R.D.B LEFROY
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MANAGEMENT OF PHOSPHORUS AND ORGANIC MATTER ON AN ACID SOIL IN JAMBI, INDONESIA D, SANTOSO; PURNOMO, J.; WIGENA, I GEDE PUTU; SUKRISTIYONUBOWO, .; LEFROY, R.D.B
Jurnal Tanah dan Iklim (Indonesian Soil and Climate Journal) No 18 (2000): Desember 2000
Publisher : Balai Besar Penelitian dan Pengembangan Sumberdaya Lahan Pertanian

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21082/jti.v0n18.2000.%p

Abstract

A field experiment was conducted at Pauh Menang village, Jambi province, to assess crop and soil response to P fertilization, compare inorganic and organic sources of P, and assess the interactions between these sources. The experiment employed an incomplete factorial combination of six levels of inorganic P (0, 19, 38, 57, 76 and 95 kg P ha-1 as SP-6), two organic matters (FYM and stylo), and lime, laid out in a randomized complete block design with four replicates. The experiment was carried out over four seasons, from rainy season 1997/1998 until dry season 1999, however, the second crop failed due to severe drought. Under limed conditions, application of SP-36 at 38-kg P ha-1crop-1 increased soil P content. Repeated application of SP-36 resulted in accumulation of residual P and built up the P status of the soil well above 100 mg P kg-1 soil. The application of SP-36 in combination with OM, stylo or FYM, did not produce higher Colwell P contents in the soil compared with application of inorganic P alone. Grain yields of all corn crops increased significantly from about 0.5 to 3.5 t ha-1 with application of inorganic P at about 57 kg P ha-1. The amount of P fertilizer required to obtain 85% relative yield decreased from about 62 to 40 to 28 kg P ha-1 for crop 1 to crop 3 and to crop 4, providing evidence of the residual effect of P fertilization. The direct use of RP at 42.6 kg P ha-1crop-1 was less effective than the readily soluble inorganic SP-36 at 38 kg P ha-1 crop-1. Liming increased and maintained corn grain yields significantly. Application of OM as FYM or stylo in combination with SP-36 or RP did not resulted in synergistic interactions, with greater increases in yields. The introduction of an erect and fast growing stylo, Stylosanthes guyanensis cultivar CIAT 184, in the cropping system offers a good opportunity to improve fertility of acid soils. The high biomass yield of stylo, ranging from 0.8 to 4.9 t ha-1 per cutting, can be fed directly to cattle or sun-dried, ground and mixed with other materials to enrich feed concentrate. Widespread adoption of this legume would enhance cattle rearing, which in turn would produce more FYM as a source of organic P fertilizer .
NUTRIENT BALANCE AND ECONOMIC ANALYSES OF P FERTILIZATION ON AN ACID UPLAND SOIL IN SUMATRA SANTOSO, DJOKO; WIGENA, I GEDE PUTU; LEFROY, R.D.B
Jurnal Tanah dan Iklim (Indonesian Soil and Climate Journal) No 19 (2001): Desember 2001
Publisher : Balai Besar Penelitian dan Pengembangan Sumberdaya Lahan Pertanian

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21082/jti.v0n19.2001.%p

Abstract

Soil and crop responses to P fertilization were assessed for seven seasons, from rainy season 1997/1998 until rainy season 2000/2001, in a field experiment at Pauh Menang village of Jambi province, Indonesia. An incomplete factorial combination of six levels of inorganic P (0, 19, 38, 57, 76 and 95 kg P ha-1 as SP-36), two sources organic matters (FYM and stylo), and lime, was laid out in a randomized complete block design with four replicates. The soil in this site was very P deficient and application of 38 kg P ha-1 increased corn yields significantly from less than 1.0 to about 3.5 t ha-1 for the first four crops. The higher rates of applied P didn?t increase further corn yields, indicating that external P requirement was fulfilled. A build-up and maintenance rate of banded application of SP-36,that required in this soil was 38 and 19 kg P ha-1, respectively. Broadcast application for the entire topsoil layer in a plot or farmland would require considerably larger amount of P fertilizer for building up of P level than the banded application. The balances of P treatments were all positive and substantiated by the increasing Colwell P content of the soil with increasing rate of applied P. Although no apparent symptom of Zn deficiency was observed, the Zn content in plant leaf decreased with increasing rate of applied P. By assuming all labour costs as cash costs in conducting economic analyses to calculate the B/C ratios, in general only the SP-36 treatments gave beneficial returns. Although many of the B/C ratios were less than 1.0, the amount of total benefits that could be earned by farmers were considerably high because the total production costs included all labour costs.