The effectiveness of time and kind of rock phosphate application in a plinthic kandiudults soil
1998
Karno, A. | Adiningsih, J.R. | Moersidi, S. (Pusat Penelitian Tanah dan Agroklimat, Bogor (Indonesia))
Fertilizers are important to increase crop production. Actually, SP-36 fertilizars were difficult to obtain in the field partly due to their high price. On the other hand, rock phosphate was in slow release fertilizer, fairly effective, relatively cheap and easily available in the field. The objective of this research was to study the effectiveness of rock phosphate and the effect of its residue on crop growth and production. The research was carried out in a Plinthic Kandiudults, North Lampung, during WS 1996/97 to WS 1997/98. Yearly cropping pattern was corn, soybean and cowpea with monoculture planting system. The experimental design was randomized complete block with 12 treatments and 3 replications. The treatments were combination of application time and type of rock phosphate. Rock phosphate was applied (1) yearly, (2) once, at the first season, and (3) twice, at the first and seventh seasons. Rock phosphate types used were Christmas Island, Ciamis and Tunisia. SP 36 was used for comparison. All treatments were incorporated with 5 tons of cattle's farmyard, except for 3P-36 treatment. The result showed that Fe and Al contents of Christmas Island rock phosphate did not influence its effectiveness. Christmas Island rock phosphate gave the lowest increase in P availability of the soil. Cattle manure application increased the availability of the soil P. The optimum contents of soil available P were 22 mg/kg for the crops in the first year, and 24 mg/kg P for corn and 15 mg/kg P for both soybean and cowpea in the second year. The dose of 160-kg P2O5/ha was the applicable dose, its residu was effective until the fifth season. In the first season, rock phosphates gave lower effectiveness than SP-36 but in the next season rock phosphate gave higher effectiveness. The second application of rock phosphate is proposed at the sixth season
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