(Bogor, Indonesia). 4 Non-Member, State Agriculture Polytechnic of Kupang (West Timor, East Nusa Tenggara, Indonesia) Accurate rainfall predictions, especially for tropical monsoonal rainfall, are among the most difficult tasks in hydrology. In this article, we discuss ANN-based long-term rainfall predictions for Oekabiti, West Timor, Indonesia. Due to the remoteness of the area, the only information available is historical rainfall data. However, by basing on previous studies into the time lag relationship between the El Niño Southern Oscillation (ENSO) and Indonesian rainfall, we utilized Sea Surface Temperature Anomaly (SSTA) Zone Niño 3.4 and the Southern Oscillation Index (SOI) to improve accuracy levels of rainfall prediction models efficiently. During our model development, it was revealed that rainfall fluctuation is more influenced by the lag 0 to lag -1 of the SOI than by the SSTA. We also found that the resulting models could dynamically predict long-term rainfall, but tended to underestimate some extreme values, which limited their utility for irrigation management planning.

This study aimed to estimate wherewith the residual effect of the crop rotation pattern with the cover crop lagoon on the dynamics of soil organic carbon and maize yield during the two growing seasons in the Kupang region of Indonesia. The treatments evaluated were: maize rotation pattern with several types of seasonal legume cover crops and how to return the legume biomass. The results showed a very significant increase in soil organic carbon and maize yield. The rotation pattern with legumes P. lunatus, M. pririens and C. juncea had a statistically significant effect on increasing soil organic carbon storage and maize yield during the two growing seasons. These three types of legumes still have a positive effect until the second planting season where there is an increase in soil organic carbon storage (at a depth of 0-30 cm) of 0.75-1.19 % C-organic (82.08 to 84.38 t.ha-1 soil carbon storage) compared to C.chayan and control treatment which decreased soil organic carbon storage was greater. About maize yields, up to PS- 2 still showed relatively stable results, namely only a decrease in maize yield (kg.ha-1) of 3.14% -4.19% compared to C. chayan which decreased yields of 15% and without control rotation ) with a reduction in yield of up to 30% . The method of restoring the cover crop legume biomass with the mulching technique was able to increase soil organic carbon storage by 0.71%, and the yield of dry shelled maize (kg.ha-1) on PS-2 only decreased yield by 2.48% compared to the immersion method which reduced the yield up to 11, 02%. This study found that the rotation pattern does not need to be done every planting season. Still, it is sufficient to do it in intervals of two to three growing seasons. The residual effect can significantly guarantee the maintenance of organic carbon stocks in the soil. With the assurance of soil organic carbon stores coupled with proper management, soil productivity is maintained and sustainable. When soil organic carbon increases, it can benefit maize and other food crops.

This study aims to determine the effect of corn cobs and rice husk biochar on Vertisol chemical properties from Kupang Regency, East Nusa Tenggara. This study used a completely randomized design with two factors and three replications. The first factor is the type of biochar which consists of biochar of corn cobs and rice husks. The second factor is the dose of biochar (% soil weight), consisting of 4 levels: 1.5%, 3%, 4.5%, and 6%, and incubated for two months. Chemical properties observed in this study included pH, C-organic, and soil cation exchange capacity (CEC). The results showed that giving biochar of corn cobs and rice husks did not significantly affect changes in soil chemical properties.