Agroeconomic approach in the system of determination of the harmfulness of weeds to crops

With the use of high doses of mineral fertilizers marked a sharp increase of weediness of grain crops. This affects their productivity. Existing methods of assessment of contamination and a decision on the feasibility of chemical weeding in the conditions of intensification of agriculture are not suitable, because they are based on quantitative method. For agro-economic analysis was taken as the results of the hospital studies for 1995-2015. The calculation of economic parameters was performed by standard techniques using market pricing. The article describes the material on the nutrient content of dominant weeds agrophytocenosis of the grain grown in different soil fertility. An analysis was conducted of the contamination of crops quantitatively-weight method. Estimated cost absorbed by weeds nutrients. Determined damages from increased infestation of crops by reducing the yield of grain crops. The experience was laid on leached chernozem, mineral fertilizers, providing reception of planned productivity of crops 3.0; 4.0; 5.0 and 6.0 t/ha of grain. Processing system and crop rotation throughout the entire experience did not change. Introduction of high doses of fertilizers (N170P65 and N230P110 kg of active ingredient per hectare) provokes a flash of weediness of grain crops. Weed biomass increased 5 times compared to the natural soil fertility, reaching 347 g/m2 with a slight increase in their number. The nutrient content of species is a feature of weeds. The maximum content of nitrogen and phosphorus was observed in perennial weeds. Mineral fertilizers stimulates additional uptake of nutrients, the content of which may increase more than three times. Potential yield losses of spring wheat from weeds: nitrogen reaches 0.91 t/ha; phosphorus is 2.44 t/ha. The damage from the debris in fields with high soil fertility without chemical weeding is 7286 rub./ha nitrogen. On fields with low phosphorus security it can achieve 19539 rubles/ha. On the sidelines with a weak contamination of annual weeds when the application of mineral fertilizers in doses of up to N120P30kg of active substance chemical weeding is economically feasible. With increasing doses of mineral fertilizers, require herbicide treatment in any type of blockage