣、鸡粪和猪粪可替代30%氮磷肥,作物产量不受影响;不同有机物培肥土壤效果为污泥、鸡粪和猪粪优于牛粪和沼渣,而沼渣的培肥效果略差。为保证土壤环境质量稳定不恶化,种植小麦时有机物铜和锌的年携入量应分别低于53.01g×hm~(-2)和221.30 g×hm~(-2),而种植玉米时应分别低于153.40 g×hm~(-2)和347.04 g×hm~(-2)。