Excessive NPK inputs but low grain yield and high environmental impact are common issues in maize production in North China Plain (NCP). The objective of our study was to test whether a combined strategy of optimizing plant density, balancing NPK input, and innovating one-time fertilizer products could achieve a more sustainable maize production in NCP. Thus, a field experiment was conducted at Luanna County NCP with the treatments of unfertilized control (CK), farmer practice (FP, conventional plant density and NPK input), conventional one-time urea-based coated fertilizer (CF, optimized plant density and NPK input), and five newly designed innovative one-time NPK fertilizers of ammonium sulphate and urea synergy (IF, optimized plant density and NPK input), innovative fertilizer with various additives of urea inhibitors (IF + UI), double inhibitors (IF + DI), micro-organisms (IF + MI), and trace elements (IF + TE). The grain yield, N sustainability indicators (N use efficiency NUE, partial factor productivity of N PFPN, and N surplus), and cost-benefits analysis were examined over the maize growing season of 2020. Results had shown that on average the five innovative fertilizers (IF, IF + UI, IF + DI, IF + MI, and IF + TE) and CF that had optimized plant density and NPK input achieved 13.5%, 98.6%, 105.9%, 37.4% higher yield, PFPN, NUE, net-benefits as well as 207.1% lower N surplus compared with FP respectively. Notably, the innovative fertilizer with various effective additives (IF + UI, IF + DI, IF + MI, and IF + TE) which can be commonly found in the fertilizer market hadn’t resulted in a significant improvement in yield and NUE rather a greater cost and lower net benefits in comparison to IF. In summary, our study highlighted the effectiveness of the combined strategy of optimized plant density, balancing NPK input, and innovative NPK fertiliser on sustainable maize production in NCP, however, the innovative fertilisers with effective additives should be properly selected for better economic benefits.

The use of vermicompost (VC) in growing medium can potentially promote plant growth and provide a way to reuse biowaste. Although VC has widely been studied recently in the production of growing medium, a quantitative assessment of the effects of VC on the physicochemical properties of the growing medium and plant growth is lacking. Therefore, we conducted a meta-analysis to synthetically evaluate the effects of VC on the physicochemical properties of growing medium and plant growth. We observed that VC significantly increased the nutrient content of the growing medium; in particular, it increased the contents of available nitrogen and phosphorus by 133.8% and 256.7%, respectively. Furthermore, VC significantly improved the water-holding porosity of the growing medium by 25.3% but slightly reduced total pore space by 2.6%. Moreover, during plant growth, VC increased seed germination rate, seedling index, shoot biomass, root biomass, and total biomass on an average by 30.4%, 57.8%, 52.6%, 58.3%, and 54.4%, respectively. Comprehensively, we also observed that cattle manure-VC was the most promising material for the production of growing medium and that the optimum proportion of VC for plant growth in growing medium was 40–60%. These results are therefore proposed to provide a reference for the regulation of the physicochemical properties of growing medium, including the selection of waste materials and the VC proportion during the production of growing medium. Similarly, the positive effects of VC on plant growth will provide more possibilities for reducing fertilizer input and cycling waste.

我国设施蔬菜生产中缺乏有效决策指标来引导养分的科学投入,过量施肥已成为设施农业可持续发展的主要瓶颈.选用土壤电导率(EC)作为控制养分投入的决策指标,探索不同土壤EC对番茄生长、产量以及品质的影响,为未来智能化设施生产提供科学依据.通过在设施番茄体系实地试验,运用可视化电导率传感器对土壤进行实时监测,并结合水肥一体化设备进行养分投入,通过测定不同土壤EC对应的番茄生长、产量以及品质指标来分析最适合番茄生长的土壤EC.结果 表明,番茄的株高、茎粗、叶片SPAD值等指标与土壤EC呈二次曲线关系,通过营养生长末期建立的二次曲线拟合得出株高在EC为4.03 mS/cm时达到最大值,茎粗和叶片SPAD值分别在EC为2.93和2.54 mS/cm时达到最大值;干物质累积量和产量也与土壤EC呈二次曲线关系,通过模型拟合得出番茄干物质累积量在EC为2.97 mS/cm时达到最大值,单果重在EC为3.19 mS/cm时达到最大值;外形品质和营养品质多个指标也与土壤EC呈二次曲线关系,模拟结果显示番茄商品果率在EC为2.77 mS/cm时达到最大值,番茄可溶性糖、有机酸、维生素C分别在EC为2.94、3.15和3.03 mS/cm时达到最大值.土壤EC与番茄生长、产量和品质均呈二次曲线关系,将土壤EC控制在合理范围既能保障高产、高品质,也有助于控制土壤养分盈余,降低环境风险.在具备水肥一体化设备的前提下,设施番茄生产中土壤EC控制在3 mS/cm左右比较适宜.

