Indonesia’s corn harvest area is decreasing so that corn production is also decreasing. The use of suboptimal land can be done to increase the harvested corn area by adding nutrients with organic fertilizers. One of the organic fertilizer ingredients is corn cob waste. The aim of the study was to examine the role of corn cob fertilizer on the growth, yield and nutrient uptake of corn. The study used a completely randomized block design with one fertilization factor with six levels, namely chemical fertilizers and corn cob organic fertilizer at a dose of 2.5, 5, 7.5, 10 or 12.5 tons/ha. Corn cob organic fertilizer has met the standard as an organic fertilizer with an organic C content of 62.21% and organic matter of 85.71%, ranking it in the high category. The total nitrogen is 1.44%, total phosphate is 1.43% and total potassium is 2.17%. Corn cob organic fertilizer had an effect on the leaf area index, root length, levels of chlorophyll a and chlorophyll b, weight of 100 seeds, cob diameter and phosphate uptake. Doses of 12.5 tons/ha produced the highest changes in chlorophyll a and b, root length and phosphate uptake. Phosphate and potassium uptake correlated with plant biomass and root length. Therefore, the results of the present study suggest that corn cob organic fertilizer is able to support the growth, yield and nutrient uptake of corn in sub-optimum land. Several gaps and research priorities in soil fertility have been identified, which need to be addressed in the future.

Background: Soybean production in Indonesia needs to be improved to fulfill 9.15% of its needs. This causes the level of soybean imports in Indonesia to be very high. Production imbalances and needs encourage the intensification of soybean cultivation. Intensification efforts are carried out with appropriate fertilization. Soybeans are a plant from the Leguminaceae family so that they can have a symbiotic relationship with many microorganisms, including rhizobium. This research examines the effect of nitrogen fertilizer and rhizobium on nodule growth and soybean yield. Methods: The method used was a two-factor factorial completely randomized design. The first factor is the dose of nitrogen fertilizer (0, 50, 100, and 150 kg.ha-1). The second factor was Rhizobium (control, inoculant, and soybean used soil). Data analysis was carried out by analysis of variance, if there is a significant difference, it was continued with Duncan's Multiple Range Test (DMRT) at the 5% level. Result: Nitrogen fertilizer reduces the number of effective root nodules. Still, it tends to increase the variables of plant height, number of leaves, root shoot ratio, plant biomass, number of pods per plant, and seed weight per plant. The optimum dose of nitrogen fertilizer to support soybean growth and yield is 95 kg.ha-1. Application of rhizobium can increase soybean yield. Application of rhizobium inoculation can increase the number of effective root nodules and seed weight per planting. The combination of nitrogen fertilizer and rhizobium inoculation can support the intensification of soybean cultivation in Indonesia.

Background: Indigofera tinctoria plays the role of a natural dye source that produces indigo color and contains the secondary metabolite indican which is highly responsive to light intensity. This study aims to examine the critical period for the formation of the secondary metabolite indican on light intensity. Methods: The method used was a completely randomized block design with a split-plot design. The study consisted of 2 treatment factors, namely: length of shade (main plot) and light intensity (subplot). The length of shade included 5 levels, namely early growth phase (up to 1 month after planting), mid-growth phase (up to 2 months after planting), maximum growth phase (up to 3 months after planting), 1 month before harvest and 2 months before harvest. Light intensity had 3 levels, namely 50% light intensity (38,464.3 lux), 25% (19,232.15 lux) and 10% (7,692.86 lux). Result: The combination of duration of shade and light intensity affected the growth, yield and content of secondary metabolites (indican) in Indigofera tinctoria. The highest number of leaves, plant fresh weight and biomass was found in the combination of shade in the early growth phase (up to 1 month after planting) with 50% light intensity. The highest indican production was found in the mid-growth shading (up to 2 months after planting) with 10% light intensity, which was 843.33 ppm. The critical period of shade to increase indican production along with the number of leaves was the mid-growth phase (up to 2 months after planting).

Local knowledge of a region is an asset that encourages the identification of a region. Hence, the specificity, uniqueness, and character that animates a particular city can distinguish it significantly from other cities. Sago tree fronds are widely applied to buildings as an alternative material for making tiles for roofs and other parts of buildings. The sago palm has long been used for making roofs and walls, especially in traditional houses. Few previous studies have used sago fronds as a manufacturing material for traditional houses. However, based on data in the field, many traditional houses still use sago fronds as a roof and wall framing material. This is also an effort to overcome the urban heat island phenomenon (UHI) in buildings. The UHI phenomenon is a phenomenon of urban development that highly affects environmental quality conditions and causes microclimate changes where air temperature conditions in urban areas are higher than the surrounding air temperatures. Sago midrib fiber is a natural composite material used as a reinforcing material for natural composite materials due to its thermal and mechanical properties. Composite materials using the hand lay-up technique—with characterization methods including the impact test and the DSC test, variations in $NaOH$ levels, and variations in the resin–catalyst matrix—were used in this study. The results obtained were then compared with those in the literature. The results showed that 6% $NaOH$ obtained the most significant impact value of 2.1 $J$, and the resin–catalyst matrix variation of 97.5%:2.5% obtained the most significant impact value, which was 2.4 $J$. Meanwhile, the DSC test results showed that the material’s best value for retaining heat was at 4% $NaOH$ content variation and a resin–catalyst matrix variation of 97.5%:2.5%.

Synthetic dyes can cause health and environmental impacts. Thus, there are opportunities to develop natural dyes, one of which is produced by Indigofera tinctoria plants. This plant is from Fabaceae that has the potential to produce a natural blue color. Natural dyes are extracted from the leaves of plants that contain indigo compounds. Indigo growth and precursors are very dependent on environmental conditions, one of which is light intensity. This study aimed to study the morphological and physiological plant responses in I. tinctoria to several levels of light intensity. The research was conducted in Puron Village, Sukoharjo, Indonesia with a complete randomized block design (RCBD) one factor, namely the level of light intensity (100 %, 50 %, and 25 %) with nine replications. Light intensity affected the morphology and physiology of I. tinctoria. Plants responded to low light intensity by increasing the leaf area index, specific leaf area and plant height. Leaf area, specific leaf area and plant height were highest at 25 % intensity. However, the number of leaves and nodes got greater at full light intensity. Higher light intensity increased the chlorophyll content a, b and total, thus, higher biomass yield which was 18.86 g at the age of 8 wk.