Adaptive variety and organic fertilizer are important components for rice cultural practices in a spesific agroecology. The research objectives were (1) to clarify the direct and the residual effect of manure on grain yield of rice, (2) to identify rice varieties most suitable for dry and for wet season planting. The research was conducted at Sukamandi Exp. Farm, West Java, during dry season (DS) of 2010 and wet season (WS) of 2010/2011, using a split-plot design with three replications. The main plots of DS experiment consisted of (1) recommended dosage of NPK (115 kg N + 50 kg P2O5 + 50 kg K2O/ha) and (2) 80% dosage of NPK + 5 t manure/ha. The WS experiment, main plots were (1) recommended NPK and (2) the residue of manure given in DS + 80% of the NPK. The subplots were fifteen improved varieties, each planted on plot 3.4 m x 5.4 m with 20 cm x 20 cm plant spacing. Data were collected for agronomic variables and grain yield. The DS 2010 experiment was attacked by brown planthopper (BPH), only two varieties, Inpari-8 and Inpari-13 were resistant, each yielded around 6 t/ha, while thirteen varieties were susceptible, yielded between 0.14 t to 3.9 t/ha. Application of 5 t manure/ha increased the averaged of biomass and grain yields by 9% and 10%, respectively, but were not consistent among varieties. In WS 2010/2011 experiment, the residual manure + 80% NPK decreased the averaged grain yield, but there was a significant interaction effect between fertilizer x variety. Seven varieties yielded less, six varieties yielded similar, and two varieties yielded more on the residual manure treatment, compared to that on no-manure treatment. Biomass weight, plant height, days to flowering, and days to harvesting, each was significantly correlated with grain yield. Five varieties were identified as suitable for WS planting, namely: Inpari-3, Inpari-10, Inpari-7, Ciherang, and Mekongga. When outbreak of BPH was suspected in the DS, Inpari-8 and Inpari-13 were suggested for planting. Suitable variety(ies) for season specific planting would optimize productivity, conversely, planting of unsuitable rice variety, during either DS or WS planting, would decreased the land production capacity.

There are many new rice varieties have been produced, introduced and breed at IRRI and the other National Agriculture Research Institutes that are tolerance to submergence condition to anticipate global warming and flash flooding around theworld. Among others are IR64-Sub 1, Suwarna-Sub 1, Inpara-1, Inpara-2, inpara-3 etc. However, those new varieties have not been tested widely yet, and the method of rice cultivation under submergence condition have not been adjusted, including the nutrient management.A greenhouse experiment was conducted at Muara Research Station, Bogor during 2008 dry season. The objectives of this experiment are (1) to study the effects of time of submergence and N application on plant growth and yield of  R64 and IR64-Sub 1 rice varieties; (2) to find the best nutrient management for submergence rice varieties. The experiment was conducted during 2008 dry season at greenhouse, Muara Research station, Bogor. The design of the  experiment was a Completely Randomized Factorial Design with three eplications. Factor 1 is rice variety (IR64 and IR64-Sub 1); Factor 2 is time of submergence (without submergence or control, submergence at vegetative phase (15 to 25 d.a.t), and at generative phase (35 to 45 d.a.t)). Factor 3 is N application, namely (F1) 300 kg Urea/ha 3x applications at 7 d.a.t- 30 d.a.t – 55 d.a.t; (F2) Mudball urea –300 kg Urea/ha applied once at 7 d.a.t. (F3) compost; and (F4) compost and urea; (F5) Urea and silikat.urea-N application at four time 0 d.a.t – 7 d.a.t – 30 d.a.t – 55 d.a.t (factor C). The results of experiments showed that submergence changes rice plant growth pattern (mainly tiller number and plant height), increased dry grain weight of IR64, namely 35.9 g at early vegetatif phase and 29.9 g at late vegetatif phase, while for IR64-Sub 1 32.6 g and 30.3 g at the same respective phase. Mudball urea and silicate application improved plant resistant to submergence and increase rice yield.

Soil amended with rice straw compost significantly reduced rice sheath blight severity. The disease caused by the fungus Rhizoctonia solani Kühn is a severe disturbance to rice cultivation in Indonesia. R. solani is soil borne fungi and highly competitive as saprophyte. In mature compost, R. solani propagules in the form of sclerotia germination were suppressed by hyperparasites and other biological control agents. Compost maturity level affects the ability of sclerotia to germinate. Initial inoculum reduction as sclerotia in steril soil was studied in glass house which is treated with the addition of variations in the maturity of the compost. Result showed that mature compost added to sterile soil in the pot decreased sclerotia germination for about 14%, otherwise fresh organic matter added to steril soil increased sclerotia germination, this condition lead R. solani grew and new sclerotia formed in the soil surface. The decomposition levels of organic matter influences disease development, it significantly affected on disease severity. Disease severity of rice sheath blight decreased by about 32.6-39.9 % with mature compost application.

Rainfed rice productivity in Indonesia is generally lower than irrigated paddy fields. The low productivity is likelihood caused by poor soil fertility and low rainfall during the dry season. This research aims to determine the role of controlled release fertilizer (CRF) and rice husk biochar (RHB) for the rice growth in two continuous seasons. The experiment was a randomized complete block design with three replicates and plot size was 5m x 6m. In wet season (WS), rice planted under direct seeded system. In dry season (DS), the rice was transplanted from seed bed. RHB rates were 0, 5, 10 t ha−1, and CRF Urea (42% N) rates were 0, 50 and 100 % of recommended dosage or equal to 0;142.5; 285 kg/ha respectively. As a positive control was 100 % dosage of recommended NPK fertilizers, namely: urea (45% N) 266 kg/ha, SP36 125 kg/ha and KCl 100 kg/ha. Agronomic traits such as plant height, tiller number, leaf greenness under DS and WS increase significantly as treated with a combination of RHB and CRF, while the distribution of roots and N uptake only increases under DS as such. Optimal plant growth and N uptake in rainfed rice were obtained at treatment of 5 t ha−1 RHB and 50% CRF. Therefore, the dosage is recommendable for developing rice production in rainfed areas both in the dry and wet season.

Plant spacing pattern may increase grain yield of rice through the manipulation of plant population. Double rows legowo is one method to manipulate population to increase yield. However, high plant population with dense plants is risky to logging during the wet season. The purpose of this research was to evaluate the effect of plant spacing pattern and seedling age on the growth and grain yield of rice. The research was conducted at Sukamandi research station for 2 seasons, dry season of 2015 and wet season of 2015/ 2016, using a split plot design. The main plots were plant spacing pattern: square pattern; double rows legowo 2:1, and double rows legowo 4:1. Seedling ages were the sub plot. The variables observed were plant height, number of tiller, yield components, and grain yield. Results showed that seedling ages and plant spacing patterns significantly affected yield components and grain yield. Planting the 20 days old seedling yielded higher grain yield than did 30 days old seedling. Dry season yield was higher compared to that of wet season. The yield of double rows legowo 2:1 in dry season was higher (7.69 t/ha dry grain) compared to that of double rows legowo 4:1 and square spacing (6.77 t/ha dry grain). However, plant spacing pattern did not significantly affect the grain yield in wet season.