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Responses of greenhouse Tomato and Pepper Yields and Nitrogen Dynamics to Applied Compound Fertilizers

Pedosphere 2004年第2期14卷 213-222页

作者： ZHUJian-Hua LIXiao-Lin ZHANGFu-Suo LIJun-Liang P,CHRISTIE P．CHRISTIE KeyLaboratoryofPlant-SoilInteractions MinistryofEducation.ChinaAgriculturalUniversityBeijing100094（China）／E-mail：zhucool@*** DepartmentofAgronomy LaiyangAgriculturalCollegeShandong265200（china） AgriculturalandEnuironmentalSciencsDepartment Queen＇sUniversityBelfastNewforgeLaneBelfastBT95PX（UX）

Yield and N uptake of tomato (Lycopersicum esculentum Mill.) and pepper(Capsicum annuum L.) crops in five successive rotations receiving two compound fertilizers (12-12-17and 21-8-11 N-P_2O_5-K_2O) were studied to determine 1) crop responses, 2) dynamics of NO_3-N andNH_4-N in different soil layers, 3) N balance and 4) system-level N efficiencies. Five treatments (2fertilizers, 2 fertilizer rates and a control), each with three replicates, were arranged in thestudy. The higher N fertilizer rate,300 kg N ha^(-1) (versus 150 kg N ha^(-1)), returned highervegetable fruit yields and total aboveground N uptake with the largest crop responses occurring forthe low-N fertilizer (12-12-17) applied at 300 kg N ha^(-1) rather than with the high-N fertilizer(21-8-11). Ammonium-N in the top 90 cm of the soil profile declined during the experiment, whilenitrate-N remained at a similar level throughout the experiment with the lower rate of fertilizer *** the higher rate of N fertilizer there was a continuous NO_3-N accumulation of over 800 kg Nha^(-1). About 200 kg N ha^(-1) was applied with irrigation to each crop using NO_3-contaminatedgroundwater. In general, about 50% of the total N input was recovered from all treatments. Pepper,relative to tomato, used N more efficiently with smaller N losses, but the crops utilized less than29% of the fertilizer N over the two and a half-year period. Local agricultural practices maintainedhigh residual soil nutrient status. Thus, optimization of irrigation is required to minimizenitrate leaching and maximize crop N recovery.

关键词： greenhouse vegetables N dynamics N efficiency N uptake N utilization

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A segmentation method for processing greenhouse vegetable foliar disease symptom images

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Information Processing in Agriculture 2019年第2期6卷 216-223页

作者： Juncheng Ma Keming Du Feixiang Zheng Lingxian Zhang Zhongfu Sun Institute of Environment and Sustainable Development in Agriculture Chinese Academy of Agricultural SciencesBeijing 100081China College of Information and Electrical Engineering China Agricultural UniversityBeijing 100083China

Uneven illumination and clutter background were the most challenging problems to segmentation of disease symptom *** order to achieve robust segmentation,a method for processing greenhouse vegetable foliar disease symptom images was proposed in this *** segmentation method was based on a decision tree which was constructed by a two-step coarse-to-fine ***,a coarse decision tree was built by the CART(Classification and Regression Tree)algorithm with a feature *** feature subset consisted of color features that was selected by Pearson’s Rank ***,the coarse decision tree was optimized by *** the optimized decision tree,segmentation of disease symptom images was achieved by conducting pixel-wise *** order to evaluate the robustness and accuracy of the proposed method,an experiment was performed using greenhouse cucumber downy mildew *** showed that the proposed method achieved an overall accuracy of 90.67%,indicating that the method was able to obtain robust segmentation of disease symptom images.

关键词： greenhouse vegetables Symptom images Decision tree Image segmentation

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Current Soil Nutrient Status of Intensively Managed greenhouses

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Pedosphere 2012年第6期22卷 825-833页

作者： HU Yun-Cai SONG Zhi-Wen LU Wen-Long C. POSCHENRIEDER U. SCHMIDHALTER Chair of Plant Nutrition Technische Universitat Miinchen D-85350 Freising (Germany) Institute of Information Tianjin Academy of Agricultural Sciences Tianjin (China)

Nine districts covering the main greenhouse vegetable areas in Tianjin Municipality of the North China Plain were selected for the soil investigation in 2010 to survey the current soil nutrient status (soil available N, P and K), acidification and salinization due to excessive input of fertilizers in greenhouses in Tianjin. The study showed that, in particular, soil available P content increased with the age of greenhouses. In contrast, our results did not reveal higher K accumulation and lowered pH in the greenhouse soils compared with cultivation in open fields. Over-fertilization, causing high NO 3 accumulation, most likely resulted in salinity problems in the greenhouses. Ninety percent of the investigated greenhouse soils had electrical conductivity values of saturated paste extracts of 2-10 d S m-1 , which might affect the yields of vegetable crops like green bean, pepper, cabbage, carrot, eggplant, lettuce, spinach, celery, cucumber and tomato. The findings of our survey of the current fertility and salinity problems in greenhouse soils suggest that there is an urgent need to improve the farmers' practices and strategies in fertilization management in greenhouses of China. Because education and the agricultural technical extension services may play a more important role in avoiding overuse of fertilizers, we suggest that current nutrient management practices should be improved in the near future through training of local farmers in farmers' schools and through strengthening the agricultural extension services with practical techniques.

关键词： electrical conductivity greenhouse vegetables over-fertilization soil pH soil survey

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