Abstract :
To study of the effect of different fertilizing systems using green manure and zeoponix on quantitative and qualitative yield of forage rape (Brassica napus) in sequential cropping system an experiment was carried out at the Experimental Farm of Tarbiat Modares University, College of Agriculture, Department of Agronomy, Tehran, Iran, during 2009 and 2010 growing season. Forage rape (cultivar Okapi) was planted on September 25, 2009 following sunflower as a second crop. The experimental data was analysed as split plot based on randomized complete block design with three replications. Chuckling vetch (Lathrus sativus) was sown as a green manure on 21 April, 2009 and was ploughed and incorporated in the soil at full blooming stage on 6 June, 2009. Some plots were remained uncultivated as a fallow treatment. Sunflower was sown in all plots on 27 June, 2009. The main experimental treatments consisted of different crop sequences including green manure (chuckling vetch) -sunflower-forage rape and fallow-sunflower-forage rape. The cropping sequence treatments were assigned to the main plots. Different integrated fertilizing treatments consisted of zeoponics+25% chemical fertilizer (according to soil test), zeoponics+50% chemical fertilizer, zeoponics+75% chemical fertilizer and sole zeoponics (100%), were assigned as subplots. Harvesting was carried out during full blooming and early podding stage in which the glocozinolate concentration is in its least amount. After the harvest, the green forage yield was measured for each plot and samples were taken and dried in open air in shade. Dried samples were ground into powder and forage quality was determined by Near Infrared Reflectance Spectroscopy (NIRS). The obtained data showed that the application of sole organic fertilizer (zeoponix) and its integrated application with 25% of chemical fertilizer (urea) significantly increased the quantitative and qualitative yield of forage rape. Green manure and organic fertilizing system had a synegitic positive effect to increase the rape forage quality. However, integration of ¾ organic fertilizer rates with ¼ chemical fertilizers in fallow sequence can compensate the decline of biodiversity and produce the quality of forage with no significant difference. It can be recommended for the arid and semi-arid zones which frequently face water deficit and fallow is considered as an integrated part of cropping system to conserve moisture in the soil.
