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392 Subandi, A.F. Fadhly and £.0. MomuatTable 6.Direct effect of four P sources and their residual effect to maize yield on Ultisol inKotabumi, North Lampung, Sumatra (Sri Adiningsih et aI., 1997)Maize yield (ton/ha)P sourceWet season 1995/96 Wet season 1996/97SP-36*) 4.464.80ChPR 3.783.34CPR 4.345.45TPR 4.385.77No P 2.231.77*) Superphosphate = phosphate fertilizer containing 36% P 2 0 SIn Indonesia, the price of phosphate rock is cheaper than TSP or SP-36. The price of one kgP 2 0 S of TSP, SP-36, and phosphate rocks in 1997 was RP. 1,333, Rp. 1,667, and Rp. 733,respectively (Sri Adiningsih et aI., 1997).On rainfed lowland in Ngawi (East Java) with Vertisol soil containing low K, the residue of Kfertilizer (KCI) applied on rice significantly affected maize crops planted after rice (Tabel 7).Table 7.Direct and residual effect of K fertilizer (KCI) to maize yield of maize-rice croppingpattern on rainfed lowland in Ngawi (East Java)*(Suyamto and Sumarno, 1992)Nutrients ManagementKCI applied on riceKCI applied on maize (kg/ha)(kg/ha) 0 50 100 150o 2.35 3.83 3.86 3.6450 2.27 3.72 3.51 3.73100 3.76 3.12 3.49 3.67ISO 3.77 3.16 3.16 4.69" The soil belongs to Vertisol, with exchangeable K of 0.28 me/IOO g soilPrincipally, nutrient management efforts are to :I) increase the availability of nutrients appliedto and in the soil, and 2) to ensure the continuity of nutrient absorption by plants in adequateamount. To do these, specific actions should be done are:- suppress the loss of nutrients from the soil- reduce nutrient transformation from available forms to unavailable one, or vice versa- enhance nutrient mobility to the root surface- promote the growth of roots- ensure the nutrient supply in appropriate time and in adequate amount to match the plantrequirementAppropriate Time and Method ofFertilizer ApplicationTime and method of fertilizer application highly affect the fertilization efficiency. Inappropriatetime and method of fertilizer application were the important reason resulting in the low efficiency offertilization in several maize production areas in East Java (Supandi and Soepangat, 1986; Dahlan etal., 1987; Ispandi and Prayitno. 1989). Most of the farmers were late in applying N fertilizer (urea).They applied two times, at 15-20 days after planting (50%), and 35-42 days after planting (50%)(Dahlan et al.. 1987; Suyamto et al., 1994). Method of urea application was found in threealternatives i.e. urea placed in dibbled hole and covered with soil, placed in dibbled hole and not