the effect of returning eruca sativa and vicia villosa residues at different nitrogen levels on soil chemical characteristics and purslane production in the semi-arid region of birjand, iran

To investigate the effect of return of eruca residues and hairy vetch at different levels of nitrogen on the yield of purslane seeds, an experiment was conducted in two crop years 2013-2014 and 2014-2015 in the research farm of birjand university. the experiment was carried using split plots based on a randomized complete block design with three replications. the factors included four levels of return of plant residues (eruca, hairy vetch, mixture of eruca and hairy vetch and control) as the main factor and three levels of pure nitrogen (zero, 50, and 100 kg ha-1) as secondary factors. the traits studied in this experiment included: organic carbon and soil nitrogen percentage, soil absorbable phosphorus, soil ph and ec, and biomass nitrogen percentage. the results showed that the use of plant residues increased the percentage of organic carbon, soil nitrogen, and absorbable phosphorus and decreased soil ph. among the treatments of the plant residues studied, the cluster flower vetch was superior to the others. also, the use of nitrogen fertilizer increased the amount of absorbable phosphorus, soil electrical conductivity, and grain yield and decreased soil ph. according to the results of this experiment, to reduce the consumption of chemical fertilizers and support sustainable agriculture, the combination of eruca and marigold without nitrogen fertilizer is recommended for maximizing nitrogen absorption in purslane biomass. to achieve the maximum seed yield of marigold, applying 100 kg of nitrogen per hectare in the birjand area is advised.