平谷桃园养分投入对土壤养分的影响

以平谷区101个桃园为研究对象,调查了施肥现状及其对土壤养分的影响。【结论】所调查的桃园施用的有机肥以鸡粪、羊粪、猪粪、牛粪为主,化肥投入以复合肥或氮磷钾配合施用居多;2016年比2006年总N、总P2O5和总K2O投入量高出1.6倍、1.6倍和1.8倍。由于桃园多年的过量养分投入,2016年调查结果与2006年调查结果和1981年二次土壤普查结果比较,土壤有机质、全氮、碱解氮、有效磷和速效钾含量均有大幅度提高;调查结果还显示,随着氮肥的施入土壤中平均碱解氮含量变化趋势不明显,随着磷肥的施入土壤中平均有效磷含量成显著的上升趋势,随着钾肥投入量的增加土壤中速效钾含量呈现先上升后下降的趋势。调查结果还显示平谷土壤氮素盈余量为444.6 kg N/ hm2,作物氮素吸收量/施氮量占比仅为45%;平谷土壤磷素盈余量为516.6 kg N/ hm2,作物磷素吸收量/施磷量占比仅为22%;由此可见,桃园氮养分和磷养分盈余造成了果园土壤氮和磷环境风险加大。因此,桃园要进行合理的养分管理以保证产量和品质的形成,以及桃园的可持续发展。     

有机肥等氮替代化肥对红壤团聚体及玉米产量和品质的影响

为研究有机肥等氮替代化肥对土壤结构、玉米产量和品质的影响,设置有机肥等氮替代化肥的10%（M10）、20%（M20）、30%（M30）、40%（M40）,以单施化肥（M0）和不施肥（CK）为对照6个施肥处理,测定玉米不同生育期的土壤团聚体变化状况。结果表明：随有机肥等氮部分替代化肥比例的增加,玉米各生育期土壤>0.25mm水稳性团聚体（R_0.25）、平均质量直径（MWD）、几何平均直径（GWD）不断增加,团聚体破坏率（PAD）、分形维数（D）不断降低。与M0处理相比,M30和M40处理显著提高了玉米子粒产量,表现为M30>M40;M20、M30、M40处理较M0处理玉米子粒蛋白质含量显著增加了13.29%~25.03%,淀粉含量显著增加了39.84%~114.06%,可溶性糖含量显著增加了36.49%~54.05%;蛋白质含量表现为M30和M20处理显著大于M40处理,M30与M20处理间差异不显著;淀粉含量表现为M40>M30>M20,差异显著;可溶性糖含量表现为M40和M30处理显著大于M20处理,M30与M40处理间差异不显著。玉米子粒产量和品质与抽雄期、成熟期土壤团聚体R_0.25呈极显著正相关（P<0.01）,与PAD、D值呈极显著负相关（P<0.01）。因此,玉米生产中,利用有机肥等氮替代化肥培肥土壤,需兼顾玉米产量和品质,30%为适宜的有机肥等氮替代化肥比例。     

芦笋种植对冷凉沙化区土壤改良的效果研究

为探索芦笋种植对冷凉沙化区土壤的改良效果,在山西省朔州市右玉县,以未种植芦笋裸沙地为对照（CK）,设置种植芦笋1、2、3和4年共4个处理,通过田间试验测定不同种植年限芦笋田土壤理化特性和芦笋生长发育情况。结果表明,与CK相比,随种植年限增加,土壤黏粒和粉砂粒含量递增,砂粒含量递减,土壤容重递减,土壤田间持水量递增;土壤pH和可溶性盐浓度（EC）递减;土壤有机质、全氮、有效磷和速效钾含量逐年递增。种植芦笋3年的土壤粒级、土壤容重、田间持水量、pH、EC值、土壤肥力发生显著变化;连续种植芦笋4年的土壤黏粒含量较CK增加到29.8%,粉砂粒含量增加到12.6%,砂粒含量降低到57.6%,田间土壤持水量显著提高,土壤容重显著降低,土壤由砂质壤土向砂质黏土转变;土壤pH降低0.75,EC值降低0.08mS/cm;土壤有机质含量增加28.89%,全氮、有效磷和速效钾含量分别增加95.12%、94.92%和45.40%;芦笋产量达6 037.5kg/hm ²。综合分析,连续种植芦笋4年可改善沙化土壤的物理结构,提高土壤养分,降低盐碱程度。芦笋是冷凉沙化区土壤改良的先锋作物之一,可实现生态效益与经济效益并举。     

