The effect of organic fertilizer source and amounts together with chemical fertilizers on crop yield and soil organic carbon in a conventional rotation in the north Khouzestan

To determine the effect of organic fertilizers together with chemical fertilizers as basic on crops yield and soil organic carbon، an experiment was carried out from 1997 to 2002 at Safi-Abad Agricultural Research Center of Dezful،Iran، in a wheat- potato - wheat - canola - corn rotation. The experimental design was a randomized complete block with a split - plot arrangement of treatments with nine treatments and in three replications. Also، in each replication an additional treatment as control plot (no application of organic fertilizer and only use of chemical fertilizers) was included. Organic fertilizer sources were as main plots consisting (farm yard manure، sugar cane bagas compost and wheat straw)، and organic fertilizer rates were as sub plots at 5، 10 and 15 t / ha. The results showed that effect of organic fertilizer amounts on canola grain yield and effect of organic fertilizer sources on potato yield were significant. As compared with control plot yield increases due to application of organic fertilizer in potato، corn، wheat and canola were about 1600، 1400، 750 and 500 kg/ha،respectively. Also، soil organic carbon increased significantly with organic fertilizer application. Therefore، application of FYM or sugar cane bagas compost at 5 t/ha in combination with optimum use of chemical fertilizers are recommended especially for potato and canola.