The soil contamination with weed seeds and methods of its reduction

Abstract

Goal. To determine the potential weediness of arable and seed layers of the soil with weed seeds in the steppe zones and propose methods for its reduction.
 Methods. Field survey and sampling the soil to determine the stocks of weed seeds in it conducted in late autumn, winter or early spring in the soil layer of 0—30 cm each 10 cm Sampling soil, laundering, and retrieval of weed seeds from them and also counts them in the soil was performed according to standard techniques.
 Results. In the fields all steppe zones of Ukraine of the potential contamination should be considered as very high. For 2015—2018, she was changed from 290.8 to 408.6 thousand pieces/m2 seed layer 0—30 cm compared to 2011—2014 the potential contamination of soil increased by 18—36%, and from 2000 to 2004 — by 1.5—3.2 times. The highest contamination with seeds of weeds differed in the soil after sunflower, maize and sorghum — more than 500 thousand units/m2, and the minimum number of weed seeds were put in the soil after Sudan grass, sugar sorghum, peas-oats mixture for green fodder and up to 100 thousand pieces/m2. Reducing the number of weed seeds in the soil relative to the initial inventory occurred only in the fields of employment and black vapor. The species and quantitative composition of the seeds of weeds were represented mainly by representatives of the families Amaranthaceae, Poaceae, Asteraceae, Brassicaceae, Chenopodiaceae. The proposed concept of integrated protection of cultural plants from weeds which includes preventing replenishment of the seed bank of weeds in soil, reducing the intensity of germination of weed seeds with cash their bank in the soil, provocation and amicable germination of weed seeds in caused by pre-sowing and post-harvest periods, with the subsequent destruction of their seedlings, tillage, increase of competitive abilities of cultivated plants against weeds.
 Conclusions. With the high potential of contamination, which has developed in Ukraine, to reduce the species and quantitative composition of weed seeds in the soil is necessary to apply complex long-term agronomic, biological, phytocenotic, chemical and organizational techniques that complement and reinforce each other.