Sustainability indices from nutrient budgets of agro-ecosystems

基于产量、养分浓度、比例、养分吸收、养分添加和养分收支的植物和小区尺度上的养分利用效率的传统衡量标准被虚假的相关性和多余的信息扭曲，因为没有考虑高水平的相互作用。安排在平衡中的整体方法可以使用组件子集之间的正交性原则来纠正这种扭曲。然后利用植物尺度的组织养分分析和小区尺度的养分收支计算营养可持续性指数(NSI)，作为与参考成分的距离。此后，可以将维持农业生态系统生产力的养分利用效率综合成指数，以便于做出正确的决策和改进养分管理做法。在植物尺度上，参考组合是使用魁北克数据集在高产水平上相互作用的养分的组合。在小区尺度上，需要进行长期试验来解释耕作制度的残余影响。利用等轴测井比或由移动设备显示的正交化平衡，在支点诊断平衡，在桶中识别组分，NSI可以计算为与参考成分的多变量距离。我们的目标是监测农业生态系统在植物和地块尺度上偏离参考成分的情况。在肥料试验和长期试验中，通过校准养分失衡的程度来诊断叶片营养。通过2008年建立的长期试验，可以监测玉米(M)-大豆(S)-小麦(W)序列和连续饲草(MMM、MSM、MSWFFF、FFF)对作物产量和土壤质量的影响。该装置还包括两种土壤耕作方法(免耕和常规)、两种残留物管理(残留在土壤上或清除)和两种施肥制度(根据当地建议进行无机肥或有机肥料的控制；不施肥对照)，重复四次(156块地块)。在2013年和2015年对最初在5、10、20、40、60和100厘米处采样的土壤进行了重新采样，并每年收集生物量和谷物样本，用于营养预算。土壤质量元数据包括团聚度和紧实度指数、导水率、pH、渗透阻力、土壤有效养分。这一新的管理工具将允许决策者和利益相关者从整体上看待营养管理策略(“衡量的东西可以明智地管理”)，避免了通常难以解释的横跨无数比率和单个组件的整体径向图。这些模型将支持加拿大化肥业4R方法(正确的施肥量、来源、时间和地点)背后的当地规模的专家系统和施肥战略的发展。四名研究生(理科硕士、博士)将构建从设计到创新的可解释天平的新系统。

Classical measures of nutrient use efficiency at plant and plot scales based on yield, nutrient concentration, ratios, nutrient uptake, nutrient additions and nutrient budgets are distorted by spurious correlations and redundant information by not accounting for high-level interactions. A holistic approach arranged into balances can correct such distortions using the principle of orthogonality between subsets of components. Nutrient sustainability indices (NSI) are then computed as distances from reference compositions using tissue nutrient analyses at plant scale and nutrient budgets at plot scale. Nutrient use efficiency sustaining agroecosystem productivity could be synthesized thereafter into indices to facilitate making sound decisions and improve nutrient management practices. At plant scale, reference copmpositions are those of nutrients interacting at high-yield level using a Québec data set. At plot scale, long-term experiments are required to account for residual effects of cropping systems. Using isometric log ratios or orthonormal balances illustrated by a mobile with balances diagnosed at fulcrums and components appreciated in buckets, NSIs can be computed as multivariate distances from reference compositions. Our objective is to monitor the departure of agroecosystems from reference compositions at plant and plot scales. Foliar nutrients are diagnosed by calibrating the degree of nutrient imbalance in fertilizer trials and the long-term experiment. The long-term experiment established in 2008 allows monitoring the effect of maize (M)-soybean (S)-wheat (W) sequences and continuous forage (MMM, MSM, MSWFFF, FFF) on crop yield and soil quality started with M) or F. The setup also comprises two soil tillage methods (no-till and conventional), two types of residue management (residues left on soil or removed) and two fertilization regimes (mineral or organic based on local recommendations; control without fertilization), replicated 4 times (156 plots). Soils sampled initially at 5, 10, 20, 40, 60 and 100 cm were resampled in 2013 and 2015, and biomass and grain samples collected annually for nutrient budgeting. Soil quality metadata are aggregation and compactness indices, hydraulic conductivity, pH, and resistance to penetration, soil available nutrients. This novel management tool will allow decision makers and stake holders look holistically at nutrient management strategies ("what is measured can be managed wisely"), avoiding the usual hard-to-interpret holistically radial diagrams across myriads of ratios and individual components. These models will support the development of expert systems at local scale and fertilization strategies behind the 4R approach of the Canadian fertilizer industry (right rate, source, time, place). Four graduate students (M.Sc., Ph.D.) will frame novel systems of interpretable balances from design to innovation.