Effects of manure, municipal waste compost and nitrogen on weed communities in corn (Zea mays L.)

A two year field experiment was carried out to evaluate the effects of municipal waste compost (C), composted cattle manure (M), and nitrogen (N) on growth and composition of weeds in a corn field in Shiraz using a split-split plot design with 3 replicates. Visual inspection of the plots showed that the manure treatments neither introduced new weed species nor increased weed density more than the other treatments. In both years of the experiment, redroot pigweed (Amaranthus retroflexus L.), field bindweed (Convolvulus arvensis L.), high mallow (Malva sylvestris L.) were dominant species, respectively. Multivariate analysis showed that wild safflower (Carthamus spp.) was associated with control, redroot pigweed with 25 tons (t) compost ha^-1, and 50 t compost ha^-1, prostrate pigweed (Amaranthus blioides L.) with N, and ground cherry (Physalis alkekengi L.) with 50 t manure ha^-1. Our results showed that contrary to the idea that application of manure might increase the risk of new weed species introduction and/or abundance of certain weed species, no introduction of new weed species or increase in certain weed species was obviously found.