为研究不同类型土壤的电导率在不同氮肥浓度投入后的时空变化规律,进一步了解土壤电导率的动态变化规律,采用DDSJ-308电导率仪对3种类型土壤不同土层深度和不同时间的电导率进行监测.结果表明:3种类型土壤的电导率随氮肥投入浓度的升高而升高,在相同氮肥投入浓度条件下,沙土各土层电导率变化较大,15～20 cm土层的电导率值最高;壤土与黏土不同土层间电导率变化较为一致,在低氮肥浓度投入时,同一土层电导率变化幅度较小,且黏土的电导率稳定性高于壤土.在氮肥累积条件下,不同土壤类型电导率随时间的延长表现为沙土各土层电导率不断下降,表层土壤下降幅度较大,底层土壤变化不显著;壤土各土层土壤电导率逐渐升高,表层土壤增加幅度最大;黏土各土层电导率增幅不大.本研究表明,过高的氮肥投入会显著增加不同类型土壤土层的电导率值,进而加重土壤盐渍化程度,制约作物的正常生长,因此,结合土壤电导率监测并适当减少氮肥投入是降低土壤盐渍化的有效措施.

以蚯蚓粪作为泥炭的替代材料,研究了不同蚯蚓粪替代比例(0％、25％、50％、75％和100％)对栽培基质理化特性及其对绿萝和吊兰两种花卉生长的影响.结果表明:蚯蚓粪替代泥炭后显著提高了基质的容重、pH值、速效钾和有效磷含量(P<0.05),而总孔隙度、有机碳含量显著降低(P<0.05).蚯蚓粪替代泥炭后基质的总孔隙度(64.2％～69.6％)、持水孔隙度(41.0％～48.4％)、通气孔隙度(18.8％～24.5％)与EC值(334.8～352.9μμS/cm)均在推荐范围内,而基质的容重(0.46～0.61 g/cm3)和pH值(7.4～7.8)超出推荐范围.蚯蚓粪替代泥炭对绿萝的植株鲜重增量、茎叶鲜重增量、根系鲜重增量、根系干重与根长无显著影响(P>0.05).但蚯蚓粪替代泥炭比例在VC50％情况下显著增加了绿萝的茎叶干重(P<0.05).在不同蚯蚓粪替代比例之间,替代比例较低时(VC25％和VC50％)更利于绿萝的生长发育(植株鲜重增量、茎叶鲜重增量、茎叶干重).蚯蚓粪替代泥炭对吊兰的株高增量、展开度增量、叶片数增量、茎叶干重、根干重及根长均无显著影响(P>0.05).同时,不同蚯蚓粪替代比例之间吊兰的各个生长指标均无显著性差异(P>0.05).生长过程中绿萝叶片SPAD值变化总体保持一致,无明显缺肥现象,而吊兰叶片SPAD值后期下降明显,出现"脱肥"现象.总之,蚯蚓粪替代泥炭明显增加了栽培基质的容重、pH值、速效钾和有效磷含量,明显降低了栽培基质的总孔隙度和有机碳含量.蚯蚓粪在低替代比例下(VC25％和VC50％)更有利于绿萝生长,但蚯蚓粪替代泥炭对吊兰的生长没有显著影响.

欧洲的养分管理主要采取“自上而下,恩威并施”的方式,既通过严格的限制性措施以及生态补贴的方式来控制有机肥和化肥的投入,如硝酸盐指令,该指令明确了有机肥投入上限以及禁用期和禁用区,成员国根据作物和土壤情况设计了不同的总氮投入上限.欧盟不同成员国的养分管理水平差异较大,对硝酸盐指令的执行度也参差不齐,其中丹麦的养分管理水平较高,将不同类型政策措施有效结合,并大力推广轮作制度,采用先进的有机肥处理和施用技术,使全国不同地区养分盈余均处于安全水平,而英国有机肥有效利用程度仍较低,多个地区养分盈余较高,管理水平仍有较大提升潜力.多种类型政策有效结合加有机肥高效利用及采用合理轮作的丹麦经验值得我国借鉴.