In the last few years, soil deterioration due to excessive application of synthetic agrochemical has become growing concern. Use of organic fertilizer is believed to be able to enhance soil quality. The objective of this experiment was to determine nitrogen, phosphorus, and potassium uptakes by sweet corn as affected by local based liquid organic fertilizer (LOF) under closed agriculture system. The experiment was conducted in Closed Agriculture Production System (CAPS) Research Station in Air Duku Village, Bengkulu, Indonesia from March to June 2015, employing Randomized Completely Block Design with 2 factors. The first factor was 3 sweet corn genotypes, i.e. Talenta, Jambore, and Asian Honey and the second factor was 5 rates of LOF, i.e. 0, 25, 50, 75, and 100 mg l-1 , respectively. Each treatment combination was replicated 3 times. Foliar application of LOF was carried out every week at 2-8 weeks after planting (WAP) with total volume of 600 ml per plant. Sweet corn leaves were sampled at the beginning of tassel emergence. The experiment revealed that sweet corn genotype significantly influenced the uptake of nitrogen, but not phosphorus and potassium. It was observed that Asian Honey genotype absorbed highest nitrogen as compared to other genotypes. In addition, increase in rates of LOF significantly raised nitrogen uptake by sweet corn, but not phosphorus and potassium.

In organic vegetable production, foliar fertilizer is often applied in conjunction with soil amended fertilizer to provide sufficient nutrients for the plant growth and development. Liquid organic fertilizer (LOF) was locally produced using Tithonia diversifolia to improve organically grown of carrot (Daucus carota L.). This experiment aimed to determine the effectiveness of tithonia-enriched LOF on organic carrot production was arranged in completely randomized block design with three replicates. Treatments comprised five levels (0, 25, 50, 75, and 100 ppm) of tithonia-enriched LOF concentrations, Results indicated that tithonia-enriched LOF did not significantly affect tuber length, tuber diameter, tuber fresh weight, shoot-tuber ratio, and number of tuber per plot. Future research should be focussed on the use of higher dosages of solid organic fertilizer and on application techniques of tithonia-enriched LOF.

Solid organic fertilizer is commonly applied for organic vegetable production in a closed agriculture production system as nutrient source. However, its availability is considered slow to sweet corn, and thus it is important to make additional nutrients supply as liquid organic fertilizer (LOF) through leaves. The experiments were conducted to compare effects of LOF application methods and to determine optimum LOF concentrations for sweet corn. Two separated factorial experiments, arranged in randomized complete block design with three replicates, were conducted from February to May and March to June 2015, respectively. The first factor was LOF application methods (soil and foliar) and the second factor was LOF concentration (0, 25, 50, 75, and 100 ppm). The observations focused on average weight of husked ear, length, weight and diameter un-husked ears. The results indicated that the effectiveness of soil application of LOF was 99.625 % as effective as foliar application in influencing sweet corn yields. Concentrations of LOF did not increase all observed variables, but yield attributes were within the range of variety description. It is concluded that in a closed production system, LOF application through soil is as effective as foliar application in affecting sweet corn yields.

Abstract-Solid organic fertilizing for organically sweet corn production should be combined with foliar application to improve fertilizing effectiveness. Each sweet corn variety had different response to particular liquid organic fertilizer (LOF). This experiment aimed to determine growth and yields of three sweet corn varieties to local-based LOF was conducted at CAPS research station (950 m above sea level) from March to June 2015, arranged in a factorial completely randomized block design with three replicates. The first factor was three sweet corn varieties, i.e. Talenta, Jambore and Asian Honey, and the second factor was five LOF concentrations, i.e. 0, 25, 50, 75, and 100 ppm, respectively. Results indicated that sweet corn varieties significantly affected plant height, plant leafarea, root fresh-weight, weight of husked ears, weight of unhusked ears, but did not affect diameter of unhusked ear and shoot freshweight. LOF concentrations did not affect all observed parameters. So did the interaction between varieties and LOF concentrations, except on shoot fresh-weight. Asian Honey variety had the highest plant height, plant leaf-area, roots fresh-weight, weight of hussked ears, and weight of unhusked ears. There were no different in plant diameter and shoot fresh weight among the tested varieties. Further research should be focused on the use of higher concentration of local-based LOF to provide effective complementary organic fertilizing in sweet corn production.

Solid organic fertilization in organic farming practices should be supplemented with liquid organic fertilizer to accelerate the availability of plant nutrients. The study aimed to determine performance and major nutrient uptake by sweet corn following application of vermicompost supplemented with liquid organic fertilizer (LOF) and to find out combined vermicompost and liquid organic fertilizer for sweet corn production. The experiment was conducted at CAPS Research Station (1054 m above sea level) from April to June 2016, arranged in split plot design with 5 rates of vermicompost as the main plot and 5 rates of LOF as the subplot. Rates of vermicompost comprised 5, 10, 15, 20, and 25 Mg ha-1 , while LOF rates consisted of control, 25, 50, 75, and 100% (initial concentration). Treatment combination was replicated 3 times. Root application of LOF was carried out every week at 2-8 weeks after planting (WAP) with total volume of 950 ml plant-1. Result pointed out that vermicompost pronouncedly raised nitrogen (N), phosphorus (P) and potassium (K) uptakes and linearly enhanced growth and yield of sweet corn, indicated by plant height, plant leaf area, shoot fresh and dry weight, weight of husked and unhusked ears, diameter of ear, and weight of husked ear per plot but length of ear. The addition of LOF had a similar effect on major nutrient uptake, growth, and yield of sweet corn. Vermicompost at the rate of 25 Mg ha-1 supplemented with 100% LOF provided greatest growth and yield, suggesting that the fertilizer combination was the most effective complementary organic fertilization for sweet corn production in the organic farming system.