利用有效积温建立夏玉米追肥时期决策模型

A summer maize dressing decision-making model based on effective accumulated temperature

  • 摘要: 精准决策作物追肥时期是提高肥料利用效率、增加作物产量的重要技术措施。通过田间连续观测作物的发育进程预判追肥时期不仅费时费力, 并且确定的追肥时期是否合理与经验存在较大关系。夏玉米生长发育及养分累积进程与积温、光照、降雨等气象因子存在密切的关系, 本文以有效积温代替天数作为步长单位, 建立区域内基于有效积温的夏玉米养分累积Logistic模型, 根据模型特点确立夏玉米养分累积的始盛期、高峰期和盛末期, 从而确定最佳追肥时期决策点, 旨在为追肥时期的精准确定提供新思路、新方法。根据田间试验及养分测试结果对模型进行检验, 显示出以有效积温为步长单位的养分累积模型对玉米养分累积的始盛期、高峰期和盛末期的预测效果优于传统的以生长天数为步长的养分累积模型, 且可以用来预测玉米的最佳施肥时期, 进一步验证了该模型的创新性及实用性。由于不同区域、不同作物品种差异, 试验区域模型并不具有广泛的适应性。为此, 针对养分累积Logistic模型的性质及参数意义, 结合田间耕作实际, 建立追肥时期决策的普适模型, 对模型检验表明, 普适模型的n-RMSE为11.9%, 能够较好地预判最佳施肥时期, 具有较强的应用价值。

     

    Abstract: Sound judgments on crop dressing time are important technical measures?to improve the utilization efficiency of fertilizers and increase crop yield. Traditional methods of predicting crop dressing time take continuous stock of crop growth processes. These methods are, however, inaccurate and depend largely on observer experiences. Growth and nutrient accumulation processes of summer maize are closely related with accumulated temperature, light intensity, precipitation and other meteorological factors. It is therefore an effective method to build a meteorological model that precisely defines the dressing times of different crops. Field trials were conducted to study the response of crop growth and development processes to temperature, light and other meteorological factors. In this paper, effective accumulated temperature (a critical factor of crop growth and development processes) replaced growing day and was used as the step unit of Logistics model that described the levels of nutrients accumulation in summer maize. Based on the characteristics of Logistics model, three key times of summer maize nutrients accumulation were defined, which were beginning full period, full period and end full period. The decision point of dressing was then determined. The field experiments and analyses on nutrients showed that nutrient accumulation by summer maize was efficiently simulated with the established Logistics model. Comparisons suggested that the key times of beginning full period, full period and end full period of maize nutrients accumulation predicted by the accumulated temperature model was more accurate than those by the growth-day model. Validation analysis further suggested that the accumulated temperature model was innovative and practical. The growth-day model failed to sufficiently capture the full range of variability in dressing time due to regional and varietal differences. Due to difference in areas, crop variety, the established model according to a certain area was not universal. To meet this problem, the model was adjusted according to the characters, meaning of model parameters and farming practices. The modified accumulated temperature model with 11.9% n-RMSE was adaptable to any region of the world and any variety of crop to efficiently predict the optimal dressing time of farm crops. The results provided the scientific basis for rational fertilizer application with significant improvements in fertilizer utilization rates.

     

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