Investigation the effect of cover crops in reducing of diversity and density of weeds and the amount of returned elements in soil of their residual

In order to investigate the effect of different summer cover crops and the amount of returned elements in soil of their residual¡ an experiment in randomized complete block design with 7 treetments and 3 replication in Iran Citrus Research Institute was carried out. Treatments included: planting 4 cover crops of legumes such as Trifolium alexandrinum L.¡ Phaseolous vulgaris L.¡ Glycine max L.¡ Vigna radiate L.¡ use of herbicide (Paraquat)¡ straw as mulch and control. This study was started from 1385. Evaluation of treatments using measurement of dry weight of grass leaf and broad leaf weeds in each plot¡ density and diversity of weeds as well as dry weight of cover crops were recorded. After combination of cover crops with soil¡ amount of Nitrogen¡ Phosphorus and Potassium measured. Results indicated that there are significant differences between treatments from dry weight¡ diversity and density point at 1% level. Also there were significant differences between treatments from percentage of K¡ N and P aspects at 1%¡ %5 and %1 levels respectively.