The Application of Rice Hull Mulch and Potassium Nitrate on Growth and Yield of Kailan (Brassica oleraceae var. Long Leaf) - Sri Ramadiana; Program Study of Agrotechnology, Faculty of Agriculture, University of Lampung, Jl. Sumantri Brojonegoro No. 1, Bandarlampung 35145 (UNIVERSITY OF LAMPUNG, 2011)