不同油葵种植方式对银北灌区盐碱地土壤温度、含水率和电导率的影响

为了探究油葵不同种植方式对盐碱地土壤水、热、盐分布状况的影响,以平播（T1）为对照,开展了半膜平播（T2）、半膜平播+膜间覆秸秆（T3）、起垄沟播（T4）、起垄沟播+沟覆秸秆（T5）、垄膜沟播（T6）、垄膜沟播+沟覆秸秆（T7）等6种种植方式对油葵田土壤温度、水分和电导率的影响研究。结果表明：与对照相比,不同种植方式均提高了早上7:00时5cm深度的土温,但油葵花期土壤增温效果明显弱于苗期,垄膜沟播种植方式更有利于减缓地 表5cm深度土温的剧烈变化。与对照相比,在油葵苗期,T7和T6的0~20cm土层土壤含水率分别提高了6.30%和5.01%,20~40cm土层分别提高了6.00%和3.38%,在油葵开花期,土壤含水率较对照提高幅度有所降低。与播种前0~20cm土层土壤电导率相比,T6在苗期和开花期均有所下降,其中开花期下降了33.81%,T7在苗期略有增加,在开花期则略有下降,其他处理在苗期增加幅度较大。因此,在银北灌区油葵生产中,垄膜沟播是一种适宜的油葵种植方式。     

以普鲁兰多糖为载体的CO2型指示标签的研制

以普鲁兰为成膜材料制备一种CO_2敏感型指示标签,以食品包装中CO_2含量作为监控指标,以甲基红和溴百里酚蓝为指示剂,与成膜材料普鲁兰多糖及甘油混合制得对CO_2敏感的凝溶液,以滤纸为基材制备指示标签,并研究普鲁兰多糖浓度、甘油添加量、倒板量对指示标签变色的影响,采用响应面分析法对指示标签的制作工艺进行优化。结果表明,指示标签制备的最佳工艺条件为:在甲基红溶液与溴百里酚蓝溶液体积比为3∶2,质量浓度为5%的混合指示液中添加普鲁兰多糖7.5 g/100 m L、甘油2 g/100 mL,将6.5 mL溶液倒入铺有滤纸的平皿中,浸泡2 h并自然晾干12 h,可制得CO_2气敏性指示标签,对其进行验证,色差值为18.21。该指示标签制备工艺简单,可重复操作,具有较大的使用价值。     

Effects of different tillage and straw retention practices on soil aggregates and carbon and nitrogen sequestration in soils of the northwestern China

Soil tillage and straw retention in dryland areas may affect the soil aggregates and the distribution of total organic carbon. The aims of this study were to establish how different tillage and straw retention practices affect the soil aggregates and soil organic carbon (SOC) and total nitrogen (TN) contents in the aggregate fractions based on a long-term (approximately 15 years) field experimentin the semi-arid western Loess Plateau, northwestern China. The experiment included four soil treatments, i.e., conventional tillage with straw removed (T), conventional tillage with straw incorporated (TS), no tillage with straw removed (NT) and no tillage with straw retention (NTS), which were arranged in a complete randomized block design. The wet-sieving method was used to separate four size fractions of aggregates, namely, large macroaggregates (LA, >2000 μm), small macroaggregates (SA, 250-2000 μm), microaggregates (MA, 53-250 μm), and silt and clay (SC, <53 μm). Compared to the conventional tillage practices (including T and TS treatments), the percentages of the macroaggregate fractions (LA and SA) under the conservation tillage practices (including NT and NTS treatments) were increased by 41.2%-56.6%, with the NTS treatment having the greatest effect. For soil layers of 0-5, 5-10 and 10-30 cm, values of the mean weight diameter (MWD) under the TS and NTS treatments were 10.68%, 13.83% and 17.65%, respectively. They were 18.45%, 19.15% and 14.12% higher than those under the T treatment, respectively. The maximum contents of the aggregate-associated SOC and TN were detected in the SA fraction, with the greatest effect being observed for the NTS treatment. The SOC and TN contents were significantly higher under the NTS and TS treatments than under the T treatment. Also, the increases in SOC and TN levels were much higher in the straw-retention plots than in the straw-removed plots. The macroaggregates (including LA and SA fractions) were the major pools for SOC and TN, regardless of tillage practices, storing 3.25-6.81 g C/kg soil and 0.34-0.62 g N/kg soil. Based on the above results, we recommend the NTS treatment as the best option to boost soil aggregates and to reinforce carbon and nitrogen sequestration in soils in the semi-arid western Loess Plateau of northwestern China.     

