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Leaching requirement conceptual models for reactive salt.

机译：活性盐的浸出要求概念模型。

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Solute modelling was extended to develop four leaching requirement (Lr) conceptual models that do not neglect solute reactions in the root-zone, surface evaporation, and the influence of immobile wetted pore space. The models were based on: (i) thewater movement equation which included an exponential water-uptake function (-e) or the 40-30-20-10 water-uptake function (-4); (ii) the solute movement equation for a reactive salt of a linear reaction term (the Lrchem-e and Lrchem-4 models); or the employment of output (salinity of soil solution, EC [electrical conductivity] vs. concentration factor, CF) of the SAO comprehensive chemical model (the LrSAO-e and LrSAO-4 models); and (iii) the inclusion of an effective soil solution volume in the transport equations. The root-zone average relative effective soil solution volume veff (L | L50, p) was of sigmoidal response to leaching fraction (L) with two adjustable parameters L50 and p; the root-zone average reduced retention coefficient decreased linearly with L; and salt concentration at soil surface was related to salt concentration of irrigation water (ECi) by the fraction of irrigation water that evaporated (epsilon). The resulted concentration profiles indicated the salt behaved as a conservativeone down to a threshold depth (xs) below of which salt was retained and precipitated. The depth of the conservative-salt front, xs increased with L and the 40-30-20-10 water-uptake pattern overestimated the xs depth relative to the exponential pattern.Concentration profiles were integrated to compute the root-zone average salinity, which was converted to crop salt-tolerance threshold (AE). The four conceptual models were successfully calibrated using experimental AE/ECi vs. Lr data with the input parameter values: sigma = 0.27, p = 1.44, L50 = 0.16, omega = 2, and epsilon = 0 or 0.1 for the exponential or the 40-30-20-10 pattern, respectively; where sigma is relative root length parameter and omega is a weighing parameter. No significant difference existed between the four model correlations at the 0.05 level. The four models require ECi and AE of the crop as input for Lr prediction. Sensitivity analysis revealed predicted Lr was sensitive the least to error in epsilon. For tolerant and moderately tolerant crops Lr was sensitive the most to sigma, and for sensitive crops to L50 and p. Model verification and validation were discussed. In deriving the present Lr models, no osmotic adjustment was required and both the exponential and the 40-30-20-10 water uptake patterns were, equivalently, applicable.
机译：溶质建模已扩展为开发四个浸出要求（Lr）概念模型，这些模型不会忽略根区中的溶质反应，表面蒸发以及固定的湿润孔隙空间的影响。这些模型基于：（i）水运动方程，其中包括指数吸水函数（-e）或40-30-20-10吸水函数（-4）; （ii）线性反应项的反应盐的溶质运动方程（Lrchem-e和Lrchem-4模型）;或使用SAO综合化学模型（LrSAO-e和LrSAO-4模型）的输出（土壤溶液的盐度，EC [电导率] vs.浓缩系数，CF）; （iii）在运输方程中包括有效的土壤溶液量。根区平均相对有效土壤溶液体积veff（L | L50，p）具有对浸出率（L）的S形响应，具有两个可调参数L50和p。根区平均降低保留系数随L呈线性下降趋势。土壤表层的盐浓度与灌溉水的盐浓度（ECi）有关，是蒸发的灌溉水（ε）的分数。所得的浓度曲线表明，该盐表现为低至阈值深度（xs）的保守酮，低于该阈值深度则盐得以保留并沉淀。保守盐锋的深度xs随L的增加而增加，而40-30-20-10的吸水模式相对于指数模式高估了xs的深度，并整合了浓度剖面来计算根区平均盐度，转换为作物的耐盐性阈值（AE）。使用输入参数值的AE / ECi与Lr实验数据成功校准了四个概念模型：sigma = 0.27，p = 1.44，L50 = 0.16，ω= 2，ε= 0或0.1（指数或40）分别为-30-20-10模式;其中sigma是相对根长度参数，而Ω是权重参数。在0.05水平上，四个模型相关性之间没有显着差异。这四个模型需要作物的ECi和AE作为Lr预测的输入。敏感性分析表明，预测的Lr对ε误差的敏感性最小。对于耐性和中度耐性作物，Lr对西格玛最敏感，而对敏感性农作物对L50和p最敏感。讨论了模型验证和确认。在推导目前的Lr模型时，不需要进行渗透调节，并且指数和40-30-20-10的吸水方式均适用。

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