Weeds seed transported by the irrigation water. I. Quantitative evaluation and factors involved

Juan Tosso T.1. Raúl Ferreyra E.2 y Leonardo Muñoz S.3

During the 1982/83 season, at La Platina Exp. Sta. (INIA), Santiago, a study was carried out on weeds seed transported by irrigation waters. In this I Part quantitative results are given, together with some information on the main weed species involved and an evaluation of their dissemination in the fields. Treatments were: T1, filtrated water (35 mesh), non sterilized soil, furrow irrigation; T2, filtrated water, sterilized soil (bromide methyl), furrow irrigation; T3, non filtrated water, sterilized soil, furrow irrigation; and T4, non filtrated water, sterilized soil, border irrigation.
Relevant conclusions were::
- The existing amount of weed seeds in the first 40 cm of soil was extremely high: more than 431 millionsof seeds/hectare were determined.
- About 90.000 weed seeds/hectare were incorporated into the area, and effectively germinated during one irrigation period, when irrigating with non filtrated water. This correspond to seeds transported by the irrigation canal.
- The irrigation method did not affect seed transport or germination.
- Wind was not an important factor in the contamination of soil by weed seeds.

1 Instituto de Investigaciones Agropecuarias (INlA), CasiIla 439/3, Santiago, Chile.
2 Estación Experimental La Platina (INIA), Casilla 439/3, Santiago, Chile.
3 a/c Juan Tosso T., Casilla 439/3, Santiago, Chile.