Effects of Various Compost Types, Rates and Application Time on Weed Density and Biomass in Cumin Fields

In order to evaluate the effects of types, rates and application times of various organic composts on weed population and biomass in cumin, a field experiment was conducted as split-split plot based on randomized complete block with four replications at Agricultural Research Station, Ferdowsi University of Mashhad during 2008-2009 growing season. Three compost types (poultry, cow and mushroom bed residue), compost rates (0, 20 and 40 t. ha-1) and compost application time (at planting date, 30 days after planting and 105 days after planting) were allocated to main plot, sub-plot and sub-sub plot, respectively. The most important weed species were broadleaf species. Winter weeds were mainly Descurinia sophia, Sisymberium irio, Stellaria media, Avena fatua, Malcolmia africana, Fumaria parviflora، and spring weeds were Chenopodium album, Polygonum aviculare, Veronica sp. and Solanum nigrum. Expect Stellaria media and Sisymberium irio, weed density in other species and also total weed density were significantly affected by compost types and rates and its application date. The highest total weed density observed with using mushroom-bed compost, applied one month after planting. Results showed that organic compost type, rate and time of application had significant effects on fresh and weed dry biomass. The lowest weed biomass was observed in cow compost plots. Compost application in 105 days after planting had lowest weed biomass. With increasing compost rates weed biomass was also increased. In conclusion, based on the results of the present study and considering the easy availability and low cost of cow manure, application of cow manure compost could help in reduction in weed density and biomass in cumin fields.