Abstract—Cattle manure and mineral fertilizers are two source of Nitrogen, which can affect the growth and quantity of potato. In this research the effects of the use of cattle manure (5, 10, 15 and 20 ton ha -1 ), Nitrogen fertilizer (50, 100 and 150 kg N ha -1 ) and their interaction on potato growth were evaluated during field experiments in 2008 with the help of Randomized Complete Block (RCB) with the factorial arrangement of three experimental replications in Iran. At the 75 th day after emergence, dry weight of Shoots, leaf area index (LAI) and plant height were recorded. Results showed that, dry weight of Shoots, LAI and plant height increased linearly and very significantly in response to the application of manure and Nitrogen fertilizer. While the interaction between manure and Nitrogen fertilizer just on the LAI and plant height was significant, somehow the maximum amount of plant height( 73 cm) was obtained by using 150 kg Nitrogen + 15 tons of manure per hectare, and maximum LAI ( 5.36) was obtained by using 150 kg Nitrogen + 20 tons of manure per hectare. Also in this experiment maximum tuber yield (36.8 tons ha -1 ) was obtained by the utilization of 150 kg Nitrogen per hectare + 20 tons manure. Keywords—Solanum tuberosum, LAI, cattle manure, mineral fertilizer, integrated management. I. INTRODUCTION IMITATION of Nitrogen can considerably reduce the growth of potato plant and the tuber yield. So that, for beneficial growth and maximum tuber yield, Nitrogen must be added in organic or inorganic form [16], [1], [2], [8], [30], [13]. Mineral Nitrogen fertilization can increase shoots weight, leaf area, plant height and subsequently total yield [9], [29], [20], [7], [27], [21], [28], [35], [18], [34]. While, the application of excessive Nitrogen leads to immoderate growth. This effect can encourage competition between the source and A. A. Najm is with the Young Researchers Club of Islamic Azad University Roudehen branch, and Faculty of Agriculture Islamic Azad M. R. Haj Seyed Hadi, is with the Faculty of Agriculture Islamic Azad University Roudehen branch(e-mail: mrhshadi@yahoo.com). F. Fazeli.is with the Faculty of Agriculture Islamic Azad University Roudehen branch (fazeli69@yahoo.com). M. T. Darzi. is with the Faculty of Agriculture Islamic Azad University Roudehen branch ( mt_darzi@yahoo.com). R. Shamorady. is with the Faculty of Agriculture Islamic Azad University Roudehen branch. sink, delayed maturity and subsequently can reduce the tuber yield [14], [18]. Also, excess Nitrogen has a negative effect on tuber quality and the environment [4], [13], [24]. These negative effects of chemical fertilizers have led nutrients management to the use of other Nitrogen sources, including organic fertilizers [22], [1], [5]. Organic fertilizers such as cattle manure, contain large amount of nutrients and influences plant growth and production via improving chemical, physical and biological fertility [31], [6], [3], [12]. Other researches showed that, LAI, shoots weight, plant height and tuber yield can be increased by application organic fertilization [25], [1], [2], But just a small amount of cattle- manure nutrients are initially available for plants use; thus it is required to application both Nitrogen fertilizers and cattle manure for optimum growth and maximum yields [19], [17], [32]. The purpose of this investigation was to determine changes in shoots dry matter, LAI, plant height ( at the75 th Day after emergence) and total tuber yield ( at the harvest) in Agria potato by the supply of Nitrogen fertilizer, cattle manure and the integrated management of both in Iran. II. MATERIALS AND METHODS The field experiment was laid out in the factorial arrangement based on Randomized Complete Block Design (RCBD) with three replications in April 2008 at the Agricultural Experiment Station of Azad University, Rudehen Branch, Tehran, Iran (35° 48’ N altitude, 52° 5’ E longitude and altitude of 1880 m above the sea level). The experimental soil was a clay loam with 1.95% organic carbon and pH 7.9. The P 2 O 5 (available), K 2 O (available), total Nitrogen, Mn, Fe, Zn and Cu contents were 25.2 ppm, 490 ppm, 0.167%, 11 mg kg -1 , 2.6 mg kg -1 , 1.1 mg kg -1 and 0.8 mg kg -1 , respectively (March, 2008). Treatments consisted of Nitrogen fertilizer of urea source in three levels (50, 100 and 150 Kg ha -1 ) and cattle manure in four levels (5, 10, 15 and 20 tons ha -1 ). Nitrogen fertilizer was supplied during three phases: planting, emergence and earting up. Cattle manure was analyzed before application and its entire rate was applied before plantation (Table I). Tuber seeds (Potatoes of Agria variety) were planted in the furrows of four rows with the depth of 15 cm, the intra-row spacing of 25 cm, and the inter-row spacing of 75 cm, on 28 st April 2008. Effect of Utilization of Organic and Inorganic Nitrogen Source on the Potato Shoots Dry Matter, Leaf Area Index and Plant Height, During Middle Stage of Growth A. A. Najm, M. R. Haj Seyed Hadi, F. Fazeli , M. Taghi Darzi , R. Shamorady L World Academy of Science, Engineering and Technology International Journal of Agricultural and Biosystems Engineering Vol:4, No:11, 2010 852 International Scholarly and Scientific Research & Innovation 4(11) 2010 scholar.waset.org/1307-6892/15448 International Science Index, Agricultural and Biosystems Engineering Vol:4, No:11, 2010 waset.org/Publication/15448 ; e-mail: amirali_najm@ yahoo.com). University Roudehen branch (corresponding author to provide