Effect of legume preceding crop biomass on weed infestation in cereals
2005
Arlauskiene, A. (Lithuanian Institute of Agriculture, Joniskelis, Pasvalys distr. (Lithuania). Research Station), E-mail: [email protected] | Maiksteniene, S. (Lithuanian Institute of Agriculture, Joniskelis, Pasvalys distr. (Lithuania). Research Station)
A series of complex field experiments was carried out at Joniskelis Experimental Station of the Lithuanian Institute of Agriculture during the period of 1997-2002 with the aim to identifying the impact of legume crops - red clover (Trifolium pratense L.), bastard lucerne (Medicago saliva L.), vetch and oats mixture (Vicia saliva L., Avena saliva L.) as preceding crops and their biomass incorporated in the soil as green manure as well as the effect of farmyard manure on the spread of weeds in cereal agrocenoses. Experimental evidence suggests that in a cereal agrocenosis after all preceding crops annual dicotyledonous weeds accounted for the larger share in the weed population. In the first year of cereals growing the greatest number of weeds emerged after lucerne as a preceding crop, i.e. 27.6 % more than after clover, in the second year - after lucerne and the mixture. In the third year of cereals cultivation the difference between the preceding crops was not significant. Continuous cultivation of cereals and application of organic fertilizers tended to increase weed incidence in cereals. Farmyard manure had a greater effect on weeds than green manure did. Of the tested green manures the biomass of vetch and oats mixture had a greater effect on weed infestation increase in cereals if compared with the biomass of perennial legumes. After vetch and oats mixture the ecological niches that appeared in the crops poorly supplied with nutrients in the second half of summer were infested with weeds. The variation in dry mass of weeds was determined by the soil conditions created by the preceding crops,fertilization, stand density of cereals, number of weeds
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