Soil organic carbon fractions and humic substances are affected by land uses of Caatinga forest in Brazil

Caatinga is a Brazilian dry ecosystem that occupies around 1 million km² and is one of the largest tropical dry forests of the world. About 46% of the area that was originally covered has been deforested. Land use can cause pronounced reduction in soil carbon stocks that play a major role in the global carbon cycle. The objective of this study was to improve our understanding of the effect of land use on oxidizable carbon fractions, total carbon stocks and humic substances in different layers of soil in a Brazilian semi-arid region. We analyzed soils from tropical dry forest (TDF), forest succession with Anadenanthera falcata (ANA), with Tabebuia alba (TAB), secondary scrubby regeneration (SCR), and non-irrigated maize (MS). Forests showed larger fractions of more labile carbon, except for TDF. The most recalcitrant fraction of carbon stock, humin fraction stock, with the different land use decreased by 38–53% compared to TDF. Oxidizable carbon fractions, carbon stocks, and humic fraction stocks were able to differentiate the successional land uses and agricultural cover from TDF, mainly in the 0–5?cm layer. Our results show that changes in land use, especially with ANA forest succession, showed a larger labile carbon fraction, indicating easy decomposition and loss. Our results provide an alternative tool for the management of deforested areas in tropical dry caatinga ecosystems. This would contribute to the conservation of dry forest systems and could serve as guideline for sustainable management of agriculturally impacted caatinga areas.     

The Relationship Between Plant Community Characteristics and Soil Organic Matter Content of Sedentary Grazing Pastures in a Typical Steppe

In order to discuss the relationship between the characteristics of plant communities and the content of topsoil organic matter under the condition of two-season sedentary grazing, authors of this paper selected a Stipa krylovii steppe for research and studied the plant community characteristics and the topsoil organic matter content. The results showed that in the sedentary grazing area, the perennial plant species decreased, the annual plant species increased, and the topsoil organic matter content decreased. There were a negative correlation between plant biomass and topsoil organic matter content, and a positive correlation between total coverage and topsoil organic matter content. The change of plant community characteristics in the sedentary grazing area was related to the implementation of the system of transferring the pasture use rights to the herdsmen and controlled grazing.     

秸秆还田对连作玉米田土壤微生物学特性的影响

以冷凉地区玉米秸秆还田土壤为研究对象,在大田条件下设玉米秸秆不还田(CK)、玉米秸秆旋耕还田(XG)和深翻还田(SF)3个处理,经过两年田间定位试验,分析短期秸秆还田对连作玉米田土壤微生物学特性的影响。结果表明,秸秆旋耕还田和深翻还田显著提高0~30 cm土壤酶活性及土壤细菌多样性,秸秆旋耕还田可提高耕层(0~30 cm)土壤细菌多样性,秸秆深翻还田可提高耕层(11~30 cm)土壤细菌多样性。秸秆深翻还田土壤中富含功能微生物,可作为筛选功能微生物的样品。     

优化施肥对滨海盐渍土棉花生长及土壤养分供应特性的影响

通过2年大田试验,研究优化施肥对东营滨海盐渍土棉花生长及土壤养分供应能力的影响。设不施肥、农民传统施肥、优化施肥、优化施肥+有机肥4个处理。结果表明:与农民传统施肥对比,优化施肥及优化施肥+有机肥处理有效提高了棉花产量、肥料农学利用率、偏生产力;施肥改变了土壤盐基离子组成,农民传统施肥、优化施肥、优化施肥+有机肥处理Na+及Cl-所占比分别减少2.29%,3.45%,6.15%,K+、Ca2+、Mg2+、SO_2-4有不同程度的提高;优化施肥+有机肥处理能明显提高土壤微生物和酶活性,其中脲酶、碱性磷酸酶活性分别比传统施肥和优化施肥高7.8%~17.0%和5.0%~13.3%;施肥提高了土壤速效养分,优化施肥+有机肥处理速效P和速效K含量总体处于较高水平,而N0-3-N、NH+4-N含量总体表现为传统施肥优化施肥+有机肥优化施肥不施肥,这说明优化施肥能有效降低土壤NO-3-N、NH+4-N含量,进而NO-3-N、NH+4-N的流失风险也随之减小。采用N、K肥基施+蕾期花期2次追施的优化施肥处理,不仅减少了肥料用量,而且提高了产量,配合施用有机肥增产效果更为显著。