Alfisols have inherent potential to increase Indonesia’s soybean production, however, alfisols also known for its low phosphorus availability. Field experiment using ameliorants consisting of quail manure, zeolites and rock phosphate was conducted to increase phosphorus (P) availability and soybean production. The aim of this study is to evaluate the effects of ameliorant combinations for improving phosphorus availability and its correlation to soybean production in alfisols. Randomized complete block design with single factor was used, with 9 combinations of ameliorants under study (P0 – P8). Obtained results showed that phosphorus availability is increased up to 72.6% and soybean yield upto 75.9%. Correlation of phosphorus availability and soybean production was significant (r = 0.854). Finally, the best treatment to increase phosphorus availability and soybean production is quail manure 2.5 t.ha-1 + rock phosphate 5 t.ha-1).

Soybean production in Indonesia could be improved by utilizing Alfisols as potential land. Zeolites and manure are used in this study as slow release materials to reduce nitrogen losses from soil. The aim of this research is reviewing the effect of zeolites and manure in improving N total contents, N absorption, and growth and production of soybean in Alfisols. Factorial randomized complete block designed of two factors (zeolite doses; 0 ton / ha, 2.5 ton / ha, and 5 ton / ha, and type of manure; P0: 0 ton / ha, P1: cow manure, P2: quail manure) were used and field experiments were conducted in this study. Obtained results showing zeolite with dose of 5 ton/ha gave the highest influence indicated by the increase of N total 35.13% and the increase of N absorption up to 53.37%. Cow manure gave the highest efficiency with total N increase of 40.54% and an increase in N absorption of 48.93%. Zeolite 5 ton/ha with cow manure gave the highest yield with an increase of total pod content 129.41%, and the increase of seed weight 35.39 %. Finally, zeolite treatment with cow manure at dose 5 ton/ha is the best treatment in this research.

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