MODELING THE EFFECT OF CONTROLLED ENVIRONMENTAL FACTORS ON CROP YIELD
Abstract
A mathematical model of effect of the controlled environmental factors on crop yield is proposed, which in contrast to empirical formulas that have no physical basis, is based on real, experimentally determined physical laws, which makes it closer to the balance class. It is necessary to know the maximum yield that is formed under perfect levels of nutrition and moistening of plants for the practical application of the proposed model. The values of all the reference model parameters (optimal soil moisture content, when maximum yield and biological minimum of soil moisture content is ensured, resulting
in stop of the crop training) are set according to the results of field experiment. The perfect and as low as practicable levels of nutrition and moistening, that ensure crop training, determine the limits for calculating (application range) dependences. The supporting values are determined at the average level during the vegetation period, which allowed to eliminate the time factor dependence. In addition, the model considers proportionality of correlation between transpiration and productivity, and it is determined that in contrast to the biological minimum for the soil moisture content, that has quite a real value, other than zero, the biological minimum of the food regime when the crop training is stopped, in particular can be equated to zero. It is shown that the maximum yield value of crop can only be set with a certain degree of probability, since it is affected by unregulated environmental factors unrecorded by calculation formula. The level of maximum yield varies from year to year depending on degree of favorability of such conditions, with the most significant factor limiting the crop (at the minimum
point). The model adequacy test is carried out by comparing the results of calculations and similar results obtained by empirical dependencies, proposed by different authors. Comparison results confirmed that the proposed model of effect of nutrition and water regimes on crop yield combines different empirical formulae (with determination ratio of 0.86–0.96).
in stop of the crop training) are set according to the results of field experiment. The perfect and as low as practicable levels of nutrition and moistening, that ensure crop training, determine the limits for calculating (application range) dependences. The supporting values are determined at the average level during the vegetation period, which allowed to eliminate the time factor dependence. In addition, the model considers proportionality of correlation between transpiration and productivity, and it is determined that in contrast to the biological minimum for the soil moisture content, that has quite a real value, other than zero, the biological minimum of the food regime when the crop training is stopped, in particular can be equated to zero. It is shown that the maximum yield value of crop can only be set with a certain degree of probability, since it is affected by unregulated environmental factors unrecorded by calculation formula. The level of maximum yield varies from year to year depending on degree of favorability of such conditions, with the most significant factor limiting the crop (at the minimum
point). The model adequacy test is carried out by comparing the results of calculations and similar results obtained by empirical dependencies, proposed by different authors. Comparison results confirmed that the proposed model of effect of nutrition and water regimes on crop yield combines different empirical formulae (with determination ratio of 0.86–0.96).
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