Program level of agrocenosis management, taking into account the impact of weeds on crops

In modern crop production, a traditional paradigm of separate management of crops and weeds as part of single agrocenosis dominates. However, mineral fertilizers simultaneously stimulates the growth and development of crops and weeds, and herbicides suppress the growth of both cultivated plants and weeds. This leads to significant yield losses and waste of fertilizers and herbicides. The purpose of this study is to develop a theoretical basis for solving the problem of managing agrocenoses, which include the main crop and weeds. The solution of this problem is aimed at eliminating the limitations of the existing paradigm of separate management of crops and weeds in the agrocenosis. Previously, we have developed a theory of management of agro-technologies, in which the object of management is an agricultural crop without considering the role of weeds in the agrocenoses. In accordance with this theory, the crop management is carried out at strategic, program and real-time levels. In the presented work, for the first time, the problem of managing agrocenoses at the program level during one growing season is posed and solved. The essence of the approach lies in the development of the programs, which are sequences of technological operations for the application of mineral fertilizers, irrigation and herbicide treatments, providing a given crop yield with minimal expenditure of resources. To solve this problem, in the previously developed theory, mathematical models for crop parameters are modified to reflect the effect of herbicides. In addition, a model of the parameters of dominant weed species was introduced into the control task, in which, in addition to the doses of herbicide treatments, the effect of the doses of mineral fertilizers is reflected. The mathematical model for the soil environment, which takes into account the influence of the parameters of the state of the cultivated crop and weeds, has also undergone significant refinement. The problem is solved on the example of sowing spring wheat as part of an agrocenoses. The presence of several spring wheat phenological phases needs to transform the structure and parameters of the mathematical models used for all phenophases. This, in turn, needs to solve the problem of forming optimal programs for managing agrocenoses separately for each interphase period and combine the received private programs into a single program. As a method for solving the problem, the Pontryagin’s maximum principle is used in combination with a dynamic programming scheme (from the end of the growing season to its beginning). The structural complexity of the control object, which is an agricultural field with agrocenoses, necessitates solving the problem of program control in three stages. At the first stage, a program is formed to change the parameters of the soil environment, which ensures the achievement of the required crop yield. At this stage, the effect of herbicide treatments on the state of crop sowing is not considered. At the second stage, a sequence of technological operations is found that provides the best approximation of soil parameters to the optimal program obtained at the first stage. Finally, at the third stage, the optimal sequence of herbicide treatments performed simultaneously with other technological operations is found. To consider the influence of these processing, the programs obtained at the first two stages are refined until the convergence of the solution of the entire problem is obtained.